JPH06326221A - Resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To obtain a resin composition for sealing a semiconductor having low hygroscopicity and high glass transition point and exhibits excellent solder heat resistance when employed far sealing a semiconductor device. CONSTITUTION:The resin composition for sealing a semiconductor contains (a). an epoxy resin, (b). a phenol based curing agent, (c). a curing accelerator, and (d). an inorganic tiller, as essential constituents, wherein the mixture of (1). an addition condensate of phenols and an aromatic aldehyde and (2). a phenol aralkyl resin is employed as the phenol based curing agent. The mixing ratio (1)/(2) is preferably set in the range of 23/75-85/15 in the weight ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for semiconductor encapsulation, which has low hygroscopicity, high glass transition temperature and excellent solder heat resistance.

[0002]

2. Description of the Related Art As a sealing method for electronic circuit parts such as semiconductor devices, hermetic sealing using metal or ceramics and resin sealing using phenol resin, silicone resin, epoxy resin, etc. have been proposed. Among them, the resin encapsulation with an epoxy resin is the main focus from the viewpoint of balance of economy, productivity and physical properties. In particular, a large amount of epoxy resin molding materials using phenol novolac as a curing agent in an epoxy resin having cresol novolac as a skeleton are used.

However, in recent years, along with the downsizing of electronic parts, the upsizing of semiconductor elements, the increase in the degree of integration, etc., conventional epoxy resin molding materials have been sufficiently compatible with respect to moisture resistance, heat resistance and reliability. It's getting harder.

Particularly in recent years, packaging and mounting on a printed circuit board have been promoted with higher density and automation. Instead of the conventional mounting method of inserting lead pins into the holes of the board,
The "surface mounting method" in which components are soldered to the surface of the board is becoming mainstream. Along with this, the package is shifting from the conventional dual in-line package (DIP) to a thin type such as a flat package (FP) or a small out package (SOP) suitable for surface mounting. With such changes in mounting methods and thinning of semiconductor packages, securing reliability of elements has become an important issue. That is, in the conventional pin insertion mounting method, the lead portion is only partially heated in the soldering process, but in the surface mounting method, the entire package is 21
Since it is heated to 0 to 280 ℃, the reliability of the conventional encapsulation resin is reduced due to cracks in the resin portion during the soldering process and peeling of the resin from the element, along with the thinning of the package. The problem of a significant drop has occurred.

The occurrence of cracks in the soldering process is
This is because moisture absorbed inside the package is vaporized and expanded at once due to heating at the time of soldering. As a countermeasure against this, various improvements of sealing resins have been studied. These improvements are based on epoxy resin, hardener,
Although it has been studied from various fields such as curing accelerators and fillers,
Among these, there are two main directions for improving the curing agent.One is a method of increasing the glass transition point by using a polyfunctional curing agent, and the other is the improvement of the phenolic hydroxyl group equivalent. It is a method of imparting low hygroscopicity and low stress by using a high curing agent.

As an example of the former, a method using tris (hydroxyphenyl) methane as a curing agent (JP-A-62-1)
No. 84012, JP-A-1-268713), and as an example of the latter, a method using a phenol aralkyl resin as a curing agent (JP-A-59-101018, JP-A-59-6).
7660 and JP-A-64-60623) are known. Also, a method of combining both (Japanese Patent Laid-Open No. 1-2920).
No. 29) has also been reported. However, the encapsulating resins improved by these methods have some effects in preventing cracks in the soldering process, but they are still insufficient, and each has drawbacks. For example, although the method using tris (hydroxyphenyl) methane as the curing agent increases the crosslink density of the resin, it has been pointed out that the water absorption rate increases and the resin itself becomes brittle. Particularly in the case of a thin package, the effect of preventing cracks is small. Further, the method using a phenol aralkyl resin as a curing agent has a drawback that the glass transition point of the resin is significantly lowered.

[0007]

In view of the above situation, the present invention provides a resin composition for semiconductor encapsulation which has both low water absorption and high glass transition point and is excellent in solder heat resistance and reliability. To aim.

[0008]

In order to solve the above-mentioned problems, the present inventor has made various studies especially on a curing agent for epoxy resin, and as a result, a phenol consisting of a mixture of phenolic resins having a specific molecular structure has been obtained. The inventors have found that the above problems can be solved by using a system hardener, and have reached the present invention.

That is, the present invention provides (a) an epoxy resin,
(B) Phenolic curing agent, (c) curing accelerator, (d)
A resin composition comprising an inorganic filler as an essential component, wherein the (b) phenolic curing agent is a mixture of an addition condensation product of phenols and an aromatic aldehyde and a phenol aralkyl resin. A characteristic resin composition for semiconductor encapsulation. Hereinafter, the present invention will be described in detail.

