JPH0525249A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition having a high glass transition temperature, excellent heat and humidity resistances and prevention of package crack by mixing an epoxy resin containing a specified polyepoxy resin with a curing agent and a cure accelerator. CONSTITUTION:An epoxy resin composition essentially consisting of an epoxy resin containing a polyepoxy resin prepared from a polyhydroxynaphthalene compound of an average molecular weight of 300-2000 prepared by cocondensing alpha-naphthol, beta-naphthol and xylenol with an aldehyde and an epihalohydrin, a curing agent and a cure accelerator. When the content of the xylenol units in the molecule is low, the humidity resistance of the epoxy resin composition is poor, and when it is excessively large, the heat resistance is problematic. The heat resistance can be improved by using beta-naphthol, but when it is used in an excessively large amount, the molecular weight is lowered because it remains uncopolymerized, and the heat resistance becomes poor.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an epoxy resin composition. More specifically, the present invention relates to an epoxy resin composition for semiconductor encapsulation, which has a high glass transition temperature, high strength at a solder reflow temperature, low hygroscopicity, and is resistant to package cracks.

[0002]

2. Description of the Related Art Conventionally, a method of encapsulating a semiconductor element with an epoxy resin composition has been widely adopted in order to protect the semiconductor element from the external environment. The general constitution of this composition is composed of an epoxy resin, a curing agent, a curing accelerator, a filler, and other compounding agents, and as the epoxy resin, a novolac resin obtained by reacting phenols with formaldehyde is epoxidized, In particular, orthocresol novolac epoxy resin has been widely used, and phenol formaldehyde novolac resin has been adopted as a curing agent.

In recent years, semiconductor devices have become more highly integrated and larger in size, flat packages with a large number of pins have been put into practical use, and the proportion of epoxy resin used in the sealed devices tends to decrease. For this reason, strong stress is likely to occur during sealing, and the mounting method is also the surface mounting method.Since the resin-sealed semiconductor is immersed in molten solder during mounting, strong thermal stress is applied and moisture is absorbed inside the resin. The exposed water is exposed to the severe environment where it vaporizes rapidly and causes volume expansion.

When a large-capacity semiconductor is encapsulated by using the epoxy resin, there arises a problem that cracks are generated in the package, the bonding wires are deformed or broken due to corrosion, and cracks in element passivation occur. There is an easy problem. Therefore, various high-performance epoxy resins have been proposed, but the problem has not been solved yet.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a novel epoxy resin composition for semiconductor encapsulation which has a high glass transition temperature, excellent heat resistance, and is resistant to cracks in a package having excellent moisture resistance. Especially.

[0006]

That is, the present invention is, as the first invention, an average molecular weight of 300 to which α-naphthol, β-naphthol, and xylenol are co-condensed with an aldehyde.
An epoxy resin composition containing, as essential components, an epoxy resin containing a polyfunctional epoxy resin produced from 2000 polyhydroxynaphthalene compounds and epihalohydrin, a curing agent, and a curing accelerator, and α-
In the co-condensation product of naphthol, β-naphthol, xylenol, and aldehyde, 55 to 15 mol% of α-naphthol molecular unit and 55 to β-naphthol molecular unit in one molecule.
15 mol% and xylenol molecular unit 30-70 mol%
(Aldehyde molecule unit excluded) included, average molecular weight is 4
It is an epoxy resin composition containing an epoxy resin containing a polyfunctional epoxy resin produced from a polyhydroxynaphthalene compound of 00 to 1500 and epihalohydrin, a curing agent, and a curing accelerator as essential components.

[Requirements Constituting Means] In the co-condensation product of α-naphthol, β-naphthol, xylenol and aldehyde used in the present invention, α-naphthol is another name of 1-naphthol and β-naphthol is another name. 2-Naphthol.

