JP2012017405A - Epoxy resin composition, molding, varnish, film adhesive, and film adhesive-coated copper foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition excellent in thermal conductivity and heat resistance; to provide a cured material, a varnish, and a film adhesive, which are obtained by using the epoxy resin composition; and to provide a film adhesive-coated copper foil.SOLUTION: The epoxy resin composition contains an epoxy resin, a curing agent and an inorganic filler. As the epoxy resin component, 50 wt.% or more of an epoxy resin obtained by epoxidizing dihydroxydiphenyl ether is used in the epoxy resin component. As the curing agent, 50 wt.% or more of a phenolic compound comprised of tris(4-hydroxyphenyl)methanes or 1,1,2,2-tetrakis(4-hydroxyphenyl)ethanes is used in the curing resin composition. The epoxy resin composition is obtained by adding 50-96 wt.% of the inorganic filler thereto.

Description

  The present invention relates to an epoxy resin composition useful as an insulating material for electrical and electronic materials such as semiconductor sealing, laminate, and heat dissipation board having excellent reliability, and a molded product, varnish, and film adhesive obtained using the same. And a copper foil with a film adhesive.

  Conventionally, as a sealing method for electrical and electronic parts such as diodes, transistors, and integrated circuits, and semiconductor devices, for example, a sealing method using an epoxy resin or a silicone resin, or a hermetic sealing method using glass, metal, ceramic, etc. In recent years, resin sealing by transfer molding, which can be mass-produced with improved reliability and cost-effective, has been the mainstream in recent years.

  In a resin composition used for resin sealing by transfer molding, a sealing material composed of an epoxy resin and a resin composition mainly composed of a phenol resin as a curing agent is generally used.

  Epoxy resin compositions used for the purpose of protecting elements such as power devices are filled with an inorganic filler such as crystalline silica at a high density in order to cope with a large amount of heat released from the element.

  Power devices include one-chip devices that incorporate IC technology and those that are modularized, and further improvements in heat dissipation, heat resistance, and thermal expansion for sealing materials are desired. .

  On the other hand, in the insulating substrate, heat generation from the mounted electronic component cannot be ignored, and this heat generation is particularly remarkable in the electronic component used at a high current and high voltage. Therefore, high heat dissipation is required for an insulating substrate on which highly exothermic electronic components are mounted.

  In order to impart high heat dissipation to an insulating substrate, a method of filling an insulating substrate material with an inorganic filler such as alumina having high thermal conductivity has been performed.

  In order to meet these requirements, the sealing material contains an inorganic filler such as crystalline silica, silicon nitride, aluminum nitride, and spherical alumina powder having a high thermal conductivity in order to improve the thermal conductivity. (Patent Documents 1 and 2), however, when the content of the inorganic filler is increased, there is a problem in that the fluidity decreases with increasing viscosity during molding, and the moldability is impaired.

  On the other hand, in the insulating substrate material, in order to improve the thermal conductivity, a thermally conductive resin composition blended at a relatively high ratio using an inorganic filler having a predetermined distribution of average particle diameter and a large thermal conductivity. Is proposed (Patent Document 3), but even if high thermal conductivity can be achieved by filling a large amount of an inorganic filler having a high thermal conductivity, the workability as an insulating adhesive layer is reduced or obtained. The surface condition of the insulating adhesive layer deteriorates, resulting in a problem that the withstand voltage characteristic and the adhesiveness are inferior. Therefore, there is a limit to the method of simply increasing the content of the inorganic filler.

  From the above background, a method for improving the thermal conductivity of the composition by increasing the thermal conductivity of the matrix resin itself has been studied. For example, Patent Document 4, Patent Document 5 and Patent Document 6 propose a liquid crystalline epoxy resin having a rigid mesogenic group and an epoxy resin composition using the same. However, in these epoxy resin compositions, although the liquid crystallinity of the cured product can be confirmed, the crystallinity of the cured product is low, which is not sufficient in terms of high thermal conductivity, low thermal expansion, low hygroscopicity, and the like. Furthermore, in order to exhibit liquid crystallinity, it is necessary to orient the molecules by applying a strong magnetic field, and there are significant restrictions in terms of equipment for wide industrial use. In addition, in the compounding system with the inorganic filler, the thermal conductivity of the inorganic filler is overwhelmingly larger than that of the matrix resin, and even if the thermal conductivity of the matrix resin itself is increased, There is a reality that it does not greatly contribute to the improvement of thermal conductivity, and a sufficient effect of improving thermal conductivity has not been obtained. Patent Document 7 discloses a composition of an epoxy resin having a diphenyl ether group and a phenolic compound having a diphenyl ether structure as a curing agent. However, a slightly lower heat resistance and a higher heat resistance resin are required. It was.

