JP2019155667A - Substrate and laminated substrate - Google Patents

Abstract

To provide a substrate and a laminate substrate for increasing thermal conductivity while maintaining adhesive strength to a metal foil.SOLUTION: There is provided a substrate containing a composite material containing an inorganic filler and a thermosetting resin, a fiber substrate and a cured product of a prepreg. In the composite material, the thermal conductivity of a cured product of a first composite material is higher than the thermal conductivity of a cured product of a second composite material and a cured product of a third composite material. In addition, the prepreg has an intermediate layer composed of a first composite material layer composed of the fiber substrate and the first composite material impregnated in the fiber substrate, a second composite material layer composed of the second composite material and a third composite material layer composed of the third composite material and the second composite material layer and the third composite material layer pinch the first composite material layer. When a thickness of the fiber substrate is defined as t, a thickness of a cured product of the first composite material layer is 1/2 t or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a substrate and a laminated substrate.

In recent years, the number of electronic devices mounted on automobiles has been increasing, and miniaturization of these electronic devices has been progressing rapidly. On the other hand, the amount of heat generated from a high-density conductor is increasing with downsizing, and how to dissipate heat is an important issue.
As a technology to improve the heat dissipation of printed circuit boards using conventional glass-epoxy resin, a copper plate is used on a metal base substrate that forms a circuit pattern on one or both sides of a metal substrate via an insulating layer, and a ceramic substrate such as alumina or aluminum nitride. There has been proposed a substrate in which these are directly bonded. It is difficult to balance the metal base substrate and the ceramic substrate in terms of performance and cost.
And in order to obtain the heat dissipation of the resin substrate, a resin composition in which the resin viscosity is lowered and an inorganic filler is filled at a high concentration, and a resin substrate have been proposed. For example, Patent Document 1 discloses a heat conductive sheet-like material that can be filled with an inorganic filler at a high concentration and excellent in heat dissipation and a heat conductive substrate using the same, and requires heat dissipation. It is thought that it is suitable for the substrate use.

Japanese Patent No. 3312723

  However, since the heat conductive substrate described in Patent Document 1 uses a resin substrate filled with an inorganic filler at a high concentration, the adhesion to a metal foil such as a copper foil is hindered by the inorganic filler, and the metal foil There is a problem that the adhesion strength with the lowering.

  This invention is made | formed in view of the said situation, and it aims at providing the board | substrate and laminated substrate which can raise thermal conductivity, maintaining the adhesive strength with metal foil.

  In order to solve the above problems, the present inventors provide the following means.

[1] A substrate containing a cured product of a prepreg,
The prepreg includes a composite material including an inorganic filler and a thermosetting resin, and a fiber base material,
The composite material includes a first composite material, a second composite material, and a third composite material,
The thermal conductivity of the cured product of the first composite material is higher than the thermal conductivity of the cured product of the second composite material and the cured product of the third composite material,
The prepreg includes the fiber base material, and an intermediate layer made of the first composite material layer made of the first composite material impregnated in the fiber base material,
A second composite material layer comprising the second composite material;
A third composite material layer comprising the third composite material;
Have
The second composite material layer and the third composite material layer sandwich the first composite material layer;
When the thickness of the fiber base material is t, the thickness of the cured product of the first composite material layer is 1/2 t or more.
A substrate characterized by that.
[2] The substrate according to [1], wherein the second composite material and the third composite material have the same material composition.
[3] A laminated substrate according to [1] or [2], comprising a cured product of a laminate having one or more prepregs.

  The first composite material impregnated in the fiber base material provided in the intermediate layer is made of metal by using a second composite material sandwiching the first composite material and a composite material having a higher thermal conductivity of the cured product than the third composite material. It is possible to provide a substrate and a laminated substrate that increase the thermal conductivity while maintaining the adhesion strength with the foil.

It is sectional drawing showing the structure of the prepreg used for the board | substrate of 1st embodiment of this invention. It is sectional drawing showing the structure of the prepreg used for the board | substrate of 2nd embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the board | substrate of 1st embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the multilayer substrate of 1st embodiment of this invention.

  Hereinafter, the present embodiment will be described in detail with appropriate reference to the drawings. In the drawings used in the following description, in order to make the characteristics of the present invention easier to understand, there are cases where the characteristic parts are enlarged for the sake of convenience, and the dimensional ratios of the respective components are different from actual ones. is there. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately modified and implemented without departing from the scope of the invention.

(substrate)
The substrate of the present invention contains a cured product of prepreg. The prepreg includes a composite material including an inorganic filler and a thermosetting resin, and a fiber base material. The composite material includes a first composite material, a second composite material, and a third composite material. The thermal conductivity of the cured product of the first composite material is higher than the thermal conductivity of the cured product of the second composite material and the cured product of the third composite material.
The prepreg includes the fiber base material, an intermediate layer made of the first composite material made of the first composite material impregnated in the fiber base material, and a second composite material layer made of the second composite material. And a third composite material layer made of the third composite material, and the second composite material layer and the third composite material layer sandwich the first composite material layer. The thickness of the cured material of the first composite material layer is 1/2 t or more, where t is the thickness of the fiber base material.

The fiber base material is a material necessary for maintaining the strength of the prepreg and the substrate, but the fiber base material uses a fiber base material because the thermal conductivity of the fiber base material is lower than the composite material of resin and inorganic filler. Since the thermal conductivity of the substrate is reduced by this, measures such as filling the inorganic filler at a high concentration are taken, but in this case, the adhesion of the copper foil is lowered.
In the present invention, by making the thermal conductivity of the composite material impregnated into the fiber base material higher than that of the surrounding composite material, the decrease in the thermal conductivity due to the fiber base material is eliminated, and the copper foil adhesion is maintained, A prepreg having high thermal conductivity can be obtained.
Moreover, it is preferable that the 2nd composite material and 3rd composite material which are used for the board | substrate of this invention consist of the same material composition. Since the second composite material layer and the third composite material layer are the same, there is no difference between the front and back of the adhesiveness of the copper foil, so that the (laminated) substrate of the present invention has improved thermal conductivity and adhesiveness. It is an excellent (laminated) substrate.

[First embodiment]
<Prepreg>
FIG. 1 is a schematic cross-sectional view of a prepreg 1 used for the substrate of this embodiment. A prepreg 1 shown in FIG. 1 includes an intermediate layer 10 including a first composite material layer 11 and a fiber base material 15, a second composite material layer 12, and a third composite material layer 13. 12 and the third composite material layer 13 are configured to sandwich the first composite material layer 11. The first composite material layer 11 is made of a first composite material impregnated in a fiber base material. When the thickness of the fiber base material 15 is t, the thickness of the cured product of the first composite material layer 11 is 1/2 t or more. The thickness of the cured product of the first composite material layer 11 is preferably 3/4 t or more, where t is the thickness of the fiber base material 15. If it is 1/2 t or more, a decrease in thermal conductivity due to the fiber substrate can be prevented, and if it is 3/4 t or more, the thermal conductivity is further improved, and if it is t or more, the fiber substrate is almost covered. Therefore, the thermal conductivity is further improved.
Further, the second composite material 12 used in the prepreg 1 according to the present embodiment may be the same as or different from the third composite material 13. The thermal conductivity of the cured product of the first composite material 11 is higher than the thermal conductivity of the cured product of the second composite material 12 and higher than the thermal conductivity of the cured product of the third composite material 13.

