JP2013040062A - Hexagonal boron nitride powder, thermally conductive resin composition containing the same, and molded product obtained by the resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hexagonal boron nitride powder that has high fluidity and high heat conductivity, which can impart both features of low viscosity and high thermal conductivity to a thermally conductive resin composition.SOLUTION: The hexagonal boron nitride powder has a crystal diameter (Lc) in a plane 002 of 450 [Å] or larger and a crystal diameter (La) in a plane 100 of 500 [Å] or larger, wherein: the crystal diameter (Lc) and the crystal diameter (La) satisfy the formula (1): 0.70≤Lc/La; and the oxygen content is 0.30 wt.% or lower.

Description

  The present invention relates to a hexagonal boron nitride powder, a thermally conductive resin composition containing the powder, and a molded body formed thereby.

  In recent years, various problems have been pointed out toward higher density of electronic devices, and one of them is a problem of heat dissipation from a device such as a transistor or a wiring. This problem is caused by the fact that the heat conduction of the filler composition used for semiconductor device chips is generally very low compared to metals, ceramics, etc., and there is a concern about performance degradation due to heat storage in the semiconductor device chips. ing.

  One technique for solving this problem is to increase the thermal conductivity of the filler composition. In this technique, the filler composition is obtained by combining the resin constituting the filler composition with the highly thermal conductive inorganic filler. The material is made highly thermally conductive to form a thermally conductive resin composition.

  On the other hand, a technique using boron nitride powder has been conventionally known as a high thermal conductive inorganic filler. As such boron nitride, for example, boron nitride powder having a specific particle size and particle size distribution is known. (For example, Patent Document 1). In addition to this, a technique using two types of mixed boron nitride having different particle characteristics such as surface area, particle size, and tap density (for example, Patent Document 2) is known.

In addition, hexagonal boron nitride (hereinafter also referred to as h-BN) powder is known as a material having excellent thermal conductivity. After washing the crude hexagonal boron nitride powder with water, it is 1500 in an inert gas stream. A technique for producing highly crystalline boron nitride by heat treatment at ˜1800 ° C. is known (Patent Document 3). In this technique, the crystallite size (La) of 100 faces of boron nitride crystallites is grown.
Patent Document 4 describes that a specific treatment is performed on a crude hexagonal boron nitride powder to obtain a hexagonal boron nitride powder having a large particle diameter and excellent lubricity. Patent Document 5 also discloses that a 002-plane crystallite is obtained by mixing a crude hexagonal boron nitride powder with a compound containing lanthanum as a main component and heat-treating it in a specific temperature range in a non-oxidizing gas atmosphere. Hexagonal boron nitride powder obtained by growing the size (Lc) is described, and this hexagonal boron nitride powder is described as having excellent dispersibility and high crystallinity.
Regarding hexagonal boron nitride, Patent Document 6 discloses that when specific firing is performed after curing a crude hexagonal boron nitride powder in an air atmosphere at 60 ° C. or lower for 1 week or longer, the particle size is large and the crystallinity is high. Patent Document 7 describes that a crude hexagonal boron nitride powder is cured in an air atmosphere at 60 ° C. or lower for 1 week or longer and then washed and then subjected to a specific baking treatment. The hexagonal boron nitride powder grown to an average particle size of 10 μm or more is described.

JP 2008-189818 A Special table 2010-505729 Japanese Patent Laid-Open No. 61-7260 JP-A-9-263402 Japanese Patent Laid-Open No. 9-295801 JP 2010-37123 A JP 2010-42963 A

  In the heat conductive resin composition containing the heat conductive particles and the resin, for example, from the viewpoint of productivity of a molded product using the resin, the content of the heat conductive particles is required to be low. In particular, in order to achieve high thermal conductivity, when a thermal conductive resin composition containing thermal conductive particles and a resin contains a large amount of boron nitride as the thermal conductive particles, the viscosity of the composition increases. Thus, there is a problem that the molding processability is lowered. Therefore, in the present invention, hexagonal nitriding having high fluidity and high thermal conductivity capable of imparting both low viscosity and high thermal conductivity properties to the thermally conductive resin composition. An object is to provide boron powder.

