JP2000265041A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor sealing epoxy resin composition having an excellent moldability and solder resistance. SOLUTION: In a resin composition essentially comprising (A) a crystalline epoxy resin, (B) a phenol resin of the formula (wherein n is an average and is 0 or a positive number no larger than 8), (C) an inorganic filler and (D) an accelerator, the degree of crystallinity of the crystalline epoxy resin is 0 to 70%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an epoxy resin composition having excellent solder resistance and a semiconductor device.

[0002]

2. Description of the Related Art Epoxy resin compositions have conventionally been developed and produced for protecting semiconductors from mechanical and chemical actions. Items required for this resin composition are changing depending on the type of semiconductor, the type of package to be sealed, the environment in which they are used, and the like, but there is a problem that cracks are generated when the package is mounted recently. . This is because the cured product of the resin composition is exposed to a high temperature such as being directly immersed in a solder bath at the time of mounting, and the moisture absorbed by the cured product of the resin composition expands, resulting in a crack. For this reason, the cured product of the resin composition is required to have low moisture absorption and high strength, and as a result of various studies on this requirement, it has been found that by including a large amount of an inorganic filler or selecting a resin system, the resin composition is resistant. Solderability was significantly improved.

[0003] In terms of low water absorption and high strength resin, for example, phenol aralkyl resin disclosed in Japanese Patent Publication No. 3-79370 is very effective. However, when this phenol aralkyl resin is used as a curing agent for an epoxy resin, there is a problem that fluidity is low due to high viscosity, and thus moldability is poor. Further, in order to further reduce water absorption, it is necessary to increase the amount of the inorganic filler to be blended, but for that purpose, it is necessary to reduce the viscosity of the resin. When trying to reduce the molecular weight and viscosity of the phenol aralkyl resin, there is a disadvantage that the curability and strength of the resin composition using the same are reduced, and the moldability and solder resistance are reduced.

[0006]

SUMMARY OF THE INVENTION The present invention is to provide a resin composition having improved moldability and solder resistance, which has improved the above-mentioned drawbacks of the phenol aralkyl resin, and a semiconductor device using the same.

[0007]

The present invention comprises (A) a crystalline epoxy resin, (B) a phenolic resin represented by the general formula (1), (C) an inorganic filler, and (D) a curing accelerator. In a resin composition as an essential component, a crystalline epoxy resin in the resin composition has a crystallinity of 0 to 70%, more preferably a crystalline epoxy resin composition. An epoxy resin composition for semiconductor encapsulation wherein the epoxy resin (A) is a biphenyl type epoxy resin represented by the general formula (2) or a stilbene type epoxy resin represented by the general formula (3), and a semiconductor element using the same Is a semiconductor device in which is sealed.

Embedded image (N is an average value and a positive number up to 0 or 8)

[0008]

Embedded image (R _{1 to} R ₄ are a hydrogen atom and a hydrocarbon having 1 to 6 carbon atoms, which may be the same or different from each other)

[0009]

Embedded image (R _{5 to} R ₁₂ are a hydrogen atom, a hydrocarbon having 1 to 6 carbon atoms,
May be the same or different from each other)

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As the crystalline epoxy resin used in the present invention, a resin which is solid at room temperature, has excellent handling workability, and has a very low melt viscosity at the time of molding is required. If the melt viscosity is low, the water absorption of the cured product of the resin composition can be reduced by increasing the blending amount of the inorganic filler, and the solder resistance is significantly improved. Examples of the crystalline epoxy resin include a glycidyl etherified product of hydroquinone, a bisphenol F epoxy resin, a biphenyl epoxy resin represented by the general formula (2), and a stilbene epoxy resin represented by the general formula (3). Among these, the resin composition when used in combination with the phenolic resin of the above general formula (1) has characteristics of low water absorption and high strength, and is excellent in soldering resistance. ), Or a stilbene epoxy resin represented by the general formula (3).