The preferable shape and physical properties of each component of the prepreg used for the substrate of this embodiment are as follows.
shape:
Fiber substrate thickness 20-200 μm (from the viewpoint of mechanical strength and dimensional stability)
Thickness of cured product of first composite material layer: 10 to 400 μm
Thickness of the cured product of the second composite material layer: 10 to 300 μm
Thickness of the cured product of the third composite material layer: 10 to 300 μm
In the prepreg 1, the cured product of the first composite material layer 11 and the thickness of the fiber substrate 15, the cured product of the first composite material layer 11, the cured product of the second composite material layer 12, and the third composite material. The method for evaluating the thermal conductivity of the cured product of the layer 13 will be described in detail in Examples.

<Composite material>
The composite material used for the prepreg of this embodiment contains an inorganic filler and a thermosetting resin.

"Inorganic filler"

The inorganic filler used for the prepreg of this embodiment is any one kind or two or more kinds of particulate inorganic materials. Specific examples of the inorganic filler include magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), boron nitride (BN), aluminum nitride (AlN), silica (SiO 2), and the like.
As the inorganic filler, magnesium oxide is preferable because it is inexpensive and has high thermal conductivity (42 to 60 W / (m · K)) and high volume resistivity (> 10 ¹⁴ Ω · cm).

The content rate of the filler contained in the composite material is not particularly limited. The filler is preferably contained in an amount of 40% by volume to 80% by volume in the total volume of the total solid content of the composite material. In the composite material, when the filler is contained at 40 volume% to 80 volume% in the entire volume, an effect of further increasing the thermal conductivity of the composite material is obtained.
The content of the filler is preferably 40% by volume to 70% by volume, and more preferably 45% by volume to 60% by volume from the viewpoint of improving thermal conductivity and fluidity.
Here, the total solid content of the composite material means a residue obtained by removing volatile components from the composite material.

The composite material used for the prepreg of the present embodiment includes a first composite material, a second composite material, and a third composite material. In the substrate described later, in order to improve the adhesion between the metal foil and the cured resin, the second composite material and the third composite material disposed in the surface layer of the prepreg have a filler content of 40% by volume to 70% in the total volume. It is preferable to contain by volume%. More preferably, it is contained in an amount of 40 to 60% by volume. Moreover, since the effect which raises the thermal conductivity of the below-mentioned board | substrate more is acquired, in the 1st composite material arrange | positioned at the intermediate | middle layer of a prepreg, a filler is contained by 50 volume%-80 volume% in the whole volume. It is preferable. More preferably, it is contained in an amount of 50% to 70% by volume.
The first to third composite materials used for the prepreg of the present embodiment use the same type of thermosetting resin or the same thermosetting resin, and the filler content of the first composite material is the second composite material and the third composite material. Larger is preferred. In that case, for example, in the first composite material, the filler is contained at 50 volume% to 70 volume% in the total volume, and in the second composite material and the third composite material, the filler is 40 volume% to 60 volume in the total volume. It is particularly preferable that it is contained in volume%.

  In addition, let the content rate (volume%) of the filler in this specification be the value calculated | required by following formula (1).

  Filler content (volume%) = (W1 / D1) / ((W1 / D1) + (W2 / D2) + Σ (Wi / Di)) × 100 (1)

Here, each variable is as follows.
W1: Mass composition ratio of filler (% by mass)
W2: Mass composition ratio (mass%) of thermosetting resin
Wi: Mass composition ratio (% by mass) of each other optional solid component other than the thermosetting resin
D1: Specific gravity of the filler D2: Specific gravity of the thermosetting resin Di: Specific gravity of each other optional solid component other than the thermosetting resin

  The said filler can be used individually by 1 type or in mixture of 2 or more types. For example, two or more kinds of fillers having different D50s, which are included in the range of the average particle diameter (D50) of 2 μm or more and 80 μm or less, can be used in combination, but are not limited to this combination.

"Thermosetting resin"

  Examples of the thermosetting resin according to this embodiment include an epoxy resin, a phenol resin, and a cyanate resin.

  The thermosetting resin of the present embodiment is not particularly limited as long as it is a compound having a thermosetting functional group, for example. Specific examples include epoxy resins, polyimide resins, polyamideimide resins, triazine resins, phenol resins, melamine resins, polyester resins, cyanate ester resins, and modified resins of these resins. These resins may be used alone or in combination of two or more.

  The thermosetting resin is preferably at least one resin selected from an epoxy resin, a phenol resin, and a triazine resin from the viewpoint of heat resistance, and more preferably an epoxy resin from the viewpoint of adhesiveness. The said epoxy resin may be used individually by 1 type, or may use 2 or more types together.

  The thermosetting resin may be a monomer or a prepolymer obtained by partially reacting the monomer with a curing agent or the like. For example, the resin having a mesogen group in the molecule is generally easy to crystallize and has a low solubility in a solvent as in the case of an epoxy resin having a mesogen group in the molecule described later, but it is polymerized by reacting partly. Since crystallization can be suppressed by making it, moldability may improve.

  It is preferable that the thermosetting resin used for the prepreg of this embodiment contains an epoxy resin.

<< Epoxy resin >>
The epoxy resin is any one kind or two or more kinds of compounds containing one or more epoxy groups (—C ₃ H ₅ O) in one molecule. Especially, it is preferable that the epoxy resin contains two or more epoxy groups in one molecule. The epoxy resin may be a monomer or a prepolymer obtained by partially reacting the monomer with a curing agent or the like.

  The type of epoxy resin is not particularly limited. For example, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, novolak type epoxy resin, cyclic aliphatic type epoxy resin and long chain aliphatic type epoxy resin Etc.

  Examples of the glycidyl ether type epoxy resin include bisphenol A type epoxy resin and bisphenol F type epoxy resin. Examples of the novolac type epoxy resin include a cresol novolac type epoxy resin and a phenol novolac type epoxy resin. In addition, the type of epoxy resin may be, for example, a flame retardant epoxy resin, a hydantoin epoxy resin, an isocyanurate epoxy resin, or the like.

  In addition, the specific example of a glycidyl ether type epoxy resin will not be specifically limited if it is a compound containing the structure (group) of a glycidyl ether type. Thus, the kind is not limited as long as a specific structure is included, and the same applies to specific examples of other epoxy resins such as a glycidyl ester type epoxy resin.

  Especially, it is preferable that the epoxy resin contains the mesogenic skeleton in one molecule. The reason is as follows.

