JP7541664B2 - Epoxy resin composition, cured product, semiconductor encapsulant, and semiconductor device - Google Patents

Description

The present invention relates to an epoxy resin composition, a cured product, a semiconductor encapsulant, and a semiconductor device.

Epoxy resin compositions, which contain epoxy resins and their curing agents as essential components, are widely used in electronic materials such as semiconductor encapsulants and printed circuit boards, conductive adhesives, other adhesives, matrices for composite materials, paints, photoresist materials, color developers, etc., due to their excellent physical properties such as high heat resistance, moisture resistance, and low viscosity.

In recent years, in the field of semiconductor encapsulation materials, the shift to surface mount packages such as BGA and CSP, as well as the need for lead-free soldering, has led to higher reflow processing temperatures, creating an even greater demand for encapsulation resin materials that are moisture-resistant and solder-resistant, meaning they have low moisture absorption and high heat resistance.

In addition, in the field of semiconductor encapsulation materials, copper wire, which has high bonding reliability in high-temperature environments, is increasingly being adopted. However, copper wire is more susceptible to corrosion than conventional gold wire, so when interfacial deterioration such as peeling occurs at the interface between the encapsulation resin and the lead frame, moisture concentrates at the peeled area due to capillary action, causing problems such as corrosion of the chip and wire bonding joints. Furthermore, moisture expands rapidly during the high-temperature reflow process, which can cause cracks, so it is essential that the encapsulation resin characteristics reduce peeling at the lead frame interface during the reflow process, and there is a strong demand for a low elastic modulus at heat that contributes to improved adhesion to the lead frame (high adhesion) and internal stress relaxation.

To meet these required characteristics, phenolic resins and epoxy resins for use in sealing materials for electronic components have been disclosed that use, for example, benzylated phenolic resins obtained by reacting phenolic resins with benzylating agents such as benzyl chloride, and epoxy resins obtained by reacting the benzylated phenolic resins with epihalohydrins (see, for example, Patent Document 1).

However, in the case of the phenolic resin and epoxy resin in Patent Document 1, although the moisture absorption rate is reduced and there is some improvement in moisture resistance and solder resistance, the other characteristic levels required in recent years are not sufficient.

As such, in the field of semiconductor encapsulation materials, there is currently no epoxy resin composition that can be used for semiconductor encapsulation and that has sufficient heat resistance, internal stress relaxation properties (low elastic modulus when heated), low moisture absorption, moisture resistance and solder resistance, and high adhesion.

Japanese Patent Application Publication No. 8-120039

The problem that the present invention aims to solve is to provide an epoxy resin composition that can contribute to high heat resistance, internal stress relaxation properties (low elastic modulus when heated), low moisture absorption, moisture resistance and solder resistance, and high adhesion, a cured product of the epoxy resin composition, a semiconductor encapsulant containing the cured product, and a semiconductor device containing the semiconductor encapsulant.

As a result of intensive research by the inventors to solve the above-mentioned problems, they discovered an epoxy resin composition that contains an epoxy resin of a specific structure obtained by reacting dihydroxybiphenyl with an aromatic vinyl compound and that contributes to high heat resistance, internal stress relaxation properties (low elastic modulus when heated), low moisture absorption, moisture resistance, solder resistance, and high adhesion, a cured product of the epoxy resin composition, a semiconductor encapsulant containing the cured product, and a semiconductor device containing the semiconductor encapsulant, thereby completing the present invention.

That is, the present invention relates to an epoxy resin composition obtained by reacting a reaction product of 1 mole of dihydroxybiphenyl and 1.5 to 8 moles of an aromatic vinyl compound with epichlorohydrin, the epoxy resin composition comprising an epoxy resin (A) represented by the following general formula (1), a compound (B) having a phenolic hydroxyl group, and an inorganic filler (C):
(In the following general formula (1), _R1 and _R2 each independently represent hydrogen or an α-methylbenzyl group, G represents a glycidyl group, p and q each independently represent a number from 0 to 4, and p+q has an average value of 1.5 to 8, and n represents a number from 0 to 5.)

The present invention relates to a cured product of the epoxy resin composition.

The present invention relates to a semiconductor encapsulant that contains the above-mentioned cured product.

The present invention relates to a semiconductor device that includes the semiconductor encapsulant.

The cured product of the epoxy resin composition of the present invention has excellent heat resistance (high glass transition temperature), internal stress relaxation properties (low elastic modulus when hot), low moisture absorption (low moisture absorption rate), moisture resistance and solder resistance, and high adhesion, so that a semiconductor device containing the cured product exhibits advantageous effects that were previously unimaginable.

The present invention is described in detail below.

<Epoxy resin (A)>
The epoxy resin composition of the present invention is characterized in that it contains an epoxy resin (A) represented by the following general formula (1), which is obtained by reacting a reaction product of 1 mole of dihydroxybiphenyl and 1.5 to 8 moles of an aromatic vinyl compound with epichlorohydrin.
In the following general formula (1), _R1 and _R2 each independently represent hydrogen or an α-methylbenzyl group, G represents a glycidyl group, p and q each independently represent a number from 0 to 4, and p+q is an average value of 1.5 to 8, and n represents a number from 0 to 5.
A cured product using the epoxy resin composition containing the epoxy resin (A) can exhibit high heat resistance (high glass transition temperature), low moisture absorption (low moisture absorption rate), high adhesion, and internal stress relaxation properties (low elastic modulus when heated), and is extremely useful in the field of semiconductor encapsulation materials.

The epoxy resin (A) is represented by the above general formula (1). In the above general formula (1), R ₁ and R ₂ are each independently hydrogen or a substituent represented by an α-methylbenzyl group. From the viewpoint of low moisture absorption, an α-methylbenzyl group is preferable. In the above general formula (1), R ₁ and R ₂ may be the same or different, and when there are a plurality of R ₁ or R ₂ , they may be the same or different.

