JP3357130B2 - Epoxy resin composition for semiconductor encapsulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition which is preferably used for encapsulating a semiconductor device or the like which gives a cured product having excellent fluidity, low moisture absorption and excellent solder heat resistance. is there.

[0002]

2. Description of the Related Art Conventionally, a resin composition containing an epoxy resin as a main component has been widely used as a semiconductor encapsulating material.
In recent years, as a method of mounting components on a printed circuit board, a shift from a conventional insertion method to a surface mounting method has been advanced. In the surface mounting method, the entire package is heated to the solder temperature, and a package crack caused by rapid volume expansion of the absorbed moisture has become a serious problem. Furthermore, in recent years, the high integration of semiconductor devices, the enlargement of device size, and the miniaturization of wiring width are rapidly progressing.
The problem of package cracks is becoming more serious.
Methods for preventing package cracks include toughening the resin structure, increasing the strength by increasing the filling of silica, and reducing the water absorption, but these methods are still insufficient.

In order to overcome the above-mentioned problems, use of an epoxy resin having low hygroscopicity and low viscosity has been proposed. As the low-viscosity epoxy resin, bisphenol A-type epoxy resin, bisphenol F-type epoxy resin and the like are generally widely used. Among these epoxy resins, those having a low viscosity are liquid at ordinary temperature, and the resin composition for transfer molding is used. It is difficult to make things. Furthermore, these epoxy resins are not sufficient in heat resistance, mechanical strength, and moisture resistance.

Further, Japanese Patent Publication No. 4-7365 discloses an epoxy resin composition for semiconductor encapsulation using a biphenyl-based epoxy resin as a main component as an improvement in handling workability, heat resistance, toughness and the like. However, there is a problem in terms of low hygroscopicity.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an epoxy resin composition for encapsulating a semiconductor device which provides a cured product having excellent fluidity, low moisture absorption and excellent solder heat resistance. It is in.

[0006]

That is, the present invention provides:
(A) an epoxy resin , (b) a polyhydric phenolic compound ,
(C) an epoxy resin composition comprising an inorganic filler, which is once crystallized into a solid as an epoxy resin component;
Melting points 50 to 120 the following general formula ranges near Ru crystalline in ° C. (1)

Embedded image (However, R represents a hydrogen atom, and R _{1 to} R ₄ represent a hydrogen atom or
A methyl group, R ₅ to R ₈ is 50 to 100-fold in the total epoxy resin epoxy resin represented by a methyl group)
It is an epoxy resin composition for semiconductor encapsulation, characterized in that the epoxy resin composition contains an amount of 1% by weight .

[0007] The epoxy resin represented by the above general formula (1) has the following general formula (2)

Embedded image (However, R ₁ to R ₄ represents a hydrogen atom or a methyl group, R ₅
~ R ₈ represents a methyl group ), and a bisphenol compound represented by the following formula: and epihalohydrin. This reaction can be performed in the same manner as a usual epoxidation reaction.

For example, after dissolving a bisphenol compound in excess epichlorohydrin or the like, sodium hydroxide,
5 in the presence of an alkali metal hydroxide such as potassium hydroxide
0 to 150 ° C, preferably 1 to 60 ° C to 120 ° C.
A method of reacting for 10 hours is exemplified. The amount of epihalohydrin used at this time is 0.8 to 2 mol, preferably 0.9 to 2 mol per mol of hydroxyl group of the bisphenol compound.
It is in the range of 1.2 mol. After completion of the reaction, excess epi was removed by distilling off rohydrin, dissolving the residue in a solvent such as toluene or methyl isobutyl ketone, filtering, washing with water to remove inorganic salts, and then distilling off the solvent to remove epoxy. It can be a resin.

However, since these epoxy resins are usually liquid even at room temperature, they need to be crystallized for use in the present invention. Examples of the crystallization method include crystallization using a solvent or crystallization by adding a crystal seed prepared in advance. In the method using a solvent, as the solvent species, alcohols such as methanol, ethanol and isopropyl alcohol, and hydrocarbon solvents such as pentane, hexane and heptane are preferably used.