  First, since the benzene rings easily overlap each other in the molecules of the epoxy resin, the distance between the benzene rings becomes small. Thereby, the density of an epoxy resin improves in the composite material containing an epoxy resin. In addition, since the cured epoxy resin is less likely to scatter molecular lattice vibration, high thermal conductivity can be obtained.

  The “mesogenic skeleton” is a general term for an atomic group including two or more aromatic rings and having rigidity and orientation. Specifically, the mesogenic skeleton is, for example, a skeleton that includes two or more benzene rings and in which the benzene rings are bonded to each other through either a single bond or a non-single bond.

  When three or more benzene rings are bonded, the direction of bonding is not particularly limited. That is, three or more benzene rings may be bonded so as to be linear, or may be bonded so as to be bent one or more times in the middle, or bonded so as to branch in two or more directions. May be.

  “Non-single bond” is a generic name for a divalent group containing one or more constituent elements and one or more multiple bonds. Specifically, the non-single bond includes, for example, any one or more of constituent elements such as carbon (C), nitrogen (N), oxygen (O), and hydrogen (H). . Non-single bonds include one or both of double bonds and triple bonds as multiple bonds.

  The mesogen skeleton may contain only a single bond, may contain only a non-single bond, or may contain both a single bond and a non-single bond as the type of bond between benzene rings. . Further, the number of non-single bonds may be only one, or two or more.

  Specific examples of the mesogenic skeleton include biphenyl and terphenyl. The terphenyl may be o-terphenyl, m-terphenyl, or p-terphenyl.

  As a specific example of the thermosetting resin used for the prepreg of this embodiment, for example, YL-6121H manufactured by Mitsubishi Chemical Corporation (tetramethylbiphenol type epoxy resin 50%, 4,4′-biphenol type epoxy resin 50% mixture, Epoxy equivalent 175 g / eq), Nippon Kayaku Co., Ltd. BREN105 (brominated polyfunctional epoxy resin, epoxy equivalent 271 g / eq), Nippon Steel & Sumikin Chemical Co., Ltd. YH434L (tetrafunctional polyglycidylamine, epoxy equivalent 122 g / eq), 830-S (bisphenol F type epoxy resin, epoxy equivalent 173 g / eq) manufactured by DIC Corporation FX289Z (phosphorus-modified epoxy resin, epoxy equivalent 225 g / eq) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.

The thermosetting resin is preferably contained in an amount of 20% by volume to 60% by volume in the total volume of the total solid content of the composite material from the viewpoints of moldability, adhesiveness, and thermal conductivity, and is 30% by volume. It is more preferably contained at ˜60% by volume, and further preferably contained at 40% by volume to 55% by volume.
In addition, when the said composite material contains the below-mentioned hardening | curing agent and hardening accelerator, the content rate of these hardening | curing agents and hardening accelerator shall be included in the content rate of a thermosetting resin here.

"Curing agent"
It is preferable that the composite material of this embodiment further includes at least one curing agent. The curing agent is not particularly limited as long as the thermosetting resin can be thermoset. Examples of the curing agent when the thermosetting resin is an epoxy resin include polyaddition curing agents such as acid anhydride curing agents, amine curing agents, phenol curing agents, and mercaptan curing agents, and imidazole. And the like, and the like.
Among these, from the viewpoint of heat resistance, it is preferable to use at least one selected from amine-based curing agents and phenol-based curing agents, and from the viewpoint of storage stability, it is preferable to use at least one phenol-based curing agent. More preferred.

  As the amine curing agent, those usually used can be used without particular limitation, and those commercially available may be used. Among these, a polyfunctional curing agent having two or more functional groups is preferable from the viewpoint of curability, and a polyfunctional curing agent having a rigid skeleton is more preferable from the viewpoint of thermal conductivity.

  Examples of the bifunctional amine-based curing agent include 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, 4,4′-diamino-3,3′-dimethoxybiphenyl. 4,4′-diaminophenylbenzoate, 1,5-diaminonaphthalene, 1,3-diaminonaphthalene, 1,4-diaminonaphthalene, 1,8-diaminonaphthalene and the like. Among these, from the viewpoint of thermal conductivity, at least one selected from 4,4′-diaminodiphenylmethane and 1,5-diaminonaphthalene is preferable, and 1,5-diaminonaphthalene is more preferable.

  As a phenol type hardening | curing agent, what is normally used can be especially used without a restriction | limiting, The commercially available low molecular phenol compound and the phenol resin which made them novolak-ized can be used.

  Examples of the low molecular weight phenol compound include monofunctional compounds such as phenol, o-cresol, m-cresol and p-cresol, bifunctional compounds such as catechol, resorcinol and hydroquinone, and 1,2,3-tri Trifunctional ones such as hydroxybenzene, 1,2,4-trihydroxybenzene, 1,3,5-trihydroxybenzene, 1,3,5-tris (4-hydroxyphenyl) benzene can be used. In addition, a phenol novolac resin obtained by connecting these low molecular phenol compounds with a methylene chain to form a novolak can also be used as a curing agent.

  As the phenol-based curing agent, 1,3,5-tris (4-hydroxyphenyl) benzene, which is a polyfunctional low-molecular phenol curing agent, is preferable from the viewpoint of thermal conductivity, heat resistance, solvent solubility, and the like.

  When the composite material of the present embodiment includes a curing agent, the content of the curing agent in the composite material is not particularly limited. For example, when the curing agent is an amine curing agent, the ratio of the active hydrogen equivalent (amine equivalent) of the amine curing agent to the epoxy equivalent of the epoxy resin (amine equivalent / epoxy equivalent) is 0.5 to 2. It is preferable that it will become 0.8-1.2. Further, when the curing agent is a phenolic curing agent, the ratio of the active hydrogen equivalent of the phenolic hydroxyl group (phenolic hydroxyl group equivalent) to the epoxy equivalent of the mesogen-containing epoxy resin (phenolic hydroxyl group equivalent / epoxy equivalent) is 0. 0.5 to 2 is preferable, and 0.8 to 1.2 is more preferable.

"Curing accelerator"
When using a phenol type hardening | curing agent in the composite material of this embodiment, you may use a hardening accelerator together as needed. By using a curing accelerator in combination, it can be further sufficiently cured. Although the kind and compounding quantity of a hardening accelerator are not specifically limited, An appropriate thing can be selected from viewpoints, such as reaction rate, reaction temperature, and storage property. Specific examples of the curing accelerator include imidazole compounds, organic phosphorus compounds, tertiary amines, and quaternary ammonium salts. These may be used alone or in combination of two or more.

  When the composite material includes a curing accelerator, the content of the curing accelerator in the composite material is not particularly limited. From the viewpoint of moldability, it is preferably 0.5% by mass to 1.5% by mass of the total mass of the thermosetting resin and the curing agent, more preferably 0.5% by mass to 1% by mass, More preferably, it is 0.75 mass%-1 mass%.

"Silane coupling agent"
The composite material 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 filler or the second filler and the thermosetting resin surrounding it (equivalent to a binder agent), and heat is efficiently It contributes to the improvement of insulation reliability by preventing the infiltration of moisture and moisture.