In the above general formula (1), p and q each independently represent a number from 0 to 4, and p+q is an average value of 1.5 to 8. Moreover, it is preferable that p and q each independently represent a number from 1.5 to 7, and more preferably a number from 1.8 to 6. When p and q are within the above ranges, a good balance of reactivity, high heat resistance, and low moisture absorption is achieved, which is preferable.

In the above general formula (1), n represents a number from 0 to 5, and is preferably an average value (number average) of 0 to 4, and more preferably 0 to 3. When the n is within the above range, the composition has low viscosity and excellent moldability, which is preferable.

The epoxy resin (A) is obtained by using a reaction product of 1.5 to 8 moles of an aromatic vinyl compound with 1 mole of dihydroxybiphenyl as an intermediate (precursor), and the reaction product is further reacted with epichlorohydrin to produce the epoxy resin (A). The substituents represented by α-methylbenzyl groups given as R ₁ and R ₂ in the general formula (1) above are groups derived from an aromatic vinyl compound (e.g., styrene).

The reactant which is an intermediate (precursor) of the epoxy resin (A) of the present invention is preferably represented by the following general formula (2): In the following general formula (2), R ₁ , R ₂ , p, and q are the same as R ₁ , R ₂ , p, and q in general formula (1).

The reactant represented by the above general formula (2) may be a mixture of components having a single compound as a main component, or having different _R1 and _R2 and different p and q.

The reactant can be produced by reacting dihydroxybiphenyl with an aromatic vinyl compound, and the amount of the aromatic vinyl compound reacted with 1 mole of dihydroxybiphenyl is in the range of 1.5 to 8 moles, preferably 1.5 to 7 moles, and more preferably 1.8 to 6 moles. By reacting at the above blending ratio, the cured product obtained using the epoxy resin (A) using the reactant can extend the distance between crosslinking points, and the hot elastic modulus can be kept low, which is useful for internal stress relaxation, compared to when the amount of the aromatic vinyl compound reacted is below the above range. In addition, when the distance between crosslinking points is usually extended, the crosslinking density decreases, so the glass transition temperature (Tg) decreases and the heat resistance tends to decrease, but in the present invention, a high Tg (high heat resistance) can be maintained, and an effect that could not be predicted from the past can be achieved, which is useful. Furthermore, by reacting a large amount of aromatic vinyl compound, a cured product that exhibits high adhesion can be obtained, and further, moisture resistance and solder resistance can be achieved, which is useful. In addition, as the blending ratio of the aromatic vinyl compound increases, the viscosity of the resulting epoxy resin (A) tends to increase. When inorganic fillers are used in semiconductor encapsulation materials, in order to prevent a decrease in the high filling properties and moldability of the inorganic fillers, it is preferable to react 2 to 4.5 moles of aromatic vinyl compound.

On the other hand, the amount of the reactant used when reacting dihydroxybiphenyl with an aromatic vinyl compound corresponds roughly to the desired number of moles of substitution (the number of moles of the substituent per mole of dihydroxybiphenyl), so the amount used can be determined accordingly. It is also possible to adopt reaction conditions in which one of the raw materials remains unreacted, but even in this case, the amount of aromatic vinyl compound used per mole of dihydroxybiphenyl should be in the range of 1.5 to 8 moles. If any of the raw materials remains unreacted, it is desirable to separate it, but if it is a small amount, it is acceptable to leave it remaining. In addition, if 8 moles or more of aromatic vinyl compound are used, unreacted aromatic vinyl compound may remain or a polymer of aromatic vinyl compound may be formed, which may cause a decrease in the heat resistance and flame retardancy of the epoxy resin.

As the dihydroxybiphenyl, for example, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, etc. can be used, and 4,4'-dihydroxybiphenyl is preferred from the viewpoint of excellent heat resistance.

Examples of the aromatic vinyl compound that can be used include styrene, styrene derivatives (p-dimethylsilylstyrene, p-vinylphenylmethylsulfide, p-hexynylstyrene, p-methoxystyrene, p-t-butyldimethylsiloxystyrene, o-methylstyrene, p-methylstyrene, p-t-butylstyrene, α-methylstyrene, etc.), vinylnaphthalene, vinylanthracene, 1,1-diphenylethylene, etc., and from the viewpoint of excellent internal stress relaxation properties (low elastic modulus when heated), styrene and α-methylstyrene are preferred, and styrene is more preferred.

As the aromatic vinyl compound, the content of styrene is preferably 60% by mass or more, and more preferably 80% by mass or more. By making the styrene content 60% by mass or more, it is preferable because it improves heat resistance and has excellent internal stress relaxation properties (low elastic modulus when heated).

In addition, it is speculated that the use of a bulky structure such as α-methylstyrene among the aromatic vinyl compounds increases the molecular rigidity, suppresses molecular motion, and further improves the glass transition temperature (Tg).

The reaction between the dihydroxybiphenyl and the aromatic vinyl compound can be carried out by a reaction method using an acid catalyst or the like. This reaction produces the above-mentioned reaction product in which the benzene ring of the dihydroxybiphenyl is substituted with the above-mentioned substituent (α-methylbenzyl group, etc.). After the reaction between the dihydroxybiphenyl and the aromatic vinyl compound is completed, the catalyst or unreacted components can be removed as necessary, and the next epoxidation reaction can be carried out. However, if the epoxidation reaction is not inhibited, it is not necessary to remove unreacted components or neutralizable components such as acid catalysts. Also, it is not necessary to remove them if they are removed in the purification process such as washing or distillation performed after the epoxidation reaction, or if they are not a problem if they are contained in the epoxy resin.