The (a) epoxy resin used in the present invention is not particularly limited, and a known epoxy resin containing two or more glycidyl groups in one molecule is used. As a specific example, the one having the formula (1) is particularly excellent in moisture resistance, low stress resistance and heat resistance.

[Chemical 1] (However, R ^{1 to} R ⁴ are alkyl groups having 1 to ⁴ carbon atoms.) Are preferably used. Further, various novolac type epoxy resins such as cresol novolac type epoxy resin and phenol novolac type epoxy resin are also preferable specific examples. In addition, bisphenol type epoxy resin with fluorene skeleton,
Bisphenol A type epoxy resin, bisphenol F type epoxy resin and the like can also be used.

The present invention is characterized in that, as the (b) phenol-based curing agent, both an addition condensation product of a phenol and an aromatic aldehyde and a phenol aralkyl resin are used as essential components.

The addition condensation product of a phenol and an aromatic aldehyde can be easily produced by reacting a phenol and an aromatic aldehyde in the presence of an acid catalyst.

Examples of the phenols used as the raw material of the above addition condensate include phenol, cresol, xylenol, ethylphenol, butylphenol, halogenated phenol, resorcin, bisphenol A, bisphenol S, bisphenol F, and the like. Phenol and cresol are preferably used.
Phenols having a condensed polycyclic aromatic skeleton such as α-naphthol, β-naphthol and naphthalenediol are also preferable specific examples.

Examples of the aromatic aldehyde include benzaldehyde, naphthaldehyde, anthracene aldehyde, and the like, and benzaldehyde and naphthaldehyde are preferable.

Examples of acid catalysts used in the reaction of phenols with aromatic aldehydes include inorganic acids such as phosphoric acid, sulfuric acid and hydrochloric acid, and organic acids such as oxalic acid, benzenesulfonic acid, toluenesulfonic acid and methanesulfonic acid. Can be mentioned.

For the reaction of phenols with aromatic aldehydes, aromatic aldehyde is charged in a ratio of 0.9 to 0.1 mol per mol of phenols, an appropriate amount of acid catalyst is added, and then usually 100 to 180. It is carried out in the range of ° C for about 1 to 10 hours. After the completion of the condensation reaction, the unreacted phenols remaining in the system are distilled off under vacuum or by an appropriate method such as steam distillation to obtain the desired product.

The phenol aralkyl resin, which is another component of the (b) phenolic curing agent of the present invention, has a repeating unit represented by the following formula (2) as a typical example, and includes aralkyl ether and aralkyl. ester,
A resin obtained by reacting aralkyl alcohol and the like with a phenol with a Friedel-Crafts catalyst, which is also called a Friedel-Crafts resin, and Zyloc resin (trade name, manufactured by Albright & Wilson) is known. For example, xylylene glycol, xylylene glycol dimethyl ether, xylylene glycol diethyl ether,
It can be obtained by the reaction of xylylene glycol diacetoxy ester or the like with phenol, and a condensate of p-xylylene glycol dimethyl ether and phenol is well known.

[0018]

[Chemical 2]

The (b) phenol-based curing agent of the present invention uses both the above-mentioned addition condensation product of a phenol and an aromatic aldehyde, and a phenol aralkyl resin. The compounding ratio of both is 25/7 in terms of the weight ratio of addition condensation product of phenol and aromatic aldehyde / phenol aralkyl resin.
A range of 5 to 85/15 is preferred. If the addition condensation product of phenol and aromatic aldehyde is less than 25% by weight,
The glass transition point does not rise so much and the object of the present invention cannot be satisfied. When the addition condensate of the phenol and the aromatic aldehyde is more than 85% by weight, the cured product obtained by adding the epoxy resin and curing the cured product tends to be slightly hard and brittle.

In the present invention, a known curing agent such as phenol novolac resin or tris (hydroxyphenyl) methane may be used in combination within the range of not impairing the effect.

The compounding ratio of the (b) phenolic curing agent to the (a) epoxy resin is in the range of 0.8 to 1.2 in terms of chemical equivalence ratio in terms of heat resistance, moisture resistance and mechanical characteristics. It is preferable.

The curing accelerator (c) used in the present invention is not particularly limited as long as it accelerates the curing reaction between the epoxy resin and the phenolic curing agent. For example, imidazoles such as 2 methyl imidazole, 2,4 dimethyl imidazole, 2 ethyl 4 methyl imidazole, 2 phenyl imidazole, 2 phenyl 4 methyl imidazole, tri (p
Examples include organic phosphine compounds such as methylphenyl) phosphine and triphenylphosphine.