  It does not specifically limit as a kind of said silane coupling agent, You may use a commercially available thing. In consideration of reducing the thermosetting resin (preferably an epoxy resin), compatibility with a curing agent contained as necessary, and reducing heat conduction defects at the interface between the resin and the filler, It is preferable to use a silane coupling agent having an epoxy group, amino group, mercapto group, ureido group, or hydroxyl group at the terminal. These silane coupling agents may be used alone or in combination of two or more.

"Other ingredients"
The composite material in the present invention may contain other components as necessary in addition to the above components. For example, an elastomer, a dispersing agent, etc. are mentioned. Examples of the elastomer include an acrylic resin, and more specifically, a homopolymer or a copolymer derived from (meth) acrylic acid or a (meth) acrylic ester. Examples of the dispersant include Ajinomoto Finetech Co., Ltd. Ajisper series, Enomoto Kasei Co., Ltd. HIPLAAD series, Kao Corporation homogenol series, and the like. Two or more kinds of these dispersants can be used in combination.

"Slurry of composite materials"
For example, when a solid thermosetting resin is used as the composite material, at least one organic solvent may be added to adjust the slurry of the composite material. By including an organic solvent, it can be adapted to various molding processes. As the organic solvent, a commonly used organic solvent can be used. Specific examples include alcohol solvents, ether solvents, ketone solvents, amide solvents, aromatic hydrocarbon solvents, ester solvents, nitrile solvents, and the like. For example, methyl isobutyl ketone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, γ-butyrolactone, sulfolane, cyclohexanone, methyl ethyl ketone and the like can be used. These may be used alone or as a mixed solvent using two or more kinds in combination.

"Semi-cured composite material"
The semi-cured composite material of the present invention (sometimes simply referred to as “composite material”) is derived from the composite material, and is obtained by semi-curing the composite material. For example, when the semi-cured composite material is formed into a sheet shape, the handleability is improved as compared with a composite material sheet made of a composite material that is not semi-cured. From this viewpoint, it is preferable that the composite material formed in the prepreg of the present embodiment is a semi-cured composite material.

  Here, the semi-cured composite material can maintain a sheet shape at room temperature, but melts when heated to a high temperature of about 100 ° C. Further, the cured composite material to be described later is not melted by heating. The viscosity is measured by a rotary rheometer (for example, Rheo Stress 6000 manufactured by Thermo Scientific Co., Ltd.). 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 composite material at a temperature of 60 ° C. to 200 ° C. for 1 minute to 30 minutes.

"Hardened composite material"
The cured product of the composite material is derived from the composite material, and is obtained by curing the composite material. The cured product of the composite material is excellent in thermal conductivity and insulation. The substrate and laminated substrate of one embodiment of the present invention are formed by curing the prepreg of the present embodiment, for example, and a cured product of the composite material formed by curing the composite material used for the prepreg of the present embodiment. Including.

The cured product of the composite material can be produced by curing the uncured composite material or the semi-cured composite material. The method of the curing treatment can be appropriately selected according to the composition of the composite material, the purpose of the cured product, etc., but is preferably a heating / pressurizing treatment.
For example, the cured material of the composite material can be obtained by heating the uncured composite material or the semi-cured composite material at 100 ° C. to 250 ° C. for 1 hour to 10 hours, preferably 130 ° C. to 230 ° C. for 1 hour to 8 hours. can get.

<Fiber base>
The fiber base material according to the present embodiment is not particularly limited as long as it is normally used when producing a metal foil-clad laminate or a multilayer printed wiring board, and a fiber base material such as a woven fabric or a nonwoven fabric is usually used. It is done.

  The opening of the fiber base material according to the present embodiment is not particularly limited. From the viewpoint of thermal conductivity and insulating properties, the mesh opening is preferably twice or more the average particle diameter (D50) of the filler. Moreover, it is preferable that the porosity of a fiber base material is 30% or more. The porosity of a fiber base material is the ratio of the area of the opening part with respect to the area of a fiber base material.

  The material of the fiber base material is not particularly limited. Specifically, inorganic fibers such as glass, alumina, boron, silica alumina glass, silica glass, tyrano, silicon carbide, silicon nitride, zirconia, aramid, polyether ether ketone, polyether imide, polyether sulfone, carbon , Organic fibers such as cellulose, and mixed papers thereof. Among these, glass fiber woven fabric is preferably used. Thereby, for example, when a substrate is formed using a prepreg, a flexible and arbitrarily bendable substrate can be obtained. Furthermore, it becomes possible to reduce the dimensional change of the multilayer substrate accompanying the temperature change and moisture absorption in the manufacturing process.

  The thickness of the fiber base material according to the present embodiment is not particularly limited. From the viewpoint of imparting better flexibility, it is more preferably 75 μm or less, and from the viewpoint of impregnation, it is preferably 60 μm or less. Although the minimum of the thickness of a fiber base material is not restrict | limited in particular, Usually, it is about 10 micrometers.

<Intermediate layer>
The intermediate layer of the prepreg of this embodiment includes a fiber base material and a layer made of the first composite material (first composite material layer). As the first composite material, a composite material having higher thermal conductivity than the second composite material and the third composite material described later is used. Examples of a method for adjusting composite materials having different thermal conductivities include a method using different thermosetting resin types, different filler types, and different filler volume contents. For example, when using a composite material containing the same thermosetting resin and the same filler, a method of adjusting the volume content of the filler is preferable.

  An intermediate | middle layer can be formed using the sheet | seat for intermediate | middle layers which consists of a fiber base material and a 1st composite material, for example.

  The intermediate layer sheet is obtained, for example, by impregnating the first composite material into the fiber base as described above. Specifically, the first composite material is impregnated into the fiber base material, and the first composite material impregnated into the fiber base material is heat-dried to obtain an intermediate layer sheet including the first composite material layer.

The amount of impregnation (content rate) of the first composite material in the intermediate layer sheet is such that the thickness of the cured product of the first composite material layer is 1/2 t (0 .5t) or more, there is no particular limitation. The thickness is preferably 0.7 t or more, and more preferably 0.9 t or more, from the viewpoint of reducing the decrease in thermal conductivity due to the fiber substrate by covering the fiber substrate with the first composite material. In addition, from the viewpoint of alignment accuracy of the multilayer substrate, formability, and metal foil adhesion, it is preferably 2 t or less, more preferably 1.5 t or less, and even more preferably 1.1 t or less. For example, when the thickness of the fiber substrate is 100 μm, there is no particular limitation as long as the thickness of the cured product of the first composite material layer is 50 μm or more, and the thickness is 70 μm or more. Is preferable, and it is more preferable that it is 90 micrometers or more.
In addition, the method to measure the thickness of the hardened | cured material of a 1st composite material layer and a fiber base material is demonstrated in detail in the below-mentioned Example.

