JPH047365B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to an epoxy resin composition for semiconductor encapsulation, and more specifically to a cured product that maintains the glass transition point of a phenol-cured epoxy resin and has a low elastic modulus and excellent crack resistance. The present invention relates to an epoxy resin composition for semiconductor encapsulation. [Prior art and its problems] When sealing a semiconductor element with resin,
Generally, resin is directly encapsulated into a semiconductor. Therefore, if there is a large difference in coefficient of linear expansion between the semiconductor element and the resin due to temperature changes, or if large thermal stress is applied, the element pellet may crack or the bonding lines of the semiconductor element may be severed. Due to this problem, it is desired to reduce the stress on the device, and in recent years, as semiconductor devices have become larger and more highly integrated, this demand has become stronger. The epoxy resin composition for semiconductor encapsulation has heat resistance,
From the viewpoint of electrical properties and water resistance, it is widely known that the epoxy resin is basically composed of a novolac type epoxy resin, a phenol novolac resin as a hardening agent, and a silica powder as a filler. However, when a semiconductor element is encapsulated using a conventional epoxy resin composition, there are problems in that when a heat cycle test is performed, cracks occur in the encapsulating resin or cracks occur in the chip, reducing the reliability of the semiconductor component. is occurring. This is because a novolak type epoxy resin with excellent heat resistance is used as the epoxy resin, and the cured product made of this resin is hard and lacks flexibility. In order to solve these problems, a method is known in which, for example, a flexibility imparting agent is added to an epoxy resin composition. However, when conventionally known flexibility-imparting agents are blended, although flexibility is improved, the glass transition point (Tg) decreases rapidly, high-temperature electrical properties also decrease, and moisture resistance The problem is that it has a large impact on sexuality. In addition, a method of blending a silicone resin with a low elastic modulus and a high glass transition temperature is known, but
Silicone resins have poor adhesion to metals and high moisture permeability, so they have the problem of lacking reliability in terms of moisture resistance. [Object of the Invention] The present invention was made in view of the above circumstances, and its purpose is to provide a cured product with low elastic modulus and excellent crack resistance while maintaining the glass transition point of the phenol-cured epoxy resin. An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation having the following properties. [Summary of the invention] That is, the present invention provides the following: (1)(a) General formula (In the formula, R represents a hydrogen atom or a methyl group,
R ¹ to ^{R 8} are hydrogen atoms, methyl groups, ethyl groups,
Indicates the same or different groups selected from the group consisting of isopropyl group, phenyl group, chlorine atom, or bromine atom. Moreover, n shows an integer of 0-5. ) 100 parts by weight of a bishydroxybiphenyl epoxy resin (b) 20 to 400 parts by weight of a novolak type epoxy resin (c) A phenol novolak resin curing agent (d) A curing accelerator (e) An inorganic filler An epoxy resin composition for semiconductor encapsulation, characterized by: The bishydroxybiphenyl epoxy resin as component (a) in the present invention has the general formula (In the formula, R represents a hydrogen atom or a methyl group, and R ¹
~ ^R8 represents the same or different groups selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, a phenyl group, a chloro atom, or a bromine atom. Moreover, n shows an integer of 0-5. ), but this resin is 4,4'-bishydroxybiphenyl, 4,4'-bishydroxy-
3,3',5,5'-tetramethylbiphenyl, 4,
4'bishydroxy-3,3',5,5'-tetramethyl-2-chlorobiphenyl, 4,4'bishydroxy-3,3',5,5'-tetramethyl-2-bromobiphenyl, 4,4'bishydroxy-3,3',
Biphenol derivatives such as 5,5'-tetraethylbiphenyl and 4,4'bishydroxy-3,3',5,5'-tetraphenylbiphenyl can be converted into epihalohydrin or β-methylepihalohydrin (hereinafter both are referred to as epihalohydrin). ) can be obtained by reacting with Specifically, () bishydroxybiphenyl or its methylated product (hereinafter, both are represented by methylated bishydroxybiphenyl) and excess epihalohydrin are reacted in the coexistence of an alkali metal hydroxide, A one-step method for producing a polyepoxy compound by simultaneously performing an addition reaction of epihalohydrin to a methylated product of bishydroxybiphenyl and a ring-closing reaction to form an epoxy ring. A two-step method is mentioned in which a polyepoxy compound is produced by carrying out an addition reaction in the presence of a basic catalyst, and then carrying out a ring-closing reaction by adding an alkali metal hydroxide. Epihalohydrin includes epichlorohydrin, epipromohydrin, β-methylepichlorohydrin, β-methylepipromohydrin, β-
Examples include methylepiiodohydrin, but epichlorohydrin is generally used. Further, as the alkali metal hydroxide, caustic potash and caustic soda can be used, and these are added as a solid or as a 40 to 50% aqueous alkali solution. Basic catalysts include tetramethylammonium chloride, tetramethylammonium bromide,
Quaternary ammonium salts such as triethylmethylammonium chloride, tetraethylammonium idide, and cetyltriethylammonium bromide can be used. In the one-stage method, the temperature is 60 to 150°C, preferably
The reaction is carried out at a temperature in the range 80-120°C. The alkali metal hydroxide is the hydroxyl group 1 of the biphenyl derivative.