Among the biphenyl type epoxy resins represented by the general formula (2), 4,4 having a good balance between workability and practical characteristics.
4'-diglycidyl biphenyl, or 3,3 ',
5,5'-Tetramethyl-4,4'-diglycidylbiphenyl and a molten mixture of both are preferred. Further, among the stilbene type epoxy resins represented by the general formula (3), 5-tert-butyl-4,4′-glycidyl-2,3 ′, 5′-trimethylstilbene having a good balance of workability and practical properties, Or 4,4′-diglycidyl-3,
Preference is given to 3 ', 5,5'-tetramethylstilbene and a molten mixture of both. The crystalline epoxy resin of the present invention can be used in combination with another epoxy resin. When used in combination, the content of the crystalline epoxy resin is preferably at least 30% by weight or more of the total epoxy resin. If it is less than 30% by weight, the fluidity characteristic of the crystalline epoxy resin is impaired, and the moldability is reduced. The epoxy resin that can be used in combination is not particularly limited, and examples thereof include dicyclopentadiene-modified epoxy resin, triphenolmethane-type epoxy resin, and ortho-cresol novolak-type epoxy resin.

The phenolic resin represented by the general formula (1) used in the present invention is a naphthol type aralkyl resin containing α or β-naphthol as naphthol, and has characteristics of low water absorption, high curability and high flame resistance. ing. By using the phenol resin represented by the general formula (1) as a curing agent for the epoxy resin, low water absorption, high strength,
In addition, a resin composition having excellent solder resistance can be obtained.
It may be used in combination with another phenol resin as long as the properties of the phenol resin of the general formula (1) are not impaired. The content of the phenol resin of the general formula (1) is preferably at least 30% by weight or more in all phenol resins from the viewpoint of low water absorption. If it is less than 30% by weight, advantages such as low water absorption will be lost, and solder resistance will decrease, which is not preferable. Examples of the phenol resin used in combination include, for example, phenol novolak resin, orthocresol novolak resin, phenol aralkyl resin, dicyclopentadiene-modified phenol resin, limonene-modified phenol novolak resin, and the like, and these may be used alone or in combination. . The equivalent ratio of the epoxy group of all epoxy resins used in the present invention to the phenolic hydroxyl group of all phenolic resins is preferably 0.5 to 2, and more preferably 0.7 to 1.5. If the ratio is out of the range of 0.5 to 2, the moisture resistance, the curability and the like are undesirably reduced.

The present inventors have calculated the crystallinity of the crystalline epoxy resin in the resin composition by MDSC and found that the crystallinity in the resin composition has a significant effect. That is, in the present invention, the crystallinity of the crystalline epoxy resin in the resin composition needs to be 0 to 70%.
If the crystallinity exceeds 70%, the curability and mechanical strength decrease, and the moldability and solder resistance decrease. When the crystallinity of the crystalline epoxy resin in the produced resin composition exceeds 70%, the kneading and dispersion were not sufficiently performed, the moldability was reduced, and the resin was sealed using this. The semiconductor device may cause a problem such as a decrease in reliability. Since crystalline epoxy resins are characterized by low viscosity when heated while in a crystalline state at room temperature, it is presumed that they remain in a crystalline state to some extent when blended with phenolic resins and other raw materials. However, there has been no example of measuring the crystallinity of a crystalline epoxy resin in a conventional resin composition, and it has been difficult to control this.

The crystallinity in the present invention is determined by MDSC (Tainst
ruments, 2910MDSC), and precisely weighed about 10 mg of the resin composition. The temperature rising rate was 3 ° C./min, and the temperature amplitude was ±
0.5 ° C., cycle of 60 seconds, −20 ° C. to 1 in a nitrogen atmosphere
Measure up to 50 ° C. In the measurement of MDSC, an irreversible reaction such as a curing reaction and a reversible reaction such as crystal melting can be separated. This is a very effective means for a thermosetting resin such as an epoxy resin composition. Heat of crystal melting of crystalline epoxy resin in resin composition (endotherm: Joule
e / g) is divided by the previously measured endothermic amount of the same crystalline epoxy resin to determine the crystallinity of the crystalline epoxy resin remaining in the resin composition. FIG. 1 shows a measurement example of a resin composition containing a stilbene type epoxy resin by MDSC. The vertical axis is Reversible Heat Flow, which can detect the endothermic amount of reversible components such as crystal melting. In FIG. 1, the endothermic peak of the stilbene type epoxy resin and the endothermic peak of the other components overlap because various components are contained in addition to the stilbene type epoxy resin and the phenol resin. In FIG.
There are two peaks at 2 ° C. and 98 ° C. The peak at 98 ° C. is attributable to the stilbene type epoxy resin,
The peak at 2 ° C. is presumed to be due to the wax.
If the peaks overlap, the two peaks are separated by calculation to determine the endothermic amount of the peak at 98 ° C. As a method for separating the peaks, the peak is divided into two at the peak portion (87 ° C. in FIG. 1) of two consecutive peaks, the respective areas are obtained, and the endothermic amount of the stilbene epoxy resin is calculated. As shown in FIG. 2, a single peak of only the crystalline epoxy resin may be shown depending on the type of the resin composition.