The epoxy resin (A) is obtained by obtaining the reactant represented by the above general formula (2) as an intermediate (precursor) and then reacting the reactant with epichlorohydrin.

In the reaction between the reactant and epichlorohydrin, it is preferable to mix 0.8 to 1.5 equivalents of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide per equivalent of hydroxyl groups in the reactant, and more preferably mix 0.85 to 1.2 equivalents. This range is preferable because it reduces the amount of residual hydrolyzable chlorine. The alkali metal hydroxide is used in the form of an aqueous solution, alcohol solution, or solid.

In the reaction, it is preferable to use an excess amount of epichlorohydrin relative to the reactants. Usually, 1.5 to 15 equivalents of epichlorohydrin are used per equivalent of hydroxyl groups in the reactants, but a range of 1.5 to 8 equivalents is preferable. This range increases production efficiency, suppresses the generation of high molecular weight epoxy resins, and also suppresses viscosity increases, resulting in excellent workability.

The reaction temperature is preferably 120°C or less, more preferably 100°C or less, and even more preferably 85°C or less, since this reduces the amount of hydrolyzable chlorine and enables high purity.

During the reaction, a quaternary ammonium salt or a polar solvent such as dimethyl sulfoxide or diglyme may be used. Examples of quaternary ammonium salts include tetramethylammonium chloride, tetrabutylammonium chloride, and benzyltriethylammonium chloride. The amount of the quaternary ammonium salt added is preferably in the range of 0.1 to 2 mass% of the reactants. Within this range, the effect of adding the quaternary ammonium salt is fully obtained, the generation of hydrolyzable chlorine can be suppressed, and high purity can be achieved. The amount of the polar solvent added is preferably in the range of 10 to 200 mass% of the reactants. Within this range, the effect of adding the quaternary ammonium salt is fully obtained, volume efficiency is not reduced, and it is economically preferable.

After the reaction is complete, excess epichlorohydrin and the solvent are distilled off, and the residue is dissolved in a solvent such as toluene or methyl isobutyl ketone, filtered, and washed with water to remove inorganic salts and residual solvent, and then the solvent is distilled off to produce epoxy resin (A).

The obtained epoxy resin (A) is further treated with an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide in an amount 1 to 30 times the amount of the remaining hydrolyzable chlorine to carry out a ring-closing reaction. The reaction temperature is usually 100°C or less, and preferably 90°C or less.

The epoxy equivalent of the epoxy resin (A) is preferably 200 to 600 g/equivalent, more preferably 220 to 500 g/equivalent, and even more preferably 240 to 400 g/equivalent. When the epoxy equivalent of the epoxy resin (A) is within the above range, the generation of secondary hydroxyl groups generated when the epoxy resin (A) reacts with the curing agent, the compound (B) having a phenolic hydroxyl group, is suppressed, and the obtained cured product has excellent heat resistance, low moisture absorption, and reflow resistance due to adhesion, etc., which is preferable. The epoxy equivalent is measured in accordance with JIS K7236.

The melt viscosity of the epoxy resin (A) is preferably 10 dPa·s or less, more preferably 0.01 to 5 dPa·s, and even more preferably 0.05 to 3 dPa·s. If the melt viscosity of the epoxy resin (A) is within the above range, it is preferable because it has low viscosity, excellent fluidity, and excellent workability, and therefore the moldability of the obtained cured product is also excellent. The melt viscosity here is measured using an ICI viscometer in accordance with ASTM D4287.

The softening point of the epoxy resin (A) is preferably 30 to 200°C, and more preferably 50 to 150°C. If the softening point of the epoxy resin (A) is within the above range, it is preferable because it has excellent moldability. The softening point here is measured based on JIS K7234 (ring and ball method).

The epoxy resin (A) preferably contains an epoxy resin represented by the above general formula (1) and is an epoxy resin having the epoxy resin (A) as a main component (50 mass% or more). Similarly, the reactant that is an intermediate of the epoxy resin (A) of the present invention preferably contains the reactant represented by the above general formula (2) and is an epoxy resin having the reactant as a main component (50 mass% or more).

In addition to the epoxy resin (A), the epoxy resin composition may contain other resins other than the epoxy resin (A) as long as the effects of the present invention are not impaired. For example, epoxy resins other than the epoxy resin (A), active esters, maleimide resins, bismaleimide resins, polymaleimide resins, polyphenylene ether resins, polyimide resins, cyanate ester resins, benzoxazine resins, triazine-containing cresol novolac resins, cyanate ester resins, styrene maleic anhydride resins, allyl group-containing resins such as diallyl bisphenol and triallyl isocyanurate, polyphosphate esters, and phosphate ester-carbonate copolymers may be used alone or in combination of two or more kinds in addition to the epoxy resin (A).

<Compound (B) Having a Phenolic Hydroxyl Group>
The epoxy resin composition of the present invention is characterized in that it contains a compound (B) having a phenolic hydroxyl group as a curing agent for the epoxy resin (A).By containing the epoxy resin (A) and the compound (B) having a phenolic hydroxyl group, the obtained cured product can have high heat resistance (high glass transition temperature), internal stress relaxation property (low elastic modulus when hot), low moisture absorption (low moisture absorption rate), moisture resistance, solder resistance, and high adhesion, which is preferable.