0.8 to 1.5 times the mole equivalent, preferably 0.9 to 1.5 times the mole
Use 1.2 mole times. In addition, in the two-stage method, the first stage reaction is 90
It is carried out at a temperature of -150°C, preferably 100-140°C.
The amount of epihalohydrin used is 1.3 to 20 times the molar amount of bishydroxybiphenyl methylated product,
It is preferably 1.5 to 14 times the molar amount, and epihalohydrin used in excess can be reused by recovering it by distillation. In addition, the basic catalyst acts on the phenolic hydroxyl group of bishydroxybiphenyl.
It is used in an amount of 0.002-0.5 mol%. The temperature of the subsequent reaction is 60-150℃, preferably 80-120℃
The alkali metal hydroxide is used in an equimolar amount to 1.1 times the molar amount of the halohydrin produced. These first-stage and second-stage reactions may be carried out in the presence of an inert organic solvent such as methyl isobutyl ketone, methyl ethyl ketone, or toluene. After the reaction of () and () is completed, the reaction product is washed with warm water to remove an alkali metal salt such as common salt, and then purified by distilling off water. Alternatively, the reaction product is dissolved in an organic solvent that is insoluble or poorly soluble in water, such as methyl isobutyl ketone, methyl ethyl ketone, toluene, etc., and this solution is brought into contact with water or hot water to dissolve inorganic impurities such as common salt in the aqueous phase. Thereafter, the organic solvent is distilled off to perform purification. Even when epihalohydrin is used in large excess, the epoxy resin represented by the general formula obtained in this way does not consist only of compounds with n=0, but with polyepoxy compounds with n=1 to 5. It usually contains less than 20% by weight. The melting point of the epoxy resin represented by this general formula depends on its degree of polymerization and molecular weight distribution, but for example, R, R ² , R ⁴ , R ⁵ , and R ⁷ are H, R ¹ ,
When R ³ , R ⁶ and R ⁸ are CH ₃ 83 to 165°C, R, R ⁴ ,
R ⁵ and R ⁷ are H, R ¹ , R ³ , R ⁶ and R ⁸ are CH ₃ and R ² is Cl
It is 41-95°C in the case of R, R ¹ ,
When R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are all H, the temperature is 145 to 190°C. Examples of the novolak epoxy resin as component (b) in the present invention include the following. () Cresol novolak type epoxy resin: For example, Epicoat 181 from Yuka Ciel Epoxy Co., Ltd.
Ciba Araldite ECN1235, Araldite 1273, Araldite
1280 (all of the above are product names), etc. () Phenol novolac type epoxy resin: For example, Epicoat 152 from Yuka Ciel Epoxy Co., Ltd.
154, Ciba's Araldite EPN1138,
1139, DOW Chemical Company's DEN438, DEN448 (all of the above are product names), etc. () Brominated phenol novolak type epoxy resin: for example, Bren from Nippon Kayaku Co., Ltd.; and as component (b), one or more selected from the group consisting of these are used. The blending ratio of the bishydroxybiphenyl diepoxy resin and the novolak epoxy resin is 20 to 400 parts by weight, preferably 30 to 300 parts by weight, of the novolak epoxy resin per 100 parts by weight of the bishydroxybiphenyl epoxy resin. . If the amount of novolak type epoxy resin is less than 20 parts by weight, the heat resistance will be low, and if it is more than 400 parts by weight, the effect of improving heat crack resistance will be extremely small. In addition, in this system, epoxy resins derived from bisphenol A, such as Epicote 828, Epicote 1001 and Epicote manufactured by Yuka Ciel Epoxy Co., Ltd.
1004, etc., and an epoxy resin derived from bisphenol F, such as Epicote 807 manufactured by Yuka Ciel Epoxy Co., Ltd., may be added in the required amount. The phenol novolak resin as component (c) used as a curing agent in the present invention is at least one selected from the group consisting of phenol, cresol, xylenol, resorcinol, chlorophenol, phenylphenol, bisphenol A, etc. It is obtained by reacting a mixture of two or more types with formaldehyde or paraformaldehyde under an acid catalyst. In order to increase the crosslinking density of the resin composition and prevent the unreacted raw material (monomer) from having an adverse effect on the semiconductor device, such a phenol novolak resin has an amount of unreacted monomer in the phenol novolak resin.
It is preferable to use 0.7% by weight or less.
Moreover, it is preferable that the softening point is 60 to 110°C. The blending amount of the above phenolic novolac resin is 0.5 to 2.0 phenolic hydroxyl groups in the phenolic resin per epoxy group in the epoxy resin in combination with the epoxy resins of components (a) and (b).