  As a result of intensive studies by the inventors, the crystallite size (Lc) of the 002 plane is 450 [Å] or more, the crystallite size (La) of the 100 plane is 500 [Å] or more, and the crystallite size ( Lc) and the crystallite size (La) satisfy the following relational expression (1), 0.70 ≦ Lc / La (1), and the oxygen content is 0.30% by weight or less. It has been found that the crystal boron nitride powder can solve the above problems, and the present invention has been achieved.

That is, the present invention is as follows.
[1] The crystallite diameter (Lc) of the 002 plane is 450 [Å] or more, the crystallite diameter (La) of the 100 plane is 500 [Å] or more, and the crystallite diameter (Lc) and the crystallite Hexagonal boron nitride powder having a diameter (La) satisfying the following relational expression (1), 0.70 ≦ Lc / La (1), and an oxygen content of 0.30 wt% or less.
[2] The hexagonal boron nitride powder according to [1], wherein the hexagonal boron nitride powder has an average particle size of 10 μm or less.
[3] A thermally conductive resin composition comprising the hexagonal boron nitride powder according to [1] or [2] and a resin.
[4] A molded article obtained by molding the thermally conductive resin composition according to [3].

  According to the present invention, the hexagonal boron nitride powder of the present invention has high fluidity and high thermal conductivity. Therefore, the heat conductive resin composition containing the hexagonal boron nitride powder and the resin of the present invention is not impaired in thermal conductivity even when the content of the hexagonal boron nitride powder is similar to the conventional one, Also, a sufficiently low viscosity is obtained. Alternatively, even when the content of the hexagonal boron nitride powder is made larger than before, not only high thermal conductivity can be obtained, but also a sufficiently low viscosity can be obtained. From this, the said heat conductive resin composition is excellent in moldability, and the molded object obtained by shape | molding this has high heat conductivity.

  Hereinafter, the present invention will be described in detail with reference to embodiments, examples, etc., but the present invention is not limited to the following embodiments, examples, etc., and can be arbitrarily set within the scope of the present invention. Can be changed and implemented.

The crystallite size referred to in the present invention is the crystallite diameter of each of the 002 and 100 planes, and the crystallite diameter (Lc) of the 002 plane is the half width of the peak at 2θ = 26.5 ° of X-ray diffraction. Can be obtained by the following equation (2). Similarly, the crystallite diameter (La) of the 100 plane is obtained by the following formula (2) by measuring the half width of the peak of 2θ = 41.5 ° of X-ray diffraction.
L (Å) = (0.9λ · 180) / (β · cosθ · π) (2)
λ: 1.54056Å
β: Peak half width

The hexagonal boron nitride powder of the present invention has a crystallite size (La) of 100 faces of 500 [Å] or more. When this La is 500 [Å] or more, the crystallite interface is sufficiently reduced, and high thermal conductivity can be obtained. This La is more preferably 550 [Å] or more, and particularly preferably 600 [Å] or more, from the viewpoint of further increasing the thermal conductivity.
On the other hand, from the viewpoint of industrial productivity, La is preferably 2000 [Å] or less, and more preferably 1000 [Å] or less.
This La is prepared, for example, by heat-treating a hexagonal boron nitride powder having a La of less than 500% at a high temperature of 1800 ° C. to 2300 ° C. in a non-oxidizing gas during the production of the hexagonal boron nitride powder of the present invention. In order to increase La, a method of performing heat treatment for a long time under conditions as high as possible in the above temperature range can be employed.

The hexagonal boron nitride powder of the present invention has a 002-plane crystallite size (Lc: hexagonal network area layer direction) of 450 [Å] or more. When Lc is 450 [Å] or more, the crystallite interface is sufficiently reduced, and high thermal conductivity can be obtained. This Lc is more preferably 470 [Å] or more, and particularly preferably 500 [Å] or more, from the viewpoint of further increasing the thermal conductivity.
On the other hand, from the viewpoint of industrial productivity, Lc is preferably 2000 [Å] or less, and more preferably 1000 [Å] or less.
In the production of the hexagonal boron nitride powder of the present invention, this Lc is prepared, for example, by heat-treating hexagonal boron nitride having an Lc of less than 450% at a high temperature of 1800 ° C. to 2300 ° C. in a non-oxidizing gas. In order to increase Lc, a method can be used in which the raw material hexagonal boron nitride having an oxygen content of less than 1.0% by weight is used.