Examples of the compound (B) having a phenolic hydroxyl group include phenol novolac resin, cresol novolac resin, aromatic hydrocarbon formaldehyde resin modified phenol resin, dicyclopentadiene phenol addition type resin, phenol aralkyl resin (Zylok resin), naphthol aralkyl resin, triphenylol methane resin, tetraphenylol ethane resin, naphthol novolac resin, naphthol-phenol co-condensed novolac resin, naphthol-cresol co-condensed novolac resin, biphenyl modified phenol resin (bismethane Examples of the polyhydric phenolic hydroxyl group-containing compounds include polyhydric phenolic hydroxyl group-containing compounds in which the phenol nucleus is linked by a benzene group), biphenyl-modified naphthol resin (polyhydric naphthol compound in which the phenol nucleus is linked by a bismethylene group), aminotriazine-modified phenolic resin (polyhydric phenolic hydroxyl group-containing compound in which the phenol nucleus is linked by melamine, benzoguanamine, etc.), and alkoxy-group-containing aromatic ring-modified novolac resin (polyhydric phenolic hydroxyl group-containing compound in which the phenol nucleus and the alkoxy-group-containing aromatic ring are linked by formaldehyde). Among these, from the viewpoints of heat resistance, insulation reliability, and flame retardancy, phenol novolac resin, phenol aralkyl resin, triphenylol methane resin, biphenyl-modified phenolic resin, etc. are more preferable. The compounds containing phenolic hydroxyl groups may be used alone or in combination of two or more.

In addition to the compound (B) having a phenolic hydroxyl group, the epoxy resin composition of the present invention can use other curing agents such as amine curing agents and acid anhydride curing agents as long as the properties of the present invention are not impaired. The curing agents may be used alone or in combination of two or more.

Examples of the amine curing agent include aliphatic amines such as diethylenetriamine (DTA), triethylenetetramine (TTA), tetraethylenepentamine (TEPA), dipropylenediamine (DPDA), diethylaminopropylamine (DEAPA), N-aminoethylpiperazine, menthenediamine (MDA), isophoronediamine (IPDA), 1,3-bisaminomethylcyclohexane (1,3-BAC), piperidine, N,N'-dimethylpiperazine, and triethylenediamine; and aromatic amines such as m-xylenediamine (XDA), methanephenylenediamine (MPDA), diaminodiphenylmethane (DDM), diaminodiphenylsulfone (DDS), benzylmethylamine, 2-(dimethylaminomethyl)phenol, and 2,4,6-tris(dimethylaminomethyl)phenol.

Examples of the acid anhydride curing agent include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tristrimellitate, maleic anhydride, tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, endomethylene tetrahydrophthalic anhydride, methyl endomethylene tetrahydrophthalic anhydride, methylbutenyl tetrahydrophthalic anhydride, dodecenyl succinic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, and methylcyclohexene dicarboxylic anhydride.

The functional group equivalent ratio of the amount of the compound (B) having a phenolic hydroxyl group to the amount of the epoxy resin (A) used (total amount of hydroxyl groups in the compound (B) having a phenolic hydroxyl group/total amount of epoxy groups in the epoxy resin (A)) is preferably 0.3 to 1.5, more preferably 0.5 to 1. If the functional group equivalent ratio is within the above range, the obtained cured product is excellent in terms of curability and heat resistance, which is preferable.

<Inorganic filler (C)>
The epoxy resin composition of the present invention is characterized by containing an inorganic filler (C). By blending the inorganic filler (C), the obtained cured product has low thermal expansion properties, flame retardancy, and excellent insulation reliability, and is useful.

The inorganic filler (C) is not particularly limited, but examples thereof include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, zirconium tungstate phosphate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, and carbon black. Of these, it is preferable to use silica. In this case, amorphous silica, fused silica, crystalline silica, synthetic silica, hollow silica, and the like can be used as the silica. The inorganic filler (C) may be used alone or in combination of two or more.

The inorganic filler (C) may be surface-treated as necessary. In this case, the surface treatment agent that can be used is not particularly limited, but may be an aminosilane coupling agent, an epoxysilane coupling agent, a mercaptosilane coupling agent, a silane coupling agent, an organosilazane compound, a titanate coupling agent, or the like. Specific examples of the surface treatment agent include 3-glycidoxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, hexamethyldisilazane, or the like.

The amount of the inorganic filler (C) used is preferably 100 to 2000 parts by mass, and more preferably 400 to 1800 parts by mass, per 100 parts by mass of the mixture of the epoxy resin (A) and the compound having a phenolic hydroxyl group (B). When the amount of the inorganic filler used is within the above range, the composition is excellent in low thermal expansion, flame retardancy, and insulation reliability, and is therefore preferable.

In addition to the inorganic filler (C), an organic filler can be blended within a range that does not impair the characteristics of the present invention. Examples of the organic filler include polyamide particles.

<Solvent>
The epoxy resin composition of the present invention may be prepared without a solvent or may contain a solvent. The solvent has a function of adjusting the viscosity of the epoxy resin composition, etc.

Specific examples of the solvent include, but are not limited to, ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ether-based solvents such as diethyl ether and tetrahydrofuran; ester-based solvents such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, mesitylene, 1,2,3-trimethylbenzene, and 1,2,4-trimethylbenzene; and amide-based solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. These solvents may be used alone or in combination of two or more.

The amount of the solvent used is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass, based on the total mass of the epoxy resin composition. If the amount of the solvent used is 10% by mass or more, this is preferred because of excellent handleability. On the other hand, if the amount of the solvent used is 90% by mass or less, this is preferred from the standpoint of economy.

<Additives>
The epoxy resin composition of the present invention may contain various additives, such as a curing accelerator, a flame retardant, a silane coupling agent, a release agent, a pigment, a colorant, and an emulsifier, if necessary.

<Curing accelerator>
The curing accelerator is not particularly limited, and examples thereof include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, urea-based curing accelerators, etc. The curing accelerators may be used alone or in combination of two or more kinds.