JP-A-11-147936 JP 2002-309067 A JP 2001-348488 A JP-A-11-323162 JP-A-2004-331811 JP-A-9-118673 WO2006 / 120993

  Accordingly, an object of the present invention is to provide an epoxy resin composition that solves the above-described problems, is excellent in thermal conductivity, and is excellent in heat resistance. Another object of the present invention is to provide a cured molded article, a varnish, a film adhesive, and a copper foil with a film adhesive having excellent thermal conductivity and excellent heat resistance.

  The present inventors specifically improved physical properties such as thermal conductivity and heat resistance by adding an inorganic filler to the epoxy resin having a diphenyl ether group and a specific phenolic compound at a content of 50 to 96 wt%. The present invention has been found.

  The present invention is an epoxy resin composition containing an epoxy resin, a curing agent, and an inorganic filler, wherein 50 wt% or more of the epoxy resin is an epoxy resin having a diphenyl ether group represented by the following formula (1): The epoxy resin composition is characterized in that 50 wt% or more of the above is a phenolic compound represented by the following formula (2) or formula (3), and the content of the inorganic filler is 50 to 96 wt%.

（但し、ｎ₁は０〜１０の数を示す。）

（但し、Ｒ₁及びＲ₂は同一又は異なっていても良く、水素原子、ハロゲン原子又は炭素数１〜６の炭化水素基を示し、ｎ₂は０〜５の数を示す。）

（但し、Ｒ₃〜Ｒ₅は同一又は異なっていても良く、水素原子、ハロゲン原子又は炭素数１〜６の炭化水素基を示し、ｎ₃は０〜５の数を示す。）

(However, n ₁ is a number of 0.)

(However, R ₁ and R ₂ may be the same or different and each represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 6 carbon atoms, and n ₂ represents a number from 0 to 5)

(However, R ₃ to R ₅ may be the same or different, represent a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 6 carbon atoms, n ₃ is a number of 0-5.)

  The inorganic filler is advantageously at least one inorganic filler selected from the group consisting of alumina, boron nitride, and aluminum nitride.

  Further, the present invention is a cured molded product obtained by molding and curing the above epoxy resin composition. Furthermore, the present invention is a varnish obtained by dissolving or dispersing the above epoxy resin composition in a solvent.

  In addition, the present invention is a film-like adhesive formed by forming the above epoxy resin composition into a film, and the above varnish is applied on a support and dried or partially cured to form a film. This is a film-like adhesive. Furthermore, the present invention is a copper foil with a film adhesive, characterized in that the above-mentioned film adhesive is laminated on a copper foil.

  The epoxy resin composition of the present invention gives a cured molded article, varnish, film adhesive and film adhesive copper foil with excellent thermal conductivity and heat resistance, semiconductor encapsulation, laminate, It is suitably applied as an insulating material for electrical and electronic materials such as a heat dissipation board, and exhibits excellent high heat dissipation, high heat resistance and high dimensional stability.

  Hereinafter, the present invention will be described in detail.

The epoxy resin used for the epoxy resin composition of the present invention contains 50 wt% or more of an epoxy resin having a diphenyl ether group represented by the above formula (1). In Formula (1), n ₁ represents a number of 0 to 10, but when the epoxy resin has a molecular weight distribution, the average (number average) number of repetitions is preferably in the above range.

When the number average value of n ₁ is in the range of 0.1 to 1.0, the effect of improving physical properties such as thermal conductivity when cured is large. This is because the smaller the n ₁ value of the epoxy resin having a diphenyl ether group, the higher the degree of orientation as a molded product.

Although the manufacturing method of the epoxy resin used for this invention is not specifically limited, It can manufacture by making the phenolic compound which has the diphenyl ether group of following formula (4), and epichlorohydrin react. This reaction can be performed in the same manner as a normal epoxidation reaction.