Xylenol is 2.3 xylenol, 2
-4 xylenol, 2.5 xylenol, 3/4 xylenol, 3.5 xylenol, or a mixture thereof is used, and 3.4 xylenol and 3.5 xylenol having high cocondensability are particularly preferable.

Aldehydes are, for example, formaldehyde,
Aliphatic aldehydes such as paraformaldehyde, acetaldehyde, propyl aldehyde, butyraldehyde,
Benzaldehyde, p-hydroxybenzaldehyde,
Aromatic aldehydes such as salicylaldehyde and polyhydric aldehydes such as glyoxal and terephthalaldehyde can be used. Among them, paraformaldehyde, benzaldehyde, p-hydroxybenzaldehyde, salicylaldehyde, glyoxal and terephthalaldehyde are preferable. One of these aldehydes may be used for the reaction, or two or more of them may be used in combination for the reaction.

The amount of each component used to obtain the cocondensate is α-naphthol 5 in terms of the amount excluding aldehyde molecules.
Aldehyde 0.3 to 0.95 mol is preferable to 1 mol of the compound of 5 to 15 mol%, β-naphthol 55 to 15 mol% and xylenol 30 to 70 mol%, and the average molecular weight of the cocondensate at this time is It is preferably 400 to 1500. still,
It is also possible to increase the amount of aldehyde used and remove some of them during the reaction.

When the content of xylenol molecular units in the molecule is low, the epoxy resin composition has poor moisture resistance,
If it is too large, heat resistance will be a problem. The heat resistance is improved by using β-naphthol, but when it is too much, the copolymer does not copolymerize, so that the molecular weight decreases and the heat resistance becomes poor. In addition, when the amount of aldehyde used is small, the cocondensate is smaller than the appropriate average molecular weight and thus has poor heat resistance,
If it is too large, the average molecular weight becomes too high, resulting in a high viscosity and a problem in moldability. A suitable average molecular weight of the cocondensate is 300 to 2000, preferably 400 to 1500.

In the co-condensation reaction, a two-step method using an acid or an alkali or a first alkali and then an acid as a catalyst is usually used, but an acid is generally used. As the acid, mineral acids such as sulfuric acid, hydrochloric acid, nitric acid and hydrobromic acid, sulfonic acids such as paratoluenesulfonic acid and benzenesulfonic acid, and carboxylic acids such as oxalic acid, succinic acid and malonic acid are used. It is also possible to react by simply heating to a high temperature without using a catalyst. Although the solvent is not always necessary, it can be reacted using a solvent such as benzene, toluene, chlorobenzene, dichlorobenzene, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dimethyl sulfoxide, dimethyl sulfamide. . Reaction temperature is 50 to 20
0 ° C., preferably 60 to 15 for aliphatic aldehydes
0 ℃, 60-190 ℃ for aromatic aldehyde, 1
Allow to react for 10 hours. Thereafter, if necessary, impurities are washed with water to remove, or unreacted monomers are removed by washing with a solvent or degassing under reduced pressure.

The polyfunctional epoxy resin based on the cocondensate of the present invention is obtained by reacting the above-mentioned polyhydroxynaphthalene compound obtained by cocondensing α-naphthol, β-naphthol and xylenol with an aldehyde and epihalohydrin. However, generally, the following two typical methods can be used for the reaction.

1) A one-step method in which a polyhydroxynaphthalene compound and an excess of epihalohydrin are simultaneously subjected to an addition reaction in the presence of an alkali metal hydroxide and a ring-closing reaction to form an epoxy ring.

2) A two-step method in which a polyhydroxynaphthalene compound and an excess of epihalohydrin are subjected to an addition reaction in the presence of a basic catalyst, and then an alkali metal hydroxide is added to carry out a ring-closing reaction.

Epihalohydrin in this reaction is
Epichlorohydrin, epibromohydrin, β-methylepichlorohydrin, β-methylepibromohydrin,
Examples thereof include β-methylepiodohydrin, and epichlorohydrin is preferable.

