JP6311820B2 - Epoxy resin composition, semi-cured epoxy resin composition, cured epoxy resin composition, resin sheet, prepreg, laminate, metal substrate, wiring board, method for producing semi-cured epoxy resin composition, and method for producing cured epoxy resin composition - Google Patents

Description

  The present invention relates to an epoxy resin composition, a semi-cured epoxy resin composition, a cured epoxy resin composition, a resin sheet, a prepreg, a laminate, a metal substrate, a wiring board, a method for producing a semi-cured epoxy resin composition, and a cured epoxy resin composition. The present invention relates to a method for manufacturing a product.

  Many electronic devices and electric devices ranging from generators and motors to printed wiring boards and IC chips are configured to include a conductor for conducting electricity and an insulating material. In recent years, since the amount of heat generation has increased with the miniaturization of these devices, how to dissipate heat in insulating materials has become an important issue.

  As an insulating material used in these devices, a cured resin product made of a thermosetting resin composition is widely used from the viewpoints of insulation and heat resistance. However, since the thermal conductivity of the cured resin is generally low and is a major factor hindering heat dissipation, development of a cured resin having high thermal conductivity is desired.

  As a cured resin having high thermal conductivity, a cured product of an epoxy resin composition having a mesogen skeleton in the molecular structure has been proposed (see, for example, Japanese Patent No. 4118691). Examples of the epoxy resin having a mesogen skeleton in the molecular structure include compounds disclosed in Japanese Patent No. 4619770, Japanese Patent Application Laid-Open No. 2011-74366, Japanese Patent Application Laid-Open No. 2011-84557, and the like.

  Further, as a technique for achieving high thermal conductivity of a cured resin product, there is a method of filling a resin composition with a thermal conductive filler made of high thermal conductive ceramic to form a composite material. As high thermal conductive ceramics, alumina, boron nitride, aluminum nitride, silica, silicon nitride, magnesium oxide, silicon carbide and the like are known. By filling the resin composition with a heat conductive filler that achieves both high thermal conductivity and electrical insulation, the composite material can achieve both high thermal conductivity and electrical insulation.

  In relation to the above, a resin composition containing a so-called mesogen skeleton-containing epoxy resin having a biphenyl skeleton, a phenol resin, and spherical alumina as essential components has been disclosed (see, for example, Japanese Patent No. 2874089), and a semiconductor encapsulation excellent in high thermal conductivity is disclosed. It is reported that it is a resin composition for stopping. Also disclosed is a resin composition containing an epoxy resin having a biphenyl skeleton, a curing agent having a xanthene skeleton, and an inorganic filler (see, for example, JP-A-2007-262398). It is said that there is. Furthermore, a resin composition containing a tricyclic mesogen skeleton-containing epoxy resin, a curing agent, and alumina powder is disclosed (for example, see JP-A-2008-13759), and has a high thermal conductivity and excellent workability. Has been.

Epoxy resin monomers having a mesogen skeleton in the molecular structure are known as thermosetting resins having high thermal conductivity, but the high thermal conductivity of the cured resin obtained by the combined curing agent varies greatly. The epoxy resin monomer forms a high-order structure having high orderness, which contributes to high thermal conductivity. However, depending on the curing agent to be combined, a high-order structure cannot be formed, and high thermal conductivity cannot be obtained. . That is, in order to obtain a cured resin having high thermal conductivity, it is important to select both the thermosetting resin and the curing agent.
On the other hand, in addition to high thermal conductivity, high heat resistance has recently been demanded for insulating materials for heat dissipation applications.

  Under such circumstances, various combinations of epoxy resin monomers and curing agents have been studied. However, no resin composition that sufficiently satisfies both thermal conductivity and heat resistance has been reported so far, including the resin compositions disclosed in the above-mentioned known documents.

  In view of the above problems, the present invention provides an epoxy resin composition, a semi-cured epoxy resin composition and a cured epoxy resin composition that can form a cured product having high thermal conductivity and high heat resistance, and a method for producing the same. Is an issue. It is another object of the present invention to provide a resin sheet, a prepreg, a laminate, a metal substrate, and a wiring board that are configured using the epoxy resin composition and have high thermal conductivity and high heat resistance.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention includes the following aspects.
<1> An epoxy resin composition containing an epoxy resin monomer represented by the following general formula (I), a curing agent containing a novolak resin obtained by novolacizing a divalent phenol compound, and an alumina filler containing α-alumina. It is a thing.

In general formula (I), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently.

<2> The curing agent is a novolak resin containing a compound having a structural unit represented by at least one selected from the group consisting of the following general formulas (II-1) and (II-2) <1> It is an epoxy resin composition as described in above.

In general formulas (II-1) and (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. R ²² , R ²³ , R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. m21 and m22 each independently represent an integer of 0-2. n21 and n22 each independently represent an integer of 1 to 7.

<3> The <1>, wherein the curing agent is a novolak resin including a compound having a structure represented by at least one selected from the group consisting of the following general formulas (III-1) to (III-4): It is an epoxy resin composition of description.

In general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar ^{31 to} Ar ³⁴ each independently represent either a group represented by the following general formula (III-a) or a group represented by the following general formula (III-b).

In the general formulas (III-a) and (III-b), R ³¹ and R ³⁴ each independently represent a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<4> The epoxy resin composition according to any one of <1> to <3>, in which the curing agent has a monomer content of 5% by mass to 80% by mass, which is a phenol compound constituting the novolak resin. It is a thing.

<5> The epoxy resin composition according to any one of <1> to <4>, wherein the content of the alumina filler is 60% by volume to 90% by volume in the entire volume.

<6> The epoxy resin composition according to any one of <1> to <5>, further comprising an elastomer having a structural unit represented by the following general formula (IV).

In the general formula (IV), R ⁴¹ , R ⁴² and R ⁴³ each independently represent a linear or branched alkyl group or a hydrogen atom. R ⁴⁴ represents a linear or branched alkyl group. n4 represents an arbitrary integer.

  The said elastomer is an epoxy resin composition as described in <6> containing the acrylic elastomer containing the structural unit represented by the following general formula (V).

In general formula (V), a, b, c, and d show the mol% of each structural unit in all the structural units, and are a + b + c + d = 90 mol% or more. R ⁵¹ and R ⁵² each independently represent a linear or branched alkyl group having a different carbon number. R ^{53 to} R ⁵⁶ each independently represent a hydrogen atom or a methyl group.

<8> A semi-cured epoxy resin composition which is a semi-cured product of the epoxy resin composition according to any one of <1> to <7>.

<9> A cured epoxy resin composition that is a cured product of the epoxy resin composition according to any one of <1> to <7>.

<10> A resin sheet that is a sheet-like molded body of the epoxy resin composition according to any one of <1> to <7>.

The prepreg which has a <11> fiber base material and the epoxy resin composition as described in any one of <1>-<7> impregnated in the said fiber base material.

<12> An adherend, an epoxy resin composition according to any one of <1> to <7>, a resin sheet according to <10>, and <11>, which is disposed on the adherend. A laminate having a semi-cured epoxy resin composition layer that is at least one semi-cured material selected from the group consisting of the prepregs described in 1. or a cured epoxy resin composition layer that is a cured material.

It is selected from the group consisting of <13> metal foil, the epoxy resin composition according to any one of <1> to <7>, the resin sheet according to <10>, and the prepreg according to <11>. A metal substrate in which a cured epoxy resin composition layer, which is at least one cured body, and a metal plate are laminated in this order.

It is selected from the group consisting of <14> a metal plate, the epoxy resin composition according to any one of <1> to <7>, the resin sheet according to <10>, and the prepreg according to <11>. A wiring board in which a cured epoxy resin composition layer, which is at least one cured body, and a wiring layer are laminated in this order.

<15> An epoxy resin monomer containing an epoxy resin monomer represented by the following general formula (I), a curing agent containing a novolak resin obtained by novolacizing a divalent phenol compound, and an alumina filler containing α-alumina. A method for producing a semi-cured epoxy resin composition comprising a step of forming an epoxy resin layer on a material and a step of heat-treating the epoxy resin layer to form a semi-cured epoxy resin layer.

In general formula (I), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently.

<16> The curing agent is a novolak resin including a compound having a structural unit represented by at least one selected from the group consisting of the following general formulas (II-1) and (II-2) <15> The manufacturing method of the semi-hardened epoxy resin composition as described in any one of.

In general formulas (II-1) and (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. R ²² , R ²³ , R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. m21 and m22 each independently represent an integer of 0-2. n21 and n22 each independently represent an integer of 1 to 7.

<17> The <15>, wherein the curing agent is a novolak resin including a compound having a structure represented by at least one selected from the group consisting of the following general formulas (III-1) to (III-4): It is a manufacturing method of the semi-hardened epoxy resin composition of description.

In general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar ^{31 to} Ar ³⁴ each independently represent either a group represented by the following general formula (III-a) or a group represented by the following general formula (III-b).

In the general formulas (III-a) and (III-b), R ³¹ and R ³⁴ each independently represent a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<18> An epoxy resin monomer containing an epoxy resin monomer represented by the following general formula (I), a curing agent containing a novolak resin obtained by novolacizing a divalent phenol compound, and an alumina filler containing α-alumina. A step of forming an epoxy resin layer on the material, a step of heat-treating the epoxy resin layer to form a semi-cured epoxy resin layer, a heat-treated epoxy resin layer of the semi-cured epoxy resin layer, and a cured epoxy resin layer A process for producing a cured epoxy resin composition.

In general formula (I), R < ¹ > -R < ⁴ > shows a hydrogen atom or a C1-C3 alkyl group each independently.

<19> The curing agent is a novolak resin including a compound having a structural unit represented by at least one selected from the group consisting of the following general formulas (II-1) and (II-2) <18> It is a manufacturing method of the cured epoxy resin composition as described in above.

In general formulas (II-1) and (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. R ²² , R ²³ , R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. m21 and m22 each independently represent an integer of 0-2. n21 and n22 each independently represent an integer of 1 to 7.

<20> The <18>, wherein the curing agent is a novolak resin including a compound having a structure represented by at least one selected from the group consisting of the following general formulas (III-1) to (III-4): It is a manufacturing method of described hardening epoxy resin composition.

In general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar ^{31 to} Ar ³⁴ each independently represent either a group represented by the following general formula (III-a) or a group represented by the following general formula (III-b).

In the general formulas (III-a) and (III-b), R ³¹ and R ³⁴ each independently represent a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

<21> <1> to <7> disposed between the semiconductor module in which the metal plate, the solder layer, and the semiconductor chip are laminated in this order, the heat dissipation member, and the metal plate and the heat dissipation member of the semiconductor module. And a cured product of the epoxy resin composition according to any one of the above.

  ADVANTAGE OF THE INVENTION According to this invention, the epoxy resin composition which can form the hardened | cured material which has high heat conductivity and high heat resistance, a semi-hardened epoxy resin composition, a hardened epoxy resin composition, and its manufacturing method can be provided. In addition, a resin sheet, a prepreg, a laminate, a metal substrate, and a wiring board that are configured using the epoxy resin composition and have high thermal conductivity and high heat resistance can be provided.

It is a schematic sectional drawing which shows an example of a structure of the power semiconductor device comprised using the resin sheet concerning this invention. It is a schematic sectional drawing which shows another example of a structure of the power semiconductor device comprised using the resin sheet concerning this invention.

  In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes. . Moreover, the numerical range shown using "to" shows the range which includes the numerical value described before and behind "to" as a minimum value and a maximum value, respectively. Furthermore, the amount of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.

<Epoxy resin composition>
The epoxy resin composition of the present invention contains an epoxy resin monomer represented by the following general formula (I), a curing agent containing a resin obtained by novolacizing a divalent phenol compound, and an alumina filler containing α-alumina. To do. The epoxy resin composition may further contain other components as necessary.
With this configuration, the epoxy resin composition of the present invention can exhibit excellent high thermal conductivity and high heat resistance after curing. Furthermore, the epoxy resin composition of the present invention exhibits excellent moldability.

In said general formula (I), R < ¹ > -R < ⁴ > represents a hydrogen atom or a C1-C3 alkyl group each independently.

  The epoxy resin monomer represented by the general formula (I) is an epoxy resin monomer having a mesogenic group in the molecular structure. It is described in Japanese Patent No. 4118691 that a cured product of an epoxy resin monomer having a mesogenic group in the molecular structure is excellent in thermal conductivity. However, by combining the epoxy resin monomer represented by the general formula (I) with a novolak resin in which a divalent phenol compound is novolaked, the heat of the cured epoxy resin composition cannot be predicted from the description of Japanese Patent No. 4118691. Conductivity is improved and heat resistance is also improved. This is considered to be because, for example, a very high-density crosslink is formed in the cured product composed of the epoxy resin monomer and the novolak resin. Generally, when the crosslink density is high, the glass transition temperature (Tg) of the cured body is increased, and when the Tg of the cured body is increased, the thermal conductivity and heat resistance tend to be improved.

  Here, the mesogenic group refers to a functional group that facilitates the expression of crystallinity or liquid crystallinity by the action of intermolecular interaction. Specific examples include a biphenyl group, a phenylbenzoate group, an azobenzene group, a stilbene group, and derivatives thereof. The epoxy resin monomer represented by the general formula (I) is also a kind of epoxy resin monomer having a mesogenic group in the molecular structure.