  The reaction between the phenolic compound and epichlorohydrin is, for example, after dissolving the phenolic compound in excess epichlorohydrin and then in the presence of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, preferably at 50 to 150 ° C., preferably The method of making it react for 1 to 10 hours in the range of 60-100 degreeC is mentioned. In this case, the amount of the alkali metal hydroxide used is in the range of 0.8 to 2.0 mol, preferably 0.9 to 1.5 mol, with respect to 1 mol of the hydroxyl group in the dihydroxy body. The epichlorohydrin is used in an excess amount with respect to the hydroxyl group in the phenolic compound, and is usually 1.5 to 15 mol with respect to 1 mol of the hydroxyl group in the phenolic compound. After completion of the reaction, excess epichlorohydrin is distilled off, the residue is dissolved in a solvent such as toluene, methyl isobutyl ketone, filtered, washed with water to remove inorganic salts, and then the target epoxy is removed by distilling off the solvent. A resin can be obtained.

  The epoxy resin used in the epoxy resin composition of the present invention can also be synthesized using a mixture of a phenolic compound having a diphenyl ether group and another phenolic compound having no diphenyl ether group. In this case, the mixing ratio of the phenolic compound having a diphenyl ether group is 50 wt% or more. Other phenolic compounds are not particularly limited and are selected from those having two or more hydroxyl groups in one molecule.

  The epoxy equivalent of the epoxy resin used in the epoxy resin composition of the present invention is usually in the range of 120 to 400, but from the viewpoint of increasing the filling rate of the inorganic filler and improving the workability, the one having a low viscosity is good. The epoxy equivalent is preferably in the range of 120 to 200.

  As the epoxy resin having a diphenyl ether group, a resin having crystallinity at normal temperature is preferably used. The range of preferable melting | fusing point is 70 to 250 degreeC, More preferably, it is the range of 80 to 200 degreeC. If it is lower than this, blocking and the like are likely to occur, resulting in poor handling as a solid, and if it is higher than this, compatibility with a curing agent or the like, solubility in a solvent, and the like are reduced.

The purity of the epoxy resin having a diphenyl ether group, in particular, the amount of hydrolyzable chlorine, is preferably smaller than the viewpoint of improving the reliability of the applied electronic component. Although it does not specifically limit, Preferably it is 1000 ppm or less, More preferably, it is 500 ppm or less. In addition, the hydrolyzable chlorine as used in the field of this invention means the value measured by the following method. That is, the potential difference the sample 0.5g were dissolved in dioxane 30 ml, 1N-KOH, after the added boiled under reflux for 30 minutes 10 ml, cooled to room temperature, 80% aqueous acetone 100ml was added, with 0.002 N-AgNO ₃ aqueous solution This is a value obtained by titration.

  In addition to the epoxy resin having a diphenyl ether group used as an essential component, the epoxy resin composition of the present invention may be used in combination with another epoxy resin having two or more epoxy groups in the molecule as an epoxy resin component. Examples include bisphenol A, bisphenol F, 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenyl sulfide, Divalent phenols such as fluorene bisphenol, 2,2'-biphenol, resorcin, catechol, t-butylcatechol, t-butylhydroquinone, allylated bisphenol A, allylated bisphenol F, allylated phenol novolak, or phenol novolak Bisphenol A novolak, o-cresol novolak, m-cresol novolak, p-cresol novolak, xylenol novolak, poly-p-hydroxystyrene, tris- (4-hydroxyphenyl) meta 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, fluoroglycinol, pyrogallol, t-butyl pyrogallol, allylated pyrogallol, polyallylated pyrogallol, 1,2,4-benzenetriol, 2,3, There are glycidyl ethers derived from 4-trihydroxybenzophenone, phenol aralkyl resins, naphthol aralkyl resins, trivalent or higher phenols such as dicyclopentadiene resins, or halogenated bisphenols such as tetrabromobisphenol A. . These epoxy resins can be used alone or in combination of two or more. Moreover, 1 type, or 2 or more types can be used also about the epoxy resin which has a mesogenic group.

  The blending ratio of the epoxy resin having a diphenyl ether group represented by the formula (1) used in the epoxy resin composition of the present invention is 50 wt% or more of the total epoxy resin, preferably 70 wt% or more, more preferably 90 wt% or more. It is. Furthermore, it is desirable that the total amount of the bifunctional epoxy resin is 90 wt% or more, preferably 95 wt% or more. If it is less than this, the effect of improving physical properties such as thermal conductivity when cured is small. This is because the higher the content of the epoxy resin having a diphenyl ether group and the higher the content of the bifunctional epoxy resin, the higher the degree of orientation as a molded product.

