JPH1060228A - Epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject resin composition with few inner and outer voids, excellent in adherability, soldering crack resistance and moisture resistance reliability, comprising each specified amount of an epoxy resin, phenolic resin curing agent, curing promoter, inorganic filler and specific silicone oil. SOLUTION: This epoxy resin composition comprises (A) an epoxy resin of e.g. bisphenol type, (B) a phenolic resin curing agent, (C) pref. 0.01-1wt.% (based on the whole composition) of a curing promoter such as 1,8-diazabicyclo(5,4,0) undecene-7, (D) pref. 65-93wt.% of an inorganic filler such as fused silica powder, and (E) 0.02-4wt.% of a silicone oil of formula I or formula II [R is phenyl, methoxy, ethoxy, C3 H6 -SH, etc.; <=(m); 0<=(n)<=300; m/(m+n)<=0.2]. It is preferable that the total amount of the components A and B accounts for 5-35wt.% of the whole resin composition.

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 for semiconductor encapsulation which has few internal and external voids, and is excellent in solder crack resistance and moisture resistance reliability.

[0002]

2. Description of the Related Art Epoxy resin-based resin compositions for semiconductor encapsulation have been developed and manufactured to protect IC bodies from mechanical and chemical actions. In order to satisfy the characteristics required for ICs, various properties are required for the resin composition for semiconductor encapsulation. A recent requirement is an improvement in solder crack resistance. Although it is necessary to reduce the water absorption of the resin composition for semiconductor encapsulation in order to improve the solder crack resistance, it is necessary to increase the compounding amount of the inorganic filler more than before. If the compounding amount is too large, it cannot be uniformly dispersed in the sealing resin, and a phenomenon that voids frequently occur during molding occurs. In order to reduce the generated voids, various techniques such as using a resin having a high viscosity or changing the particle size distribution of the inorganic filler have been tried. An example of an effective method for reducing voids is the addition of silicone oil having a structure in which a block copolymer of polyethylene oxide and polypropylene oxide is grafted or block-copolymerized onto a silicone main chain (Japanese Patent Publication No. 2-36148).
No.). However, when this method was applied to current surface mount materials, the effect of reducing voids was not sufficiently exhibited.
Further, the addition of these silicone oils also has a problem that the solder crack resistance is reduced, particularly the adhesion to various metals is reduced.

[0003]

As a result of intensive studies to solve the above-mentioned drawbacks, the present invention has found that when the resin flowing during molding is non-uniform, the leading edge of the flow becomes very non-uniform and voids are generated. Noting that voids occur frequently,
The purpose is to develop a resin composition for semiconductor encapsulation that can reduce the occurrence of internal and external voids.At the same time, by improving the adhesion to various metal components, solder crack resistance is improved. An object of the present invention is to provide an excellent epoxy resin composition for semiconductor encapsulation.

[0004]

The present invention provides an epoxy resin, a phenol resin curing agent, a curing accelerator, an inorganic filler,
And a silicone oil represented by the following formula, wherein the amount of the silicone oil in the total resin composition is 0.02 to 4% by weight.

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[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Each component will be described below.
The epoxy resin used in the present invention is not particularly limited as long as it has two or more epoxy groups in a molecule, and is preferably, for example, an orthocresol novolak type epoxy resin, a phenol novolak type epoxy resin. , Bisphenol type epoxy resin, biphenyl type epoxy resin, triphenol methane type epoxy resin, alkyl modified triphenol methane type epoxy resin, stilbene type epoxy resin, dicyclopentadiene type epoxy resin, imide modified epoxy resin, and silicone modified products thereof And these may be used alone or as a mixture. The epoxy equivalent and the softening point are not particularly limited.

[0006] The phenolic resin curing agent used in the present invention is not particularly limited as long as it has a hydroxyl group in the molecule. Preferred examples thereof include phenol novolak resin, cresol novolak resin, and dicyclopentadiene-modified resin. Examples thereof include phenol resins, paraxylylene-modified phenol resins, triphenolmethane-type phenol resins, terpene-modified phenol resins, imide-modified phenol resins, and silicone-modified products thereof. These may be used alone or in combination.
Further, the hydroxyl equivalent and the softening point are not particularly limited. The total amount of the epoxy resin and the phenol resin in the entire resin composition is preferably from 5 to 35% by weight. If it is less than 5% by weight, the fluidity during molding is poor, and if it exceeds 35% by weight, the solder crack resistance is poor.