  In addition, the present inventors have formed a higher order structure having higher ordering around the α-alumina filler, the epoxy resin monomer represented by the general formula (I) having a mesogenic group in the molecular structure, It has been found that the thermal conductivity of the cured product is dramatically improved. That is, since the cured product of the epoxy resin monomer serves as a heat conduction path between the α-alumina fillers, higher heat conductivity can be achieved. Also in the cured epoxy resin composition obtained by curing the epoxy resin composition of the present invention, the epoxy resin monomer represented by the general formula (I) forms a higher-order structure having higher orderness centering on the α-alumina filler. Demonstrates excellent thermal conductivity.

Here, the higher order structure means a structure including a higher order structure in which the constituent elements are arranged to form a micro ordered structure, and corresponds to, for example, a crystal phase or a liquid crystal phase. The presence confirmation of such a higher-order structure can be easily determined by observation with a polarizing microscope. In other words, in the observation in the crossed Nicols state, it can be determined by seeing interference fringes due to depolarization.
This higher-order structure usually exists in an island shape in the cured epoxy resin composition to form a domain structure, and one of the islands corresponds to one higher-order structure. The constituent elements of this higher order structure are generally formed by covalent bonds.

In addition, presence of the higher order structure in the cured epoxy resin composition containing an α-alumina filler can be confirmed as follows.
Cured body (thickness: composition) obtained by adding 5% by volume to 10% by volume of α-alumina filler to the epoxy resin monomer represented by formula (I) having a mesogenic group in the molecular structure and the curing agent 0.1 μm to 20 μm) is prepared. Observation is performed using a polarizing microscope (for example, Olympus BX51) in a state where the obtained cured body is sandwiched between slide glasses (thickness: about 1 mm). An interference pattern is observed around the α-alumina filler in the region where the α-alumina filler is present, but no interference pattern is observed in the region where the α-alumina filler is not present. From this, it can be seen that the cured product of the epoxy resin monomer represented by the general formula (I) centering on the α-alumina filler forms a higher order structure.

  Note that the observation needs to be performed not in the crossed Nicols state but in a state where the analyzer is rotated by 60 ° with respect to the polarizer. When observed in a crossed Nicol state, a region where no interference pattern is observed (that is, a region where the cured resin body does not form a higher order structure) becomes a dark field, and cannot be distinguished from the α-alumina filler portion. However, by rotating the analyzer by 60 ° with respect to the polarizer, the region where no interference pattern is observed is not a dark field, and can be distinguished from the alumina filler portion.

In a cured product that does not contain an alumina filler and is composed only of a resin and a curing agent, the resin forms a higher-order structure depending on whether an interference pattern is observed or a dark field is observed in observation in a crossed Nicol state. It can be determined whether or not.
On the other hand, in a cured body containing an alumina filler, when observed in a crossed Nicol state, the dark field region where no interference pattern is observed is because the resin does not form a higher order structure. It is impossible to determine whether it is a thing. Therefore, it is necessary to observe the analyzer with the analyzer rotated by 60 ° with respect to the polarizer. The alumina filler becomes a dark field regardless of the angle between the polarizer and the analyzer, but the portion where the resin does not form a higher order structure is observed with the analyzer rotated 60 ° relative to the polarizer. It is not a dark field, but a little light is transmitted and it looks bright. That is, it is possible to distinguish between a portion where the resin does not form a higher order structure and one derived from an alumina filler.

In other words, a combination of an epoxy resin monomer represented by the above general formula (I), a resin in which a divalent phenol compound is novolakized, and an α-alumina filler makes it possible to cure with high thermal conductivity and high heat resistance. An epoxy resin composition capable of forming a body is obtained.
In addition, a resin sheet and a prepreg configured using the epoxy resin composition, and further, a laminated board, a metal substrate, and a wiring board provided with an insulating layer obtained by curing the epoxy resin composition have higher thermal conductivity and higher Demonstrate heat resistance.
Hereinafter, the material used for the epoxy resin composition and the physical properties of the epoxy resin composition will be described.

(Epoxy resin monomer)
The said epoxy resin composition contains at least 1 sort (s) of the epoxy resin monomer represented by the following general formula (I).

  The epoxy resin monomer represented by the general formula (I) tends to form a higher order structure having higher ordering with α-alumina as the center. As a result, the thermal conductivity after curing tends to improve dramatically. It is considered that the cured product of the epoxy resin having a higher order structure formed by the presence of α-alumina becomes an efficient heat conduction path, and high heat conductivity is obtained.

  The epoxy resin monomer represented by the general formula (I) has a transition temperature to the liquid crystal phase, that is, a melting temperature as high as 150 ° C. Therefore, when the epoxy resin monomer is to be melted, the curing reaction generally proceeds simultaneously with melting, depending on the curing agent and the curing catalyst used. As a result, the epoxy resin monomer becomes a cured body before forming a higher order structure. However, in a system containing α-alumina, a cured product in which the epoxy resin monomer forms a higher order structure tends to be obtained even when heated at a high temperature.

  This is presumably because the higher-order structure formation effect of the epoxy resin monomer by using α-alumina is remarkable. That is, it is considered that a higher-order structure is quickly formed around the α-alumina before the curing reaction of the epoxy resin monomer proceeds.

  Furthermore, the epoxy resin monomer represented by the general formula (I) can exhibit only a nematic structure with the epoxy resin monomer alone. For this reason, it is relatively difficult to form a higher order structure in an epoxy resin monomer having a mesogenic group in the molecular structure. However, by using a composite material combined with an alumina filler containing α-alumina, the epoxy resin monomer represented by the general formula (I) exhibits a smectic structure having a higher order than a nematic structure. As a result, the thermal conductivity is unpredictably high from a cured product composed of a single epoxy resin monomer.

  Note that each of the nematic structure and the smectic structure is a kind of liquid crystal structure. The nematic structure is a liquid crystal structure in which the molecular long axis is oriented in a uniform direction and has only alignment order. On the other hand, the smectic structure is a liquid crystal structure having a one-dimensional positional order in addition to the orientation order and having a layer structure. The order is higher in the smectic structure than in the nematic structure. For this reason, the thermal conductivity of the cured resin is also higher when it exhibits a smectic structure.

In the general formula (I), R ^{1 to} R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, It is more preferably an atom or a methyl group, and further preferably a hydrogen atom.
Further, 2 to ⁴ of R ^{1 to} R ⁴ are preferably hydrogen atoms, 3 or 4 are preferably hydrogen atoms, and all 4 are preferably hydrogen atoms. When any of R ^{1 to} R ⁴ is an alkyl group having 1 to 3 carbon atoms, at least one of R ¹ and R ⁴ is preferably an alkyl group having 1 to 3 carbon atoms.

  In addition, as a preferable form of the said epoxy resin monomer, it is as having described in Unexamined-Japanese-Patent No. 2011-74366. Specifically, the epoxy resin monomer includes 4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl-4- (2,3-epoxypropoxy) benzoate and 4- {4- (2,3- Epoxypropoxy) phenyl} cyclohexyl-4- (2,3-epoxypropoxy) -3-methylbenzoate is preferred.

  The epoxy resin monomer may be used as a prepolymer obtained by partially reacting the epoxy resin monomer with a curing agent described later. Epoxy resin monomers having a mesogenic group in the molecular structure are generally easily crystallized, and the solubility in solvents is often lower than that of general epoxy resin monomers. The epoxy resin monomer represented by the general formula (I) also corresponds to this. However, since the crystallization can be suppressed by partially polymerizing the epoxy resin monomer represented by the general formula (I), the solubility in a solvent is improved, and the moldability may be further improved.

The epoxy resin monomer is preferably contained in an amount of 10% by volume to 40% by volume in the total volume of the total solid content of the epoxy resin composition from the viewpoint of moldability, adhesiveness, and thermal conductivity, and 15% by volume. More preferably, it is contained at ˜35% by volume, and further preferably contained at 15% by volume to 30% by volume.
In addition, when the said epoxy resin composition contains the below-mentioned hardening | curing agent or hardening accelerator, the content rate of these hardening | curing agents and hardening accelerator is included in the content rate of an epoxy resin monomer here unless there is particular notice. And

  In addition, let the content rate (volume%) of the epoxy resin monomer containing the hardening | curing agent and hardening accelerator in this specification be the value calculated | required by following Formula. Hereinafter, the content rate (volume%) of the material used for the epoxy resin composition is a value obtained based on this method.

  Content (% by volume) of epoxy resin monomer = {((Aw / Ad) + (Bw / Bd) + (Cw / Cd)) / ((Aw / Ad) + (Bw / Bd) + (Cw / Cd) + (Dw / Dd) + (Ew / Ed))} × 100

Here, each variable is as follows.
Aw: mass composition ratio of epoxy resin monomer (mass%)
Bw: mass composition ratio (% by mass) of curing agent
Cw: mass composition ratio (mass%) of curing accelerator (optional component)
Dw: mass composition ratio of alumina filler (mass%)
Ew: Mass composition ratio (% by mass) of other optional components (excluding organic solvents)
Ad: Specific gravity of epoxy resin monomer Bd: Specific gravity of curing agent Cd: Specific gravity of curing accelerator (optional component) Dd: Specific gravity of alumina filler Ed: Specific gravity of other optional components (excluding organic solvent)

(Curing agent)
The epoxy resin composition includes a curing agent including a novolak resin obtained by novolacizing a divalent phenol compound (hereinafter sometimes referred to as “specific novolak resin”).

  Examples of the divalent phenol compound include catechol, resorcinol, hydroquinone, 1,2-naphthalenediol, 1,3-naphthalenediol, and the like. A novolak resin obtained by novolacizing a divalent phenol compound refers to a novolak resin in which these compounds are connected by a methylene chain. The thermal conductivity of the epoxy resin composition is improved by using a divalent phenol compound, and the heat resistance is further improved by making these compounds novolak.

  The specific novolac resin preferably includes a compound having a structural unit represented by at least one selected from the group consisting of the following general formulas (II-1) and (II-2).

In the general formulas (II-1) and (II-2), R ²¹ and R ²⁴ each independently represents an alkyl group, an aryl group, or an aralkyl group. The alkyl group, aryl group and aralkyl group represented by R ²¹ or R ²⁴ may further have a substituent, if possible. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, and a hydroxyl group.

R ²¹ and R ²⁴ each independently represent an alkyl group, an aryl group, or an aralkyl group, and are an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 13 carbon atoms. It is preferable that it is a C1-C6 alkyl group, and it is more preferable.

m21 and m22 each independently represents an integer of 0 to 2. If m21 is 2, two R ²¹ may be the same or different and when m22 is 2, two R ²⁴ may be different even in the same. In the present invention, m21 and m22 are each independently preferably 0 or 1, and more preferably 0.
N21 and n22 each independently represents an integer of 1 to 7, and represents the number of structural units represented by the general formula (II-1) or the structural unit represented by the general formula (II-2). Show.

In the general formulas (II-1) and (II-2), R ²² , R ²³ , R ²⁵ and R ²⁶ each independently represent a hydrogen atom, an alkyl group, an aryl group or an aralkyl group. The alkyl group, aryl group and aralkyl group represented by R ²² , R ²³ , R ²⁵ or R ²⁶ may further have a substituent, if possible. Examples of the substituent include an alkyl group, an aryl group, a halogen atom, and a hydroxyl group.

R ²² , R ²³ , R ²⁵ and R ²⁶ in the present invention are preferably a hydrogen atom, an alkyl group or an aryl group from the viewpoint of storage stability and thermal conductivity, and are preferably a hydrogen atom, a carbon number of 1 to More preferably, it is a 4 alkyl group or an aryl group having 6 to 12 carbon atoms, and more preferably a hydrogen atom.
Furthermore, from the viewpoint of heat resistance, at least one of R ²² and R ²³ or at least one of R ²⁵ and R ²⁶ is also preferably an aryl group, and more preferably an aryl group having 6 to 12 carbon atoms. .
In addition, the said aryl group may contain the hetero atom in the aromatic group, and it is preferable that it is a heteroaryl group from which the total number of a hetero atom and carbon becomes 6-12.

  The curing agent may contain one type of compound having the structural unit represented by the general formula (II-1) or the structural unit represented by the general formula (II-2). It may contain more than species. From the viewpoint of thermal conductivity, the curing agent preferably includes at least a compound having a structural unit represented by General Formula (II-1), and is represented by General Formula (II-1) and is a structure derived from resorcinol. More preferably, it contains at least a compound having a unit.

When the compound having the structural unit represented by the general formula (II-1) has a structural unit derived from resorcinol, it may further include at least one kind of partial structure derived from a phenol compound other than resorcinol. Good. As phenol compounds other than resorcinol in the general formula (II-1), phenol, cresol, catechol, hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene, 1,3,5 -Trihydroxybenzene etc. can be mentioned. The compound having the structural unit represented by the general formula (II-1) may contain a partial structure derived from these phenol compounds alone or in combination of two or more.
In addition, the compound represented by the general formula (II-2) and having a structural unit derived from catechol may contain at least one kind of partial structure derived from a phenol compound other than catechol.