  There is no restriction | limiting in particular in the method of impregnating a fiber base material with a 1st composite material. For example, the method of apply | coating with a coating machine can be mentioned. Specifically, a vertical coating method in which the fiber base material is pulled through the first composite material, and a horizontal coating method in which the first composite material is coated on the support film and then impregnated by pressing the fiber base material. Can be mentioned.

  Specifically, as the first composite material, for example, when each of the epoxy resin and the curing agent contained in the first composite material is solid, the first composite material is pulverized and mixed into a powder form. An intermediate layer sheet can be obtained by heating and melting one composite material and impregnating the fiber base material into the melted first composite material.

  In addition, when a solvent such as methyl ethyl ketone or cyclohexanone is added to the first composite material to make a slurry of the first composite material, the fiber base material is impregnated in the slurry of the first composite material. Thereafter, the solvent is removed by drying, and the resin composition is solidified.

The drying method is not particularly limited as long as at least a part of the organic solvent contained in the slurry can be removed, and can be appropriately selected from commonly used drying methods according to the organic solvent contained in the slurry. In general, a heat treatment method at about 60 ° C. to 150 ° C. can be exemplified.
Solidification at this time means that the liquid material having fluidity changes to a solid state in which it can stand on its own. A state in which the organic solvent contained in the slurry partially remains and a semi-cured state can be included in the solidified state. For example, it can be solidified at 60 to 150 ° C. for about 1 to 120 minutes, preferably at 70 to 120 ° C. for about 3 to 90 minutes.

  The term “the first composite material impregnated in the fiber base material” in the present invention means the mutual relationship between the fiber base material and the first composite material, and the fiber base material or the intermediate layer sheet is specified. It is not meant to be limited by a simple manufacturing method. For example, in the prepreg 1 shown in FIG. 1 which is an example of the prepreg of the present embodiment, the intermediate layer 10 is formed so as to fill the first composite material into the gap formed between the fibers of the fiber base material 15. Has been. Part or all of the fiber base material 15 is included in the first composite material layer 11.

  In that sense, the method of impregnating the fiber base material with the first composite material of the present invention is particularly limited as long as it can be formed so that a part of the voids of the fiber base material is filled with the first composite material. There is nothing. For example, the intermediate layer sheet is formed by spreading the molten first composite material or the slurry of the first composite material on one surface or both surfaces of the fiber base material by coating or the like, and then allowing to cool or cool. Can be obtained. Further, using a sheet made of the first composite material (not including the fiber base material) obtained by the same method as that of the second composite material sheet described later, this sheet is placed on one or both sides of the fiber base material. The intermediate layer sheet can be produced by a method such as hot pressing so that the first composite material fills at least a part of the voids of the fiber base material.

<Second composite material layer>
The second composite material sheet is made of a second composite material containing a second inorganic filler and a second thermosetting resin. The cured product of the second composite material has a lower thermal conductivity than the cured product of the first composite material. As the second composite material, a different kind of inorganic filler and a different kind of thermosetting resin can be used. Also, different types of inorganic fillers and the same type of thermosetting resin may be used as the first composite material, or the same types of inorganic filler and different types of thermosetting resin may be used as the first composite material. Good. It is preferable to use the same kind of inorganic filler and the same kind of thermosetting resin as the first composite material. For example, when using the same type of inorganic filler and the same type of thermosetting resin as the first composite material, the filler content (volume%) of the second composite material is equal to the filler content (volume) of the first composite material. %), A second composite material having a thermal conductivity lower than that of the first composite material can be obtained.

  The second composite material layer can be produced by laminating with the intermediate layer sheet using a second composite material sheet. The second composite material sheet is formed by forming the second composite material into a sheet shape. The second composite material sheet can be produced, for example, by applying the composite material on a release film and removing the solvent contained as necessary. By forming the resin sheet from the composite material, the resin sheet is excellent in thermal conductivity, fluidity, and flexibility.

  The thickness of the second composite material sheet is not particularly limited and can be appropriately selected according to the purpose. For example, the thickness of the cured sheet can be 10 μm to 400 μm, and is 20 μm to 100 μm from the viewpoints of formability, metal foil adhesion, thermal conductivity, electrical insulation, and flexibility. Is preferred.

  The second composite material sheet is, for example, a slurry of a composite material prepared by adding an organic solvent such as methyl ethyl ketone or cyclohexanone to a release film such as a PET film (hereinafter, simply referred to as “slurry”). Can be produced by removing at least a part of the organic solvent from the coating layer and drying.

  The slurry can be applied by a known method. Specific examples include methods such as comma coating, die coating, lip coating, and gravure coating. As a coating method for forming a composite material layer with a predetermined thickness, a comma coating method in which an object to be coated is passed between gaps, a die coating method in which a composite material slurry whose flow rate is adjusted from a nozzle, or the like is applied. . For example, when the thickness of the coating layer (composite material 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 slurry can be removed, and can be appropriately selected from commonly used drying methods according to the organic solvent contained in the slurry. In general, a heat treatment method at about 60 ° C. to 150 ° C. can be exemplified.

  Since the composite material layer of the second composite material sheet hardly undergoes a curing reaction, the composite material layer has flexibility, but has low flexibility as a sheet, and in the state where the PET film as a support is removed, the sheet is self-supporting. It is difficult to handle. When manufacturing the prepreg of the present embodiment using the second composite material sheet, for example, the second composite material sheet and the support are laminated in that order on the first composite material sheet, and then the support. There is a way to remove.

  The second composite material sheet is preferably a semi-cured resin composition obtained by semi-curing a resin composition constituting the second composite material sheet. That is, the resin sheet is preferably a semi-cured second composite material sheet that is further heat-treated until it is semi-cured. When the resin sheet is composed of a semi-cured composite material obtained by semi-curing the composite material, the resin sheet is excellent in thermal conductivity and electrical insulation, and is excellent in flexibility and pot life.

  The conditions for heat-treating the resin sheet can be appropriately selected according to the structure of the resin composition. For the heat treatment, a heat treatment method selected from hot vacuum press, hot roll laminating and the like is preferable for the purpose of eliminating voids in the resin composition layer generated during coating.

  In addition, the second composite material layer is formed by using the above-described intermediate layer sheet in place of the release film such as the PET film in the same manner, on the intermediate layer sheet. ) Can also be formed.

<Third composite material layer>
The third composite material layer is made of a third composite material containing a third inorganic filler and a third thermosetting resin. The cured product of the third composite material has a lower thermal conductivity than the cured product of the first composite material. As the third composite material, a different kind of inorganic filler and a different kind of thermosetting resin can be used. Also, different types of inorganic fillers and the same type of thermosetting resin may be used as the first composite material, or the same types of inorganic filler and different types of thermosetting resin may be used as the first composite material. Good. It is preferable to use the same kind of inorganic filler and the same kind of thermosetting resin as the first composite material. For example, when using the same type of inorganic filler and the same type of thermosetting resin as the first composite material, the filler content (volume%) of the third composite material is the filler content (volume) of the first composite material. %), A third composite material having a thermal conductivity lower than that of the first composite material can be obtained.