In the hexagonal boron nitride powder of the present invention, the relationship between Lc and La satisfies the following relational expression (1).
0.70 ≦ Lc / La (1)
The relational expression (1) indicates the shape anisotropy of the hexagonal boron nitride powder of the present invention. The closer Lc / La is to 1, the smaller the shape anisotropy is. When the hexagonal boron nitride powder of the present invention satisfies the above-mentioned relational expression (1), it can be prevented that the viscosity of the composition increases when it is contained in the composition together with the resin. The relationship between Lc and La is more preferably 0.75 ≦ Lc / La, and particularly preferably 0.78 ≦ Lc / La.
On the other hand, the relationship between Lc and La is preferably Lc / La ≦ 1.2 from the viewpoint of reducing shape anisotropy.

The hexagonal boron nitride powder of the present invention has an oxygen content of 0.30% by weight or less. When the oxygen content of the hexagonal boron nitride powder is 0.30% by weight or less, when this is contained in the composition together with the resin, the thermal conductivity of the composition becomes preferable. The oxygen content is more preferably 0.25% by weight or less, and particularly preferably 0.15% by weight or less. On the other hand, the lower limit of the oxygen content is usually 0.01 weight or more.
Setting the oxygen content of the hexagonal boron nitride powder of the present invention in such a range can be achieved by firing in a non-oxidizing gas atmosphere in the process for producing the hexagonal boron nitride powder described below. In order to reduce the oxygen content, firing in a nitrogen gas atmosphere is particularly preferable.
In the present invention, the oxygen content of the hexagonal boron nitride powder can be measured by an inert gas melting-infrared absorption method using a HORIBA oxygen / nitrogen analyzer.

The hexagonal boron nitride powder of the present invention preferably has an average particle size of 10 μm or less. In addition, the hexagonal boron nitride powder of the present invention preferably has an average particle size of 7 μm or less, more preferably 5 μm or less, and particularly preferably 4 μm or less. On the other hand, the average particle size is preferably 0.1 μm or more from the viewpoint of obtaining good thermal conductivity and good fluidity.
The heat conductive resin composition of the present invention can impart high heat conductivity to the heat conductive resin composition by containing hexagonal boron nitride powder having high heat conductivity. Therefore, for example, when a molded body formed by molding this is used as a filling layer between semiconductor substrates, the semiconductor device can be stably stabilized by promoting the heat conduction between the semiconductor substrates and lowering the temperature of the semiconductor device substrate. It becomes possible to operate.
The average particle diameter of the hexagonal boron nitride powder in the present invention can be measured, for example, by dispersing it in an appropriate solvent and using a Horiba laser diffraction / scattering particle size distribution analyzer LA-920. The average particle size of the hexagonal boron nitride powder can be obtained from the obtained particle size distribution. The average particle diameter referred to here is a volume-based average particle diameter. Similarly, the average particle size of the hexagonal boron nitride powder in the heat conductive resin composition can be dispersed in a suitable solvent and measured with the same apparatus as described above.

For example, in a highly integrated three-dimensional integrated circuit to which the molded article of the present invention can be applied, the thickness of the layer between chips made of the heat conductive resin composition is as small as about 10 to 50 μm. . Therefore, when the particle size of the hexagonal boron nitride powder blended in the thermally conductive resin composition exceeds 10 μm, the hexagonal boron nitride powder protrudes on the surface of the layer after curing, and the surface shape of the layer tends to deteriorate. is there.
On the other hand, if the particle size of the hexagonal boron nitride powder is too small, the number of necessary heat conduction paths increases and the probability of connecting from the top to the bottom in the thickness direction between the chips decreases, and the epoxy resin having high heat conductivity and Even if combined, the thermal conductivity in the thickness direction of the layer becomes insufficient. On the other hand, if the particle size of the hexagonal boron nitride powder is too small, the hexagonal boron nitride powder tends to aggregate and the dispersibility in the heat conductive resin composition becomes poor.
Here, by setting the average particle diameter of the hexagonal boron nitride powder within the above range, excessive aggregation between the hexagonal boron nitride powders can be suppressed, and a layer having sufficient thermal conductivity in the thickness direction can be obtained. it can.

In addition, the hexagonal boron nitride powder may be agglomerated immediately after synthesis and may not satisfy the above particle size range. Therefore, it is preferable to use the hexagonal boron nitride powder after pulverization so as to satisfy the above particle size range.
The method of pulverizing the hexagonal boron nitride powder is not particularly limited, and a conventionally known pulverization method such as jet mixing and the like can be applied together with a pulverizing medium such as zirconia beads.
Further, the hexagonal boron nitride powder may be appropriately subjected to a surface treatment in order to improve dispersibility in the heat conductive resin composition.