Further, as the alkali metal hydroxide in this reaction, caustic soda and caustic potash are used,
These remain as solids or are added to the reaction system as 40-50% aqueous solutions.

As the basic catalyst in the above reaction, tetramethylammonium chloride, tetramethylammonium bromide, tetraethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide, triethylmethylammonium chloride, trimethylbenzyl. Quaternary ammonium salts such as ammonium chloride, triethylbenzylammonium chloride are used.

In the above-mentioned one-step method, 50 to 150
The reaction is carried out at a temperature of 80 ° C, preferably 80 to 120 ° C. The alkali hydroxide is used in an amount of 0.8 to 1.5 molar equivalent, preferably 0.9 to 1.1 molar equivalent, per equivalent of hydroxyl group of the polyhydroxynaphthalene compound.

In the above two-step method, the reaction in the first step is carried out at a temperature of 60 to 150 ° C, preferably 100 to 140 ° C. The amount of epihalohydrin used is 1.3 to 1 equivalent of hydroxyl group of the polyhydroxynaphthalene compound.
20 molar equivalents, preferably 2 to 10 molar equivalents, excess epihalohydrin can be recovered and reused after the reaction.

The basic catalyst is used in an amount of 0.002 to 3.0 with respect to the hydroxyl group of the polyhydroxynaphthalene compound.
Used in a molar percentage. The latter reaction is 50 to 15
0 degreeC Preferably it carries out at 60-120 degreeC. Alkali metal hydroxide is usually 1 to 1 to the halohydrin formed.
1.1 molar amount is used.

These first-stage and second-stage reactions may be carried out in the absence of a solvent or in the presence of an inert solvent such as methyl isobutyl ketone, cyclohexane or toluene. After completion of the reaction, these are purified by washing with water or solvent, or evaporated and degassed to obtain the polyfunctional epoxy resin of the present invention.

The polyfunctional epoxy resin of the present invention may be used alone or may be 70% by weight or less, preferably 50% by weight.
It can also be used in combination with the following general epoxy resins such as ortho-cresol resin epoxy resin, bisphenol A base epoxy resin, and phenol resin epoxy resin.

Next, the curing agent of the present invention has two or more, preferably three or more phenolic hydroxyl groups in the molecule. Specifically, phenol and substituted phenols,
For example, o-cresol, p-cresol, t-butylphenol, cumylphenol, phenylphenol and formaldehyde are reacted with an acid or an alkali. Instead of formaldehyde, other aldehydes such as benzaldehyde, crotonaldehyde,
Those using salicylaldehyde, hydroxybenzaldehyde, glyoxal, and terephthalaldehyde can also be used. A reaction product of resorcin and an aldehyde and polyvinylphenol can also be used as the curing agent of the present invention.

The mixing ratio of the curing agent is such that the equivalent ratio of the phenolic hydroxyl group of the curing agent to the epoxy group of the epoxy resin (epoxy group / phenolic hydroxyl group) is usually 1/0.
The range of 8 to 1 / 1.2, preferably 1 / 0.9 to 1 / 1.1 is selected from the viewpoint of heat resistance and moisture resistance.

The curing accelerator used in the present invention is an ordinary catalyst and is not particularly limited. Specific examples of the curing accelerator include, for example, triphenylphosphine, tris-2,
Phosphorus compounds such as 6-dimethoxyphenylphosphine, tri-p-tolylphosphine, and triphenylphosphite;
2-methylimidazole, 2-phenylimidazole,
2-undecylimidazole, 2-heptadecylimidazole, imidazoles such as 2-ethyl-4-methylimidazole, 2-dimethylaminomethylphenol,
Tertiary amines such as benzyldimethylamine and α-methylbenzylmethylamine, organic of 1,8-diazabicyclo (5,4,0) undecene-7,1,8-diazabicyclo (5,4,0) undecene-7 Examples thereof include acid salts.

The compounding amount of the curing accelerator is preferably 0.1 to 3.0% in the composition of the present invention from the viewpoint of heat resistance and moisture resistance.