（但し、Ｚは単結合、メチレン基又は硫黄原子を示し、ｒは０〜１の数を示す。） As an epoxy resin other than an epoxy resin having a diphenyl ether group, a bisphenol-based epoxy resin represented by the following general formula (5) is preferable.

(However, Z shows a single bond, a methylene group, or a sulfur atom, and r shows the number of 0-1.)

  These epoxy resins can be synthesized, for example, by performing a normal epoxidation reaction using hydroquinone, 4,4'-dihydroxydiphenylmethane, or 4,4'-dihydroxydiphenyl sulfide as a raw material. You may synthesize | combine these epoxy resins using what was mixed with the dihydroxy compound which has a mesogen group in a raw material stage.

  The hardening | curing agent used for the epoxy resin composition of this invention contains 50 wt% or more of phenolic compounds represented by the said Formula (2) or Formula (3). When both of the phenolic compounds represented by the above formula (2) or formula (3) are included, the total may be 50 wt% or more.

In the above formula (2) or formula (3), R ₁ and R ₂ , and R _{3 to} R ₅ represent the same or different hydrogen atom, halogen atom, or hydrocarbon group having 1 to 6 carbon atoms. n ₂ and n ₃ indicate the number of independently 0-5. When the phenolic compound represented by the formula (2) or formula (3) has a molecular weight distribution, n ₂ and n ₃ represent an average (number average) number of repetitions and are in the range of 0 to 5. Is good.

In n ₂ and n ₃ is a number average value, it is large property enhancement effect such as the thermal conductivity in the range of 0 to 1.0. This is because the smaller the n _{2 value of} the curing agent represented by the formula (2) and the n ₃ value of the curing agent represented by the formula (3), the higher the degree of orientation as a molded product.

  Preferred examples of the curing agent used in the epoxy resin composition of the present invention include tris (4-hydroxyphenyl) methane and 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane.

  The amount of the phenolic compound represented by the formula (2) or formula (3) used as the curing agent is 50 wt% or more of the total curing agent, preferably 70 wt% or more, more preferably 80 wt% or more. If it is less than this, the effect of improving physical properties such as thermal conductivity when cured is small. This is because the higher the content of the phenolic compound represented by the formula (2) or the formula (3), the higher the degree of orientation as a molded product.

  As the curing agent used in the epoxy resin composition of the present invention, in addition to the phenolic compound represented by the above formula (2) or formula (3), other curing agents generally known as curing agents are used in combination. Can be used. Examples include phenolic curing agents other than the phenolic compounds used in the present invention, amine curing agents, acid anhydride curing agents, polymercaptan curing agents, polyaminoamide curing agents, isocyanate curing agents, and block isocyanates. System curing agent and the like. What is necessary is just to set the compounding quantity of these other hardening | curing agents suitably considering the kind of hardening | curing agent to mix | blend and the physical property of the heat conductive epoxy resin molded object obtained. However, it is necessary to use it in a range of less than 50 wt% of the total curing agent.

  In the epoxy resin composition of the present invention, the mixing ratio of the epoxy resin and the curing agent is preferably in the range of 0.8 to 1.5 in terms of the equivalent ratio of the functional group of the epoxy resin / curing agent. Outside this range, unreacted epoxy groups or functional groups in the curing agent remain after curing, and the reliability of the insulating material for electronic parts is lowered.

  An inorganic filler is blended in the epoxy resin composition of the present invention at a content of 50 to 96 wt%. The content of the inorganic filler is preferably 85 to 95 wt% in the epoxy resin composition. If it is less than this, effects such as high thermal conductivity, high heat resistance, and low thermal expansion will not be sufficiently exhibited. These effects are improved as the added amount of the inorganic filler is increased, but are not improved in accordance with the volume fraction, and are drastically improved from the point when the added amount exceeds the specific amount. These physical properties are due to the effect of controlling the higher order structure in the polymer state, and since this higher order structure is achieved mainly on the surface of the inorganic filler, a specific amount of inorganic filler is required. It is thought to be. On the other hand, when the added amount of the inorganic filler is larger than this, the viscosity becomes high and the workability is lowered.