These curing accelerators may be used depending on the purpose.
, Or two or more kinds may be used in combination, and the addition amount thereof is
(A) 0.2 to 5 relative to 100 parts by weight of epoxy resin
The range of parts by weight is preferable in terms of curing characteristics and physical properties.

Examples of the inorganic filler (d) used in the present invention include fused silica, crystalline silica, alumina, glass, calcium silicate, gypsum, calcium carbonate, magnesite, clay, kaolin, talc, mica, magnesia,
Among them, barium sulfate and the like, among them, fused silica and crystalline silica are most preferable in terms of high purity and low coefficient of thermal expansion.

The amount of these inorganic fillers added is such that the ratio to the entire semiconductor encapsulating resin composition of the present invention is 60 to 9.
It is preferably 0% by weight. When the content of the inorganic filler is less than 60% by weight, solder heat resistance and linear expansion coefficient are insufficient, and when it exceeds 90% by weight, the fluidity of the molded product is insufficient.

Regarding the particle size distribution of the inorganic filler, close packing is performed by appropriately setting the distribution by combining coarse particles and fine particles, and adding the inorganic filler without impairing the fluidity during molding. The amount can be increased.

The semiconductor encapsulating composition according to the present invention contains a releasing agent such as natural waxes, synthetic waxes, metal salts of linear fatty acids, acid amides, esters or paraffins, if necessary. , Flame retardants such as halogen compounds and phosphorus compounds such as chlorinated paraffin, bromotoluene, hexabromobenzene, halogenated epoxy resins, flame retardant aids such as antimony trioxide, colorants such as carbon black, silane coupling agents, etc. May be appropriately added and blended.

As a general method for preparing the resin composition for semiconductor encapsulation of the present invention as a molding material, the raw material components selected in a predetermined composition ratio are thoroughly mixed by, for example, a mixer, and then further heated. It can be easily obtained by adding a kneading process using a kneader or a kneader.

[0029]

EXAMPLES The present invention will be specifically described below with reference to examples. [Production Example 1] (Production of addition condensation product A of phenol and aromatic aldehyde) Stirrer, thermometer, condenser,
And a four-necked flask equipped with a nitrogen gas introduction tube, 470 parts by weight of phenol, 265 parts by weight of benzaldehyde, p
-Add 1 part by weight of toluenesulfonic acid (monohydrate) and add 1
The mixture was heated to 40 ° C., and the reaction was performed while dehydration was continued until generation of condensed water was not observed. P-in the system by washing with water
After removing the toluenesulfonic acid, the unreacted phenol was removed by vacuum distillation to obtain the target product.
The addition condensation product obtained had a softening point of 70 ° C. and a hydroxyl equivalent of 158 g / eq.

[Production Example 2] (Production of Addition Condensation Product B) 540 parts by weight of orthocresol, 265 parts by weight of benzaldehyde and p-toluenesulfonic acid (monohydrate) were added to the apparatus used in Production Example 1.
1 part by weight was added, the mixture was heated to 140 ° C., and the reaction was performed while dehydration was performed until generation of condensed water was not observed. Thereafter, the unreacted cresol in the system was removed by vacuum distillation to obtain the target product. The obtained addition condensate had a softening point of 73 ° C. and a hydroxyl equivalent of 172 g / eq.

[Production Example 3] (Production of Addition Condensate C) Using the apparatus used in Production Example 1, 575 parts by weight of 1-naphthol, 210 parts by weight of benzaldehyde, p-toluenesulfonic acid (monohydrate) 1 A part by weight was added, and the mixture was heated to 140 ° C. and dehydrated, and the reaction was performed until generation of condensed water was not observed. Thereafter, the reaction product was dissolved in dichloromethane, washed with water, and then the solvent and unreacted 1-naphthol were removed from the organic layer by steam distillation under reduced pressure to obtain the target product.
The obtained addition condensate had a softening point of 85 ° C. and a hydroxyl group equivalent of 208 g / eq.

Production Example 4 (Production of Addition Condensate D) Using the apparatus used in Production Example 1, 470 parts by weight of phenol, 390 parts by weight of 1-naphthaldehyde, p-toluenesulfonic acid (monohydrate) 1 part by weight was added, and the mixture was heated to 140 ° C. and dehydration was carried out until the generation of condensed water was not observed. Thereafter, the unreacted cresol in the system was removed by vacuum distillation to obtain the target product. The addition condensation product obtained had a softening point of 82 ° C. and a hydroxyl group equivalent of 195 g / eq.