<Method for producing hexagonal boron nitride powder>
Examples of raw materials used to obtain the hexagonal boron nitride powder of the present invention include commercially available hexagonal boron nitride, commercially available α and β-boron nitride, boron nitride prepared by a reduction nitriding method of boron compound and ammonia, boron Any of boron nitride synthesized from a compound and a nitrogen-containing compound such as melamine and boron nitride produced from sodium borohydride and ammonium chloride can be used without limitation, but hexagonal boron nitride is particularly preferably used.
Among these raw materials, the hexagonal boron nitride powder is a hexagonal boron nitride powder so that the hexagonal boron nitride powder of the present invention has a predetermined crystallite size, and particularly La is 300 [３００] or more, more preferably, It is particularly preferable to use a material having Lc of 250 [Å] or more and Lc / La of 0.8 to 1.0.

The hexagonal boron nitride powder of the present invention can be obtained by firing the above raw material at a temperature of 1800 ° C. to 2300 ° C. in a non-oxidizing gas atmosphere.
As the non-oxidizing gas, nitrogen gas, helium gas, argon gas, ammonia gas, carbon monoxide and the like can be used, and nitrogen gas is particularly preferably used.
The firing time is about 1 hour to 20 hours, more preferably 3 to 15 hours, and particularly preferably 5 to 15 hours.
The firing temperature and firing time can be determined by appropriately adjusting so that Lc and La of the hexagonal boron nitride powder of the present invention simultaneously increase.
The furnace used for firing is particularly preferably a carbon furnace, and the crucible into which the hexagonal boron nitride powder is put during firing is particularly preferably made of carbon.
In addition, an additive may be added in the firing so long as the desired crystal growth of the hexagonal boron nitride powder is not inhibited.

<Thermal conductive resin composition>
The heat conductive resin composition of the present invention contains the hexagonal boron nitride powder of the present invention and a resin.
The content of hexagonal boron nitride powder in the heat conductive resin composition of the present invention is preferably 35 to 80% by weight. By setting the content of the boron nitride powder to 35% by weight or more, the thermal conductivity of the molded body by the heat conductive resin composition tends to be a preferable value. On the other hand, when the content of the hexagonal boron nitride powder is 80% by weight or less, the moldability of the thermally conductive resin composition is suitably maintained, and a uniform molded product tends to be obtained. The content of the hexagonal boron nitride powder is more preferably 40% by weight or more and 70% by weight or less from the viewpoint of increasing the thermal conductivity in the molded body.

Although the resin is contained in the heat conductive resin composition of this invention, this resin is an organic compound also including an oligomer and a monomer. When an oligomer or monomer is contained, it can be cured at the time of molding the resin.
As such an organic compound, any polymerizable organic compound (curable resin monomer), a polymer thereof, a thermoplastic resin, and rubber can be used without limitation.
The curable resin monomer may be any polymerizable monomer such as thermosetting, photocurable, and electron beam curable. However, in terms of heat resistance, water absorption, dimensional stability, the thermosetting resin monomer may be used. Particularly preferable examples include an epoxy resin monomer and a silicone resin monomer.

  Examples of the thermoplastic resin include polyolefin resins such as polyethylene resin, polypropylene resin, and ethylene-vinyl acetate copolymer resin, polyester resins such as polyethylene terephthalate resin, polybutylene terephthalate resin, and liquid crystal polyester resin, polyvinyl chloride resin, and phenoxy. Resins, acrylic resins, polycarbonate resins, polyphenylene sulfide resins, polyphenylene ether resins, polyamide resins, polyamideimide resins, polyimide resins, polyetheramideimide resins, polyetheramide resins, and polyetherimide resins. Moreover, copolymers, such as those block copolymers and a graft copolymer, are also contained.

  Examples of the rubber component include natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, butadiene-acrylonitrile copolymer rubber. , Isobutylene-isoprene copolymer rubber, chloroprene rubber, silicone rubber, fluorine rubber, chlorosulfonated polyethylene, and polyurethane rubber.