  The inorganic filler is preferably spherical and is not particularly limited as long as it has a spherical shape including those having a cross section on an ellipse, but from the viewpoint of improving workability, it should be as close to a true sphere as possible. Is particularly preferred. Thereby, it is easy to take a close-packed structure such as a face-centered cubic structure or a hexagonal close-packed structure, and a sufficient filling amount can be obtained. When the amount is not spherical, the friction between the fillers increases as the filling amount increases, and the viscosity increases before the upper limit is reached, resulting in a decrease in workability.

  From the viewpoint of improving the thermal conductivity, it is preferable that 50 wt% or more, preferably 80 wt% or more of the inorganic filler has a thermal conductivity of 20 W / m · K or more. As such an inorganic filler, alumina, boron nitride, and aluminum nitride are suitable. Among these, spherical alumina is excellent. In addition, an amorphous inorganic filler such as fused silica or crystalline silica may be used in combination, if necessary, regardless of the shape.

  In addition, the average particle size and the maximum particle size of the inorganic filler can not be said unconditionally because the preferred maximum particle size and the average particle size vary depending on the target to be applied, but from the viewpoint of high thermal conductivity, the maximum particle size, A larger average particle size is advantageous. However, if the maximum particle size is too large, the workability is lowered, the appearance of the molded product is deteriorated, and the strength is lowered.

  A conventionally well-known hardening accelerator can be used for the epoxy resin composition of this invention. Examples include amines, imidazoles, organic phosphines, Lewis acids, etc., specifically 1,8-diazabicyclo (5,4,0) undecene-7, triethylenediamine, benzyldimethylamine, Tertiary amines such as ethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol, imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, Organic phosphines such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine, tetraphenylphosphonium / tetraphenylborate, tetraphenylphosphonium / ethyltriphenyl Rate, tetra-substituted phosphonium tetra-substituted borate such as tetrabutylphosphonium-tetrabutyl borate, 2-ethyl-4-methylimidazole · tetraphenyl port rate, and the like tetraphenyl boron salts such as N- methylmorpholine-tetraphenyl port rate. These may be used alone or in combination.

  As for the addition amount of the said hardening accelerator, 0.1-10.0 wt% is preferable with respect to the sum total of an epoxy resin and a hardening | curing agent. If it is less than 0.1 wt%, the gelation time will be delayed, resulting in a decrease in workability due to a decrease in rigidity during heating reaction. Conversely, if it exceeds 10.0 wt%, the reaction will progress during processing, resulting in poor appearance. It becomes easy.

  In the epoxy resin composition of the present invention, in addition to the above components, a coupling agent, a thermoplastic oligomer, a release agent, and other components that can be generally used for an epoxy resin composition are appropriately blended and used. be able to. For example, phosphorus-based flame retardants, flame retardants such as bromine compounds and antimony trioxide, and colorants such as carbon black and organic dyes can be used.

  As the coupling agent, for example, epoxy silane can be used. The addition amount of the coupling agent is preferably 0.1 to 2.0 wt% with respect to the epoxy resin composition. If it is less than 0.1 wt%, the resin and the base material are not well-matched and the processability is deteriorated. On the other hand, if it exceeds 2.0 wt%, the processed product is soiled by bleeding out. The coupling agent is used to improve the adhesion between the inorganic filler and the resin component.

  Thermoplastic oligomers include C5 and C9 petroleum resins, styrene resins, indene resins, indene / styrene copolymer resins, indene / styrene / phenol copolymer resins, indene / coumarone copolymer resins, indene / benzothiophene. Examples thereof include copolymer resins. As addition amount, it is the range of 2-30 weight part normally with respect to 100 weight part of epoxy resins. Thermoplastic oligomers are used to improve fluidity during processing of the epoxy resin composition and to improve adhesion to the substrate.

  When the epoxy resin composition of the present invention is applied, for example, as a sealing material, the blending components (excluding the coupling agent) including components such as an epoxy resin, a curing agent and an inorganic filler are uniformly mixed with a mixer or the like. After mixing, a coupling agent can be added and kneaded by a heated roll, a kneader or the like. There is no restriction | limiting in particular in the mixing | blending order of these components except a coupling agent. Further, after kneading, the melt-kneaded material can be pulverized to be powdered or tableted.