In order to determine whether the obtained endothermic peak is due to the stilbene type epoxy resin or to other raw materials, for example, a method by wide-angle X-ray diffraction or a study by compounding is required. No. When the diffraction of the crystal due to the stilbene-type epoxy resin is confirmed by wide-angle X-ray diffraction, it can be determined that the endothermic peak of MDSC is due to the stilbene-type epoxy resin. Also, a formulation excluding other raw materials having the same melting point as the stilbene-type epoxy resin was prepared for comparison, and the M of the resin composition was adjusted.
Confirmation is possible by performing DSC measurement. The inventor of the present invention has proposed that the crystallinity of the crystalline epoxy resin is controlled by controlling the maximum particle size of coarse grinding of the epoxy resin, using a molten mixture of the crystalline epoxy resin and the phenol resin, adjusting the kneading temperature and kneading conditions. I found something that I could control. Reducing the crystallinity can be achieved by changing the kneading conditions such as reducing the particle size of the crystalline epoxy resin, increasing the kneading temperature and the kneading machine output with a molten mixture with the phenol resin. In order to increase the degree of crystallinity, a method reverse to the above may be used. However, these control methods are examples, and there is no problem even if the control of the crystallinity is performed by other means.

The curing accelerator used in the present invention is not particularly limited as long as it accelerates the reaction between the epoxy group and the phenolic hydroxyl group. For example, 1,8-diazabicyclo (5,4,0) undecene-7 is used. And triphenylphosphine, tetraphenylphosphonium / tetraphenylborate, tetraphenylphosphonium / tetrabenzoic acid borate, tetraphenylphosphonium / tetranaphthoic acid borate, and the like, and these may be used alone or in combination.

The kind of the inorganic filler used in the present invention is not particularly limited, and a known inorganic filler can be used. For example, fused silica powder, fused spherical silica powder, crystalline silica powder, secondary aggregated silica powder, alumina, titanium white, aluminum hydroxide, talc,
Clay, glass fiber, etc. are mentioned, and especially fused spherical silica powder is preferable. The shape is preferably infinitely spherical, and the amount of filler can be increased by mixing particles having different particle sizes. The content of the inorganic filler is preferably from 70 to 94% by weight in the whole resin composition. The inorganic filler that does not burn even when heated has a function of depriving the thermal energy when exposed to a flame and improving the flame retardancy of the resin composition. When the content is less than 70% by weight, the resin composition has a small heat capacity and easily burns in a flame retardancy test. If the amount of the inorganic filler exceeds 94% by weight, the fluidity becomes insufficient.

The resin composition of the present invention comprises, in addition to the components (A) to (D), if necessary, a silane coupling agent such as epoxy silane, a coloring agent such as carbon black, a brominated epoxy resin, antimony oxide, Incorporation of flame retardants such as phosphorus compounds, low stress components such as silicone oil and silicone rubber, release agents such as natural wax, synthetic wax, higher fatty acids and their metal salts or paraffin, and various additives such as antioxidants. Can be. The resin composition of the present invention,
The components (A) to (D) and other additives are mixed at room temperature using a mixer, kneaded with a kneader such as a roll or an extruder, cooled, and pulverized. In order to manufacture a semiconductor device by encapsulating an electronic component such as a semiconductor using the resin composition of the present invention, it is only necessary to cure and mold by a conventional molding method such as transfer molding, compression molding and injection molding.