The curing accelerator used in the present invention may be any as long as it promotes a curing reaction between an epoxy group and a hydroxyl group.
What is generally used for the resin composition for semiconductor encapsulation can be widely used. For example, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, tetraphenylphosphonium / tetraphenylborate, benzyldimethylamine, 2-methylimidazole, tetraphenylphosphonium / tetrabenzoic acid Borates, tetraphenylphosphonium / tetranaphthoic acid borate, and the like can be mentioned, and they may be used alone or as a mixture. The amount of the curing accelerator in the entire resin composition is preferably from 0.01 to 1% by weight. If it is less than 0.01% by weight, curing is insufficient, and if it exceeds 1% by weight, curing is too fast to obtain sufficient fluidity.

The inorganic filler used in the present invention includes:
Fused silica powder, spherical silica powder, crystalline silica powder, 2
Sub-agglomerated silica powder, alumina and the like are mentioned, and in particular, spherical silica powder is desirable from the viewpoint of improving the fluidity of the resin composition for semiconductor encapsulation. Regarding the shape of the spherical silica powder, in order to improve the fluidity, it is desirable that the shape of the particles themselves be infinitely spherical and that the particle size distribution be broad. The amount of the inorganic filler in the entire resin composition is preferably from 65 to 93% by weight. If it is less than 65, the solder resistance is poor, and if it exceeds 93% by weight, sufficient fluidity cannot be obtained.

The silicone oil used in the present invention comprises:
Since this is an important technical point in the present invention, it will be described in detail. Normally, silicone oil has polydimethylsiloxane as its basic skeleton, but the silicone oil used in the present invention is different from this, and the main chain SiO
The unit R (phenyl, phenethyl, epoxy, mercapto, alkoxy) is bonded, and has characteristics significantly different from those of conventional polydimethylsiloxane. In the case of conventional polydimethylsiloxane, since silicone oil molecules are thermally stable in an α-helix state, that is, a helical state, the silicone oil molecules have a methyl group on the surface and are hydrophobic and have low surface tension. It has a structure.
However, the silicone oil used in the present invention is SiO 2
80% by mole or more of the functional groups other than the methyl group
Are bonded to each other, the oil molecule cannot take a helical structure, and R and SiO other than the methyl group are exposed on the surface of the molecule. Therefore, the silicone oil used in the present invention has not only the hydrophobicity characteristic of the silicone oil, but also the hydrophilicity of the SiO unit, and further has a functional group R for epoxy resin and various metals. There is a great feature that it has affinity and reactivity.

The silicone oil of the present invention has both hydrophilic and hydrophobic amphipathic properties and therefore has a surfactant effect.
Since the inorganic filler and the resin can be uniformly dispersed, voids during molding can be reduced. Due to its affinity for various metals, various metals (42 alloy, copper, A
g, Au), and the solder crack resistance is improved.

The functional group R in the silicone oil used in the present invention is a phenyl group, a phenethyl group, an epoxy group,
An alicyclic epoxy group, a mercapto group, or an alkoxy group. These functional groups may be the same or different. n is 2 to 300. If it is less than 2, the viscosity is too low and it tends to volatilize, and the number of voids in the molded product increases. 300
If the ratio exceeds the range, the compatibility with the sealing resin is reduced, and both effects of reducing voids and improving solder crack resistance are not exhibited. M is 0 or more. However, m / (m +
n) needs to be 0.2 or less. There is no problem if m = 0, that is, no dimethylsiloxane unit is present. Further, if m / (m + n) exceeds 0.2, the characteristics of the conventional polydimethylsiloxane appear, and the solder cracking resistance decreases due to a decrease in the adhesion to the substrate, which is not preferable.

The amount of the silicone oil used in the present invention is not particularly limited, but is preferably 0.02 to 4% by weight based on 100% by weight of the whole resin composition. If the amount is less than 0.02% by weight, the effect of the silicone oil is not obtained, and the voids of the molded product are not reduced. If it exceeds 4% by weight, the mechanical strength of the molded product is reduced, and the solder resistance is reduced. Further, the silicone oil used in the present invention can be used in combination with another silicone oil without any problem. However, the silicone oil used in combination is preferably 30% by weight or less of the total silicone oil. If it exceeds 30% by weight, solder crack resistance and void characteristics are reduced.