  Here, the partial structure derived from a phenol compound means a monovalent or divalent group constituted by removing one or two hydrogen atoms from the aromatic ring portion of the phenol compound. The position where the hydrogen atom is removed is not particularly limited.

  In the compound having the structural unit represented by the general formula (II-1), the partial structure derived from a phenol compound other than resorcinol includes phenol, cresol, and catechol from the viewpoint of thermal conductivity, adhesiveness, and storage stability. It is preferably a partial structure derived from at least one selected from hydroquinone, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene, And a partial structure derived from at least one selected from hydroquinone.

  Moreover, when the compound which has a structural unit represented by general formula (II-1) contains the structural unit derived from resorcinol, there is no restriction | limiting in particular about the content rate of the partial structure derived from resorcinol. From the viewpoint of the elastic modulus, the content ratio of the partial structure derived from resorcinol to the total mass of the compound having the structural unit represented by the general formula (II-1) is preferably 55% by mass or more. From the viewpoint of the expansion coefficient, it is more preferably 60% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more from the viewpoint of thermal conductivity.

  Furthermore, the specific novolak resin is more preferably a novolak resin containing a compound having a structure represented by at least one selected from the group consisting of the following general formulas (III-1) to (III-4).

In general formulas (III-1) to (III-4), m31 to m34 and n31 to n34 each independently represent a positive integer. Ar ^{31 to} Ar ³⁴ each independently represent either a group represented by the following general formula (III-a) or a group represented by the following general formula (III-b).

In the general formulas (III-a) and (III-b), R ³¹ and R ³⁴ each independently represent a hydrogen atom or a hydroxyl group. R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

  The curing agent having a structure represented by at least one selected from the group consisting of the above general formulas (III-1) to (III-4) is produced by the production method described below for novolacizing a divalent phenol compound. It can be generated as a by-product.

The structure represented by at least one selected from the group consisting of the above general formulas (III-1) to (III-4) may be included as the main chain skeleton of the curing agent, It may be included as part. Furthermore, each repeating unit constituting the structure represented by any one of the general formulas (III-1) to (III-4) may be included randomly or regularly. It may be included in a block shape.
In the general formulas (III-1) to (III-4), the hydroxyl substitution position is not particularly limited as long as it is on the aromatic ring.

For each of the general formulas (III-1) to (III-4), a plurality of Ar ³¹ to Ar ³⁴ may all be the same atomic group, or may include two or more atomic groups. Good. Ar ^{31 to} Ar ³⁴ each independently represent either a group represented by the general formula (III-a) or a group represented by the general formula (III-b).

R ³¹ and R ³⁴ in the general formulas (III-a) and (III-b) are each independently a hydrogen atom or a hydroxyl group, and preferably a hydroxyl group from the viewpoint of thermal conductivity. Further, the substitution positions of R ³¹ and R ³⁴ are not particularly limited.

In the general formulas (III-a) and (III-b), R ³² and R ³³ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms in R ³² and R ³³ include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, heptyl group, An octyl group etc. are mentioned. In addition, the substitution positions of R ³² and R ^{33 in} the general formulas (III-a) and (III-b) are not particularly limited.

Ar ^{31 to} Ar ³⁴ in the above general formulas (III-1) to (III-4) are each independently a group derived from dihydroxybenzene (ie, from the viewpoint of achieving the effect of the present invention, particularly excellent thermal conductivity) In the above general formula (III-a), R ³¹ is a hydroxyl group and R ³² and R ³³ are hydrogen atoms), and a group derived from dihydroxynaphthalene (that is, in the above general formula (III-b)) R ³⁴ is preferably at least one selected from the group consisting of a hydroxyl group.

  Here, the “group derived from dihydroxybenzene” means a divalent group formed by removing two hydrogen atoms from the aromatic ring portion of dihydroxybenzene, and the position at which the hydrogen atom is removed is not particularly limited. In addition, “group derived from dihydroxynaphthalene” has the same meaning.

In addition, from the viewpoint of productivity and fluidity of the epoxy resin composition, Ar ^{31 to} Ar ³⁴ are preferably each independently a group derived from dihydroxybenzene, such as 1,2-dihydroxybenzene (catechol). More preferably, it is at least one selected from the group consisting of a group derived from and a group derived from 1,3-dihydroxybenzene (resorcinol). Furthermore, Ar ^{31 to} Ar ³⁴ preferably include at least a group derived from resorcinol from the viewpoint of particularly enhancing thermal conductivity.
Moreover, it is preferable that the structural unit represented by n31-n34 contains at least the partial structure derived from a resorcinol from a viewpoint which raises heat conductivity especially.

  When the specific novolak resin includes a partial structure derived from resorcinol, the content of the partial structure derived from resorcinol is a structure represented by at least one of general formulas (III-1) to (III-4) It is preferably 55% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, and still more preferably 90% by mass or more, based on the total mass of the compound having the above.

  From the viewpoint of fluidity, m31 to m34 and n31 to n34 in the general formulas (III-1) to (III-4) are preferably m / n = 20/1 to 1/5, respectively. / 1 to 5/1 is more preferable, and 20/1 to 10/1 is still more preferable. Further, (m + n) is preferably 20 or less, more preferably 15 or less, and still more preferably 10 or less, from the viewpoint of fluidity. In addition, the lower limit of (m + n) is not particularly limited. Here, when n is n31, m is m31, when n is n32, m is m32, when n is n33, m is m33, and when n is n34, m is m34.

The novolak resin having a structure represented by at least one selected from the group consisting of the general formulas (III-1) to (III-4) is particularly preferably substituted or unsubstituted dihydroxybenzene in which Ar ^{31 to} Ar ³⁴ are substituted or unsubstituted. When at least one kind of unsubstituted dihydroxynaphthalene is used, compared to a novolak resin or the like obtained by simply novolacizing these, the synthesis thereof is easy, and a novolak resin having a low softening point tends to be obtained. Therefore, there exists an advantage that manufacture and handling of such a novolak resin as a hardening | curing agent become easy.
In addition, the novolak resin having a structure represented by any one of the above general formulas (III-1) to (III-4) is obtained as a fragment component of the structure by field desorption ionization mass spectrometry (FD-MS). Can be specified.

The molecular weight of the novolak resin having the structure represented by any one of the general formulas (III-1) to (III-4) is not particularly limited. From the viewpoint of fluidity, the number average molecular weight (Mn) is preferably 2000 or less, more preferably 1500 or less, and further preferably 350 or more and 1500 or less. Further, the weight average molecular weight (Mw) is preferably 2000 or less, more preferably 1500 or less, and further preferably 400 or more and 1500 or less.
These Mn and Mw are measured by a normal method using GPC.

  The hydroxyl group equivalent of the novolak resin having a structure represented by any one of the general formulas (III-1) to (III-4) is not particularly limited. From the viewpoint of the crosslinking density involved in heat resistance, the hydroxyl group equivalent is preferably 50 to 150, more preferably 50 to 120, and even more preferably 55 to 120 on average.

  The specific novolac resin may contain a monomer that is a phenol compound constituting the novolac resin. There is no restriction | limiting in particular as a content ratio (henceforth "monomer content ratio") of the monomer which is a phenol compound which comprises specific novolak resin. From the viewpoint of thermal conductivity, heat resistance, and moldability, the monomer content ratio is preferably 5% by mass to 80% by mass, more preferably 15% by mass to 60% by mass, and 20% by mass to 50% by mass. More preferably, it is mass%.

  When the monomer content is 80% by mass or less, the amount of monomers that do not contribute to crosslinking during the curing reaction is reduced and the number of crosslinked high molecular weight substances is increased, so that a higher-order higher-order structure is formed and heat conduction is increased. Improves. Moreover, since it is easy to flow at the time of shaping | molding because it is 5 mass% or more, adhesiveness with a filler improves more and more excellent thermal conductivity and heat resistance can be achieved.

  The content of the curing agent in the epoxy resin composition is not particularly limited. The ratio (phenolic hydroxyl group equivalent / epoxy equivalent) of the active hydrogen equivalent of the phenolic hydroxyl group in the curing agent (phenolic hydroxyl group equivalent) to the epoxy equivalent of the epoxy resin monomer represented by formula (I) is 0.5 to 0.5. 2 is preferable, and 0.8 to 1.2 is more preferable.

Moreover, the epoxy resin composition may further contain a curing accelerator as necessary. By further including a curing accelerator, it can be further sufficiently cured. The type and content of the curing accelerator are not particularly limited, and an appropriate type and content can be selected from the viewpoint of reaction rate, reaction temperature, storage property, and the like. Specific examples of the curing accelerator include imidazole compounds, organic phosphorus compounds, tertiary amines, quaternary ammonium salts, and the like. These may be used alone or in combination of two or more.
Among these, from the viewpoint of heat resistance, it is preferably at least one selected from the group consisting of an organic phosphine compound and a complex of an organic phosphine compound and an organic boron compound.

  Specific examples of the organic phosphine compound include triphenylphosphine, diphenyl (p-tolyl) phosphine, tris (alkylphenyl) phosphine, tris (alkoxyphenyl) phosphine, tris (alkylalkoxyphenyl) phosphine, and tris (dialkylphenyl). Phosphine, tris (trialkylphenyl) phosphine, tris (tetraalkylphenyl) phosphine, tris (dialkoxyphenyl) phosphine, tris (trialkoxyphenyl) phosphine, tris (tetraalkoxyphenyl) phosphine, trialkylphosphine, dialkylarylphosphine, Examples thereof include alkyl diaryl phosphine.

  Specific examples of the complex of an organic phosphine compound and an organic boron compound include tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, tetrabutylphosphonium tetraphenylborate, and tetraphenylphosphonium n-butyl. Examples thereof include triphenyl borate, butyl triphenyl phosphonium tetraphenyl borate, and methyl tributyl phosphonium tetraphenyl borate.

  One type of curing accelerator may be used alone, or two or more types may be used in combination. As a method for efficiently producing a semi-cured epoxy resin composition and a cured epoxy resin composition, which will be described later, a method of mixing and using two kinds of curing accelerators having different reaction start temperatures and reaction rates between an epoxy resin monomer and a novolac resin Is mentioned.

  When using two or more types of curing accelerators in combination, the mixing ratio should be determined without any particular restrictions depending on the properties required for the semi-cured epoxy resin composition (for example, how much flexibility is required). Can do.

  When the epoxy resin composition includes a curing accelerator, the content of the curing accelerator in the epoxy resin composition is not particularly limited. From the viewpoint of moldability, the content of the curing accelerator is preferably 0.5% by mass to 1.5% by mass of the total mass of the thermosetting resin having a mesogenic group in the molecule and the curing agent. It is more preferably 5% by mass to 1% by mass, and further preferably 0.75% by mass to 1% by mass.

(Alumina filler)
The epoxy resin composition contains an alumina filler containing α-alumina. By using alumina as a filler, it is excellent in thermal conductivity, moldability, adhesiveness, mechanical strength, and electrical insulation, and by containing α-alumina, thermal conductivity, mechanical strength, and electrical insulation are further increased. Excellent.

  The alumina filler may further contain alumina other than α-alumina as necessary. Examples of alumina other than α-alumina include γ-alumina, θ-alumina, δ-alumina, and the like, but from the viewpoint of thermal conductivity, it is preferably composed of only α-alumina. In addition, it is preferable that the shape of an alumina filler is round shape. The shape of the alumina filler can be confirmed by a scanning electron microscope (SEM).

  The presence of α-alumina in the alumina filler can be confirmed by an X-ray diffraction spectrum. Specifically, according to the description in Japanese Patent No. 3759208, the presence of α-alumina can be confirmed using a peak peculiar to α-alumina as an index.

  The content of α-alumina in the alumina filler is preferably 80% by volume or more, more preferably 90% by volume or more, and 100% by volume from the viewpoint of thermal conductivity and fluidity. More preferably. When an alumina filler having a high α-alumina content is used, the higher-order structure forming force due to the epoxy resin monomer represented by the general formula (I) is large, and a better thermal conductivity tends to be obtained. is there. The content of α-alumina in the alumina filler can be confirmed by an X-ray diffraction spectrum.

  The alumina filler content in the epoxy resin composition is not particularly limited. The alumina filler content is preferably 60% by volume to 90% by volume in the total volume of the total solid content of the epoxy resin composition. When the content of the alumina filler in the epoxy resin composition is 60% by volume or more, the thermal conductivity is more excellent. A moldability and adhesiveness improve more that the content rate of an alumina filler is 90 volume% or less. The content of the alumina filler is more preferably 65% by volume to 85% by volume, and 70% by volume to 85% by volume in the total volume of the total solid content of the epoxy resin composition from the viewpoint of increasing the thermal conductivity. More preferably.

  In addition, let the content rate (volume%) of the alumina filler in this specification be the value calculated | required by following Formula.