The phosphorus-based curing accelerator may, for example, be an organic phosphine compound such as triphenylphosphine, tributylphosphine, tri-para-tolylphosphine, diphenylcyclohexylphosphine, or tricyclohexylphosphine; an organic phosphite compound such as trimethylphosphite or triethylphosphite; or a phosphonium salt such as ethyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, butylphosphonium tetraphenylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylphosphinetriphenylborane, tetraphenylphosphonium thiocyanate, tetraphenylphosphonium dicyanamide, butylphenylphosphonium dicyanamide, or tetrabutylphosphonium decanoate.

Examples of the amine-based curing accelerator include triethylamine, tributylamine, N,N-dimethyl-4-aminopyridine (4-dimethylaminopyridine, DMAP), 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo[5.4.0]-undecene-7 (DBU), 1,5-diazabicyclo[4.3.0]-nonene-5 (DBN), etc.

The imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyano Examples include ethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, and 2-methylimidazoline.

Examples of the guanidine-based curing accelerator include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-butylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, and 1-phenylbiguanide.

Examples of the urea-based curing accelerator include 3-phenyl-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, chlorophenylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, etc.

Among the above-mentioned curing accelerators, it is preferable to use phosphorus-based curing accelerators and imidazole-based curing accelerators from the viewpoint of curability, and phosphorus-based curing accelerators are particularly preferable from the viewpoint of insulation reliability.

The amount of the curing accelerator used can be adjusted as appropriate to obtain the desired curing properties, but is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the total amount of the epoxy resin (A) and the compound (B) having a phenolic hydroxyl group (and, if other resins or other curing agents are contained, the mixture including these). When the amount of the curing accelerator used is within the above range, the curing properties and insulation reliability are excellent, and this is preferable.

<Flame retardants>
The flame retardant is not particularly limited, and examples thereof include inorganic phosphorus-based flame retardants, organic phosphorus-based flame retardants, halogen-based flame retardants, etc. The flame retardants may be used alone or in combination of two or more kinds.

The inorganic phosphorus-based flame retardant is not particularly limited, but examples thereof include red phosphorus; ammonium phosphates such as monoammonium phosphate, diammonium phosphate, triammonium phosphate, and ammonium polyphosphate; and phosphoric acid amides.

The organic phosphorus flame retardant is not particularly limited, but may be methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, dibutyl phosphate, monobutyl phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, bis(2-ethylhexyl) phosphate, monoisodecyl acid phosphate, lauryl acid phosphate, tridecyl acid phosphate, stearyl acid phosphate, Phosphate esters such as isostearyl acid phosphate, oleyl acid phosphate, butyl pyrophosphate, tetracosyl acid phosphate, ethylene glycol acid phosphate, and (2-hydroxyethyl) methacrylate acid phosphate; diphenylphosphines such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and diphenylphosphine oxide; 10-(2,5-dihydroxyphenyl)-10H-9-oxa- Phosphorus-containing phenols such as 10-phosphaphenanthrene-10-oxide, 10-(1,4-dioxynaphthalene)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, diphenylphosphinylhydroquinone, diphenylphosphinyl-1,4-dioxynaphthalene, 1,4-cyclooctylenephosphinyl-1,4-phenyldiol, and 1,5-cyclooctylenephosphinyl-1,4-phenyldiol; cyclic phosphorus compounds such as 10-(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(2,7-dihydroxynaphthyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide; and compounds obtained by reacting the phosphoric acid ester, diphenylphosphine, or phosphorus-containing phenol with an epoxy resin, an aldehyde compound, or a phenol compound.

The halogen-based flame retardant is not particularly limited, but examples include brominated polystyrene, bis(pentabromophenyl)ethane, tetrabromobisphenol A bis(dibromopropyl ether), 1,2-bis(tetrabromophthalimide), 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine, and tetrabromophthalic acid.

The amount of the flame retardant used is preferably 0.01 to 20 parts by mass, and more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the epoxy resin (A). When the amount of the flame retardant used is within the above range, flame retardancy can be imparted, which is preferable.

<Cured Product>
The present invention relates to a cured product of the epoxy resin composition. The cured product is obtained by using an epoxy resin composition containing the epoxy resin, and is therefore useful because it has excellent heat resistance (high glass transition temperature), internal stress relaxation (low elastic modulus when heated), low moisture absorption (low moisture absorption rate), moisture resistance, solder resistance, and high adhesion. In particular, the cured product of the epoxy resin composition has excellent internal stress relaxation (low elastic modulus when heated), and is therefore suitable for use as a semiconductor encapsulant.

As a method for obtaining a cured product by subjecting the epoxy resin composition to a curing reaction, for example, the heating temperature during heat curing is not particularly limited, but is preferably 150 to 250°C and the heating time is preferably 1 to 10 hours.

<Semiconductor encapsulation material>
The present invention relates to a semiconductor encapsulant comprising the above-mentioned cured product. The semiconductor encapsulant obtained by using the epoxy resin composition contains the above-mentioned epoxy resin, and the obtained cured product has high heat resistance (high glass transition temperature), internal stress relaxation property (low elastic modulus when heated), low moisture absorption (low moisture absorption rate), moisture resistance, solder resistance, and high adhesion, which is preferable.

The method for obtaining the semiconductor encapsulant includes a method in which optional additives are added to the epoxy resin composition as necessary, and the mixture is thoroughly melt-mixed until homogeneous using an extruder, kneader, roll, or the like.

<Semiconductor Device>
The present invention relates to a semiconductor device comprising the semiconductor encapsulant. A semiconductor device comprising the semiconductor encapsulant containing a cured product of the epoxy resin composition is preferable because it has high heat resistance (high glass transition temperature), internal stress relaxation properties (low elastic modulus when heated), low moisture absorption (low moisture absorption rate), moisture resistance, solder resistance, and high adhesion.

The semiconductor device can be obtained by molding the semiconductor encapsulant using a casting machine, transfer molding machine, injection molding machine, or the like, and then heating and curing the material at 150 to 250°C for 1 to 10 hours.