The resin composition for encapsulating a semiconductor of the present invention may contain, if necessary, a coloring agent such as carbon black, a brominated epoxy resin, a flame retardant such as antimony trioxide, γ-glycidoxypropyltrimethoxysilane and the like. Coupling agent,
Low stress components such as rubber and wax components such as carnauba wax can be added. The resin composition for encapsulating a semiconductor of the present invention comprises an epoxy resin, a phenol resin curing agent, a curing accelerator, a silicone oil, an inorganic filler, and other additives mixed at room temperature with a mixer, and a kneader such as a roll or an extruder. , And after cooling, pulverized to obtain a molding material.

Hereinafter, the present invention will be described specifically with reference to Examples. << Example 1 >> The following composition Biphenyl type epoxy resin (E-1) 10.5 parts by weight Phenol novolak resin (H-1) 7.3 parts by weight Spherical silica (average particle diameter 15 μm) 80.0 parts by weight 1, 8-diazabicyclo (5,4,0) undecene-7 0.2 parts by weight Carbon black 0.2 parts by weight Carnauba wax 0.2 parts by weight Brominated phenol novolak epoxy resin 0.5 parts by weight Antimony trioxide 0.4 Parts by weight γ-glycidoxytrimethoxysilane 0.2 parts by weight Silicone oil (S-1) 0.5 parts by weight was mixed at room temperature with a mixer, kneaded at 100 ° C. with a biaxial roll, cooled and ground. The resulting material was dried with dry air to complete the materialization. The presence or absence of voids in the molding material and the solder crack resistance were evaluated.
Table 1 shows the results.

<< Evaluation Method >> Evaluation of void: 160 pQFP (1 × 28 × 28 mm)
60 pQFP) at molding temperature; 175 ° C., injection time;
Molding was performed under the conditions of seconds, curing time: 120 seconds (including the injection time), preheating time: 80 ° C., and the number of internal voids in the molded product was confirmed by an ultrasonic flaw detector. The number of voids inside and outside of the four packages (one having a size of 0.5 mmφ or more) is summed and converted into the number of voids per package. -Solder crack resistance evaluation: 80pQFP (1.5m thickness)
m), after post-curing, in a constant temperature and constant temperature bath at 85 ° C.
Treat at / 85% for 168 hours. Immediately after the treatment, a treatment is performed at 240 ° C. for 10 seconds using an IR reflow furnace. After the reflow treatment, the peeling state inside the package is observed using an ultrasonic flaw detector. Evaluate how many packages have peeled out of 8 packages. The number of peeled packages after soldering.

Examples 2 to 12 A molding material was obtained at the same compounding ratio as in Example 1 except that the type of silicone oil [(S-2) to (S-12)] was changed, and evaluated in the same manner. .
Table 1 shows the results. << Examples 13 to 15 and Comparative Examples 1 to 3 >> In Example 15, silicone oil (S-1) and silicone oil (S-1) were used.
5) was used in combination, and in Examples 13 and 14 and Comparative Examples 1 to 3, molding materials were obtained in the same compounding ratio as in Example 1 except that the amount of addition of the silicone oil (S-1) was changed. evaluated. However, the amount by which the silicone oil was increased or decreased was adjusted by increasing or decreasing the spherical silica. Table 2 shows the results. << Examples 16 to 20 >> Types of epoxy resin [(E-1)
~ (E-5)] and the type of phenol resin curing agent [(H
-1) to (H-3)] and [Epoxy resin + phenol resin curing agent] molding material in the same compounding ratio as in Example 1 except that the added amount of NO was 17.8 parts by weight. And evaluated similarly. Table 2 shows the results. << Comparative Examples 4-7 >> Silicone oils other than the silicone oil used in the present invention [(S-13) to (S-16)]
A molding material was obtained at the same compounding ratio as in Example 1 except for using, and the same evaluation was performed. Table 2 shows the results.

[0017]

[Table 1]

[0018]

[Table 2]

The types of silicone oils, epoxy resins and phenolic resin curing agents used in the examples and comparative examples are as follows.

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[0020]

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[0021]

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[0022]

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[0023]

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[0024]

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[0025]

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[0026]

According to the present invention, by encapsulating a semiconductor element using the epoxy resin composition for semiconductor encapsulation of the present invention, it is possible to obtain a semiconductor device having few voids, high reliability, and excellent solder crack resistance. Can be. Therefore, a dry pack is not required, which has a great effect on reduction of man-hours and cost.

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Claims (1)

[Claims] An epoxy resin, a phenol resin curing agent,
An epoxy resin for semiconductor encapsulation comprising a curing accelerator, an inorganic filler, and a silicone oil represented by the following formula, wherein the amount of the silicone oil in the total resin composition is 0.02 to 4% by weight. Composition. Embedded image