In the present invention, in addition to the above-mentioned components, various compounds may be blended as required. For example, it is a surface treatment agent for treating the surface of the filler or the filler, a flame retardant, a release agent, a coloring agent, and a flexibility imparting agent.

The filler is not particularly limited, and examples thereof include crystalline silica powder, fusible silica powder, quartz glass powder,
Examples thereof include talc, calcium silicate powder, zirconium silicate powder, alumina powder, calcium carbonate powder and the like, with silica-based powders being preferred.

The compounding ratio of the filler is 6 with respect to the total composition.
It is 0 to 90 wt%, preferably 70 to 85 wt%.
If the blending amount of the filler exceeds 90 wt%, the fluidity of the composition will be low and molding will be difficult. If it is less than 60 wt%, the thermal expansion tends to be large.

Examples of the surface treatment agent include known silane coupling agents, flame retardants such as antimony trioxide, antimony pentoxide, phosphates and bromides, and release agents including various waxes. Carbon black or the like is used as the colorant, and silicone resin, butadiene-acrylonitrile rubber or the like is used as the flexibility-imparting agent. However, it is not limited to these.

The method for preparing the epoxy resin composition of the present invention is not particularly limited and can be carried out by a conventional method. The conditions for encapsulating a semiconductor using the resin composition of the present invention are not particularly limited, and are usually 175 ° C. and a molding pressure of 100 kg.
/ Cm ² , conditions such as molding for 3 minutes and post-curing at 180 ° C. for 6 hours are adopted.

[0033]

EXAMPLES Hereinafter, the embodiments of the present invention will be specifically illustrated and described with reference to Examples. The invention is not limited to these examples.

Production Example 1 of Epoxy Resin Production of Co-condensate 72 g of α-naphthol and 2 of β-naphthol were placed in a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet.
4 g, 3.4 g of xylenol, 41 g, paraformaldehyde 23 g, and oxalic acid 0.2 g were charged, and the mixture was heated to 110 ° C. and stirred under a nitrogen stream for 8 hours to react. After this, 2
It heated at 00 degreeC and 5 mmHg removed the unreacted material and water.
The average molecular weight of the obtained cocondensate was 570.

Production of Epoxy The total amount of the above cocondensate, 2000 g of epichlorohydrin and 3 g of tetrabutylammonium bromide were charged and reacted under heating and reflux for 3 hours, and excess epichlorohydrin was removed under reduced pressure. Add the same amount of toluene as the contents, 60
Cool to ℃, attach a water removal device, and add sodium hydroxide 4
0 g is added, and the generated water is decompressed at 100 to 150 mmH.
The ring-closing reaction was carried out while continuously removing with g. After washing with water to remove salts and unreacted alkali, toluene and water were removed under reduced pressure.

Epoxy resin production example 2 In the production of a cocondensation product, 36 g of α-naphthol and β
-36 g of naphthol and 61 of 3.5 xylenol
g, and an epoxy resin was produced in the same manner as in Production Example 1 except that 21 g of paraformaldehyde was used. The average molecular weight of the obtained cocondensate was 450.

Production Example 3 of Epoxy Resin In the production of the cocondensation product, 24 g of α-naphthol and β were used.
-Using 24 g of naphthol and 82 of 3.5 xylenol
g, and an epoxy resin was produced in the same manner as in Production Example 1 except that the amount of paraformaldehyde was 27 g. The average molecular weight of the obtained cocondensate was 800.

Production Example 4 of Epoxy Resin In the production of a cocondensation product, 90 g of benzaldehyde was used instead of paraformaldehyde, and p- was used instead of oxalic acid.
An epoxy resin was produced in the same manner as in Production Example 2 except that toluenesulfonic acid was used. The average molecular weight of the obtained cocondensate was 980.