  Content of alumina filler (% by volume) = {(Dw / Dd) / ((Aw / Ad) + (Bw / Bd) + (Cw / Cd) + (Dw / Dd) + (Ew / Ed))}} 100

Here, each variable is as follows.
Aw: mass composition ratio of epoxy resin monomer (mass%)
Bw: mass composition ratio (% by mass) of curing agent
Cw: mass composition ratio (mass%) of curing accelerator (optional component)
Dw: mass composition ratio of alumina filler (mass%)
Ew: Mass composition ratio (% by mass) of other optional components (excluding organic solvents)
Ad: Specific gravity of epoxy resin monomer Bd: Specific gravity of curing agent Cd: Specific gravity of curing accelerator (optional component) Dd: Specific gravity of alumina filler Ed: Specific gravity of other optional components (excluding organic solvent)

  The alumina filler may have a single peak or a plurality of peaks when a particle size distribution curve is drawn with the particle diameter on the horizontal axis and the frequency on the vertical axis. By using an alumina filler having a particle size distribution curve having a plurality of peaks, the filling property of the alumina filler is further improved, and the thermal conductivity as the cured epoxy resin composition is further improved.

  When the alumina filler has a single peak when drawing a particle size distribution curve, an average particle size (D50) which is a particle size corresponding to 50% weight cumulative from the small particle size side of the weight cumulative particle size distribution of the alumina filler. ) Is preferably 0.1 μm to 100 μm, more preferably 0.1 μm to 50 μm from the viewpoint of thermal conductivity. In addition, the alumina filler having a plurality of peaks in the particle size distribution curve can be configured by combining two or more fillers having different average particle diameters (D50), for example.

  The average particle diameter (D50) of the alumina filler is measured using a laser diffraction method, and corresponds to the particle diameter at which the weight accumulation becomes 50% when the weight accumulation particle size distribution curve is drawn from the small particle diameter side. The particle size distribution measurement using the laser diffraction method can be performed using a laser diffraction scattering particle size distribution measuring device (for example, LS230 manufactured by Beckman Coulter, Inc.).

  As an example of a combination of two filler groups having different average particle sizes, the alumina filler (A) having an average particle size (D50) of 10 μm or more and 100 μm or less, and an average particle size ( A mixed filler with an alumina filler (B) in which D50) is ½ or less of the filler (A) and is 0.1 μm or more and less than 10 μm can be mentioned. The mixed filler is based on the total volume of the alumina filler (100 volume%), the alumina filler (A) is 60 volume% to 90 volume%, and the alumina filler (B) is 10 volume% to 40 volume% (however, alumina The total volume% of the fillers (A) and (B) is preferably 100% by volume).

  Moreover, when the case where three types of filler groups having different average particle sizes are combined is exemplified, an alumina filler (A ′) having an average particle size (D50) of 10 μm or more and 100 μm or less, and an average particle size (D50) of an alumina filler ( A ′) 1/2 or less of alumina filler (B ′) that is 1 μm or more and less than 10 μm, and the average particle diameter (D50) is 1/2 or less of alumina filler (B ′), 0.1 μm or more and less than 1 μm. A mixed filler with a certain alumina filler (C ') can be mentioned. The mixed filler is based on the total volume of the alumina filler (100% by volume), 30% to 89% by volume of the alumina filler (A ′), 10% to 40% by volume of the alumina filler (B ′), and alumina. The filler (C ′) is preferably 1% by volume to 30% by volume (provided that the total volume% of the fillers (A ′), (B ′), and (C ′) is 100% by volume). is there.

  The average particle diameter (D50) of the alumina fillers (A) and (A ′) is a cured epoxy in a target resin sheet or laminate when the epoxy resin composition is applied to a resin sheet or laminate described later. When applying the epoxy resin composition to the film thickness of the resin composition layer and the prepreg described later, the film thickness of the target prepreg and the fineness of the fiber substrate are selected as appropriate. It is preferable.

  When there is no other limitation, the average particle diameter of the fillers (A) and (A ′) is preferably as large as possible from the viewpoint of thermal conductivity. On the other hand, it is preferable to make the film thickness as thin as possible within a range in which necessary insulation is ensured from the viewpoint of thermal resistance. Therefore, the average particle diameter of the fillers (A) and (A ′) is preferably 10 μm to 100 μm, more preferably 10 μm to 80 μm from the viewpoint of filler filling property, thermal resistance, and thermal conductivity, and 10 μm. It is more preferably ˜50 μm, further preferably 1 μm to 30 μm, and further preferably 1 μm to 20 μm.

  Moreover, the said epoxy resin composition may further contain the alumina filler whose average particle diameter (D50) is 1 nm or more and less than 100 nm (0.001 micrometer or more and less than 0.1 micrometer) as needed.

  When the microparticle size filler is highly filled, the viscosity is remarkably increased due to the interaction between the filler surface and the resin, which may easily enclose air bubbles by entraining air. Moreover, the frequency with which fillers are fitted increases, and the fluidity may be significantly reduced. As a solution to these problems, there is a method of adding a small amount of a nanoparticle-size filler, which is also disclosed in Japanese Patent Application Laid-Open No. 2009-13227.

  When an epoxy resin composition contains the alumina filler whose average particle diameter (D50) is 1 nm-100 nm (0.001 micrometer-0.1 micrometer), there is no restriction | limiting in particular in the content rate of this alumina filler. The content of the alumina filler is preferably 0.01 vol% to 1 vol% in the total volume of the total solid content of the epoxy resin composition, preferably 0.01 vol% to 0.5 vol% More preferably it is contained. By containing 0.01 vol% to 1 vol% of the total volume, the lubricity between the microparticle size alumina filler and between the microparticle size alumina filler and the fiber substrate is further improved, and the epoxy resin. An effect of further increasing the thermal conductivity of the composition can be expected.

  The epoxy resin composition may further contain an inorganic filler other than the alumina filler as necessary. Examples of inorganic fillers other than the alumina filler include boron nitride, aluminum nitride, silica, magnesium oxide, silicon nitride, and silicon carbide. When the epoxy resin composition contains an inorganic filler other than the alumina filler, the content is preferably 50% by volume or less, more preferably 30% by volume or less with respect to the content of the alumina filler.

(Elastomer)
The epoxy resin composition preferably further contains an elastomer having at least a structural unit represented by the following general formula (IV) in the molecule. By including the elastomer having the structural unit represented by the general formula (IV), the dispersibility of the alumina filler is further improved, and the flexibility of the B stage sheet described later is further improved. Moreover, in the resin sheet and prepreg described later, effects such as improvement in density and reduction in insulation due to reduction of internal voids can be obtained.

In the general formula (IV), R ⁴¹ , R ⁴² and R ⁴³ each independently represent a linear or branched alkyl group or a hydrogen atom. R ⁴⁴ represents a linear or branched alkyl group. n4 is an arbitrary integer indicating the number of structural units.

  The elastomer is preferably a homopolymer or copolymer derived from at least one monomer selected from the group consisting of (meth) acrylic acid and (meth) acrylic acid ester. In one embodiment of the present invention, it is preferable to use an acrylic resin copolymer mainly containing a structural unit represented by the general formula (IV) as the elastomer.

In general formula (IV), when any of R ⁴¹ , R ⁴² or R ⁴³ is an alkyl group, from the viewpoint of imparting flexibility, the number of carbon atoms is preferably 1 to 12, and a low glass transition temperature (Tg ), The number of carbon atoms is more preferably 1-8. In a preferred embodiment of the present invention, R ⁴¹ and R ⁴² are each a hydrogen atom, R ⁴³ is a hydrogen atom or a methyl group, and more preferably R ⁴¹ , R ⁴² and R ⁴³ are a hydrogen atom. .

In the general formula (IV), R ⁴⁴ is a linear or branched alkyl group. The alkyl group in R ⁴⁴ preferably has 2 to 16 carbon atoms from the viewpoint of imparting flexibility, and has 3 to 14 carbon atoms from the viewpoint of small inhibition of higher-order structure formation in the epoxy resin monomer. It is more preferable, and it is still more preferable that it is 4-12 from a viewpoint of acquisition and the ease of synthesis.

In addition, the elastomer preferably has a structural unit number of carbon atoms of the alkyl group represented by R ⁴⁴ is represented by two or more different formula (IV). For example, when the elastomer has two structural units represented by the general formula (IV), the carbon number of the alkyl group in one structural unit is 2 to 7 carbon atoms from the viewpoint of low Tg. Preferably, it is 3-6. Moreover, as for carbon number of the alkyl group in the other structural unit, it is preferable that carbon number is 8-16 from a viewpoint of softness | flexibility provision, and it is more preferable that it is 10-14.

  In the general formula (IV), n is an arbitrary integer indicating the number of structural units. The number of structural units represented by n4 means the average value of the total number of structural units represented by the general formula (IV) contained in the elastomer molecule. n4 = 100 to 1000 is preferable, n4 = 100 to 500 is more preferable from the viewpoint of imparting flexibility, and n4 = 100 to 300 is still more preferable from the viewpoint of low Tg.

  By using an elastomer having a structural unit represented mainly by the general formula (IV), a soft structure (flexibility) can be imparted to the epoxy resin composition. Therefore, it is possible to improve the problems such as a decrease in flexibility of the sheet due to the high filling of the inorganic filler as seen in the conventional heat conductive sheet.

  The elastomer having at least the structural unit represented by the general formula (IV) in the molecule preferably further has at least one of a carboxy group and a hydroxy group in the molecule, and has a structural unit having at least one of a carboxy group and a hydroxy group. It is more preferable that a structural unit having at least a carboxy group is included.

Examples of the monomer that can form a structural unit having a carboxy group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and the like. Among these, acrylic acid and methacrylic acid are preferable.
Moreover, as a monomer which can form the structural unit which has a hydroxyl group, the (meth) acrylic acid ester containing a C2-C20 hydroxyalkyl group can be mentioned, A C2-C6 hydroxyalkyl group is mentioned. It is preferable that it is a (meth) acrylic ester containing. Specific examples include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and the like.

When a carboxy group or a hydroxyl group is present in the elastomer, they can undergo a crosslinking reaction with the epoxy resin monomer during the curing reaction, so that the crosslinking density is further improved, and as a result, the thermal conductivity can be further improved.
In addition, since the carboxy group releases hydrogen ions, it is easy to open the epoxy group during the curing reaction, thereby providing an effect of acting as a catalyst. Furthermore, since the carboxy group acts with the hydroxyl group on the surface of the alumina filler, it brings about the effect of surface treatment on the alumina filler. The effect of such a surface treatment is that the wettability between the alumina filler and the elastomer is improved, so that the viscosity of the epoxy resin composition (varnish) further containing a solvent tends to be lowered and the coating tends to be easy. Furthermore, the alumina filler is more highly dispersed by the improvement of wettability, which contributes to the improvement of thermal conductivity.

  When the elastomer has at least one of carboxy group and hydroxy group, the content of the structural unit having at least one of carboxy group and hydroxy group contained in the elastomer is not particularly limited. From the viewpoint of filler dispersibility, the content of the structural unit having at least one of a carboxy group and a hydroxy group in the elastomer is preferably 10 mol% to 30 mol% based on the entire elastomer molecule (100 mol%). 14 mol% to 28 mol% is more preferable.

  The elastomer having at least the structural unit represented by the general formula (IV) in the molecule preferably further contains at least one amino group in the molecule, and preferably contains at least one structural unit having an amino group. More preferred. The amino group is preferably a secondary amino group or a tertiary amino group from the viewpoint of preventing moisture absorption. Further, from the viewpoint of improving thermal conductivity, an N-methylpiperidino group is particularly preferable. When an N-methylpiperidino group is present in the elastomer, the compatibility is remarkably improved by the interaction with a curing agent containing a novolac resin obtained by novolacizing a divalent phenol compound. Thus, when the acrylic monomer excellent in compatibility is added to an epoxy resin composition, the loss of heat conductivity becomes smaller. Further, the interaction between the N-methylpiperidino group and a curing agent containing a novolac resin obtained by novolacizing a divalent phenol compound exhibits a stress relaxation effect due to slippage between different molecules, and contributes to further improvement of the adhesive force. It will be.

  When the elastomer has an amino group, the content of the amino group contained in the elastomer is not particularly limited. From the viewpoint of compatibility, the content of the structural unit having an amino group in the elastomer is preferably 0.5 mol% to 5 mol%, more preferably 0.7 mol% to 3.5 mol%. preferable.

  In one embodiment of the present invention, it is more preferable to use an acrylic elastomer containing a structural unit represented by the following general formula (V). By containing the acrylic elastomer containing the structural unit represented by the general formula (V), the flexibility of the B stage sheet, which is a semi-cured epoxy resin composition described later, is improved, and the internal voids in the resin sheet and prepreg described later are included. Effects such as density improvement and insulation improvement by reduction can be obtained more remarkably.

In general formula (V), a, b, c, and d show the mol% of each structural unit in all the structural units, and are a + b + c + d = 90 mol% or more. R ⁵¹ and R ⁵² each independently represent a linear or branched alkyl group having a different carbon number. R ^{53 to} R ⁵⁶ each independently represent a hydrogen atom or a methyl group.

  In the general formula (V), a + b + c + d = 90 mol% or more, preferably 95 mol% or more, and more preferably 99 mol% or more.