[0019]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. The mixing unit is parts by weight. Example 1 7.8 parts by weight of an epoxy resin containing the formula (E-1) as a main component

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Phenol resin (H-1) 9.1 parts by weight

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Fused spherical silica (average particle size: 15 μm) 80 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.2 part by weight Brominated bisphenol A type epoxy resin 1 part by weight Part Antimony trioxide 0.8 part by weight Carbon black 0.2 part by weight Epoxysilane coupling agent 0.3 part by weight Silicone oil (graft polymer of dimethylsiloxane and poly (ethylene oxide / propylene oxide) copolymer) 3 parts by weight of carnauba wax 0.3 part by weight was mixed at room temperature using a mixer, kneaded using a biaxial roll, cooled, and pulverized to obtain a resin composition. The obtained resin composition was evaluated by the following method. Table 1 shows the results.

Evaluation method Spiral flow: A mold conforming to EMMI-I-66 was used, and the molding temperature was measured at 175 ° C.・ Curast meter torque value: Curast meter V type (Orientec) is used. The dice is 35φ,
The amplitude angle was 1 degree, the temperature was 175 ° C, and the torque value after 90 seconds was measured to evaluate the curability. -Flame retardancy: Molded products having a thickness of 3.2 mm and 1.6 mm were prepared and subjected to a combustion test according to UL-94. Solder crack resistance: 80 pQFP (package size 14 × 20) using a low-pressure transfer molding machine at a molding temperature of 175 ° C., a pressure of 70 kg / cm ² , and a curing time of 2 minutes.
× 2.7 mm, element size 9 mm × 9 mm),
After post-curing at 175 ° C. for 8 hours, the six packages were absorbed for 168 hours at 85 ° C. and a relative humidity of 65%, and then subjected to IR reflow treatment at 220 ° C. to determine the number of package cracks by ultrasonic inspection. Observed by machine. When the number of cracked packages is n, it is indicated as n / 6.

The epoxy resins (E-2) to (E-4) and the phenol resin (H-2) used in other examples and comparative examples,
The structure of (H-3) is shown below. (E-2)
Resin 2 mainly composed of stilbene epoxy resin (a)
(E-3) is a molten mixture of 1 part by weight of a stilbene-type epoxy resin (b) and 1 part by weight of a stilbene-type epoxy resin (c). This is a molten mixture with 2 parts by weight of a resin mainly composed of an epoxy resin (d).

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[0024]

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[0025]

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[0026]

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[0027]

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Examples 2 to 7 Compounded according to the formulation shown in Table 1, a resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Example 4
Are the epoxy resins (E-1), (E-4) and (H-
1) A molten mixture of (H-3). Table 1 shows the results. Comparative Examples 1-3 Compounded according to the formulation in Table 2, a resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 2 shows the results.

[Table 1]

[0029]

[Table 2]

[0030]

The epoxy resin composition for semiconductor encapsulation of the present invention is excellent in moldability and solder resistance, and a semiconductor device using this is excellent in reliability.

[Brief description of the drawings]

FIG. 1 is a state diagram showing a state where a stilbene type epoxy resin and a heat absorbing portion caused by another raw material overlap.

FIG. 2 is a state diagram showing an endothermic portion of only a stilbene type epoxy resin.

Claims (3)

[Claims] 1. A crystalline epoxy resin, (B) a phenolic resin represented by the formula (1), (C) an inorganic filler,
And (D) a resin composition containing a curing accelerator as an essential component, wherein the crystallinity of the crystalline epoxy resin in the resin composition is 0 to 70%. object. Embedded image (N is an average value and a positive number up to 0 or 8) 2. The semiconductor encapsulation according to claim 1, wherein (A) the crystalline epoxy resin is a biphenyl type epoxy resin represented by the general formula (2) or a stilbene type epoxy resin represented by the general formula (3). Epoxy resin composition for use. Embedded image (R _{1 to} R ₄ are a hydrogen atom and a hydrocarbon having 1 to 6 carbon atoms, which may be the same or different from each other). (R _{5 to} R ₁₂ are a hydrogen atom, a hydrocarbon having 1 to 6 carbon atoms,
May be the same or different from each other) 3. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to claim 1.