Epoxy Resin Production Example 5 An epoxy resin was produced in the same manner as in Production Example 4 except that 98 g of p-hydroxybenzaldehyde was used instead of benzaldehyde in the production of the co-condensate, and the reaction temperature was 180 ° C. The average molecular weight of the obtained cocondensate was 107.
It was 0.

Epoxy Resin Production Example 6 An epoxy resin was produced in the same manner as in Production Example 4 except that 25 g of glyoxal was used instead of benzaldehyde in the production of the cocondensate. The average molecular weight of the obtained cocondensate was 690.

Production Example 7 of Epoxy Resin In the production of the co-condensate, 57 g of terephthalaldehyde was used in place of benzaldehyde, and other production example 4 was used.
An epoxy resin was produced in the same manner as in. The average molecular weight of the obtained cocondensate was 690.

Examples 1 to 7 and Comparative Example 1 As the epoxy resin, each epoxy resin obtained in Production Examples 1 to 7 of epoxy resin, commercially available o-cresol novolac epoxy resin (EOCN1020 manufactured by Nippon Kayaku Co., Ltd.), and A commercially available brominated phenol novolac epoxy resin (BREN-S manufactured by Nippon Kayaku Co., Ltd.) was used, a phenol novolac resin (Tamanol 752 manufactured by Arakawa Chemical Co., Ltd.) was used as a curing agent, and triphenylphosphine was used as a curing accelerator. Fins, spherical silica (BF100 manufactured by Mitsubishi Metals Co., Ltd.) as a filler, and antimony trioxide, a silane coupling agent, a wax, and a carbon black as other materials are blended in the proportions shown in Table 1, and 7 with this roll
After kneading at a temperature of 0 to 110 ° C., the mixture was cooled and pulverized to prepare an epoxy resin composition for semiconductor encapsulation.

The composition obtained was treated at 175 ° C. and 100 kg.
/ Cm ² , molded under curing conditions of 3 minutes, then 180
Post-curing was performed under the conditions of ° C and 6 hours to prepare a molded test piece.

The bending strength (high temperature strength) of the obtained test piece at 200 ° C., the glass transition temperature, the coefficient of thermal expansion, 85
The water absorption after a humidity test at 500 ° C. and 85% RH for 500 hours was examined, and the heat shock resistance was tested as follows.

A semiconductor element is placed on a heat shock resistant die bonding plate, and ten small IC molded products are prepared. 85 ° C, 85% RH, 7
After 2 hours, 10 times each in liquid nitrogen and a solder bath at 260 ° C.
It was soaked for a second, and the number of occurrence of cracks was examined.

The results are shown in Table 2.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

EFFECT OF THE INVENTION The epoxy resin composition of the present invention has a high glass transition temperature of a cured resin, excellent heat resistance, high mechanical strength, and low moisture absorption rate since it contains xylenol in the molecule as a skeleton. It is suitable for IC encapsulation because it has excellent crack resistance and extremely few cracks even during soldering.

Continued front page    (72) Inventor Shinya Akizuki             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd.

Claims (2)

[Claims] 1. An average molecular weight of 300 to 300 obtained by co-condensing α-naphthol, β-naphthol and xylenol with an aldehyde.
An epoxy resin composition containing, as essential components, an epoxy resin containing a polyfunctional epoxy resin produced from 2000 polyhydroxynaphthalene compounds and epihalohydrin, a curing agent, and a curing accelerator. 2. A co-condensation product of α-naphthol, β-naphthol, xylenol and aldehyde, wherein 55 to 15 mol% of α-naphthol molecular unit, 55 to 15 mol% of β-naphthol molecular unit and xylenol molecule are contained in one molecule. Epoxy resin, curing agent, and curing agent containing a polyfunctional epoxy resin containing a polyhydroxynaphthalene-based compound having a unit of 30 to 70 mol% (aldehyde molecule unit excluded) and an average molecular weight of 400 to 1500 and epihalohydrin An epoxy resin composition containing an accelerator as an essential component.