Examples 1 to 5 Addition Condensates A to D of Phenols and Aromatic Aldehydes Obtained in Production Examples 1 to 4
And a phenol aralkyl resin (condensation product of p-xylylene glycol dimethyl ether and phenol, E in Table 1) were used as a curing agent, and this was mixed with the epoxy resin and other compounding agents in the proportions shown in Table 2. Then, after sufficiently premixing, kneading with a mixing roll and cooling,
By crushing this, a molding material made of the intended resin composition for semiconductor encapsulation was obtained. Various physical properties of the sealing material sample thus obtained were measured and evaluated. The results are shown in Table 2.

The physical properties of these sealing materials were measured by the following methods. (1) Moisture absorption rate A molded cured product (diameter 50 m) for measuring the moisture absorption rate from a molding material.
m, thickness 3 mm) by low pressure transfer molding under the condition of 175 ° C. × 150 seconds, and then 150 ° C. × 2 hours + 1
Post cure was performed at 80 ° C. for 6 hours. The test piece was treated for 96 hours in a thermo-hygrostat at 80 ° C./90% humidity, and the moisture absorption rate was measured.

(2) Glass transition point From the molding material, a cured product of 5 × 5 × 2 mm (molding condition: 1
75 ° C. × 150 seconds, post cure condition: 150 ° C. × 2 hours + 180 ° C. × 6 hours) was prepared, and the glass transition point was determined by the TMA method.

(3) Solder heat resistance The molding material was subjected to low-pressure transfer molding under the conditions of 175 ° C. × 150 seconds, and a semiconductor element for testing (6.7 mm × 6.7) was formed.
mm), then 150 ° C x 2 hours + 180 ° C x 6
I did a time post cure. This test element is 80
After treatment for 96 hours in a constant temperature / humidity bath at a temperature of 90 ° C./90% humidity, the rate of occurrence of cracks was checked when immersed in a solder bath at 260 ° C. for 10 seconds.

[Comparative Examples 1 to 4] Phenol aralkyl resin, phenol novolac resin, and addition condensates of phenols and aromatic aldehydes were used alone as a phenol-based curing agent, and epoxy resins and other resins were prepared in the same manner as in Examples. The compounding agent was mixed with the compounding agent in the proportions shown in Table 3, a molding material for sealing was prepared, and the physical properties of the obtained material were measured in the same manner as in Examples 1 to 5. The results are shown in Table 3.

As is clear from the results of Tables 2 and 3, Examples 1 to 1 in which an addition condensate of a phenol and an aromatic aldehyde and a phenol aralkyl resin were used in combination as a curing agent
In No. 5, the moisture absorption rate was low and the glass transition point was high. Also, the occurrence of cracks after immersion in the solder bath was very small.

On the other hand, in Comparative Example 1 in which only the phenol aralkyl resin was used as the curing agent, although the moisture absorption rate was low, the glass transition point was low and the solder heat resistance was inferior to that of any of the Examples. Further, in Comparative Examples 2 to 3 in which only the phenol novolac resin was used as the curing agent, the glass transition point was high, but the moisture absorption rate was large, and many cracks were generated during solder immersion. Furthermore, in Comparative Example 4 using only the addition condensate of phenols and aromatic aldehyde, the moisture absorption rate, the glass transition point, and the solder heat resistance are inferior to the molding material of the resin composition of the present invention.

[0040]

The resin composition of the present invention using a mixture of an addition condensate of a phenol and an aromatic aldehyde and a phenol aralkyl resin as a curing agent has both low hygroscopicity and high glass transition point. When used for encapsulating a semiconductor device, it is extremely excellent in solder heat resistance and reliability, and therefore has an extremely great industrial value as an encapsulating material for electronic circuit parts.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location C08L 63/00 NJR (72) Inventor Haruyuki Kano 2-16-2 Sotokanda, Chiyoda-ku, Tokyo Residence Kinkako Co., Ltd.

Claims (2)

[Claims] 1. A resin composition comprising (a) an epoxy resin, (b) a phenolic curing agent, (c) a curing accelerator, and (d) an inorganic filler as an essential component.
(B) The resin composition for semiconductor encapsulation, wherein the phenol-based curing agent is a mixture of an addition condensation product of phenols and an aromatic aldehyde and a phenol aralkyl resin. 2. The resin composition for semiconductor encapsulation according to claim 1, wherein the compounding ratio of the addition condensation product of a phenol and an aromatic aldehyde / phenol aralkyl resin is in the range of 25/75 to 85/15 by weight. .