In the above general formula (1), the substituents R ₁ to
R ₄ represents a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 6 carbon atoms. Examples of the hydrocarbon group include a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, and a tert-butyl group.
Examples thereof include an amyl group and a phenyl group. Further, the substituent R
₅ to R ₈ is a hydrogen atom or a methyl group. The preferred range of the melting point of the crystalline epoxy resin used is 40 to 13
0 ° C, more preferably in the range of 50 to 120 ° C. If it is lower than this, there is a problem such as blocking at the time of storage, and if it is higher than this, the solubility is poor and the mixing property with the curing agent is reduced.

Melting point, viscosity, reactivity and heat resistance of the cured product;
In consideration of moisture resistance, preferred examples of the crystalline epoxy resin include crystalline 1,4-bis (4-hydroxycumyl) benzene diglycidyl ether compound having a melting point of 55 to 75 ° C., and a melting point of 75 to 75 ° C. Crystalline 1, which is 95 ° C
And diglycidyl ether of 4-bis (3-methyl-4-hydroxycumyl) benzene. Those having a melting point lower than the above range are unfavorable because there are many oligomer components of dimers or more, and there are problems of an increase in viscosity and a decrease in heat resistance.

As the curing agent used in the resin composition of the present invention, a curing agent having a phenolic hydroxyl group is used.
For example, divalent phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4′-biphenol, 2,2′-biphenol, hydroquinone, resorcinol, and naphthalene diol, tris- (4-hydroxyphenyl) methane,
Trivalent or higher phenols represented by 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, phenol novolak, o-cresol novolak, naphthol novolak, polyvinyl phenol, etc., further, phenols, naphthols, Divalent phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquinone, resorcinol, and naphthalene diol are converted to formaldehyde, acetaldehyde, benzaldehyde, and p-hydroxybenzaldehyde. And polyhydric phenolic compounds synthesized by condensation with a condensing agent such as p-xylylene glycol. These curing agents can be used alone or in combination of two or more.

[0013] In addition to the epoxy resin used as an essential component of the present invention, a normal epoxy resin having two or more epoxy groups in a molecule may be used in the resin composition of the present invention. Examples include dihydric phenols such as bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, 4,4'-biphenol, 2,2'-biphenol, hydroquino, resorcin, and tris- (4 -Hydroxyphenyl)
It is derived from trivalent or higher phenols such as methane, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, phenol novolak, o-cresol novolac, or halogenated bisphenols such as tetrabromobisphenol A. Glycidyl ether compounds. These epoxy resins can be used alone or as a mixture of two or more, but the amount of the epoxy resin according to the present invention is preferably in the range of 50 to 100% by weight based on the entire epoxy resin.

Further, the resin composition of the present invention contains an inorganic filler. As the inorganic filler, for example, spherical or crushed fused silica, silica powder such as crystalline silica,
Alumina powder, glass powder and the like are used, and the amount used is preferably 70% by weight or more, but is more preferably 75% by weight or more from the viewpoint of low moisture absorption and improvement in solder heat resistance.

If necessary, conventionally known curing accelerators can be used in the resin composition of the present invention. Examples include amines, imidazoles, organic phosphines, Lewis acids, and the like. The amount of addition is in the range of 0.2 to 5 parts by weight based on 100 parts by weight of the epoxy resin.

If necessary, the resin composition of the present invention may further contain a release agent such as carnauba wax or OP wax, γ.
-Coupling agents such as glycidoxypropyltrimethoxysilane, coloring agents such as carbon black, flame retardants such as antimony trioxide, low stress agents such as silicone oil, and lubricants such as calcium stearate can be used.