It is preferable to mix the number of particles, more preferably about one. The curing accelerator used in the present invention as component (d) accelerates the reaction between the epoxy resin and the phenol novolac resin to accelerate curing. Examples of such curing accelerators include tertiary amines such as 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, benzyldimethylamine, and α-methylbenzyldimethylamine. , 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecyl imidazole, 2-ethyl-4-methylimidazole, and other imidazoles; and triphenylphosphin and other phosphins. The blending amount is preferably 0.02 to 1.0% by weight in the epoxy resin composition. The inorganic filler as component (e) used in the present invention may be any inorganic filler that is normally used as an inorganic filler. Such inorganic fillers include fused silica powder, crystalline silica powder, quartz glass powder, talc, calcium silicate powder, zirconium silicate powder, alumina powder, calcium carbonate powder, clay powder, barium sulfate powder, and glass fiber. One or more types selected from the group consisting of these are used, but silica powder is particularly preferred. The amount of the above-mentioned inorganic filler to be blended depends on the type of inorganic filler to be blended, and the desired elastic modulus and
The amount may be sufficient as long as it provides a coefficient of linear expansion, a glass transition temperature, etc., but it is preferably 50 to 85% by weight in the resin composition. If it is less than 50% by weight, the coefficient of linear expansion will increase, while if it exceeds 85% by weight, the fluidity of the resin composition will decrease. The resin composition of the present invention is produced by mixing the five components described above, but the mixing order is not particularly limited. However, it is preferable that the epoxy resins (a) and (b) are mixed in advance. In the present invention, a mold release agent, a coloring agent, a coupling agent, a flame retardant, etc. may be further added as necessary. Examples of mold release agents include natural waxes, synthetic waxes, higher fats and their metal salts, paraffin, etc. Colorants include carbon, and flame retardants include antimony trioxide, pentoxide, etc. Examples include antimony, phosphoric acid, and phosphorus compounds. [Effects of the Invention] According to the present invention, the cured resin material maintains the glass transition point of the phenol-cured epoxy resin,
It is possible to obtain an epoxy resin composition for semiconductor encapsulation that has a low elastic modulus and excellent crack resistance. [Embodiments of the invention] Production example of bishydroxybiphenyl epoxy resin 1 Epoxy resin A Internal volume 5 equipped with a stirring device, thermometer, and cooler
In a three-necked flask, 4,4'-bishydroxy-3,3',5,5'-tetramethylbiphenyl 242
(1.0 mol), 2220 g (24 mol) of epichlorohydrin, and 1.9 g of tetramethylammonium chloride were charged, and an addition reaction was carried out under heating and reflux for 2 hours. The contents were then cooled to 60°C, equipped with a water removal device, and then 88 g (2.2 g) of sodium hydroxide was added.
mol) added, reaction temperature 55-60℃, degree of vacuum 100-150
The ring-closing reaction was carried out while continuously azeotropically removing the water produced at mmHg. The point at which the produced water reached 36 ml was defined as the end point of the reaction. (After 2 hours) After the reaction product was filtered under reduced pressure, the filtered product was washed repeatedly with water in a mixer to remove salt. Further, the liquid was distilled under reduced pressure to recover residual epichlorohydrin. In this way, a pale yellow solid, 4,4'-bis(2,
330 g of 3-epoxypropoxy)-3,3',5,5'-tetramethylbiphenyl were obtained. Production Example 2 Epoxy Resin B In the previous Production Example 1, 4,4'-bishydroxy-
186 g of 4,4'-bishydroxybiphenyl (1.0
273 g of 4,4'-bis(2,3-epoxypropoxy)-biphenyl, a pale yellow solid with an epoxy equivalent of 157 g/equivalent and a melting point of 151°C, was prepared in the same manner as in Production Example 1 except that 273 g of 4,4'-bis(2,3-epoxypropoxy)-biphenyl was used. I got it. Examples 1 to 6, Comparative Examples 1 to 6 Curing of epoxy resin Epoxy resins A and B obtained in Production Examples 1 and 2, bisphenol A type epoxy resin (manufactured by Yuka Ciel Epoxy Co., Ltd.: E-828 (trade name) ), cresol novolak type epoxy resin (manufactured by Yuka Ciel Epoxy Co., Ltd.:
E-181 (product name)), phenol novolac type epoxy resin (manufactured by Yuka Ciel Epoxy Co., Ltd.: E-154 (product name)), phenol novolak resin (manufactured by Gunei Kagaku Co., Ltd.: Retop PSF4224 (product name)) , 2-undecylimidazole and fused silica were blended in the composition ratios shown in Table 1, melt-mixed, precured by press molding at 160°C for 20 minutes, and then 170°C/
After 5 hours of curing, a test piece was prepared. The crack resistance was evaluated using Olyphant's washer method. Table 1 shows the physical properties of the obtained cured product.

【table】

【table】

Claims (1)

[Claims] 1 (a) General formula (In the formula, R represents a hydrogen atom or a methyl group,
^R1 to ^R8 represent the same or different groups selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, a phenyl group, a chloro atom, or a bromine atom. Moreover, n shows an integer of 0-5. ) 100 parts by weight of a bishydroxybiphenyl epoxy resin (b) 20 to 400 parts by weight of a novolak type epoxy resin (c) A phenol novolak resin curing agent (d) A curing accelerator (e) An inorganic filler An epoxy resin composition for semiconductor encapsulation characterized by: