JPH0770291A - Epoxy resin composition for encapsulation - Google Patents

Abstract

(57) [Summary] [Structure] The present invention is an epoxy resin composition for encapsulation, which comprises using β-type silicon nitride as a filler. According to the present invention, an epoxy resin composition having high thermal conductivity can be obtained, and by extension, a resin-encapsulated semiconductor device having high thermal conductivity can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing epoxy resin composition, and more particularly to a sealing epoxy resin having high thermal conductivity.

[0002]

2. Description of the Related Art Epoxy resin compositions are used in integrated circuits (IC),
Widely used for encapsulating large-scale integrated circuits (LSIs), semiconductor devices such as transistors, electronic circuits, and other parts.

When an exothermic semiconductor device, an electronic component or the like is sealed with an epoxy resin composition, it is necessary to effectively dissipate internally generated heat to the outside. There is a need for epoxy resin compositions. However, it has been difficult to obtain sufficient thermal conductivity with conventional epoxy resin compositions using silica as a filler.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxy resin composition for encapsulation which has high thermal conductivity.

[0005]

In order to achieve the above object, the present inventor has conducted extensive research using silicon nitride instead of silica as a filler, and as a result, among silicon nitrides, those having a β-type crystal structure It was found that, when it is used as a filler only, a highly heat conductive epoxy resin composition for encapsulation can be obtained, and the present invention has been completed.

That is, the present invention comprises (a) an epoxy resin, (b) a hardener that cures two or more phenolic hydroxides in one molecule, (c) β-type silicon nitride, and (d) an organic phosphine compound. It is a characteristic epoxy resin composition for sealing.

The above epoxy resin is generally known and is not particularly limited. For example, bisphenol A type epoxy resin, phenol novolac type epoxy resin, etc. glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, An epoxy resin having two or more epoxy groups in one molecule such as a halogenated epoxy resin can be mentioned. However, these epoxy resins are of one type or two types.
You may use in the mixed system of 1 or more types. A more preferable epoxy resin is a novolac type epoxy resin having an epoxy equivalent of 170 to 300, and examples thereof include a phenol novolac type epoxy resin, a cresol novolac type epoxy resin, and a halogenated phenol novolac type epoxy resin. These epoxy resins have a chlorine ion content of 10 pp
It is desirable that the content of m or less and the content of hydrolyzable chlorine be 0.1% by weight or less. The reason is that if more than 10 ppm of chlorine ions or more than 0.1% by weight of hydrolyzable chlorine are contained, the aluminum electrode of the sealed semiconductor element is likely to be corroded.

The curing agent having two or more phenolic hydroxyl groups in one molecule used in the present invention is a phenol resin, polyoxystyrene, phenol aralkyl resin and polyhydric phenol compound. , Phenol novolac resin, cresol novolac resin, tert-butylphenol novolac resin,
Examples thereof include novolac type phenol resin such as nonylphenol novolac resin, resol type phenol resin, polyoxystyrene such as polyparaoxystyrene, bisphenol A and the like, and halogen compounds of these compounds. Among these, novolac type phenol resin, phenol aralkyl resin and polyoxystyrene are most preferable. These curing agents can be used alone or in a mixture of two or more.

Regarding the compounding ratio of the epoxy resin and the above curing agent, the compounding ratio is such that the ratio of the number of phenolic hydroxyl groups of the curing agent to the number of epoxy groups of the epoxy resin (number of phenolic hydroxyl groups / number of epoxy groups) is in the range of 0.5 to 1.5. It is desirable to do. The reason is that if it is out of the above range, the reaction does not sufficiently occur, and the characteristics of the cured product are likely to deteriorate.

The silicon nitride used in the present invention is limited to silicon nitride mainly composed of β type which is one of α type and β type which is known as a crystal system of silicon nitride.
The effect of the present invention cannot be obtained with a silicon nitride type. Industrially, it is difficult to obtain pure α-type and β-type crystal systems, and generally α-phase and β-phase are mixed.

If the ratio of β-type contained in the crystal is sufficiently larger than that of α-type, the β-type effect can be obtained, and it can be substantially regarded as β-type silicon nitride. When the ratio of the β-type crystal system contained in the crystal is expressed as a β ratio, if the β ratio is 80% or more, it can be regarded as the β-type silicon nitride of the present invention.
More preferred is silicon nitride having a β ratio of 90% or more.

In the present invention, β-type silicon nitride is preferably contained in the epoxy resin composition in an amount of 60% by weight or more. This is because if it is less than this range, sufficient thermal conductivity cannot be obtained.

The particle size distribution of β-type silicon nitride is preferably powder having an average particle size of 1 to 100 μm and a maximum particle size of 500 μm or less.

The characteristics of the epoxy resin composition can be further improved by treating β-type silicon nitride with a surface treatment agent such as a silane coupling agent.

Other fillers (silica, alumina, calcium carbonate, etc.) may be used in combination, but it is necessary to use them so that the thermal conductivity of the composition does not decrease so much.

It is necessary to add a curing accelerator to the encapsulating epoxy resin composition of the present invention. The curing accelerator is
It is useful for shortening the curing time and improving the properties of the cured product.

It is necessary to use an organic phosphine compound in order to obtain a highly reliable epoxy resin for sealing and thus a resin-sealed semiconductor device.

The organic phosphine compound has the formula:

[0019]

[Chemical 1] In the third phosphine compound all R ₁ to R ₃ is an organic group, the second phosphine compound is hydrogen only R _3, there is first a phosphine compound R _2, R ₃ are both hydrogen. Specifically, triphenylphosphine, tributylphosphine, tricyclohexylphosphine, methyldiphenylphosphine, butylphenylphosphine,
Examples include diphenylphosphine, phenylphosphine, and octylphosphine. Further, R ₁ may be an organic group containing an organic phosphine. For example, 1,2-bis (diphenylphosphine) ethane, bis (diphenylphosphino)
For example, methane. Of these, arylphosphine compounds are preferable, and triphenylphosphine, tritolylphosphine, and 1,2-bis (diphenylphosphino) are particularly preferable.
Most preferred are ethane, bis (diphenylphosphino) methane and the like. These organic phosphine compounds may be used alone or in a mixture of two or more. However, the composition ratio of the organic phosphine compound may be generally in the range of 0.01 to 20% by weight of the resin component (epoxy resin and curing agent), but preferable characteristics are obtained in the range of 0.01 to 5% by weight.

The encapsulating epoxy resin composition of the present invention includes
Further, if necessary, other additives such as natural waxes, synthetic waxes, metal salts of linear fatty acids, release agents such as acid amides, esters or paraffins, chlorinated paraffin, bromotoluene, hexa and the like. Flame retardants such as brombenzene and antimony trioxide, colorants such as carbon black, silane coupling agents and the like may be appropriately added and blended. A general method for preparing the above-mentioned encapsulating epoxy resin composition as a molding material is to thoroughly mix raw material crude components selected to have a predetermined composition ratio with, for example, a mixer, and then perform melt-mixing treatment with a hot roll, or An epoxy resin molding material can be easily obtained by adding a mixing treatment with a kneader or the like.

The resin-encapsulated semiconductor device of the present invention can be easily manufactured by encapsulating the semiconductor device with the encapsulating epoxy resin composition. The most common sealing method is the low pressure transfer molding method,
Sealing by injection molding, compression molding, casting, etc. is also possible. The epoxy resin composition is heated and cured during encapsulation, and finally a resin-encapsulated semiconductor device encapsulated with the cured product of this composition can be obtained. It is particularly desirable to heat to 150 ° C or higher during curing.

[0022]

【Example】

Examples 1 to 3 Cresol novolac type epoxy resin having an epoxy equivalent of 200 (epoxy resin A), brominated epoxy novolac resin having an epoxy equivalent of 290 (epoxy resin B), phenol novolac resin curing agent having a molecular weight of 700, and β ratio of 95 as a filler. %
Silicon nitride (β-type silicon nitride [I]), 90% β-rate silicon nitride (β-type silicon nitride [II]), α-rate 90% silicon nitride (α-type silicon nitride [I]), α-rate 70 % Silicon nitride (α-type silicon nitride [II]), crystalline silica powder, fused silica powder,
A triphenylphosphine curing accelerator, antimony trioxide, carnauba wax, carbon black, and a silane coupling agent (γ-glycidoxypropyltrimethoxysilane) were selected for the composition (parts by weight) shown in Table 1. Regarding the filler, the volume% and the weight% in the composition are added in the table so that they can be compared with each other.

Nine kinds of transfer molding materials including Comparative Examples were prepared by mixing these compositions with a mixer and kneading with a heating roll.