In the acrylic elastomer represented by the general formula (V), the structural unit (hereinafter also referred to as “structural unit a”) present in the proportion of a can impart flexibility to the resin sheet and can also conduct heat. It is possible to achieve both sex and flexibility. Further, the structural unit present in the ratio of b (hereinafter also referred to as “structural unit b”) makes the flexibility of the resin sheet more preferable in the combination with the structural unit a shown above. Thus, the carbon number of the alkyl group represented by R ⁵¹ and R ⁵² in the structural units a and b that imparts a soft structure (flexibility) is not particularly limited. When the carbon number of the alkyl group is 16 or less, the glass transition temperature (Tg) of the acrylic elastomer does not become too high, and the flexibility improvement effect obtained by adding the acrylic elastomer to the epoxy resin composition is sufficiently obtained. Tend. On the other hand, when the carbon number of the alkyl group of R ⁵¹ and R ⁵² is 2 or more, the flexibility of the acrylic elastomer itself is further improved, and the flexibility effect obtained by adding the acrylic elastomer tends to be sufficiently obtained. In such a viewpoint, the carbon number of the alkyl group of R ⁵¹ and R ⁵² is preferably in the range of 2 to 16, more preferably in the range of 3 to 14, and still more preferably in the range of 4 to 12.

The alkyl groups represented by R ⁵¹ and R ⁵² have different carbon numbers. Although the difference in carbon number in R ⁵¹ and R ⁵² is not particularly limited, the difference in carbon number is preferably 4 to 10 and more preferably 6 to 8 from the viewpoint of the balance between flexibility and flexibility. .
Furthermore, from the viewpoint of the balance between flexibility and flexibility, R ⁵¹ has preferably 2 to 6 carbon atoms, R ⁵² preferably has 8 to 16 carbon atoms, and R ⁵¹ has 3 to 5 carbon atoms. More preferably, R ⁵² has 10 to 14 carbon atoms.

  In the general formula (V), the range of mol% of the structural units a and b is not particularly limited. Further, the ratio between the structural units a and b may be arbitrary. It is preferable to use an acrylic elastomer that includes a combination of structural units a and b, rather than any of structural units a and b. The combination of structural units a and b may increase the number of side chains and increase the flexibility of the acrylic elastomer, and may increase Tg. However, Tg can be controlled within a suitable range by appropriately adjusting the proportion of mol% of the structural units a and b in the acrylic elastomer.

  Specifically, for example, from the viewpoint of flexibility and filler dispersibility of the resin sheet, the content of the structural unit a is preferably 50 mol% to 85 mol%, and more preferably 60 mol% to 80 mol%. Moreover, 2 mol%-20 mol% are preferable, and, as for the content rate of the structural unit b, 5 mol%-15 mol% are more preferable. Furthermore, 4-10 are preferable and, as for the content ratio of the structural unit a with respect to the structural unit b, 6-8 are more preferable.

In the above general formula (V), the presence of a carboxy group in the acrylic elastomer derived from the structural unit present in the proportion of c (hereinafter also referred to as “structural unit c”) improves thermal conductivity and The effect of improving the wettability between the filler and the resin is obtained. Further, the presence of N-methylpiperidino group in the acrylic elastomer derived from the structural unit present in the proportion of d (hereinafter also referred to as “structural unit d”) improves compatibility and adhesion. An effect is obtained. These effects become more prominent when carboxy groups and N-methylpiperidino groups coexist in the acrylic elastomer. More specifically, the N-methylpiperidino group can accept hydrogen ions from a carboxy group and then allows interaction with a novolak resin, for example, included as a curing agent. Thus, the compatibility with the acrylic elastomer in the epoxy resin composition is improved by the interaction with the novolac resin. Further, the intramolecular interaction between the carboxy group and the N-methylpiperidino group contributes to the stress relaxation due to the low elasticity. This can be considered, for example, because the entire molecule of the acrylic elastomer has a curved structure instead of a linear structure. From such a viewpoint, in one embodiment of the acrylic elastomer represented by the general formula (V), the proportion of the structural units c and d is preferably in the range of 10 mol% to 28 mol%, more preferably It is in the range of 14 mol% to 28 mol%, more preferably in the range of 20 mol% to 28 mol%, d is preferably in the range of 0.5 mol% to 5 mol%, more preferably from 0.7 mol% to It is in the range of 3.5 mol%, more preferably in the range of 0.7 mol% to 1.4 mol%.
Moreover, 0.01-0.5 are preferable, as for the content ratio of the structural unit c with respect to the structural unit d, 0.03-0.3 are more preferable, and 0.035-0.25 are still more preferable.

R ^{53 to} R ⁵⁶ are each independently a hydrogen atom or a methyl group, but preferably at least one of R ⁵³ and R ⁵⁴ is a hydrogen atom and the other is a methyl group, R ⁵³ is a hydrogen atom and R ⁵⁴ is More preferred is a methyl group. Also preferably the other is a methyl group at least one hydrogen atom of the pair of R ⁵⁵ and R ^56, and more preferably R ⁵⁶ R ⁵⁵ is a hydrogen atom is a methyl group.

The acrylic elastomer having the structure represented by the general formula (V) may further include a structural unit other than the structural units a to d. There is no restriction | limiting in particular as structural units other than structural unit ad. Examples of the structural unit other than the structural units a to d include a structural unit derived from a (meth) acrylic acid ester containing a hydroxyalkyl group and a structural unit derived from a (meth) acrylic acid ester containing a tertiary amino group. Can do.
The content of structural units other than the structural units a to d in the acrylic elastomer is 10 mol% or less, preferably 5 mol% or less, and more preferably 1 mol% or less.

The weight average molecular weight of the acrylic elastomer is not particularly limited. Among these, from the viewpoint of thermal conductivity and flexibility, it is preferably 10,000 to 100,000, more preferably 10,000 to 50,000, and 10,000 to 30,000. Is more preferable. Furthermore, when the weight average molecular weight of the acrylic elastomer is within the above range, the dispersibility of the inorganic filler is further improved, and the viscosity of the epoxy resin composition tends to be further decreased.
The weight average molecular weight of the acrylic elastomer is measured by a normal method using GPC.

In the epoxy resin composition according to the present invention, the content of the acrylic elastomer is 0.1 parts by mass to 99 parts by mass when the total mass of the epoxy resin components (epoxy resin monomer and curing agent) is 100 parts by mass. The range is preferably 1 to 20 parts by mass, more preferably 1 to 10 parts by mass.
When the content of the acrylic elastomer is 0.1 parts by mass or more, a decrease in thermal conductivity is further suppressed, and the adhesive force with the adherend tends to be further improved. On the other hand, when the amount is 99 parts by mass or less of the acrylic elastomer, a decrease in the adhesive force with the adherend is further suppressed, and the thermal conductivity tends to be further improved. Therefore, it becomes easy to express various characteristics in a well-balanced manner by adjusting the content of the acrylic elastomer to the above range.

(Silane coupling agent)
The epoxy resin composition preferably further includes at least one silane coupling agent. As an effect of adding a silane coupling agent, it plays the role of forming a covalent bond between the surface of the alumina filler and the thermosetting resin surrounding it (equivalent to the binder agent), and the effect of transferring heat more efficiently In addition, an effect of improving insulation reliability can be obtained by preventing moisture from entering.

  It does not specifically limit as a kind of said silane coupling agent, It can select from a commercially available thing suitably. To reduce the compatibility between the epoxy resin monomer represented by the general formula (I) having a mesogenic group in the molecular structure and the curing agent, and the heat conduction defect at the interface between the cured epoxy resin monomer and the alumina filler. In view of the above, in the present invention, it is preferable to use a silane coupling agent having at least one functional group selected from the group consisting of an epoxy group, an amino group, a mercapto group, a ureido group and a hydroxyl group at the terminal.

  Specific examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. Silane coupling agents having an epoxy group such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3- (2-aminoethyl) aminopropyltrimethoxysilane, 3- Silane coupling agents having an amino group such as (2-aminoethyl) aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane; 3-mercaptopropyltrimethoxysilane, 3-mercapto bird Silane coupling agent having a ureido group such as 3-ureidopropyltriethoxysilane; silane coupling agent having a mercapto group such Tokishishiran the like. Further, silane coupling agent oligomers (manufactured by Hitachi Chemical Coated Sand Co., Ltd.) typified by SC-6000KS2 can also be mentioned. These silane coupling agents may be used alone or in combination of two or more.

(Other ingredients)
The epoxy resin composition may further contain at least one organic solvent. By including an organic solvent, it can be easily adapted to various molding processes. The organic solvent can be appropriately selected from commonly used organic solvents. Specific examples include alcohol solvents, ether solvents, ketone solvents, amide solvents, aromatic hydrocarbon solvents, ester solvents, nitrile solvents, sulfoxide solvents, and the like. Specific examples of organic solvents include ketone solvents such as methyl isobutyl ketone, cyclohexanone, and methyl ethyl ketone; amide solvents such as dimethylacetamide, dimethylformamide, and N-methyl-2-pyrrolidone; ester solvents such as γ-butyrolactone; dimethyl sulfoxide, sulfolane And the like can be used. These may be used alone or as a mixed solvent using two or more kinds in combination.

  The epoxy resin composition can contain other components as needed in addition to the above components. Examples of other components include a dispersant. Examples of the dispersant include Ajinomoto Finetech Co., Ltd. Ajisper series, Enomoto Kasei Co., Ltd. HIPLAAD series, Kao Corporation homogenol series, and the like. These may be used alone or in combination of two or more.

<Semi-cured epoxy resin composition>
The semi-cured epoxy resin composition of the present invention is derived from the epoxy resin composition, and is obtained by semi-curing the epoxy resin composition. For example, when the semi-cured epoxy resin composition is molded into a sheet shape, the handleability is improved as compared with a resin sheet made of an epoxy resin composition that is not semi-cured.

Here, the semi-cured epoxy resin composition means that the semi-cured epoxy resin composition has a viscosity of 10 ⁴ Pa · s to 10 ⁵ Pa · s at room temperature (25 to 30 ° C.). It has the characteristic which falls to 10 < ² > Pa * s-10 < ³ > Pa * s at ° C. Moreover, the cured epoxy resin composition after curing described later does not melt by heating. The viscosity is measured by dynamic viscoelasticity measurement (DMA) (for example, ARES-2KSTD manufactured by TA Instruments). The measurement conditions are a frequency of 1 Hz, a load of 40 g, a temperature increase rate of 3 ° C./min, and a shear test.

  Examples of the semi-curing treatment include a method of heating the epoxy resin composition at a temperature of 100 ° C. to 200 ° C. for 1 minute to 30 minutes.

<Curing epoxy resin composition>
The cured epoxy resin composition of the present invention is derived from the epoxy resin composition, and is obtained by curing the epoxy resin composition. The cured epoxy resin composition is excellent in thermal conductivity. For example, the epoxy resin monomer represented by the general formula (I) having a mesogenic group in the molecular structure contained in the epoxy resin composition is an α-alumina filler. It can be considered that a higher-order structure is formed around the center. Moreover, the said cured epoxy resin composition is excellent in heat resistance.

The cured epoxy resin composition can be produced by curing the uncured epoxy resin composition or the semi-cured epoxy resin composition. Although the method of the said hardening process can be suitably selected according to the structure of an epoxy resin composition, the objective of a cured epoxy resin composition, etc., it is preferable that they are a heating and a pressurization process.
For example, the epoxy resin composition in an uncured state or the semi-cured epoxy resin composition is heated at 100 ° C. to 250 ° C. for 1 hour to 10 hours, preferably at 130 ° C. to 230 ° C. for 1 hour to 8 hours. A resin composition is obtained.

<Resin sheet>
The resin sheet of the present invention is formed by molding the epoxy resin composition into a sheet shape. The said resin sheet can be manufactured by providing the said epoxy resin composition on a release film, for example, and removing the solvent contained as needed. The resin sheet is excellent in thermal conductivity and heat resistance by being formed from the epoxy resin composition.

The density of the resin sheet is not particularly limited, for ^example, be a ^{3.0g / cm 2 ~3.5g / cm 2} . In consideration of the compatibility between the flexibility and the thermal conductivity of the resin sheet, 3.1 g / cm ^{2 to} 3.4 g / cm ² is preferable, and 3.1 g / cm ^{2 to} 3.3 g / cm ² is more preferable. The density of the resin sheet can be adjusted, for example, by appropriately selecting the content of the alumina filler in the epoxy resin composition.

  The thickness of the resin sheet is not particularly limited and can be appropriately selected according to the purpose. For example, the thickness of the resin sheet can be 50 μm to 500 μm, and is preferably 80 μm to 300 μm from the viewpoint of thermal conductivity, electrical insulation, and flexibility.

  The resin sheet is a varnish-like epoxy resin composition (hereinafter referred to as “resin varnish”) prepared by adding an organic solvent such as methyl ethyl ketone or cyclohexanone to the epoxy resin composition on a release film such as a PET film. Can be produced by removing at least a part of the organic solvent from the coating layer and drying.

  The application of the resin varnish can be performed by a known method. Specific examples include methods such as comma coating, die coating, lip coating, and gravure coating. Examples of the coating method for forming the epoxy resin composition layer to a predetermined thickness include a comma coating method in which an object to be coated is passed between gaps, and a die coating method in which a resin varnish with a flow rate adjusted from a nozzle is applied. . For example, when the thickness of the coating layer (resin composition layer) before drying is 50 μm to 500 μm, it is preferable to use a comma coating method.