As the resin, it is preferable to use an epoxy resin from the viewpoint of the heat resistance of the molded body described later.
The epoxy resin may be only an epoxy resin having one type of structural unit, but a plurality of epoxy resins having different structural units may be combined.
Here, in combination with coating properties or film-forming properties and adhesiveness, in order to obtain a highly heat-conductive cured product by reducing voids at the time of bonding, at least a phenoxy resin (hereinafter referred to as “epoxy resin” (to be described later) as an epoxy resin. A) ”is preferably included, and it is particularly preferable that the weight ratio of the epoxy resin (A) to the total amount of the epoxy resin is in the range of 5 to 95% by weight. More preferably, it is contained in the range of 10 to 90% by weight, still more preferably 20 to 80% by weight.
Hereinafter, the epoxy resin (A) will be described.

(Epoxy resin (A))
The phenoxy resin usually refers to a resin obtained by reacting an epihalohydrin and a dihydric phenol compound, or a resin obtained by reacting a divalent epoxy compound and a divalent phenol compound. Among these, a phenoxy resin which is a high molecular weight epoxy resin having a weight average molecular weight of 10,000 or more is particularly referred to as an epoxy resin (A).

  The epoxy resin (A) is preferably a phenoxy resin having at least one skeleton selected from the group consisting of naphthalene skeleton, fluorene skeleton, biphenyl skeleton, anthracene skeleton, pyrene skeleton, xanthene skeleton, adamantane skeleton and dicyclopentadiene skeleton. . Among them, a phenoxy resin having a fluorene skeleton and / or a biphenyl skeleton is particularly preferable because the heat resistance is further improved.

As described above, the epoxy resin may include a plurality of epoxy resins having different structural units.
The epoxy resin other than the epoxy resin (A) is preferably an epoxy resin having two or more epoxy groups in the molecule (hereinafter sometimes referred to as “epoxy resin (B)”). Bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, phenol aralkyl type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene Various epoxy resins, such as a type epoxy resin, a glycidyl ester type epoxy resin, a glycidyl amine type epoxy resin, and a polyfunctional phenol type epoxy resin, can be mentioned.
These can be used alone or as a mixture of two or more.

  The average molecular weight of the epoxy resin (B) is preferably 100 to 5000, more preferably 200 to 2000, from the viewpoint of controlling the melt viscosity. When the average molecular weight is lower than 100, the heat resistance tends to be inferior. When the average molecular weight is higher than 5000, the melting point of the epoxy resin increases, and the workability tends to decrease.

  In addition, the epoxy resin composition of the present invention may contain an epoxy resin other than the epoxy resin (A) and the epoxy resin (B) (hereinafter referred to as “other epoxy resin”) as long as the purpose is not impaired. . The content of the other epoxy resin is usually 50% by weight or less, preferably 30% by weight or less based on the total of the epoxy resin (A) and the epoxy resin (B).

In the epoxy resin composition of the present invention, the ratio of the epoxy resin (A) in the total epoxy resin including the epoxy resin (A) and the epoxy resin (B) is 10 to 90% by weight, with the total as 100% by weight, Preferably it is 20 to 80 weight%. The "all epoxy resins including epoxy resin (A) and epoxy resin (B)" means that the epoxy resin contained in the epoxy resin composition of the present invention is only an epoxy resin (A) and an epoxy resin (B). In the case, it means the sum of the epoxy resin (A) and the epoxy resin (B), and when it contains other epoxy resins, the sum of the epoxy resin (A), the epoxy resin (B) and the other epoxy resins. Means.
When the ratio of the epoxy resin (A) is 10% by weight or more, the effect of improving the thermal conductivity by blending the epoxy resin (A) can be sufficiently obtained, and desired high thermal conductivity can be obtained. it can. When the proportion of the epoxy resin (A) is less than 90% by weight and the epoxy resin (B) is 10% by weight or more, the blending effect of the epoxy resin (B) is exhibited, and the curability and physical properties of the cured product are sufficient. It will be a thing.

The heat conductive resin composition of this invention may contain the further component in the range with which the effect of this invention is acquired. Such additional components include, for example, functional resins imparting functionality to the above resins, such as liquid crystalline epoxy resins, nitride particles such as aluminum nitride, silicon nitride, and fibrous boron nitride, alumina, and fibrous Insulating metal oxides such as alumina, zinc oxide, magnesium oxide, beryllium oxide and titanium oxide, insulating carbon components such as diamond and fullerene, resin curing agents, resin curing accelerators, viscosity modifiers, dispersion stabilizers, and solvents Is mentioned.
Further, in the heat conductive resin composition containing the hexagonal boron nitride powder of the present invention, in addition to those exemplified as the nitride particles and the insulating metal oxide, as long as the effect is not impaired, An inorganic filler such as aluminum hydroxide or magnesium hydroxide, a surface treatment agent such as a silane coupling agent that improves the interfacial adhesive strength between the inorganic filler and the matrix resin, a reducing agent, or the like may be added.