  When the epoxy resin composition of the present invention is applied, for example, for an insulating substrate, the components constituting the composition are changed to a predetermined solvent such as N, N-dimethylformamide (DMF), N, N-dimethylacetamide, Amide solvents such as N-methyl-2-pyrrolidone (NMP), ether solvents such as 1-methoxy-2-propanol, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and cyclopentanone, toluene, It can be used for production after forming a varnish by dissolving or dispersing it in a mixture of one or more aromatic solvents such as xylene. The components constituting the composition are not necessarily dissolved in the solvent as long as they are uniformly dispersed in the solvent.

  This varnish can be combined with a fibrous base material such as glass fiber to form a composite material. For example, a varnish obtained by dissolving or dispersing the epoxy resin composition of the present invention in a solvent can be impregnated into a sheet-like fiber base material, dried by heating, and partially reacted with the epoxy resin to obtain a prepreg.

  In addition, a film-like adhesive may be formed by applying this varnish on a base film as a support and drying it, or by applying this varnish on a copper foil and drying it. A copper foil may be formed. Here, as for the film support before curing in the film-like adhesive or the copper foil with the film-like adhesive, the higher the solvent residual rate, the better the film support, but the solvent residual rate is too high The film-like adhesive or the copper foil with the film-like adhesive is tacked or foamed during curing. Therefore, the solvent residual ratio is preferably 5% by weight or less. In addition, the solvent residual rate here is the value calculated | required by the measurement of the net weight decreasing rate of a film adhesive part at the time of drying for 60 minutes in 180 degreeC atmosphere. Moreover, about the said film adhesive and copper foil with a film adhesive, after apply | coating the epoxy resin composition of this invention which does not contain a solvent on the base film as a support material in a heat-melting state, it is made to cool. May be obtained.

  Examples of the support material used when forming the film adhesive or the copper foil with the film adhesive include polyethylene terephthalate (PET), polyethylene, copper foil, aluminum foil, release paper, and the like. The thickness is generally 10 to 100 μm.

  When a metal foil such as a copper foil or an aluminum foil is used as the support material, the method for producing the metal foil may be an electrolytic method or a rolling method. In these metal foils, the surface on the side in contact with the insulating layer is preferably roughened from the viewpoint of adhesion to the insulating layer.

  In addition, the film-like adhesive or the copper foil with film-like adhesive is laminated on the base film as the support material, and then the other surface that is not bonded is covered with a film as the protective material to form a roll. It can also be wound and stored. Examples of the protective material used at this time include polyethylene terephthalate, polyethylene, release paper, and the like. The thickness of the protective material is generally 10 to 100 μm. In the case of a copper foil with a film adhesive, a copper foil is used as a support material.

  The epoxy resin composition of the present invention is particularly suitable as an epoxy resin composition for electronic materials because it is excellent for electronic component sealing and heat dissipation substrates.

  In order to obtain a cured molded product using the epoxy resin composition of the present invention, for example, a heat molding method such as transfer molding, press molding, cast molding, injection molding, extrusion molding or the like is applied. From the viewpoint, transfer molding is preferable for the sealing material, and press molding is preferable for the insulating substrate.

  Even when the epoxy resin composition of the present invention is composed only of a bifunctional epoxy resin and a curing agent, when the epoxy resin and the curing agent are heated and reacted, the epoxy resin and the curing agent react with each other. Since this part further reacts with the epoxy group in the epoxy resin, it usually gives a three-dimensional cured product, but in some cases, by use of an organic solvent, selection of a curing accelerator type, and control of heating reaction conditions such as reaction temperature, It can be set as the thermoplastic molding substantially comprised only by the two-dimensional polymer.

  The cured molded product of the present invention preferably has crystallinity from the viewpoints of high thermal conductivity, high heat resistance, and low thermal expansion. The expression of crystallinity of the molded product can be confirmed by observing an endothermic peak accompanying melting of the crystal as a melting point by differential scanning calorimetry. A preferred melting point is in the range of 120 ° C. to 280 ° C., more preferably in the range of 150 ° C. to 250 ° C.

  Here, the effect of crystallinity will be briefly described. Generally, in a cured epoxy resin, a glass transition point is used as an index of heat resistance. This is because a normal epoxy resin cured product is an amorphous (glassy) molded product having no crystallinity, and the physical properties greatly change at the glass transition point. Therefore, in order to increase the heat resistance of the cured epoxy resin, that is, to increase the glass transition point, it is necessary to increase the crosslink density. On the other hand, the cured molded product of the present invention is characterized in that crystallinity is developed, but since the change in physical properties is small up to the melting point, the melting point can be used as an index of heat resistance. Since the polymer material has a melting point higher than the glass transition point, the cured molded product of the present invention can ensure high heat resistance while maintaining high flexibility due to low crosslink density. In addition, the expression of crystallinity means a high intermolecular force, which suppresses the movement of molecules, achieves low thermal expansibility, exhibits high thermal diffusivity, and improves thermal conductivity.