  The drying method is not particularly limited as long as at least a part of the organic solvent contained in the resin varnish can be removed, and can be appropriately selected from commonly used drying methods according to the organic solvent contained in the resin varnish. In general, a heat treatment method at about 80 ° C. to 150 ° C. can be mentioned.

  Since the epoxy resin composition layer of the resin sheet hardly undergoes a curing reaction, it has flexibility, but the sheet has poor flexibility, and in the state where the PET film as a support is removed, the sheet is self-supporting. It may be difficult to handle.

  The resin sheet is preferably a semi-cured epoxy resin composition obtained by semi-curing an epoxy resin composition constituting the resin sheet. That is, the resin sheet is preferably a B stage sheet that is further heat-treated until it is in a semi-cured state (B stage state). Since the resin sheet is composed of a semi-cured epoxy resin composition obtained by semi-curing the epoxy resin composition, it has excellent thermal conductivity and heat resistance, and is flexible and usable as a B-stage sheet. Excellent.

Here, the B-stage sheet has a viscosity of 10 ⁴ Pa · s to 10 ⁵ Pa · s at room temperature (25 to 30 ° C.), whereas 10 ² Pa · s to 10 ³ Pa at 100 ° C. -It has the characteristic which falls to s. Moreover, the cured epoxy resin composition after curing described later is not melted by heating. The viscosity is measured by DMA (frequency 1 Hz, load 40 g: temperature rising rate 3 ° C./min).

  The conditions for heat-treating the resin sheet are not particularly limited as long as the epoxy resin composition layer can be brought into a B-stage state, and can be appropriately selected according to the configuration of the epoxy resin composition. For the heat treatment, a heat treatment method selected from hot vacuum press, hot roll laminating and the like is preferred for the purpose of eliminating voids in the resin layer generated during coating. Thereby, a flat B stage sheet | seat can be manufactured efficiently.

  Specifically, for example, the epoxy resin composition is heated and pressurized under reduced pressure (for example, 1 kPa) at a temperature of 100 ° C. to 200 ° C. for 1 minute to 3 minutes with a press pressure of 1 MPa to 5 MPa. It can be semi-cured to the B stage state.

  It is preferable that after the two resin sheets obtained by applying the epoxy resin composition on the release film and drying are pasted together, the above heating and pressurizing processes are performed to semi-cure to the B stage state. At this time, it is desirable to bond the application surfaces (the surfaces opposite to the surfaces in contact with the release film in the epoxy resin composition layer formed by applying the epoxy resin composition to the release film). When two sheets are bonded together in this way, both sides of the resulting B-stage resin sheet become flatter and the adhesiveness to the adherend becomes better, so it can be applied to laminates, metal substrates, and wiring boards described later. It exhibits higher thermal conductivity when it is applied.

  The thickness of the B stage sheet can be appropriately selected depending on the purpose, and can be, for example, 50 μm to 500 μm, and is 80 μm to 300 μm from the viewpoint of thermal conductivity, electrical insulation, and flexibility. It is preferable.

  The solvent remaining rate in the B-stage sheet is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, from the viewpoint of suppressing bubble formation due to outgas generation during curing. More preferably, it is 5 mass% or less.

  The solvent residual ratio is determined from the change in mass before and after drying when a B-stage sheet is cut into a 40 mm square and dried in a thermostat preheated to 190 ° C. for 2 hours.

  The B-stage sheet is excellent in fluidity. Specifically, the flow amount in the B stage sheet is preferably 130% to 210%, and more preferably 150% to 200%. This flow amount is an indicator of melt fluidity during thermocompression bonding. When the flow amount is 130% or more, sufficient embeddability can be obtained, and when it is 210% or less, generation of burrs due to excessive flow can be suppressed.

  The flow amount is as follows. When a sample obtained by punching a 200 mm thick B stage sheet into a 10 mm square was pressed for 1 minute under atmospheric pressure, at a temperature of 160 ° C., and at a press pressure of 1.6 MPa, Calculated as the area change rate. The area change rate is obtained from the change rate of the area (number of pixels) after taking an external projection image of the sample with a scanner of 300 DPI or more, binarizing with image analysis software (Adobe Photoshop).

  Flow amount (%) = (Area of B stage sheet after pressing) / (Area of B stage sheet before pressing)

The resin sheet may be a cured epoxy resin composition obtained by curing the epoxy resin composition. A resin sheet made of a cured epoxy resin composition can be produced by curing an uncured resin sheet or B-stage sheet. Although the method of the said hardening process can be suitably selected according to the structure of an epoxy resin composition, the objective of a cured epoxy resin composition, etc., it is preferable that they are a heating and a pressurization process.
For example, a resin comprising a cured epoxy resin composition by heating an uncured resin sheet or B stage sheet at 100 ° C. to 250 ° C. for 1 hour to 10 hours, preferably 130 ° C. to 230 ° C. for 1 hour to 8 hours. A sheet is obtained. The heating is preferably performed while applying a pressure of 1 MPa to 5 MPa.

  In addition, the following method is mentioned as an example of the method of manufacturing the resin sheet which consists of a cured epoxy resin composition which has high heat conductivity and high heat resistance. First, the B stage sheet is sandwiched so as to be in contact with the roughened surfaces of two copper foils (thickness 80 μm to 120 μm) each having a roughened surface, and the temperature is 130 ° C. to 230 ° C. for 3 minutes to 10 minutes Heating and pressurizing are performed with a press pressure of 1 MPa to 5 MPa to bond the B stage sheet and the copper foil. Subsequently, the epoxy resin composition is cured by heating at 130 to 230 ° C. for 1 to 8 hours to obtain a resin sheet with copper foil. There is a method of removing a copper foil portion of the obtained resin sheet with copper foil by etching treatment to obtain a resin sheet made of a cured epoxy resin composition.

<Prepreg>
The prepreg of the present invention includes a fiber base material and the epoxy resin composition impregnated in the fiber base material. With such a configuration, a prepreg excellent in thermal conductivity and heat resistance is obtained. Moreover, since the thixotropy improves the epoxy resin composition containing an alumina filler, it can suppress sedimentation of the alumina filler in the below-mentioned coating process or impregnation process. Therefore, the occurrence of the density distribution of the alumina filler in the thickness direction of the prepreg can be suppressed, and as a result, a prepreg excellent in thermal conductivity and heat resistance can be obtained.

  The fiber base material constituting the prepreg is not particularly limited as long as it is usually used when producing a metal foil-clad laminate or a multilayer wiring board, and is appropriately selected from fiber base materials such as woven fabrics and nonwoven fabrics that are usually used. Selected.

  The opening of the fiber base material is not particularly limited. From the viewpoint of thermal conductivity and electrical insulation, the mesh opening is preferably 5 times or more the average particle diameter (D50) of the alumina filler. Further, when the particle size distribution curve of the alumina filler has a plurality of peaks, it is more preferable that the opening is 5 times or more the particle diameter corresponding to the peak having the largest particle diameter.

  The material of the fiber base material is not particularly limited. Specifically, inorganic fibers such as glass, alumina, boron, silica alumina glass, silica glass, tyranno, silicon carbide, silicon nitride, zirconia, carbon, aramid, polyetheretherketone, polyetherimide, polyether Examples thereof include organic fibers such as sulfone and cellulose, and mixed papers thereof.

  Among these, a glass fiber woven fabric is preferably used as the fiber base material. Thereby, for example, when a wiring board is configured using prepreg, a wiring board that is flexible and can be arbitrarily bent can be obtained. Furthermore, it becomes possible to reduce the dimensional change of the wiring board accompanying the temperature change, moisture absorption, etc. in the manufacturing process.

  The thickness of the fiber base material is not particularly limited. From the viewpoint of imparting better flexibility, the thickness is more preferably 30 μm or less, and from the viewpoint of impregnation, it is preferably 15 μm or less. Although the minimum of the thickness of a fiber base material is not restrict | limited in particular, Usually, it is about 5 micrometers.

  The impregnation amount (content ratio) of the epoxy resin composition in the prepreg is preferably 50% by mass to 99.9% by mass in the total mass of the fiber base material and the epoxy resin composition.

  The prepreg is produced by impregnating a fiber base material with the epoxy resin composition prepared in a varnish form in the same manner as described above, and removing at least part of the organic solvent by heat treatment at 80 ° C to 150 ° C. Can do.

  Moreover, there is no restriction | limiting in particular in the method of impregnating a fiber base material with an epoxy resin composition. For example, the method of apply | coating with a coating machine can be mentioned. Specifically, a vertical coating method in which a fiber base material is pulled through an epoxy resin composition, a horizontal coating method in which an epoxy resin composition is coated on a support film and then impregnated by pressing the fiber base material, etc. be able to. From the viewpoint of suppressing the uneven distribution of the alumina filler in the fiber base material, the horizontal coating method is preferable.

  The prepreg in the present invention may be used after the surface is smoothed in advance by hot press treatment with a press, a roll laminator or the like before lamination or sticking. The method of the hot press treatment is the same as the method mentioned in the method for producing the B stage sheet. Further, the processing conditions such as the heating temperature, the degree of pressure reduction, and the pressing pressure in the hot pressurizing process of the prepreg are the same as the conditions mentioned in the heating and pressurizing process of the B stage sheet.

  The residual solvent ratio in the prepreg is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and further preferably 0.5% by mass or less.

  The solvent residual rate is obtained from the mass change before and after drying when the prepreg is cut into 40 mm square and dried in a thermostat preheated to 190 ° C. for 2 hours.

<Laminated plate>
The laminate in the present invention has an adherend and a semi-cured epoxy resin composition layer or a cured epoxy resin composition layer disposed on the adherend. The semi-cured epoxy resin composition layer and the cured epoxy resin composition layer are derived from at least one selected from the group consisting of an epoxy resin composition layer composed of the epoxy resin composition, the resin sheet, and the prepreg. It is at least one selected from the group consisting of a semi-cured epoxy resin composition layer and a cured epoxy resin composition layer. By having a semi-cured epoxy resin composition layer or a cured epoxy resin composition layer formed from the epoxy resin composition, a laminate having excellent thermal conductivity and heat resistance is obtained.

  Examples of the adherend include a metal foil and a metal plate. The adherend may be attached to only one side of the semi-cured epoxy resin composition layer or the cured epoxy resin composition layer, or may be attached to both sides.

  The metal foil is not particularly limited, and can be appropriately selected from commonly used metal foils. Specifically, gold foil, copper foil, aluminum foil, etc. can be mentioned, and copper foil is generally used. The thickness of the metal foil is not particularly limited as long as it is 1 μm to 200 μm, and a suitable thickness can be selected according to the electric power used.

  Further, as the metal foil, nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy or the like is used as an intermediate layer, and a copper layer of 0.5 μm to 15 μm and 10 μm to A three-layer composite foil provided with a 150 μm copper layer, or a two-layer composite foil in which aluminum and copper foil are combined can also be used.

  The metal plate is preferably made of a metal material having high thermal conductivity and a large heat capacity. Specific examples include copper, aluminum, iron, alloys used for lead frames, and the like.

  The plate | board thickness of the said metal plate can be suitably selected according to a use. For example, the material of the metal plate can be selected according to the purpose, such as selecting aluminum when priority is given to weight reduction or workability, and selecting copper when priority is given to heat dissipation.

  In the laminated board, as a semi-cured epoxy resin composition layer or a cured epoxy resin composition layer, in a form having one layer derived from any one of the epoxy resin composition layer, the resin sheet, or the prepreg. There may be a form in which two or more layers are laminated. In the case of having two or more semi-cured epoxy resin composition layers or cured epoxy resin composition layers, two or more epoxy resin composition layers, two or more resin sheets, and two prepregs are used. Any form having at least one sheet may be used. Furthermore, you may have combining any 2 or more of the said epoxy resin composition layer, the said resin sheet, and the said prepreg.

  The laminated board in the present invention, for example, forms the epoxy resin composition layer by applying the epoxy resin composition on an adherend, and heats and pressurizes it to semi-cur the epoxy resin composition layer. Or it is obtained by making it harden | cure and sticking to a to-be-adhered material. Alternatively, it is obtained by preparing a laminate of the resin sheet or the prepreg on the adherend and heating and pressurizing it to make the resin sheet or the prepreg semi-cured or cured and to adhere to the adherend. It is done.

  The curing method for semi-curing or curing the epoxy resin composition layer, the resin sheet, and the prepreg is not particularly limited. For example, heat treatment and pressure treatment are preferable. The heating temperature in the heating and pressure treatment is not particularly limited. Usually, it is the range of 100 to 250 degreeC, Preferably it is the range of 130 to 230 degreeC. Moreover, the pressurization conditions in a heating and pressurizing process are not specifically limited. Usually, it is in the range of 1 MPa to 10 MPa, preferably in the range of 1 MPa to 5 MPa. Moreover, a vacuum press is used suitably for a heating and pressurizing process.

  The thickness of the laminate is preferably 500 μm or less, and more preferably 100 μm to 300 μm. When the thickness is 500 μm or less, the flexibility is excellent and the occurrence of cracks during bending is suppressed, and when the thickness is 300 μm or less, this tendency is more apparent. Further, when the thickness is 100 μm or more, the workability is excellent.