  The resin curing agent is appropriately selected according to the type of resin used. For example, as the resin curing agent for epoxy resin, an acid anhydride curing agent and an amine curing agent can be used. Examples of the acid anhydride curing agent include tetrahydrophthalic acid anhydride, methyltetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, and benzophenone tetracarboxylic acid anhydride. Examples of the amine curing agent include aliphatic polyamines such as ethylenediamine, diethylenetriamine, and triethylenetetramine, aromatic polyamines such as diaminodiphenylsulfone, diaminodiphenylmethane, diaminodiphenyl ether, and m-phenylenediamine, and dicyandiamide. If it is a hardening | curing agent for epoxy resins, it will mix | blend in the range of 0.3-1.5 normally by an equivalent ratio with respect to an epoxy resin.

  The resin curing accelerator is appropriately selected according to the type of resin used and the resin curing agent. For example, as the resin curing accelerator for the acid anhydride curing agent, for example, boron trifluoride monoethylamine, 2-ethyl-4-methylimidazole, 1-isobutyl-2-methylimidazole, 2-phenyl-4-methylimidazole Is mentioned. If it is a hardening accelerator for epoxy resins, it will be used at a content of 0.1 to 5 parts by mass with respect to 100 parts by mass of the epoxy resin.

  A solvent can be used from a viewpoint of reducing the viscosity of a heat conductive resin composition. As the solvent, a solvent that dissolves the resin from among known solvents is used. Examples of such solvents include methyl ethyl ketone, acetone, cyclohexanone, toluene, xylene, monochlorobenzene, dichlorobenzene, trichlorobenzene, phenol, and hexafluoroisopropanol. A solvent is used by content of 0-10,000 mass parts with respect to 100 mass parts of resin.

<Thermal conductive resin composition / Method for producing molded article>
The heat conductive resin composition (also referred to as a composite material composition) of the present invention is obtained by uniformly mixing the hexagonal boron nitride powder, a resin, and a material containing additional components as necessary by stirring or kneading. be able to. For example, the composition of the present invention can be obtained by kneading the above materials by heating as necessary using a general kneading apparatus such as a mixer, kneader, single-screw or twin-screw kneader.

On the other hand, the molded article of the present invention is formed by molding the thermally conductive resin composition of the present invention. Molding of the molded body can be appropriately performed according to the state of the thermally conductive resin composition and the type of resin using a method generally used for molding of the thermally conductive resin composition.
For example, the heat conductive resin composition having plasticity and fluidity can be molded by curing the heat conductive resin composition in a desired shape, for example, in a state of being accommodated in a mold. In the production of such a molded body, injection molding, injection compression molding, extrusion molding, and compression molding can be used. When the said heat conductive resin composition is a thermosetting resin composition containing an epoxy resin, a silicone resin, etc., shaping | molding of a molded object, ie, hardening, can be performed on each hardening temperature conditions. When the thermal conductive resin composition contains a thermoplastic resin, the molded body can be molded under conditions of a temperature equal to or higher than the melting temperature of the thermoplastic resin and a predetermined molding speed and pressure. Moreover, the said molded object can be obtained also by cutting out the hardened | cured material of a heat conductive resin composition in a desired shape.

Applications of the heat conductive resin composition of the present invention include, for example, a thermoplastic heat conductive sheet having flexibility to attach between a heat sink such as a heat radiating fin or a heat radiating plate and a semiconductor package and a wiring board, and high heat resistance. Resin composite heat conductive materials such as polyimide, used for use in the required environment, thermoplastic resin composite materials for motor parts for HEV and electric vehicles, semiconductor sealing materials, interlayer filling compositions such as underfill, Examples thereof include an interlayer filling composition for a three-dimensional integrated circuit.
Hereinafter, a method for producing a three-dimensional integrated circuit will be described as one of uses of a molded body that can be produced using the heat conductive resin composition of the present invention.
This manufacturing method includes a step of laminating these semiconductor substrates by press-bonding them after forming the above-described thermally conductive resin composition on a plurality of semiconductor substrates.
In this manufacturing method, a thin film of a heat conductive resin composition is first formed on a semiconductor substrate.
For example, a film made of a thermally conductive resin composition is formed on a semiconductor substrate by an arbitrary method using a material obtained by heating and melting a thermally conductive resin composition in a temperature range where resin curing does not start. It is good.
In addition, since the heat conductive resin composition of the present invention has sufficient elongation suitable for film molding, the heat conductive resin composition of the present invention is formed into a film and the film is placed on a semiconductor substrate. You may form into a film.