[0024]

[Table 1] Using the above molding materials, power IC in a transfer molding machine
The (integrated circuit) was sealed with resin and the moldability was examined. The results are shown in Table 2. The transfer molding was performed by molding a molding material heated to 90 ° C by a preheater at 180 ° C for 3 minutes.

[0025]

[Table 2] As shown in Table 2, a composition of α-type crystalline silicon nitride and silica containing 73% by volume of the filler had poor fluidity and could not be transfer-molded, so that a molded body could not be obtained. With respect to the remaining 6 types, the thermal conductivity of the obtained molded body was measured. The results are shown in Table 3. The thermal conductivity was measured at room temperature (23 ° C) using the laser flash method.

[0026]

[Table 3] Examples 4 and 5 Next, as shown in Table 4, Examples 4 and 5 were prepared by using the same raw materials as in Examples 1 to 3, and in addition to the above raw materials, alumina powder as a filler and 1.8- as a curing accelerator. Diaza
Bicyclo (5,4,0) undecene-7 (DBU), Cureazole CN
Comparative Examples 7 to 17 were prepared using (Shikoku Chemical Industry Co., Ltd. imidazole trade name). These compositions are described in Example 1.
In the same manner as in Nos. 3 to 3, mixing with a mixer and kneading with a roll were performed to prepare a transfer molding material.

When the moldability of the above molding material was examined by the same method as in Examples 1 to 3, all were moldable.

Next, the thermal conductivity of the molded body was measured by the same method as in Examples 1-3. The results are shown in Table 5.

[0029]

[Table 4]

[0030]

[Table 5] Furthermore, in order to investigate the reliability of the semiconductor devices encapsulated with the resin compositions of Examples 1-5 and Comparative Examples 1-17, the thermal conductivity was 50%.
The evaluation test described below was conducted using a resin composition having a temperature of × 10 ^-4 cal / cm s ° C or higher.

(1) Thermal Cycle Test This test is performed to evaluate the reliability when the resin-sealed semiconductor device is repeatedly exposed to high temperature and low temperature. 2
Two thermostats of 00 ° C and -65 ° C were prepared, and 20 resin-sealed semiconductor devices each were placed in the thermostat of -65 ° C and left for 30 minutes. Then take it out and leave it at room temperature for 5 minutes, then
After being placed in a constant temperature bath at 30 ° C. for 30 minutes, it was left again at room temperature for 5 minutes. The above operation was set as one cycle, and the heat cycle test was continuously performed. The cycle was interrupted as needed in accordance with the progress of the thermal cycle test, the characteristics of the resin-sealed semiconductor device were measured using a tester, and the occurrence of failure was investigated. The results are shown in Table 6
Shown in.

[0032]

[Table 6] (2) Pressure cooker test (PCT) This test is performed to evaluate the moisture resistance of resin-sealed semiconductor devices.

20 pieces of each of the above resin-encapsulated semiconductor devices were left in saturated steam at 121 ° C. and 2 atm, and a moisture resistance test was carried out to examine a failure in which the aluminum wiring of the element was corroded by water and disconnected. The results are shown in Table 7.

[0034]

[Table 7]

[0035]

As described above in detail, according to the present invention, a sealing epoxy resin composition having high heat conductivity can be obtained. The resin-encapsulated semiconductor device using the resin composition of the present invention is excellent in reliability in the heat cycle test and the humidity resistance test, and its industrial value is great.

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Claims (6)

[Claims] 1. A seal containing (a) an epoxy resin, (b) a curing agent having two or more phenolic hydroxyl groups in one molecule, and (c) a β-type silicon nitride (d) an organic phosphine compound. Stopping epoxy resin composition. 2. The epoxy resin has an epoxy equivalent of 170 to
The epoxy resin composition for sealing according to claim 1, which is 300 novolac type epoxy resin. 3. The epoxy resin composition for encapsulation according to claim 1, wherein the curing agent is a novolac type phenol resin. 4. The epoxy resin composition for encapsulation according to claim 1, wherein the β ratio of the β-type silicon nitride is 80% or more. 5. The β-type silicon nitride in the composition is 60% by weight.
The epoxy resin composition for encapsulation according to claim 1, which is contained above. 6. The β-type silicon nitride has an average particle size of 1 to 100.
The encapsulating epoxy resin composition according to claim 1, which is a powder having a size of μm.