<Resin cured body with metal foil, metal substrate>
As an example of the said laminated board, the resin cured body with metal foil and metal substrate which can be used for producing the below-mentioned wiring board can be mentioned.

The said resin cured body with metal foil is comprised using two metal foils as the adherend in the said laminated board. Specifically, one metal foil, the cured epoxy resin composition layer, and the other metal foil are laminated in this order.
Details of the metal foil and the cured epoxy resin composition layer constituting the cured resin body with metal foil are as described above.

Moreover, the said metal substrate is comprised using a metal foil and a metal plate as an adherend in the said laminated board. Specifically, the metal substrate is configured by laminating the metal foil, the cured epoxy resin composition layer, and the metal plate in this order.
The details of the metal foil and the cured epoxy resin composition layer constituting the metal substrate are as described above.

  The metal plate is not particularly limited and can be appropriately selected from commonly used metal plates. Specifically, an aluminum plate, an iron plate, etc. can be mentioned. The thickness of the metal plate is not particularly limited. From the viewpoint of workability, the thickness is preferably 0.5 mm or more and 5 mm or less.

  Moreover, it is preferable that the said metal plate is cut | disconnected to the size to be used, after producing a larger size than necessary and mounting an electronic component from a viewpoint of improving productivity. Therefore, it is desirable that the metal plate used for the metal substrate is excellent in cutting workability.

  When aluminum is used as the metal plate, aluminum or an alloy mainly composed of aluminum can be selected as the material. Many types of aluminum or alloys containing aluminum as a main component are available depending on the chemical composition and heat treatment conditions. Among them, it is preferable to select a type having high workability such as easy cutting and excellent strength.

<Wiring board>
The wiring board of the present invention is formed by laminating a metal plate, a cured epoxy resin composition layer, and a wiring layer in this order. The cured epoxy resin composition layer is a cured epoxy resin composition layer derived from at least one selected from an epoxy resin composition layer composed of the epoxy resin composition, the resin sheet, and the prepreg. By having the cured epoxy resin composition layer formed from the epoxy resin composition, it becomes a wiring board excellent in thermal conductivity and heat resistance.

  The said wiring board can be manufactured by carrying out circuit processing of the metal foil in the at least one metal foil in the resin cured body with metal foil as stated above, or a metal substrate. An ordinary photolithography method can be applied to the circuit processing of the metal foil.

  Preferred embodiments of the wiring board are, for example, the same as the wiring board described in paragraph No. 0064 of JP2009-214525A and the wiring boards described in paragraph Nos. 0056 to 0059 of JP2009-275086A. Can be mentioned.

<Power semiconductor device>
The resin sheet which is a sheet-like molded body of the epoxy resin composition of the present invention can be applied to, for example, a power semiconductor device. An example of a power semiconductor device configured using the resin sheet will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an example of the configuration of a power semiconductor device. In FIG. 1, the cured resin sheet 2 is disposed between the metal plate 6 and the heat dissipation base substrate 4 in the semiconductor module in which the metal plate 6, the solder layer 10, and the semiconductor chip 8 are laminated in this order, and the semiconductor module is sealed. Sealed with a stopper 14. FIG. 2 is a schematic cross-sectional view showing another example of the configuration of the power semiconductor device. In FIG. 2, the resin sheet cured body 2 is disposed between the metal plate 6 and the heat dissipation base substrate 4 in the semiconductor module in which the metal plate 6, the solder layer 10, and the semiconductor chip 8 are laminated in this order. The base substrate 4 is molded with a mold resin 12.
Thus, the cured body of the resin sheet, which is a sheet-like molded body of the epoxy resin composition of the present invention, can be used as a heat radiation adhesive layer between the semiconductor module and the heat radiation base substrate as shown in FIG. It is. In addition, when the whole is molded as shown in FIG. 2, it can be used as a heat dissipation material between the heat dissipation base substrate and the metal plate.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The material used for preparation of an epoxy resin composition and its abbreviation are shown below.
(Epoxy resin monomer)
Resin monomer A:

4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl 4- (2,3-epoxypropoxy) benzoate, epoxy equivalent: 212, production method: described in JP 2011-74366 A.

Resin monomer B:

  4- {4- (2,3-epoxypropoxy) phenyl} cyclohexyl 4- (2,3-epoxypropoxy) -3-methylbenzoate, epoxy equivalent: 219, production method: described in JP 2011-74366 A.

(Curing agent)
Curing agent 1 [catechol novolac resin, manufactured by Hitachi Chemical Co., Ltd., containing 50% cyclohexanone]

<Method for synthesizing curing agent 1>
Catechol 220g, 37% formaldehyde 81.1g, oxalic acid 2.5g, and water 100g were placed in a 2L separable flask equipped with a stirrer, cooler, and thermometer, and heated to about 100 ° C while heating in an oil bath. The temperature rose. The mixture was refluxed at around 104 ° C., and the reaction was continued at the reflux temperature for 3 hours. Thereafter, the temperature in the flask was raised to 150 ° C. while distilling off water. The reaction was continued for 12 hours while maintaining 150 ° C. After the reaction, concentration was performed under reduced pressure for 20 minutes, water in the system was removed, and a novolak resin as the target curing agent 1 was obtained.
When the structure of the obtained curing agent 1 was confirmed by FD-MS, the presence of the structure represented by the general formula (III-1) and the structure represented by the general formula (III-2) could be confirmed.

Curing agent 2 [catechol resorcinol novolak (preparation ratio: 30/70) resin, manufactured by Hitachi Chemical Co., Ltd., containing 50% cyclohexanone]

<Method for synthesizing curing agent 2>
462 g of resorcinol, 198 g of catechol, 316.2 g of 37% formaldehyde, 15 g of oxalic acid and 300 g of water are placed in a 3 L separable flask equipped with a stirrer, a cooler and a thermometer, and heated to 100 ° C. while heating in an oil bath. The temperature rose. The mixture was refluxed at around 104 ° C., and the reaction was continued at the reflux temperature for 4 hours. Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water. The reaction was continued for 8 hours while maintaining 170 ° C. After the reaction, concentration was performed under reduced pressure for 20 minutes to remove water and the like in the system, and a novolak resin as the target curing agent 2 was obtained.
When the structure was confirmed by FD-MS about the obtained hardening | curing agent 2, all presence of the structure represented by either of general formula (III-1)-(III-4) has been confirmed.

Curing agent 3 [catechol resorcinol novolak (preparation ratio: 5/95) resin, manufactured by Hitachi Chemical Co., Ltd., containing 50% cyclohexanone]

<Method for synthesizing curing agent 3>
Into a 3 L separable flask equipped with a stirrer, a cooler, and a thermometer, 627 g of resorcinol, 33 g of catechol, 316.2 g of 37% formaldehyde, 15 g of oxalic acid, and 300 g of water were heated to 100 ° C. while heating in an oil bath. The temperature rose. The mixture was refluxed at around 104 ° C., and the reaction was continued at the reflux temperature for 4 hours. Thereafter, the temperature in the flask was raised to 170 ° C. while distilling off water. The reaction was continued for 8 hours while maintaining 170 ° C. After the reaction, concentration was performed under reduced pressure for 20 minutes to remove water and the like in the system, and a novolak resin as the target curing agent 3 was obtained.
When the structure was confirmed by FD-MS about the obtained hardening | curing agent 3, all existence of the structure represented by either of general formula (III-1)-(III-4) has been confirmed.

In addition, about the said hardening | curing agents 1-3, the measurement of the physical-property value was performed as follows.
The number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured using a high performance liquid chromatography L6000 manufactured by Hitachi, Ltd. and a data analyzer C-R4A manufactured by Shimadzu Corporation. G2000HXL and G3000HXL manufactured by Tosoh Corporation were used as analytical GPC columns, the sample concentration was 0.2% by mass, tetrahydrofuran was used as the mobile phase, and measurement was performed at a flow rate of 1.0 ml / min. A calibration curve was prepared using a polystyrene standard sample, and the number average molecular weight (Mn) and the weight average molecular weight (Mw) were measured in terms of polystyrene using the standard curve.

The hydroxyl equivalent was measured by acetyl chloride-potassium hydroxide titration method. The determination of the titration end point was performed by potentiometric titration rather than coloration with an indicator because the solution color was dark. Specifically, the hydroxyl group of the phenol resin to be measured is acetylated with acetyl chloride in a pyridine solution, the excess reagent is decomposed with water, and the acetic acid produced is titrated with a potassium hydroxide / methanol solution to measure the hydroxyl group equivalent. did.
The physical property values of the curing agents 1 to 3 are shown below.

Curing agent 1: a mixture containing a compound having a structure represented by at least one of the general formulas (III-1) and (III-2), wherein Ar ³¹ and Ar ³² are represented by the general formula (III) A novolak resin (hydroxyl equivalent: 112, Mn: 400, Mw: 550) which is a group derived from 1,2-dihydroxybenzene (catechol) in which R ³¹ = OH and R ³² = R ³³ = H in -a) ) Novolac resin composition.

Curing agent 2: a mixture containing a compound having a structure represented by at least one of the general formulas (III-1) to (III-4), wherein Ar ^{31 to} Ar ³⁴ are represented by the general formula (III) A novolak which is a group derived from 1,2-dihydroxybenzene (catechol) or a group derived from 1,3-dihydroxybenzene (resorcinol), wherein R ³¹ = OH and R ³² = R ³³ = H in -a) It was a novolak resin composition containing a resin (hydroxyl equivalent: 108, Mn: 540, Mw: 1,000).

Curing agent 3: a mixture containing a compound having a structure represented by at least one of the general formulas (III-1) to (III-4), wherein Ar ^{31 to} Ar ³⁴ are represented by the general formula (III) -a) a in ^R 31 = ^OH, a group or a 1,3-dihydroxybenzene (group derived from resorcinol) derived from is ^R 32 ⁼ R ^{33 =} H 1,2- dihydroxybenzene (catechol), It was a novolak resin composition containing a novolak resin (hydroxyl equivalent: 62, Mn: 422, Mw: 564) containing 35% of a monomer component (resorcinol) as a low molecular diluent.

(Alumina filler)
AA-18 [α-alumina, manufactured by Sumitomo Chemical Co., Ltd., average particle diameter (D50): 18 μm]
AA-3 [α-alumina, manufactured by Sumitomo Chemical Co., Ltd., average particle size (D50): 3 μm]
AA-04 [α-alumina, manufactured by Sumitomo Chemical Co., Ltd., average particle diameter (D50): 0.4 μm]

(Elastomer)
・ REB122-4:

  Hitachi Chemical Co., Ltd., containing 55% ethyl lactate, production method: see JP 2010-106220 A.

(Additive)
[Curing accelerator]
・ TPP: Triphenylphosphine [silane coupling agent]
KBM-573: 3-phenylaminopropyltrimethoxysilane [manufactured by Shin-Etsu Chemical Co., Ltd.]

(Organic solvent)
・ MEK: Methyl ethyl ketone ・ CHN: Cyclohexanone

(Support)
PET film [Fujimori Industry Co., Ltd., 75E-0010CTR-4]
・ Copper foil [Furukawa Electric Co., Ltd., thickness: 80 μm, GTS grade]

Example 1
<Preparation of epoxy resin composition>
15.62 parts by mass of resin monomer A, 16.51 parts by mass of curing agent 1, 225.4 parts by mass of alumina filler (AA-18: 148.76 parts by mass (66% by volume), AA-3: 54 10 parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), 0.19 parts by mass of TPP, 0.24 parts by mass of KBM-573, and a total of 51 organic solvents. .44 parts by mass (MEK: 44.77 parts by mass, CHN: 6.67 parts by mass) were mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

The ratio of the alumina filler to the total volume of the epoxy resin monomer, the curing agent, and the alumina filler, where the density of the mixture of the resin monomer A and the curing agent 1 is 1.20 g / cm ³ and the density of the alumina filler is 3.97 g / cm ³ Was calculated to be 74% by volume.

<Preparation of semi-cured epoxy resin composition>
The epoxy resin varnish was applied on a PET film using an applicator so that the thickness after drying was 200 μm, and then dried at room temperature (20 ° C. to 30 ° C.) for 15 minutes and further at 130 ° C. for 5 minutes. Then, hot pressurization (press temperature: 130 ° C., vacuum degree: 1 kPa, press pressure: 1 MPa, pressurization time: 1 minute) is performed in a vacuum press, and a sheet-like semi-cured epoxy resin composition having a thickness of 190 μm I got a thing.

<Preparation of cured epoxy resin composition with copper foil>
After peeling off the PET film from the sheet-like semi-cured epoxy resin composition obtained above, the two copper foils are used so that the mat surfaces of the two copper foils face the semi-cured epoxy resin composition, respectively. The semi-cured epoxy resin composition was sandwiched, and vacuum thermocompression bonding (temperature: 150 ° C. to 180 ° C., vacuum degree: 1 kPa, press pressure: 4 MPa, pressurization time: 5 minutes) was performed with a vacuum press. Then, it heated at 140 degreeC for 2 hours, 165 degreeC for 2 hours, and also at 190 degreeC for 2 hours under atmospheric pressure conditions, and obtained the cured epoxy resin composition with copper foil.