Next, after heating the film | membrane which consists of a heat conductive resin composition formed into a film by the said method and expresses tackiness, temporary bonding with the semiconductor substrate of joining object is performed. Although it depends on the composition of the epoxy resin, the temporary bonding temperature is preferably 80 to 150 ° C. When the bonding of the semiconductor substrates is a plurality of layers, the temporary bonding may be repeated for the number of layers of the substrates, or the substrates on which the B-staging film is formed are stacked and then heated to be temporarily combined. It may be adhered. In temporary bonding, it is preferable to apply a load of 1 gf / cm ^{2 to 1} Kgf / cm ² between the substrates as necessary.

After the temporary bonding, the semiconductor substrate is finally bonded. When the temporarily bonded semiconductor substrate is pressure-bonded to 200 ° C. or higher, preferably 220 ° C. or higher, thereby reducing the melt viscosity of the resin of the heat conductive resin composition and promoting the connection of electrical terminals between the semiconductor substrates. At the same time, the solder in the composition can be realized by activating the flux in the composition. The upper limit of the heating temperature is a temperature at which the epoxy resin to be used is not decomposed or altered, and is appropriately determined depending on the type and grade of the resin, but is usually 300 ° C. or lower.
In addition, it is preferable to apply a load of 10 gf / cm ² to 10 Kgf / cm ² between the substrates as needed at the time of pressure bonding.

By using the hexagonal boron nitride powder of the present invention as the thermally conductive particles in the resin composition, not only the viscosity as the resin composition is reduced and the molding processability can be improved, but also high thermal conductivity can be maintained. Therefore, it is possible to greatly improve the increase in viscosity, which has been a problem with conventional resin compositions containing a large amount of boron nitride powder. Utilizing this feature, the thermally conductive resin composition containing the hexagonal boron nitride powder of the present invention can be used as, for example, an interlayer filler composition used in the lamination of semiconductor device chips, and molding it. In this case, it becomes a layer between the semiconductor device chips.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

<Measurement of thermal conductivity of thermal conductive resin composition>
The thermal conductivity of the thermally conductive resin composition was determined by measuring the thermal diffusivity, specific gravity and specific heat with the following apparatus and multiplying these three measured values.
1) Thermal diffusivity: A sample for thermal conductivity evaluation was cut out and formed into a disk-shaped specimen having a diameter of 12 mm and a thickness of about 0.5 mm, and then fully automatic laser flash method thermal constant measuring device TC manufactured by ULVAC-RIKO Co., Ltd. The thermal diffusivity was measured using -7000.
2) Specific gravity: A balance manufactured by METTLER TOLEDO Co., Ltd. Specific gravity was measured using a product name “XS204” (using “Solid Specific Gravity Measurement Kit”).
3) Specific heat: Differential scanning calorimeter manufactured by PerkinElmer Co., Ltd. Using the product name “DSC7”, the specific heat at 25 ° C. was measured using DSC7 software under the temperature rising condition of 10 ° C./min.

<Measurement of viscosity of thermally conductive resin composition>
About the thermally conductive resin composition before adding the curing agent, which was passed five times through three rolls, which will be described later, a dynamic viscoelasticity measuring device ARES (diameter 8 mm parallel plate, gap interval, manufactured by TA Instruments) 0.3 mm) was used to measure the dynamic viscosity at a temperature of 25 ° C., an angular frequency of 1 rad / s, and a strain of 0.2%.

<Measurement of crystallite size of hexagonal boron nitride powder by X-ray diffraction>
As described above, the crystallite diameter (Lc) of the 002 plane of the hexagonal boron nitride powder is obtained by measuring the half width of the peak at 2θ = 26.5 ° of X-ray diffraction and calculating the above formula (2). It was. Similarly, the half width of the peak at 2θ = 41.5 ° of X-ray diffraction was also measured for the crystallite diameter (La) of the 100 plane, and was obtained by the above formula (2). As an X-ray diffractometer, PW1700 manufactured by PANalytical was used.

<Measurement of oxygen content of hexagonal boron nitride powder>
The oxygen content of the hexagonal boron nitride powder was measured by quantitative analysis using an inert gas melting-infrared absorption method. An oxygen / nitrogen analyzer EMGA-620W manufactured by HORIBA was used as an analyzer.

<Example 1>
The hexagonal boron nitride powder of the present invention is 200 g of R-BN (hexagonal boron nitride having a 002 crystallite size of 299 mm and a 100 crystallite size of 339 mm in X-ray diffraction) manufactured by Nisshin Rifratech. It was obtained by placing in a carbon crucible and firing in a nitrogen furnace at 2100 ° C. for 15 hours in a nitrogen gas atmosphere. The obtained hexagonal boron nitride powder had an average particle size of 3.5 μm.
5 g of this hexagonal boron nitride powder and 5 g of epoxy resin (Mitsubishi Chemical's epoxy resin, 1750 and YED216 were blended at a weight ratio of 90/10) were added (content of hexagonal boron nitride powder 34.8 vol%). Then, it passed 5 times through 3 rolls (made by Kodaira Manufacturing Co., Ltd.) which adjusted the gap space | interval to 10 micrometers, and obtained the heat conductive resin composition.
The viscosity measurement of the obtained heat conductive resin composition was implemented. The results are shown in Table 1.
Furthermore, 2 parts of 2-ethyl-4-methylimidazole as a curing agent was added to 2.5 g of the obtained heat conductive resin composition, and the mixture was uniformly stirred and mixed. Put release PET on a glass plate, adjust the gap to 500 μm with silicone rubber, sandwich the thermally conductive resin composition containing a curing agent, cure at 100 ° C. for 1 h, then at 150 ° C. for 4 h, and evaluate thermal conductivity A sample was obtained. Using the obtained sample, the thermal conductivity was measured. The results are shown in Table 1.

<Comparative Example 1>
Instead of firing the hexagonal boron nitride powder used in Example 1, commercially available boron nitride powder (trade name R-BN, manufactured by Nisshin Rifratech) was used without any firing, and the same method was used. The viscosity and the thermal conductivity were measured. The results are shown in Table 1. The average particle size of the hexagonal boron nitride powder was 2.0 μm.

<Comparative example 2>
In place of the calcined hexagonal boron nitride powder used in Example 1, 200 g of commercially available boron nitride powder (trade name SP2 manufactured by Denki Kagaku Kogyo Co., Ltd.) was placed in a carbon crucible and used at 2100 ° C. using a carbon furnace. Viscosity was measured and thermal conductivity was measured in the same manner as in Example 1 except that a material fired in a nitrogen gas atmosphere for 15 hours was used. The results are shown in Table 1. The obtained hexagonal boron nitride powder had an average particle size of 5.3 μm.

<Comparative Example 3>
In place of the fired hexagonal boron nitride powder used in Example 1, 200 g of a commercially available boron nitride powder (trade name SP3-7, manufactured by Denki Kagaku Kogyo Co., Ltd.) was placed in a carbon crucible, and 2100 using a carbon furnace. Viscosity was measured and thermal conductivity was measured in the same manner as in Example 1 except that a material fired at 15 ° C. for 15 hours in a nitrogen gas atmosphere was used. The results are shown in Table 1. The obtained hexagonal boron nitride powder had an average particle size of 2.5 μm.

Claims (4)

The crystallite diameter (Lc) of the 002 plane is 450 [Å] or more,
100 crystallite diameter (La) is 500 [Å] or more,
The crystallite diameter (Lc) and the crystallite diameter (La) satisfy the following relational expression (1):
0.70 ≦ Lc / La (1)
Hexagonal boron nitride powder having an oxygen content of 0.30% by weight or less.   The hexagonal boron nitride powder according to claim 1, wherein the hexagonal boron nitride powder has an average particle size of 10 μm or less.   A thermally conductive resin composition comprising the hexagonal boron nitride powder according to claim 1 or 2 and a resin.   The molded object formed by shape | molding the heat conductive resin composition of Claim 3.