JPH0570556A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide an epoxy resin compsn. which gives a curd resin having a high glass transition point excellent heat resistance, high mechanical strengths, low water absorption, excellent moisture resistance because of naphthalene rings contained, extremely reduced cracking in soldering and is hence suitable for sealing IC. CONSTITUTION:An epoxy resin contg. a polyepoxy resin prepd. by cocondensing naphthol or dihydroxynaphthalene and naphthalene with an aldehyde and reacting the resulting polyhydroxynaphthalene compd. with an epihalohydrin is compounded with a curing agent and a cure accelerator, as the essential components, to give an epoxy resin compsn.

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 cracking.

[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 composition of the 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 be applied during the encapsulation, and the mounting method is also the surface mounting method.Since the resin-encapsulated semiconductor is immersed in the molten solder during mounting, it is subjected to strong thermal stress and is absorbed into the resin. The water is exposed to a severe environment where the water 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 cracking in a package having excellent moisture resistance. Especially.

[0006]

That is, the present invention relates to an epoxy containing a polyfunctional epoxy resin produced from a polyhydroxynaphthalene compound obtained by co-condensing naphthol or dihitoloxynaphthalene and naphthalene with an aldehyde, and epihalohydrin. An epoxy resin composition containing a resin, a curing agent, and a curing accelerator as essential components.

[Requirements Constituting Means] In the cocondensation product of naphthol or dihydroxynaphthalene and naphthalene condensed with an aldehyde used in the present invention, α-naphthol and β-naphthol can be used as naphthol, and particularly excellent reactivity is obtained. Α-naphthol is preferred. Dihydroxynaphthalene is 1.5 dihydroxynaphthalene, 1
・ 6 dihydroxynaphthalene, 1.7 dihydroxynaphthalene, 2.6 dihydroxynaphthalene, 2.7 dihydroxynaphthalene, 1.4 dihydroxynaphthalene, 1
-2 dihydroxy naphthalene, 1.3 dihydroxy naphthalene, 2.3 dihydroxy naphthalene, etc. are mentioned. Among them, highly reactive 1,6 dihydroxynaphthalene, 2,7 dihydroxynaphthalene, and 1,4 dihydroxynaphthalene are particularly preferable.

As the naphthalene, an alkylnaphthalene such as naphthalene or methylnaphthalene can be used.

As the aldehyde, aliphatic aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, butyraldehyde and glyoxal, and aromatic aldehydes such as benzaldehyde, p-hydroxybenzaldehyde, salicylaldehyde and terephthalaldehyde can be used. And benzoaldehyde, p-hydroxybenzaldehyde, salicylaldehyde and terephthalaldehyde are preferred. One of these aldehydes may be used in the reaction, or two or more of them may be used in combination.

The amount of each component used to obtain the cocondensate is 0.3 to 0.95 mol of aldehyde per 1 mol of the total mol of naphthol or dihydroxynaphthalene.

The use of naphthalene improves the moisture resistance. When the amount of aldehyde used is small, the condensate becomes smaller than the appropriate average molecular weight, resulting in poor heat resistance. When the amount of aldehyde is too large, the average molecular weight becomes too high, resulting in high viscosity and a problem in moldability. The appropriate average molecular weight of the polyhydroxynaphthalene compound, which is the condensate, is 300 to 2000.
And preferably 400 to 1500.

[0012] In the condensation reaction, an acid or an alkali is usually used as a catalyst, but an acid is generally used. Acids include mineral acids such as sulfuric acid, hydrochloric acid, nitric acid and hydrobromic acid, sulfonic acids such as paratoluenesulfonic acid and benzenesulfonic acid, carboxylic acids such as oxalic acid, succinic acid and malonic acid, aluminum chloride and trifluoride. Lewis acids such as boron are used.

Although a solvent is not always necessary, benzene, toluene, chlorobenzene, dichlorobenzene, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dimethyl sulfoxide,
The reaction can be performed using a solvent such as dimethyl sulfamide. The reaction temperature is 50 to 200 ° C. and the reaction is performed for 1 to 10 hours. Thereafter, if necessary, impurities are washed with water to be removed, 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 can be obtained by reacting epihalohydrin with the above-mentioned polyhydroxynaphthalene compound obtained by cocondensing naphthol or dihydroxynaphthalene with an aldehyde. 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 subjected to an addition reaction in the presence of an alkali metal hydroxide and a ring-closing reaction to form an epoxy ring at the same time.

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 closure reaction.

Epihalohydrin in this reaction is
Epichlorohydrin, epibromohydrin, β-methylepichlorohydrin, β-methylepibromohydrin,
Examples include β-methylepiiodohydrin, with epichlorohydrin being preferred.

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 ℃, preferably 80 to 120 ℃. The alkali hydroxide is used in an amount of 0.8 to 1.5 molar equivalents, preferably 0.9 to 1.1 molar equivalents, 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 the hydroxyl group of the polyhydroxynaphthalene compound.
20 molar equivalents, preferably 2 to 10 molar equivalents, and 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 ° C., preferably 60 to 120 ° C. The alkali metal hydroxide is usually 1 to the halohydrin formed.
1.1 molar amount is used.