<Measurement of thermal conductivity>
The copper foil of the cured epoxy resin composition with copper foil obtained above was removed by etching to obtain a sheet-shaped cured epoxy resin composition. The obtained cured epoxy resin composition was cut into a 10 mm square and blackened with a graphite spray, and then the thermal diffusivity was evaluated by a xenon flash method (LFA447 nanoflash manufactured by NETZSCH). The thermal conductivity of the cured epoxy resin composition was determined from the product of this value, the density measured by the Archimedes method, and the specific heat measured by DSC (DSC Pyris 1 manufactured by Perkin Elmer). The obtained thermal conductivity results are shown in Table 1.

<Measurement of glass transition temperature (Tg)>
The copper foil of the cured epoxy resin composition with copper foil obtained above was removed by etching to obtain a sheet-shaped cured epoxy resin composition. After the obtained cured epoxy resin composition was cut into 30 mm × 5 mm squares, Tg was determined from the peak of tan δ obtained from dynamic viscoelasticity measurement (DMA) (RSA III manufactured by TA Instruments). The obtained Tg results are shown in Table 1.

<Measurement of breakdown voltage>
The copper foil of the cured epoxy resin composition with copper foil obtained above was removed by etching to obtain a sheet-like cured epoxy resin composition, which was cut out with a size of 100 mm square or more to obtain a sample. Using a YST-243-100RHO made by Yamayo Tester Co., Ltd., the sample was sandwiched between cylindrical electrodes with a diameter of 25 mm, and the dielectric breakdown voltage was measured at a pressure increase rate of 500 V / s, room temperature, and air. Five or more points were measured, and the average value and the minimum value were obtained. The results obtained are shown in Table 1.

(Example 2)
15.82 parts by mass of resin monomer A, 16.12 parts by mass of curing agent 2, 225.4 parts by mass of alumina filler (AA-18: 148.76 parts by mass (66% by volume), AA-3: 54 10 parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), 0.19 parts by mass of TPP, 0.24 parts by mass of KBM-573, and a total of 51 organic solvents. .63 parts by mass (MEK: 44.77 parts by mass, CHN: 6.86 parts by mass) were mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

The density of the mixture of the resin monomer A and the curing agent 2 is 1.20 g / cm ³ , and the density of the alumina filler is 3.97 g / cm ³ , and the alumina filler with respect to the total volume of the epoxy resin monomer, the curing agent, and the alumina filler The ratio was calculated to be 74% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Example 3)
18.48 parts by mass of resin monomer A, 10.81 parts by mass of curing agent 3, and 225.4 parts by mass of alumina filler (AA-18: 148.76 parts by mass (66% by volume), AA-3: 54 10 parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), 0.19 parts by mass of TPP, 0.24 parts by mass of KBM-573, and a total of 54 organic solvents. .29 parts by mass (MEK: 44.77 parts by mass, CHN: 9.52 parts by mass) were mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

The density of the mixture of the resin monomer A and the curing agent 3 is 1.20 g / cm ³ , and the density of the alumina filler is 3.97 g / cm ³ , and the alumina filler with respect to the total volume of the epoxy resin monomer, the curing agent, and the alumina filler The ratio was calculated to be 74% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

Example 4
18.61 parts by mass of resin monomer B, 10.54 parts by mass of curing agent 3, and 225.4 parts by mass of alumina filler (AA-18: 148.76 parts by mass (66% by volume), AA-3: 54 10 parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), 0.19 parts by mass of TPP, 0.24 parts by mass of KBM-573, and a total of 54 organic solvents. .42 parts by mass (MEK: 44.77 parts by mass, CHN: 9.65 parts by mass) were mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

The density of the mixture of the resin monomer B and the curing agent 3 is 1.20 g / cm ³ , and the density of the alumina filler is 3.97 g / cm ^{3. The} alumina filler with respect to the total volume of the epoxy resin monomer, the curing agent, and the alumina filler The ratio was calculated to be 74% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Example 5)
18.49 parts by mass of resin monomer A, 10.78 parts by mass of curing agent 3, and 225.4 parts by mass of alumina filler (AA-18: 148.76 parts by mass (66% by volume), AA-3: 54 .10 parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), 2.65 parts by mass of REB122-4, 0.19 parts by mass of TPP, and 0.09 of KBM-573. A total of 42.37 parts by mass (MEK: 35.82 parts by mass, CHN: 6.55 parts by mass) of 24 parts by mass and an organic solvent were mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent.

The density of the mixture of the resin monomer A and the curing agent 3 is 1.20 g / cm ³ , and the density of the alumina filler is 3.97 g / cm ³ , and the alumina filler with respect to the total volume of the epoxy resin monomer, the curing agent, and the alumina filler The ratio was calculated to be 74% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Comparative Example 1)
17.55 parts by mass of YL6121H (manufactured by Mitsubishi Chemical Corporation), which is an epoxy resin monomer having a structure different from that of general formula (I), 12.65 parts by mass of curing agent 3, and 225.4 parts by mass of alumina filler (AA) -18: 148.76 parts by mass (66% by volume), AA-3: 54.10 parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), TPP 0.19 An epoxy resin composition containing an organic solvent by mixing mass parts, 0.24 parts by mass of KBM-573, and 53.36 parts by mass (MEK: 44.77 parts by mass, CHN: 8.59 parts by mass) of an organic solvent. An epoxy resin varnish was obtained as a product.

The density of the mixture of YL6121H a curing agent 3 1.20 g / cm ^3, and 3.97 g / cm ³ density of the alumina filler as, the proportion of alumina filler to the total volume of the curing agent and the alumina filler and epoxy resin monomer Was calculated to be 74% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Comparative Example 2)
1- (3-Methyl-4-oxiranylmethoxyphenyl) -4- (4-oxiranylmethoxyphenyl) -1-cyclohexene (epoxy equivalent: 201) which is an epoxy resin monomer having a structure different from that of the general formula (I) No. 4619770, hereinafter referred to as “resin monomer C”) is 18.25 parts by mass, curing agent 3 is 11.26 parts by mass, and alumina filler is 225.4 parts by mass (AA-18: 148.76 parts by mass (66% by volume), AA-3: 54.10 parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), 0.19 parts by mass of TPP, As an epoxy resin composition containing an organic solvent, 0.24 parts by weight of KBM-573 and 54.06 parts by weight (MEK: 44.77 parts by weight, CHN: 9.29 parts by weight) of an organic solvent are mixed. To obtain a sheet resin varnish.

The density of the mixture of the resin monomer C and the curing agent 3 is 1.20 g / cm ³ , and the density of the alumina filler is 3.97 g / cm ³ , and the alumina filler with respect to the total volume of the epoxy resin monomer, the curing agent, and the alumina filler The ratio was calculated to be 74% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Comparative Example 3)
16.02 parts by mass of resin monomer A, 7.86 parts by mass of curing agent TD-2131 (phenol novolac resin, manufactured by DIC Corporation), and 225.4 parts by mass of alumina filler (AA-18: 148.76 parts by mass) Parts (66% by volume), AA-3: 54.10 parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), 0.19 parts by mass of TPP, and KBM-573. A total of 59.69 parts by mass (MEK: 44.77 parts by mass, CHN: 14.92 parts by mass) of 0.24 parts by mass and an organic solvent was mixed to obtain an epoxy resin varnish as an epoxy resin composition containing an organic solvent. It was.

The density of the mixture of resin monomer A and TD-2131 is 1.20 g / cm ³ , and the density of the alumina filler is 3.97 g / cm ³ , and the alumina filler with respect to the total volume of the epoxy resin monomer, the curing agent, and the alumina filler The ratio was calculated to be 74% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

(Comparative Example 4)
18.96 parts by mass of resin monomer A, 4.92 parts by mass of catechol, and 225.4 parts by mass of alumina filler (AA-18: 148.76 parts by mass (66% by volume), AA-3: 54.10 Parts by mass (24% by volume), AA-04: 22.54 parts by mass (10% by volume)), 0.19 parts by mass of TPP, 0.24 parts by mass of KBM-573, and 59.69 parts by mass of the solvent. Parts (MEK: 44.77 parts by mass, CHN: 14.92 parts by mass) were mixed to obtain an epoxy resin varnish as an epoxy resin composition containing a solvent.

The density of the mixture of resin monomer A and catechol is 1.20 g / cm ³ , and the density of the alumina filler is 3.97 g / cm ³ , and the ratio of the alumina filler to the total volume of the epoxy resin monomer, the curing agent, and the alumina filler is The calculated volume was 74% by volume.

A semi-cured epoxy resin composition and a cured epoxy resin composition were prepared in the same manner as in Example 1 except that the epoxy resin varnish obtained above was used, and evaluated in the same manner as described above.
The results are shown in Table 1.

  From Table 1, it turns out that the cured epoxy resin composition of Examples 1-5 obtained by hardening | curing the epoxy resin composition of this invention is excellent in thermal conductivity compared with Comparative Examples 1-4. It can also be seen that the glass transition temperature is high and the heat resistance is excellent.

The disclosures of Japanese Patent Application No. 2011-241668, Japanese Patent Application No. 2012-090473 and International Application No. PCT / JP2011 / 075345 are incorporated herein by reference in their entirety.
All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference, Incorporated herein by reference.

Claims (15)

The epoxy resin composition containing the epoxy resin monomer represented by the following general formula (I), the hardening | curing agent containing the novolak resin which made the divalent phenol compound novolak, and the alumina filler containing alpha alumina.

[In General Formula (I), R ^{1 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms] 2. The epoxy resin composition according to claim 1 , wherein the curing agent has a content ratio of a monomer that is a phenol compound constituting the novolak resin of 5% by mass to 80% by mass. The epoxy resin composition according to claim 1 or 2 , wherein the content of the alumina filler is 60% by volume to 90% by volume in the entire volume. Furthermore, the epoxy resin composition of any one of Claims 1-3 containing the elastomer which has a structural unit represented by the following general formula (IV).

[In General Formula (IV), R ⁴¹ , R ⁴² and R ⁴³ each independently represents a linear or branched alkyl group or a hydrogen atom. R ⁴⁴ represents a linear or branched alkyl group. n4 represents an arbitrary integer] The epoxy resin composition according to claim 4 , wherein the elastomer contains an acrylic elastomer containing a structural unit represented by the following general formula (V).

[In the general formula (V), a, b, c and d represent the mol% of each structural unit in all structural units, and a + b + c + d = 90 mol% or more. R ⁵¹ and R ⁵² each independently represent a linear or branched alkyl group having a different carbon number. R ^{53 to} R ⁵⁶ each independently represent a hydrogen atom or a methyl group] The semi-hardened epoxy resin composition which is a semi-hardened body of the epoxy resin composition of any one of Claims 1-5 . The cured epoxy resin composition which is a hardening body of the epoxy resin composition of any one of Claims 1-5 . The resin sheet which is a sheet-like molded object of the epoxy resin composition of any one of Claims 1-5 . The prepreg which has a fiber base material and the epoxy resin composition of any one of Claims 1-5 impregnated in the said fiber base material. The epoxy resin composition according to any one of claims 1 to 5 , the resin sheet according to claim 8 , and the resin sheet according to claim 9 , which are disposed on the adherend and the adherend. A laminate having a semi-cured epoxy resin composition layer that is at least one semi-cured material selected from the group consisting of prepregs, or a cured epoxy resin composition layer that is a cured material. At least 1 selected from the group consisting of metal foil, the epoxy resin composition according to any one of claims 1 to 5 , the resin sheet according to claim 8 , and the prepreg according to claim 9. A metal substrate in which a cured epoxy resin composition layer, which is one cured body, and a metal plate are laminated in this order. At least 1 selected from the group which consists of a metal plate, the epoxy resin composition of any one of Claims 1-5 , the resin sheet of Claim 8 , and the prepreg of Claim 9. A wiring board in which a cured epoxy resin composition layer, which is one cured body, and a wiring layer are laminated in this order. The epoxy resin monomer represented by the following general formula (I), an epoxy resin composition containing a curing agent containing a novolak resin obtained by novolacizing a divalent phenol compound and an alumina filler containing α-alumina Providing and forming an epoxy resin layer;
A step of heat-treating the epoxy resin layer to form a semi-cured epoxy resin layer;
A method for producing a semi-cured epoxy resin composition.

[In General Formula (I), R ^{1 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms] The epoxy resin monomer represented by the following general formula (I), an epoxy resin composition containing a curing agent containing a novolak resin obtained by novolacizing a divalent phenol compound and an alumina filler containing α-alumina Providing and forming an epoxy resin layer;
A step of heat-treating the epoxy resin layer to form a semi-cured epoxy resin layer;
A step of heat-treating the semi-cured epoxy resin layer to form a cured epoxy resin layer;
The manufacturing method of the cured epoxy resin composition containing this.

[In General Formula (I), R ^{1 to} R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms] A semiconductor module in which a metal plate, a solder layer and a semiconductor chip are laminated in this order;
A heat dissipating member;
The cured body of the epoxy resin composition according to any one of claims 1 to 5 , which is disposed between the metal plate of the semiconductor module and the heat dissipation member,
Power semiconductor device including