  A method similar to the method for manufacturing the third composite material layer and the method for manufacturing the second composite material layer described above can be used.

  When manufacturing the third composite material layer (sheet) directly on the intermediate layer sheet having the first composite material layer, when the second composite material layer is formed on one surface of the intermediate layer sheet, the other surface A third composite material layer may be formed on the top.

<Method for producing prepreg>
The manufacturing method of the prepreg used for the substrate of the present embodiment is particularly limited as long as the second composite material layer and the third composite material layer can be formed on both sides of the intermediate layer having the first composite material layer and the fiber base material, respectively. Absent. For example, the second composite material sheet, the intermediate layer sheet, and the third composite material sheet are stacked in that order and heated and pressed at a predetermined temperature and a predetermined pressure. A prepreg is obtained.

    Next, a method for manufacturing the prepreg 1 shown in FIG.

As an example of the manufacturing method of the prepreg 1, the following processes are included, for example.
(I) a step of forming a sheet for intermediate layer by the same method as above,
(II) forming a second composite material sheet in the same manner as described above,
(III) forming a third composite material sheet by the same method as above,
(IV) A step of laminating the second composite material sheet, the third composite material sheet, and the intermediate layer sheet in that order.

As another example of the manufacturing method of the prepreg 1, for example, the following steps are included.
(I) a step of forming a sheet for intermediate layer by the same method as above,
(II) A step of forming the second composite material layer 12 on one surface of the intermediate layer sheet in the same manner as the second composite material sheet manufacturing method, except that the intermediate layer sheet is used instead of the release film. ,
(III) The third composite material is formed on the other surface of the intermediate layer sheet in the same manner as the third composite material sheet manufacturing method, except that the sheet obtained in (II) is used instead of the release film. Forming the layer 13;

As another example of the manufacturing method of the prepreg 1, for example, the following steps are included.
(I) A step of impregnating the fiber base material 15 with the first composite material and forming the first composite material layer 11 in the same manner as described above,
(II) forming a second composite material layer 12 on one surface of the first composite material layer 11;
(III) forming a third composite material layer 13 on the other surface of the first composite material layer 11;
(IV) A step of drying and semi-curing the first composite material layer 11 to the third composite material layer 13.

  The prepreg may be used after the surface is smoothed in advance by hot pressing with a press, a roll laminator or the like before being laminated or pasted. The method of the hot press treatment is the same as the method mentioned in the method for producing the semi-cured composite material sheet. In addition, the processing conditions such as the heating temperature, the degree of pressure reduction, and the press pressure in the hot press treatment of the prepreg are the same as those mentioned in the heat and press treatment of the semi-cured composite material.

  When the prepreg is produced using a slurry of composite material, the solvent remaining rate in the prepreg is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and 0.8 More preferably, it is at most mass%.

  The solvent residual rate is determined from the change in mass 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.

  Specific examples of the prepreg used in the substrate of this embodiment are shown in Table 1.

Epoxy resin A: Epoxy resin (YL-6121H manufactured by Mitsubishi Chemical Corporation)
Curing agent A: (1,3,5-tris (4-hydroxyphenyl) benzene)
Epoxy resin B: Epoxy resin (YH434L manufactured by Nippon Steel & Sumikin Co., Ltd.)
Curing agent B: (HE200 manufactured by Air Water Co., Ltd.)
Epoxy resin C: Epoxy resin (830-S manufactured by DIC Corporation)
Curing agent C: (4,4′-diaminodiphenylmethane)

<Board>
The substrate of this embodiment is obtained by curing the above-described prepreg and includes a cured product of the prepreg. Moreover, the hardened | cured material contains the hardened | cured material and inorganic filler of the thermosetting resin of this invention. That is, the substrate of the present invention includes a cured product of the first composite material, a cured product of the second composite material, a cured product of the third composite material, and a fiber base material. The substrate of this embodiment may further have a metal foil such as a copper foil. Since the prepreg used for the substrate of this embodiment is a cured substrate, a substrate with high thermal conductivity can be obtained.
The substrate of this embodiment is obtained by curing a prepreg used for the substrate of this embodiment. As shown in FIGS. 3A to 3C, for example, the metal foil 35 is provided on both surfaces of the prepreg 1, and the substrate 5 can be formed by a heating press / molding process. The metal foil 35 of the substrate 5 can be further processed by a circuit forming process such as patterning. Hereinafter, the substrate 5 will be described in detail with reference to FIG.

  The board | substrate 5 is comprised by the hardened | cured material of the prepreg 1 shown, for example in FIG. A metal foil 35 is further laminated on the surface layer to form a metal foil-clad substrate. The metal foil 35 may be attached to only one surface or may be attached to both surfaces.

  In the example shown in FIG. 3, the number of prepregs 1 used for the substrate 5 is one, but the number is not limited to one and may be two or more. This number can be appropriately set based on conditions such as the thickness and strength of the resin prepreg 1.

  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 a high thermal conductivity and a large heat capacity. Specific examples include copper, aluminum, iron, and alloys used for lead frames.

  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 aluminum when priority is given to weight reduction and workability, and copper when priority is given to heat dissipation.

  In the said board | substrate 5, in order to raise metal foil (copper foil) peel strength, there may exist the pre-process of surface-treating metal foil by the conventionally well-known method.

The conditions for pressing and molding the metal foil 35 and the prepreg 1 are not particularly limited as long as the uncured and semi-cured thermosetting resin of the prepreg 1 can be cured. Unlike the prepreg manufacturing method described above, it is preferable that the conditions are such that the curing reaction substantially proceeds. 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 20 MPa, preferably in the range of 1 MPa to 15 MPa. Moreover, a vacuum press is used suitably for a heating and pressurizing process.
The adhesion strength must be high so that the metal foil and the cured prepreg are not easily peeled off. The adhesion strength can be measured by a metal foil peel strength (peeling strength) described later.

  The substrate of this embodiment has a thermal conductivity of 3 W / (m · K) or more, and the adhesion between the metal (copper foil) and the cured product of the thermosetting resin is based on the result of evaluation by the adhesion evaluation method described later. High nature.

[Second Embodiment]
FIG. 2 is a schematic cross-sectional view of the prepreg 2 used for the substrate of this embodiment. The prepreg 2 shown in FIG. 2 includes an intermediate layer 20 including a first composite material layer 21 and a fiber base material 25, a second composite material layer 22, and a third composite material layer 23, and includes a second composite material layer. 22 and the third composite material layer 23 are configured to sandwich the first composite material layer 21. The first composite material layer 21 is made of a first composite material impregnated in a fiber base material. When the thickness of the fiber substrate 25 is t, the thickness of the cured product of the first composite material layer 21 is 1/2 t or more. The first composite material layer 21 is preferably 3/4 t or more, and more preferably t or more, where t is the thickness of the fiber base 25.
The second composite material 22 used in the prepreg 2 shown in FIG. 2 which is an example of the prepreg according to the present embodiment is a composite material having the same composition as the third composite material 23. The thermal conductivity of the first composite material 21 is higher than the thermal conductivity of the second composite material 22. About others, it is the same as the prepreg 1 used for the board | substrate of 1st embodiment shown in FIG.