  Accordingly, the higher the degree of crystallinity of the cured molded product of the present invention, the better. Here, the degree of crystallization can be evaluated from the endothermic amount accompanying the melting of the crystal in the differential scanning calorimetry. A preferable endothermic amount is 10 J / g or more per unit weight of the resin component excluding the filler. More preferably, it is 30 J / g or more, Most preferably, it is 50 J / g or more. If it is smaller than this, the effect of improving the thermal conductivity, heat resistance and low thermal expansion as a molded product is small. The endothermic amount referred to here refers to the endothermic amount obtained by measuring with a differential scanning calorimeter using a sample accurately weighed about 10 mg under a nitrogen stream under a temperature rising rate of 10 ° C./min. . Further, the crystallized cured molded product of the present invention can be observed as a clear peak even in wide-angle X-ray diffraction. In this case, the crystallinity can be obtained by dividing the area obtained by subtracting the peak of the amorphous resin that is not crystallized from the entire peak area by the entire peak area. The desired crystallinity thus obtained is 15% or more, more preferably 30% or more, and particularly preferably 50% or more in the resin component excluding the filler.

  The cured molded product of the present invention can be obtained by heat reaction by the above molding method. Usually, the molding temperature is 80 ° C. to 250 ° C. In order to increase the crystallinity of the molded product, It is desirable to react at a temperature lower than the melting point of the molded product. A preferable molding temperature is in the range of 100 ° C to 200 ° C, more preferably 130 ° C to 180 ° C. The preferable molding time is 30 seconds to 2 hours, more preferably 1 minute to 1 hour. Further, after molding, the crystallinity can be further increased by post-cure. Usually, the post-cure temperature is 130 ° C. to 250 ° C. and the time is in the range of 1 hour to 20 hours, but the temperature is 5 ° C. to 40 ° C. lower than the endothermic peak temperature in the differential scanning calorimetry, and it is 1 to 24 hours. It is desirable to post-cure over time.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.
The raw materials used to obtain the resin compositions of Examples and Comparative Examples and their abbreviations are as follows.

1. Epoxy resin Epoxy resin A: Glucidyl etherified product of 4,4′-dihydroxydiphenyl ether (YSLV-80DE, manufactured by Nippon Steel Chemical Co., Ltd., epoxy equivalent 163, melting point 83 ° C.)
Epoxy resin B: glycidyl etherified product of 3,3 ′, 5,5′-tetramethyl-4,4′-dihydroxybiphenyl (YX4000H manufactured by Mitsubishi Chemical, epoxy equivalent 192, melting point 105 ° C.)
Epoxy resin C: o-cresol novolac type epoxy resin (EOCN-1020-65 Nippon Kayaku, epoxy equivalent 200, softening point 65 ° C.)

2. Curing agent Curing agent A: Tris (4-hydroxyphenyl) methane (manufactured by Asahi Organic Materials Co., Ltd., OH equivalent 97)
Curing agent B: 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane (manufactured by Asahi Organic Materials Co., Ltd., OH equivalent 100)
Curing agent C: Phenol novolak (softening point 80 ° C.) (Tamanol 758 Arakawa Chemical Industries, OH equivalent 107, softening point 80 ° C.)
Curing agent D: 4,4′-dihydroxydiphenyl ether (reagent, OH equivalent 101)