[0017]

The present invention will be described more specifically with reference to the following examples. Reference Example 1 1,4-bis (4-hydroxycumyl) benzene 120
g was dissolved in 720 g of epichlorohydrin, 0.3 g of benzyltriethylammonium chloride was further added, and 56.6 g of a 48% aqueous sodium hydroxide solution was added dropwise at 70 ° C. under reduced pressure (about 150 mmHg) over 4 hours. Water generated during this time was removed from the system by azeotropic distillation with epichlorohydrin, and the distilled epichlorohydrin was returned to the system. After the completion of the dropwise addition, the reaction was further continued for one hour. Thereafter, salts produced by filtration were removed, and after washing with water, epichlorohydrin was distilled off.
51 g were obtained. 1, prepared in advance on the obtained resin
Fine powder crystals of a dicrisidyl ether compound of 4-bis (4-hydroxycumyl) benzene were added, and the mixture was allowed to stand at 30 ° C. to obtain a white crystalline epoxy resin. Epoxy equivalent was 243 and melting point was 64.5 ° C. 2
The viscosity in m-cresol (30% by weight) at 5 ° C. was 28 cP.

Reference Example 2 120 g of 1,4-bis (3-methyl-4-hydroxycumyl) benzene, 48% aqueous sodium hydroxide solution
The reaction was carried out in the same manner as in Reference Example 1 using 4 g to obtain 150 g of a white crystalline epoxy resin. The epoxy equivalent was 245 and the melting point was 88.5 ° C. The viscosity in m-cresol (30% by weight) at 25 ° C. is 64.5.
cP.

Examples 1 and 2 The epoxy resin obtained in Reference Example 1 was used as an epoxy resin component, a phenol novolak resin (PSF-4300, manufactured by Gun Ei Chemical Co., Ltd.) as a curing agent, and crushed silica (PS) as a filler. Kneading with an average particle size of 16 μm) or spherical silica (average particle size of 22 μm), triphenylphosphine as a curing accelerator, γ-glycidoxypropyltrimethoxysilane as a silane coupling agent and other additives as shown in Table 1. Thus, an epoxy resin composition was obtained. The epoxy resin composition was molded at 175 ° C., post-cured at 175 ° C. for 12 hours to obtain a cured product test piece, which was then subjected to various physical property measurements. Also, an 84-pin IC was molded using the epoxy resin composition, and after post-curing, an 85-pin IC was formed.
C. and 85% RH for 24 hours, 48 hours and 72 hours, immersed in a 260 ° C. solder bath for 10 seconds, and observed cracks in the package. Table 1 shows the results.

Example 3 Using the epoxy resin obtained in Reference Example 2 as an epoxy resin component, compounding, kneading, molding and evaluation were performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 Using an o-cresol novolak type epoxy resin (softening point: 71 ° C.) as an epoxy resin component, an epoxy resin composition was obtained in the same manner as in Example 1, and then molded and evaluated. Table 1 shows the results.

[0022]

[Table 1]

[0023]

Since the epoxy resin used in the present invention has an extremely low viscosity in a molten state, it maintains excellent molding fluidity and can be filled with silica at a high level.
The crack resistance of a package obtained by sealing a semiconductor element with the present composition is significantly improved.

Continuation of front page (56) References JP-A-2-222443 (JP, A) JP-A-6-56964 (JP, A) JP-A-6-157710 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) C08G 59/24 C08G 59/62 H01L 23/29

Claims (2)

(57) [Claims] A method according to claim 1] (a) an epoxy resin (b) a polyhydric phenol compound (c) an epoxy resin composition comprising an inorganic filler, as the epoxy resin component, once crystallized to a solid
And the following general formula crystalline range near Ru having a melting point of 50 to 120 ° C. (1) ## STR1 ## (However, R represents a hydrogen atom, and R _{1 to} R ₄ represent a hydrogen atom or
A methyl group, R ₅ to R ₈ is 50 to 100-fold in the total epoxy resin epoxy resin represented by a methyl group)
An epoxy resin composition for encapsulating a semiconductor, characterized in that the epoxy resin composition contains an amount of 1% by weight . Wherein the inorganic filler according to claim 1 epoxy resin composition for semiconductor encapsulation of wherein and this <br/> blending 75% by weight or more.