  Specific examples of the prepreg used for the substrate of this embodiment are shown in Table 2.

Epoxy resins A to C: Table 1
Curing agents A to C: Table 1

  The substrate of this embodiment can be produced by the same method as that of the first embodiment except that the prepreg used for the substrate of this embodiment is used.

(Laminated substrate)
The laminated substrate of the present invention is obtained by laminating and curing one or more prepregs, and includes a cured product of the prepreg laminate. The cured product includes a cured product of a thermosetting resin and an inorganic filler. That is, the laminated substrate of the present invention includes a cured product of the first composite material, a cured product of the second composite material, a cured product of the third composite material, and a fiber base material. The laminated substrate of the present invention may further have a metal foil. Since it is the board | substrate which hardened | cured the prepreg of this invention, a board | substrate with high heat conductivity is obtained.
The laminated substrate of one embodiment of the present invention is obtained by curing a prepreg used for the substrate of the first embodiment or the second embodiment of the present invention. As shown in FIGS. 4 (a) to (c), for example, two prepregs 1 used for the substrate of the first embodiment of the present invention are used to provide metal foil 35 on both sides, and by a hot press / molding step, A laminated substrate 7 can be formed. The metal foil 35 of the substrate 7 can be further processed by a circuit forming process such as patterning.

  As shown in FIGS. 4D to 4F, the laminated substrate 7 is further heated by using four prepregs 1 used for the substrate of the first embodiment of the present invention and providing a metal foil 35 on the outside. The laminated substrate 9 can be formed by a pressing / molding process. The metal foil 35 of the laminated substrate 9 can be further processed by a circuit formation process such as patterning.

  In the example shown in FIG. 4, the number of the prepregs 1 used for the laminated substrate 7 is two, but the number is not limited to two, and may be one or three or more. This number can be appropriately set based on conditions such as the thickness and strength of the resin prepreg 1. Moreover, although the number of the prepregs 1 used for the laminated substrate 9 is six, it is not limited to six, but may be four, five, or seven or more.

  The metal foil used for the laminated substrates 7 and 9, heating press and molding conditions are the same as those of the substrate 5.

  The thickness of the multilayer substrate of the present invention is preferably 5000 μm or less, and more preferably 200 μm to 3000 μm. When the thickness is 5000 μm or less, the flexibility is excellent and the generation of cracks during bending is suppressed, and when the thickness is 3000 μm or less, the tendency is more visible. Further, when the thickness is 200 μm or more, the workability is excellent.

  The laminated substrate of the present invention has a thermal conductivity of 3 W / m · K or more, and the adhesion between the metal (copper foil) and the cured product of the thermosetting resin is determined from the result of evaluation by the adhesion evaluation method described later. high.

  Embodiments of the present invention will be described in detail.

Example 1
<Sheet for intermediate layer having first composite material layer>
The following materials were prepared as the first composite material.
As a thermosetting resin, epoxy resin (tetramethylbiphenol type epoxy resin 50%, 4,4′-biphenol type epoxy resin 50% mixture, epoxy equivalent 175 g / eq, YL-6121H manufactured by Mitsubishi Chemical Corporation) 60 parts by mass
Curing agent (1,3,5-tris (4-hydroxyphenyl) benzene (THPB), active hydrogen equivalent 118 g / eq) 40 mass parts
Curing accelerator (2-ethyl-4-methylimidazole, 2E4MZ, manufactured by Shikoku Chemicals Co., Ltd.) 1 part by weight as an organic solvent, methyl ethyl ketone 50 parts by weight These materials were added to a medialess disperser (Desperm MD-10, manufactured by Asada Tekko Co., Ltd.) The mixture was stirred and stirred to prepare a resin mixture. Next, magnesium oxide powder (average particle size 30 μm, thermal conductivity 45 W / (m · K)) was added to the resin mixture as an inorganic filler, and well stirred and dispersed to prepare a slurry of the first composite material. At this time, the magnesium oxide powder was adjusted to 65 volume% (hereinafter referred to as filling factor) when the solid content volume obtained by removing methyl ethyl ketone from the slurry of the first composite material was 100 volume%. Further, a glass fiber woven fabric (IPC standard 1080, manufactured by Arisawa Manufacturing Co., Ltd.) having a thickness of 0.05 mm as a fiber base material is impregnated in the slurry of the first composite material, and then the first composite material layer is formed in the prepreg. The thickness of the cured product was adjusted to 0.025 mm. Methyl ethyl ketone was removed by heating and drying at 100 ° C. to obtain an intermediate layer sheet including the first composite material layer and the fiber base material.

<Second composite material sheet>
The second composite material is the same as the first composite material except that the filler type is magnesium oxide powder (average particle size 30 μm, thermal conductivity 45 W / (m · K)) and the filling rate is 52 vol%. A slurry was prepared.
After applying the slurry of the second composite material to the surface of the support (PET film, thickness = 0.05 mm), the liquid second composite material was dried (temperature = 100 ° C.). Thereby, since the 2nd composite material layer was formed in the surface of a support body, the 2nd composite material sheet (thickness = 0.06mm) which is a single layer body was obtained.

<Third composite material sheet>
The third composite material is the same as the second composite material except that the filler type is magnesium oxide powder (average particle size 30 μm, thermal conductivity 45 W / (m · K)) and the filling rate is 48% by volume. A slurry was prepared.
A third composite sheet was obtained in the same manner as the second composite sheet.
<Prepreg>
The obtained second composite material sheet and the third composite material sheet were laminated at 100 ° C. so as to sandwich the obtained intermediate layer sheet, thereby forming a prepreg 1.

<Board>
As shown in FIGS. 4A to 4C, two prepregs 1 obtained in this embodiment are stacked and heated and pressurized (temperature 170) so that the prepreg 1 is sandwiched between two copper foils 35. In addition, the second heating and pressurization (temperature 200 ° C., 4 MPa for 1 hour) is performed, and an inorganic filler-containing epoxy resin cured product having a thickness of 0.3 mm is provided ( Lamination) A substrate 7 was obtained. A (laminated) substrate 7 having a wiring pattern was formed by an etching method.

<Laminated substrate>
As shown in FIGS. 4D to 4F, two prepregs are arranged on both surfaces of the (laminated) substrate 7 having the obtained wiring pattern, and two copper foils are used ( Lamination) After placing the substrate 7 in between, heating and pressing (temperature 170 ° C., 20 minutes at 1 MPa) are performed, and in addition, the second heating and pressing (temperature 200 ° C., 4 MPa for 1 hour) is performed. The laminated substrate 9 provided with the inorganic filler containing epoxy resin hardened | cured material of thickness 0.9mm was obtained. A wiring pattern was formed on both surfaces by an etching method, and a laminated substrate 9 having the wiring pattern was formed.

(Example 2)
A glass fiber woven fabric having a thickness of 0.05 mm as a fiber base material is impregnated with the solution of the first composite material so that the thickness of the cured product of the first composite material layer becomes 0.05 mm in the subsequent prepreg. Except for the adjustment, the intermediate layer sheet of this example was obtained in the same manner as in Example 1.
Moreover, the (laminated | stacked) board | substrate of a present Example was obtained by the method similar to Example 1 except having used the sheet | seat for intermediate | middle layers of a present Example.

(Example 3)
The intermediate layer of this example is the same as Example 2 except that the filler filling rate of the second composite material is 50% by volume and the third composite material is the same composite material as the second composite material. A sheet was obtained.
Moreover, the (laminated | stacked) board | substrate of a present Example was obtained by the method similar to Example 1 except having used the sheet | seat for intermediate | middle layers of a present Example.

(Comparative Example 1)
The intermediate layer sheet of this comparative example was obtained in the same manner as in Example 2 except that the filler filling rate of the first composite material, the second composite material, and the third composite material was 55% by volume.
Moreover, the prepreg and laminated substrate of this comparative example were obtained in the same manner as in Example 1 except that the intermediate layer sheet of this comparative example was used.

(Comparative Example 2)
A glass fiber woven fabric having a thickness of 0.05 mm as a fiber substrate was impregnated with the solution of the first composite material, and the thickness of the first composite material layer was adjusted to 0.017 mm in the subsequent prepreg. The intermediate layer sheet of this comparative example was obtained in the same manner as in Example 3 except for the above.
Moreover, the prepreg and laminated substrate of this comparative example were obtained in the same manner as in Example 1 except that the intermediate layer sheet of this comparative example was used.

(Comparative Example 3)
Except that the filler filling rate of the first composite material was 53% by volume and the filler filling rate of the second composite material and the third composite material was 56% by volume, the same method as in Example 2 was used. An intermediate layer sheet was obtained.
Moreover, the prepreg and laminated substrate of this comparative example were obtained in the same manner as in Example 1 except that the intermediate layer sheet of this comparative example was used.

(Evaluation methods)
When the characteristics of the prepreg, the substrate, and the laminated substrate were examined, the results shown in Table 3 were obtained. Here, the moldability of the prepreg was examined, and the thermal conductivity of the (laminated) substrate and the adhesion with the copper foil were examined.

<Thermal conductivity of cured composite material>
The evaluation method of the heat conductivity of the hardened | cured material of Examples 1-3 and Comparative Examples 1-3 of the 1st composite material-3rd composite material is as follows.
After applying the slurry of the composite material to be evaluated to the surface of the support (PET film, thickness = 0.05 mm) so that the cured material thickness of the composite material is 0.1 mm, the liquid composite The material was dried (temperature = 100 ° C.). Thereby, a composite material layer was formed on the surface of the support, and a composite material sheet as a single layer body was obtained. After that, the composite material layer is peeled off from the support, and 10 single composite material layers are stacked and heated and pressed (temperature 170 ° C., 1 MPa for 20 minutes). (Temperature 200 ° C., 4 MPa for 1 hour), and a cured composite material having a thickness of 1.0 mm was obtained. The thermal conductivity of the cured product was measured in the same manner as described below for “thermal conductivity of substrate”. As a result, the thermal conductivity of the cured product of the composite material to be evaluated was obtained.
For example, a cured product of the first composite material of Example 1 was obtained under the above curing conditions. It was 5.0 W / (m * K) when the heat conductivity of this hardened | cured material was measured. As a result, as shown in Table 3, the thermal conductivity of the cured product of the first composite material of Example 1 was 5.0 W / (m · K).

<Thermal conductivity of the substrate>
The evaluation methods of the thermal conductivity of the substrates of Examples 1 to 3 and Comparative Examples 1 to 3 are as follows.
Six prepregs to be evaluated are stacked and heated and pressed (temperature 170 ° C., 20 minutes at 1 MPa), and then the second heating and pressing (temperature 200 ° C., 4 MPa for 1 hour) is performed. A cured product (substrate) having a thickness of 870 to 900 μm was obtained. The obtained substrate was cut to prepare a circular measurement sample (diameter = 10 mm, thickness = 0.87 to 0.9 mm). Subsequently, the measurement sample was analyzed using a thermal conductivity measuring device (TC series manufactured by Advance Riko Co., Ltd. (formerly ULVAC Riko Co., Ltd.)), and the thermal diffusion coefficient α (m ² / s) was measured. Further, the specific heat Cp of the measurement sample was measured using differential scanning calorimetry (DSC) using sapphire as a standard sample. Furthermore, the density r of the measurement sample was measured using the Archimedes method. Finally, the thermal conductivity λ (W / (m · K)) was calculated based on the following formula (2).

λ = α × Cp × r (2)
(Λ is thermal conductivity (W / (m · K)), α is thermal diffusivity (m ² / s), Cp is specific heat (J / kg · K), and r is density (kg / m ³ ). .)

<Strength of copper foil beer on the substrate>
(Measurement of copper foil peel strength)
In accordance with JIS C6481, a test piece (150 mm x 150 mm x 10 mm) with a circuit width of 10 mm (laminated) substrate (laminated) substrate was used and pulled in the direction perpendicular to the copper foil at a speed of 50 mm / min. The value divided by the thickness was defined as the copper foil peel strength. The unit is kN / m.

<Thickness of cured product of first composite material layer>
After cutting the substrate in the thickness direction and polishing the cut cross section, the substrate was observed with a scanning electron microscope (SEM), and the thickness of the fiber base material and the thickness of the cured product of the first composite material layer were measured. .

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and omission of configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible.

1, 2, ... prepreg,
5 ... Substrate (Laminated substrate)
7, 9 ... Multilayer substrate 10, 20 ... Intermediate layer,
12, 22 ... second composite material layer,
11, 21 ... first composite material layer,
13, 23 ... third composite material layer,
15, 25 ... fiber base material,
35 ... Metal foil.

Claims (3)

A substrate containing a cured product of prepreg,
The prepreg includes a composite material including an inorganic filler and a thermosetting resin, and a fiber base material,
The composite material includes a first composite material, a second composite material, and a third composite material,
The thermal conductivity of the cured product of the first composite material is higher than the thermal conductivity of the cured product of the second composite material and the cured product of the third composite material,
The prepreg includes the fiber base material, and an intermediate layer made of the first composite material layer made of the first composite material impregnated in the fiber base material,
A second composite material layer comprising the second composite material;
A third composite material layer comprising the third composite material;
Have
The second composite material layer and the third composite material layer sandwich the first composite material layer;
When the thickness of the fiber base material is t, the thickness of the cured product of the first composite material layer is 1/2 t or more.
A substrate characterized by that.   The substrate according to claim 1, wherein the second composite material and the third composite material have the same material composition.   It is a board | substrate of Claim 1 or Claim 2, Comprising: The laminated substrate characterized by including the hardened | cured material of the laminated body which has one or more of the said prepregs.

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