<Other uses>
The cured product obtained from the epoxy resin composition of the present invention is excellent in high heat resistance (high glass transition temperature), internal stress relaxation properties (low elastic modulus when hot), low moisture absorption (low moisture absorption rate), moisture resistance and solder resistance, and high adhesion, and therefore can be suitably used not only for semiconductor encapsulation materials and semiconductor devices, but also for prepregs, circuit boards, build-up films, build-up boards, adhesives, resist materials, etc. In addition, it can be suitably used for various applications such as matrix resins for fiber reinforced resins, and the applications are not limited thereto.

The present invention will be described in more detail below using examples, but the present invention is not limited to these scopes. Measurement and evaluation of physical properties and characteristics were carried out as follows, and the composition and evaluation results are shown in Tables 1 to 3.

<Softening point>
The softening point (° C.) was measured in accordance with JIS K7234 (ring and ball method).

<Measurement of epoxy equivalent>
Measurement was performed based on JIS K 7236.

<Melt Viscosity Measurement Method at 150°C>
The viscosity was measured using an ICI viscometer in accordance with ASTM D4287.

<GPC Measurement>
Measurement equipment: "HLC-8320 GPC" manufactured by Tosoh Corporation,
Column: Guard column "HXL-L" manufactured by Tosoh Corporation
+ Tosoh Corporation "TSK-GEL G2000HXL"
+ Tosoh Corporation "TSK-GEL G2000HXL"
+ Tosoh Corporation "TSK-GEL G3000HXL"
+ Tosoh Corporation "TSK-GEL G4000HXL"
Detector: RI (differential refractometer)
Data processing: Tosoh Corporation's "GPC Workstation EcoSEC-WorkStation"
Measurement conditions: Column temperature 40°C
Developing solvent: Tetrahydrofuran
Flow rate: 1.0 ml/min. Standard: The following monodisperse polystyrene with known molecular weight was used in accordance with the measurement manual for the above-mentioned "GPC Workstation EcoSEC-WorkStation."
(Polystyrene used)
"A-500" manufactured by Tosoh Corporation
"A-1000" manufactured by Tosoh Corporation
"A-2500" manufactured by Tosoh Corporation
"A-5000" manufactured by Tosoh Corporation
"F-1" manufactured by Tosoh Corporation
"F-2" manufactured by Tosoh Corporation
"F-4" manufactured by Tosoh Corporation
"F-10" manufactured by Tosoh Corporation
"F-20" manufactured by Tosoh Corporation
"F-40" manufactured by Tosoh Corporation
"F-80" manufactured by Tosoh Corporation
"F-128" manufactured by Tosoh Corporation
Sample: 1.0% by mass in terms of resin solid content, obtained by filtering a tetrahydrofuran solution through a microfilter (50 μl).

Synthesis Example 1
[Synthesis of epoxy resin intermediate (1)]
In a flask equipped with a thermometer, a dropping funnel, a cooling tube, a fractionating tube, a nitrogen gas inlet tube, and a stirrer, 186.2 g (1.0 mol) of 4,4'-dihydroxybiphenyl and 208.3 g of toluene were charged, 4.2 g of p-toluenesulfonic acid was added, and the temperature was raised to 110°C. 416.6 (4.0 mol) g of styrene was dropped over 2 hours, and the mixture was reacted at 110°C for 2 hours. After the reaction was completed, the temperature was lowered to 80°C, and the mixture was neutralized using a 20% by mass aqueous sodium hydroxide solution. The toluene was removed under reduced pressure by heating, and 542.5 g of an epoxy resin intermediate (1) was obtained. The appearance of the obtained epoxy resin intermediate (1) was solid, and the hydroxyl equivalent was 316 g/equivalent. The GPC chart of the epoxy resin intermediate (1) is shown in Figure 1.

Synthesis Example 2
[Synthesis of epoxy resin (1)]
In a flask equipped with a thermometer, a dropping funnel, a cooling tube, a fractionating tube, a nitrogen gas inlet tube, and a stirrer, 316.0 g (1.0 equivalent of hydroxyl group) of the epoxy resin intermediate (1) obtained in Synthesis Example 1, 740.0 g (8.0 equivalents) of epichlorohydrin, and 158.0 g of n-butanol were charged and dissolved while purging with nitrogen gas. After heating to 60°C, 220.0 g (1.1 equivalents) of a 20% by mass aqueous solution of sodium hydroxide was dropped over 5 hours. Stirring was then continued for 0.5 hours under the same conditions. Thereafter, unreacted epichlorohydrin was distilled off by reduced pressure distillation. 744.0 g of methyl isobutyl ketone was added to the crude epoxy resin thus obtained and dissolved. Further, 5.0 g of a 20% by mass aqueous solution of sodium hydroxide was added to this solution and reacted at 80°C for 2 hours, and then the solution was washed three times with 372.0 g of water until the pH of the washing liquid became neutral. The system was then dehydrated by azeotropy, and after microfiltration, the solvent was distilled off under reduced pressure to obtain 334.9 g of epoxy resin (1). The resulting epoxy resin (1) had a melt viscosity (measurement method: ICI viscometer method, measurement temperature: 150°C) of 1.1 dPa s, a softening point of 72°C, and an epoxy equivalent of 384 g/equivalent. The GPC chart of the resulting epoxy resin (1) is shown in Figure 2.

Synthesis Example 3
[Synthesis of epoxy resin intermediate (2)]
The same procedure as in Synthesis Example 1 was carried out, except that the amount of styrene was changed to 208.3 (2.0 mol) g, to obtain 374.8 g of an epoxy resin intermediate (2). The appearance of the obtained epoxy resin intermediate (2) was solid, and the hydroxyl equivalent was 187 g/equivalent. The GPC chart of the epoxy resin intermediate (2) is shown in FIG. 3.

Synthesis Example 4
[Synthesis of epoxy resin (2)]
In a flask equipped with a thermometer, a dropping funnel, a cooling tube, a fractionating tube, a nitrogen gas inlet tube, and a stirrer, 187.0 g (1.0 equivalent of hydroxyl group) of the epoxy resin intermediate (2) obtained in Synthesis Example 3, 740.0 g (8.0 equivalents) of epichlorohydrin, and 158.0 g of n-butanol were charged and dissolved while purging with nitrogen gas. After heating to 60°C, 220.0 g (1.1 equivalents) of a 20% by mass aqueous solution of sodium hydroxide was dropped over 5 hours. Stirring was then continued for 0.5 hours under the same conditions. Then, unreacted epichlorohydrin was distilled off by vacuum distillation. 486.0 g of methyl isobutyl ketone was added to the crude epoxy resin obtained and dissolved. Furthermore, 5.0 g of a 20% by mass aqueous solution of sodium hydroxide was added to this solution and reacted at 80°C for 2 hours, and the solution was washed with 243.0 g of water three times until the pH of the washing liquid became neutral. The system was then dehydrated by azeotropy, and after microfiltration, the solvent was distilled off under reduced pressure to obtain 228.4 g of epoxy resin (2). The resulting epoxy resin (2) had a melt viscosity (measurement method: ICI viscometer method, measurement temperature: 150°C) of 0.7 dPa s, a softening point of 107°C, and an epoxy equivalent of 267 g/equivalent. The GPC chart of the resulting epoxy resin (2) is shown in Figure 4.

Synthesis Example 5
[Synthesis of epoxy resin intermediate (3)]
The same procedure as in Synthesis Example 1 was carried out, except that the amount of styrene was changed to 104.2 (1.0 mol) g, to obtain 278.4 g of an epoxy resin intermediate (3). The appearance of the obtained epoxy resin intermediate (3) was solid, and the hydroxyl equivalent was 145 g/equivalent. The GPC chart of the epoxy resin intermediate (3) is shown in FIG. 5.

Synthesis Example 6
[Synthesis of epoxy resin (3)]
In a flask equipped with a thermometer, a dropping funnel, a cooling tube, a fractionating tube, a nitrogen gas inlet tube, and a stirrer, 145.0 g (1.0 equivalent of hydroxyl group) of the epoxy resin intermediate (3) obtained in Synthesis Example 5, 740.0 g (8.0 equivalents) of epichlorohydrin, and 158.0 g of n-butanol were charged and dissolved while purging with nitrogen gas. After heating to 60°C, 220.0 g (1.1 equivalents) of a 20% by mass aqueous sodium hydroxide solution was dropped over 5 hours. Stirring was then continued for 0.5 hours under the same conditions. Then, unreacted epichlorohydrin was distilled off by vacuum distillation. 402.0 g of methyl isobutyl ketone was added to the crude epoxy resin obtained and dissolved. Further, 5.0 g of a 20% by mass aqueous sodium hydroxide solution was added to this solution and reacted at 80°C for 2 hours, and the solution was washed with 201.0 g of water three times until the pH of the washing liquid became neutral. The system was then dehydrated by azeotropy, and after microfiltration, the solvent was distilled off under reduced pressure to obtain 192.9 g of epoxy resin (3). The resulting epoxy resin (3) had a melt viscosity (measurement method: ICI viscometer method, measurement temperature: 150°C) of 0.3 dPa s, a softening point of 109°C, and an epoxy equivalent of 231 g/equivalent. The GPC chart of the resulting epoxy resin (3) is shown in Figure 6.

[Epoxy resin (4)]
As the epoxy resin (4), a commercially available product, trade name "NC-3000" manufactured by Nippon Kayaku Co., Ltd. (melt viscosity (measurement method: ICI viscometer method, measurement temperature: 150°C): 1.3 dPa s, softening point: 60°C, epoxy equivalent: 275 g/equivalent) was used.

<Preparation of epoxy resin composition for semiconductor encapsulation and production of cured product>
The raw materials shown in Table 1 were mixed according to the compositions shown in Table 2, and the mixture was melt-kneaded using a two-roll mill at 90° C. for 5 minutes to prepare epoxy resin compositions for semiconductor encapsulation.
Each of these epoxy resin compositions for semiconductor encapsulation was pulverized and molded in a transfer molding machine at a pressure of 70 kg/ ^cm2 , a ram speed of 5 cm/sec, a temperature of 175°C, and a time of 180 seconds into a disk shape with a diameter of 50 mm and a thickness of 3 mm, or into a rectangle with a width of 12.7 mm, a length of 127 mm, and a thickness of 1.6 mm. The molded product was then further cured at 180°C for 5 hours to obtain a cured product for evaluation.
In addition, in evaluating the adhesion, during the transfer molding, a copper foil (manufactured by Furukawa Circuit Foil Co., Ltd., thickness 35 μm, GTS-MP treated and the shine surface was used as the adhesive surface for the epoxy resin composition for semiconductor encapsulation) was placed on one side of the mold, and molded into a rectangle with a width of 12.7 mm, a length of 127 mm and a thickness of 1.6 mm. This was further cured at 180° C. for 5 hours (cured product) to prepare a test specimen.
The physical properties of the obtained cured products were evaluated by preparing test pieces and evaluating the heat resistance, hot elastic modulus, moisture absorption, moisture resistance, solder resistance, and adhesion according to the methods described in the respective evaluation methods below.
The evaluation results are shown in Table 3.