3. Inorganic filler alumina A: spherical, maximum particle size 100 μm, D ₅₀ 45.9 μm
Alumina B: spherical, maximum particle size 68 μm, D ₅₀ 11.1 μm
Alumina C: spherical, maximum particle size 7 μm, D ₅₀ 0.40 μm
Commercially available spherical alumina was used for all inorganic fillers. Parameters relating to the particle size distribution of alumina were measured by the following method.
The alumina powder to be measured was weighed and mixed in a 0.2 wt% sodium hexametaphosphate solution as a dispersion medium so that the sample concentration was 0.04 wt%, and dispersed using an ultrasonic homogenizer for 3 minutes. The particle size distribution of this alumina dispersion was measured from scattered light obtained by irradiation with a semiconductor laser having a wavelength of 780 nm, using a particle size distribution measuring apparatus Microtrac MT3300EX (manufactured by Nikkiso).
The maximum particle size is a particle size distribution obtained by the above measurement method. When the total particle volume is 100%, the distribution curve of the volume fraction of the particle size has all the particle distribution probabilities above a certain particle size. The minimum value of the particle diameter when 0 is shown.
The average particle diameter D50 indicates the particle diameter when the particle volume distribution obtained by the measurement method is 50% cumulative in the cumulative curve of the volume fraction of the particle diameter when the total volume of the particles is 100%. .

4). Curing accelerator Curing accelerator A: Triphenylphosphine (reagent)

  Compounding was performed using the raw materials shown above. The mixing ratio of the epoxy resin and the curing agent was 1.0 for the epoxy resin / curing agent functional group equivalent ratio.

  In blending, cyclopentanone was used as a solvent, and only an epoxy resin and a curing agent were stirred and dissolved at room temperature in a container equipped with a stirrer. Thereafter, alumina powder was blended and stirred and dispersed. Finally, a curing accelerator was blended, stirred and dissolved to prepare an epoxy resin composition varnish. In all the examples in Table 1, since the solvent used is cyclopentanone, the description is omitted. This epoxy resin composition varnish was applied onto a PET film having a thickness of 31 μm so that the resin thickness after drying would be 120 to 180 μm, and dried at 90 ° C. for 7 minutes to obtain a film adhesive. . Furthermore, each test piece was obtained by hardening this film adhesive for 1 hour at 180 degreeC, and the physical property was evaluated. The results are summarized in Table 1. In addition, the number of each component in Table 1 represents parts by weight.

[Evaluation]
(1) Thermal conductivity Thermal conductivity was measured by a laser flash method using a xenon flash analyzer LFA447 type thermal conductivity meter manufactured by NETZSCH.
(2) Glass transition temperature Using a thermomechanical analyzer (TMA measuring device, manufactured by Seiko Instruments Inc.), the specimen is 3 mm wide and the distance between chucks is 20 mm. The temperature was determined by scanning up to 300 ° C. at a temperature rate of 10 ° C./min.

  It was confirmed that the test pieces obtained in Examples 1 and 2 were excellent in thermal conductivity and gave an epoxy resin composition excellent in heat resistance.

  On the other hand, Comparative Examples 1 to 4 that do not satisfy the conditions defined in the present invention are not as excellent in these characteristics as the examples. That is, since Comparative Example 1 does not contain the curing agent defined in the present invention, the thermal conductivity and heat resistance are inferior. Since Comparative Example 2 does not contain the curing agent defined in the present invention, the heat resistance is inferior. Since the comparative example 3 and the comparative example 4 do not contain the epoxy resin which has the diphenyl ether group prescribed | regulated by this invention, thermal conductivity is inferior.

Claims (7)

In an epoxy resin composition containing an epoxy resin, a curing agent, and an inorganic filler, 50 wt% or more of the epoxy resin is an epoxy resin having a diphenyl ether group represented by the following formula (1), and 50 wt% or more of the curing agent. Is a phenolic compound represented by the following formula (2) or formula (3), and the content of the inorganic filler is 50 to 96 wt%.

(However, n ₁ is a number of 0.)

(However, R ₁ and R ₂ may be the same or different and each represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 6 carbon atoms, and n ₂ represents a number from 0 to 5)

(However, R ₃ to R ₅ may be the same or different, represent a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 6 carbon atoms, n ₃ is a number of 0-5.)   The epoxy resin composition according to claim 1, wherein the inorganic filler is at least one inorganic filler selected from the group consisting of alumina, boron nitride, and aluminum nitride.   A cured molded product obtained by molding and curing the epoxy resin composition according to claim 1.   A varnish obtained by dissolving or dispersing the epoxy resin composition according to claim 1 or 2 in a solvent.   A film adhesive, wherein the varnish according to claim 4 is applied on a support and dried or partially cured to form a film.   The film adhesive formed by forming the epoxy resin composition of Claim 1 or 2 in a film form.   A film-like adhesive-attached copper foil, wherein the film-like adhesive according to claim 5 or 6 is laminated on a copper foil.