These first-stage and second-stage reactions may be carried out without 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 a 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 70 wt% or less, preferably 50 wt% or less.
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,
Imidazoles such as 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-dimethylaminomethylphenol,
Tertiary amines such as benzyldimethylamine and α-methylbenzylmethylamine, 1,8-diazabicyclo (5,4,0) undecene-7,1,8-diazabicyclo (5,4,0) undecene-7 organic Examples thereof include acid salts.

From the standpoint of heat resistance and humidity resistance, it is preferable that the amount of the curing accelerator is 0.1 to 3.0% in the composition of the present invention.

In the present invention, in addition to the above-mentioned components, various compounds may be blended as required. For example, a filler, a surface treatment agent for treating the surface of 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 and calcium carbonate powder, with silica-based powders being preferred.

The compounding ratio of the filler is 6 with respect to the total composition.
0 to 90 wt%, preferably 70 to 85 wt%. When the compounding amount of the filler exceeds 90 wt%, the fluidity of the composition becomes low and molding is difficult, and when it is less than 60 wt%, the thermal expansion tends to increase.

Examples of the surface treatment agent include known silane coupling agents, examples of the flame retardant include antimony trioxide, antimony pentoxide, phosphate and bromide, and examples of the release agent include 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.

[0034]

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 In a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen inlet, 130 g of α-naphthol, 14 g of methylnaphthalene, 23 g of paraformaldehyde and sulfuric acid of 0.1 g were added. 5 g
Was charged, heated to 120 ° C., and stirred under a nitrogen stream for 8 hours to react. Then, it heated at 200 degreeC and 5 mmHg removed the unreacted material and water. The average molecular weight of the obtained cocondensate was 720.

Production of Epoxy The total amount of the co-condensate, 2000 g of epichlorohydrin and 3 g of tetrabutylammonium bromide were charged and reacted under heating under 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 3
7g 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.

Production Example 2 of Epoxy Resin An epoxy resin was produced in the same manner as in Production Example 1 except that 116 g of α-naphthol, 28 g of naphthalene, 21 g of paraformaldehyde and 34 g of sodium hydroxide were used in the production of the cocondensate. The average molecular weight of the obtained co-condensate is 6
It was 70.

Epoxy Resin Production Example 3 An epoxy resin was produced in the same manner as in Production Example 1, except that 116 g of α-naphthol, 28 g of naphthalene, 90 g of benzaldehyde and 34 g of sodium hydroxide were used in the production of the co-condensate. The average molecular weight of the obtained cocondensate was 109.
It was 0.

Epoxy Resin Production Example 4 In the production of a cocondensate, 1 was used in place of α-naphthol.
An epoxy resin was produced in the same manner as in Production Example 2 except that 128 g of 6-dihydroxynaphthalene was used and 66 g of sodium hydroxide was used. The average molecular weight of the obtained cocondensate is 7
It was 70.

Epoxy Resin Production Example 5 An epoxy resin was produced in the same manner as in Production Example 4, except that 1.4 dihydroxynaphthalene was used in place of 1.6 dihydroxynaphthalene in the production of the cocondensate. The average molecular weight of the obtained cocondensate was 760.

Epoxy Resin Production Example 6 An epoxy resin was produced in the same manner as in Production Example 4 except that 2.7 dihydroxynaphthalene was used instead of 1.6 dihydroxynaphthalene in the production of the cocondensate. The average molecular weight of the obtained cocondensate was 770.

Epoxy resin production example 7 In the production of a cocondensation product, 1 was used instead of α-naphthol.
An epoxy resin was produced in the same manner as in Production Example 3 except that 128 g of 4 dihydroxynaphthalene was used and 66 g of sodium hydroxide was used. The average molecular weight of the obtained cocondensate is 1
It was 130.

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, wax, and carbon black as other materials are mixed in the proportions shown in Table 1, and 7 with this roll
The mixture was kneaded at a temperature of 0 to 110 ° C., cooled, and then 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.

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

Heat shock resistance A semiconductor element is placed on a 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.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

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 a low water absorption rate since it contains a naphthalene ring as a skeleton in the molecule. It is suitable for IC encapsulation because it has excellent properties and cracks are extremely few even during soldering.

Front Page Continuation (72) Inventor Shinya Akizuki 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (2)

[Claims] 1. An epoxy resin containing a polyfunctional epoxy resin produced from a polyhydroxynaphthalene compound obtained by co-condensing naphthol or dihydroxynaphthalene and naphthalene with an aldehyde, and epihalohydrin, a curing agent, and a curing accelerator are essential components. Epoxy resin composition. 2. The epoxy resin composition according to claim 1, wherein the polyhydroxynaphthalene compound has an average molecular weight of 300 to 2,000.