<Heat resistance (glass transition temperature)>
The obtained cured product was cut into a size of 5 mm x 54 mm, and a Rheometrics "Solid Viscoelasticity Measuring Device RSAII" was used to measure DMA (dynamic viscoelasticity) by the rectangular tension method, and the temperature at which the change in elastic modulus of the test piece was maximum (the rate of change in tan δ was the largest) was measured as the glass transition temperature (Tg) (°C) to evaluate heat resistance. The measurement conditions were a frequency of 1 Hz and a heating rate of 3°C/min. The higher the evaluation result, the better, and if it is marked ○, it can be used without any problems in practical use.
[Evaluation criteria for glass transition temperature]
◯: 130℃ or higher ×: Less than 130℃

<Storage modulus at 260°C (elastic modulus when heated)>
The obtained cured product was cut into a size of 5 mm x 54 mm, and the storage modulus (hot modulus) (MPa) at 260°C was measured and evaluated by DMA (dynamic viscoelasticity) measurement by the rectangular tension method using a Rheometrics "Solid Viscoelasticity Measuring Device RSAII." Note that the lower the evaluation result value, the better, and a rating of ◎ or ◯ indicates that the product can be used without any problems in practical use.
[Evaluation Criteria for Hot Elastic Modulus]
◎: Less than 5 〇: 5 or more but less than 20 ×: 20 or more

<Low hygroscopicity (moisture absorption rate)>
The obtained cured product was cut into a disk shape with a diameter of 50 mm and a thickness of 3 mm. This was used as a test piece and treated in a thermo-hygrostat at 85°C/85% RH for 300 hours. The mass change ( The moisture absorption rate was measured as % by mass. The lower the evaluation result, the better. If the evaluation result was rated as ⊚ or ◯, the sample could be used without any problems in practice.
Moisture absorption rate (%) = [(mass of test piece after test - mass of test piece before test) / (mass of test piece before test)] x 100
[Evaluation criteria for moisture absorption rate]
◎: Less than 0.15% 〇: 0.15% to less than 0.2% ×: 0.2% or more

<Moisture resistance and solder resistance>
The obtained cured product was cut into a disk shape of 50 mm in diameter x 3 mm in thickness, and used as a test piece, which was left in an atmosphere of 85°C/85% RH for 168 hours to absorb moisture, and then immersed in a solder bath at 260°C for 10 seconds, and visually observed for the presence or absence of cracks. If the evaluation result was ○, it could be used without any problems in practical use.
[Evaluation Criteria for Moisture Resistance and Solder Resistance]
〇: No cracks × Cracks present

<Adhesion (peel strength)>
The obtained cured product was cut into a size of 100 mm x 10 mm, and used as a test piece for peel strength evaluation. The peel strength (N/m) was measured under the measurement conditions of a 25°C environment, a peel angle of 90 degrees, and a peel speed of 50 mm/min, and the adhesion was evaluated. The higher the evaluation result, the better, and a ◎ or ○ indicates practical use without any problems.
[Evaluation Criteria for Peel Strength]
◎: 1.2 N/m or more 〇: Less than 1.2 N/m to 1.0 N/m or more ×: Less than 1.0 N/m

From the evaluation results in Table 3 above, it was confirmed that the epoxy resin compositions (blends) for semiconductor encapsulation obtained in all Examples have high heat resistance, low elastic modulus when heated, excellent internal stress relaxation properties, and are cured products with low moisture absorption, moisture resistance, solder resistance, and high adhesion, making them suitable for semiconductor encapsulation applications.

On the other hand, from the evaluation results in Table 3 above, in Comparative Example 1, because an epoxy resin (3) was used that used an epoxy resin intermediate with a styrene content below the desired range, the properties of the elastic modulus at hot time, moisture absorption rate, moisture resistance and solder resistance, and adhesion were also inferior to those of the Examples. In particular, the reason for the high moisture absorption rate is presumably due to the epoxy resin (3) used having a lower epoxy equivalent than the other epoxy resins, resulting in a high secondary hydroxyl group concentration during the curing reaction. In addition, in Comparative Example 2, because a biphenyl aralkyl type epoxy resin (not modified with styrene) was used as the epoxy resin, the properties of the elastic modulus at hot time, moisture resistance and solder resistance, and adhesion were also inferior to those of the Examples.

The cured product obtained using the epoxy resin composition of the present invention has excellent heat resistance (high glass transition temperature), internal stress relaxation properties (low elastic modulus when hot), low moisture absorption (low moisture absorption rate), moisture resistance and solder resistance, and high adhesion, so it can be used not only as a semiconductor encapsulant and semiconductor device, but also as a prepreg, circuit board, build-up film, build-up board, adhesive, resist material, etc. It can also be used for various applications such as a matrix resin for fiber reinforced resin.

FIG. 2 is a GPC chart of the epoxy resin intermediate (1). FIG. 1 is a GPC chart of epoxy resin (1). FIG. 2 is a GPC chart of an epoxy resin intermediate (2). FIG. 2 is a GPC chart of epoxy resin (2). FIG. 2 is a GPC chart of an epoxy resin intermediate (3). FIG. 2 is a GPC chart of epoxy resin (3).

Claims (4)

An epoxy resin composition obtained by reacting a reaction product of 1.5 to 8 moles of styrene or a styrene derivative with 1 mole of dihydroxybiphenyl with epichlorohydrin, the composition comprising an epoxy resin (A) represented by the following general formula (1), a compound (B) having a phenolic hydroxyl group, and an inorganic filler (C).
(In the above general formula (1), _R1 and _R2 represent an α -methylbenzyl group, G represents a glycidyl group, p and q each independently represent a number from 0 to 4, and p+q has an average value of 1.5 to 8, and n represents a number from 0 to 5.)


A cured product of the epoxy resin composition according to claim 1. A semiconductor encapsulant comprising the cured product according to claim 2. A semiconductor device comprising the semiconductor encapsulation material according to claim 3.