JP3359445B2 - Resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent solder heat resistance in surface mounting of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits have been sealed with a thermosetting resin. In particular, in an integrated circuit, an ortho-cresol novolak type epoxy resin having excellent heat resistance and moisture resistance is used. An epoxy resin composition cured with a mold phenol resin is used. However, in recent years, the chip has been gradually increased in size with the increase in the degree of integration of integrated circuits, and the package has changed from a conventional DIP type to a small, thin flat package surface-mounted, SOP, TSOP, SOJ, QFP, TQFP, etc. Is coming. That is, a large chip is sealed in a small and thin package, and cracks are generated due to stress, and problems such as a decrease in moisture resistance due to the cracks have been greatly highlighted. In particular, there has been a problem in that abrupt exposure to a high temperature of 200 ° C. or more in a soldering process causes a crack in a package and a peeling of a resin and a chip to deteriorate moisture resistance.
Development of a highly reliable sealing resin composition suitable for sealing these large chips has been desired.

In order to solve these problems, addition of thermoplastic oligomers (Japanese Patent Laid-Open No. 62-15849) and addition of various silicone compounds (Japanese Patent Laid-Open No. 62-15849) have been proposed for the purpose of reducing thermal shock during soldering. No. 11585, 62-
116654, 62-128162) and silicone modification (Japanese Patent Application Laid-Open No. 62-136860). However, since the resin strength is reduced, heat stress in the soldering process is reduced. On the other hand, resin cracks usually occurred. On the other hand, in order to obtain an epoxy resin composition for semiconductor encapsulation having excellent heat stress resistance during soldering, that is, excellent solder heat resistance, a biphenyl-type epoxy resin is used as a resin system (Japanese Patent Laid-Open No. 64-65).
No. 116) has been studied, but by using a biphenyl type epoxy resin, the adhesion to the lead frame and low water absorption are improved, and the solder heat resistance is improved, especially the occurrence of cracks is reduced. However, the solder heat resistance was insufficient, and it was not possible to obtain a highly reliable epoxy resin composition for semiconductor encapsulation.

[0004]

SUMMARY OF THE INVENTION The present invention solves such a problem by using a phenol resin curing agent represented by the formula (1) as a phenol resin curing agent so that a semiconductor package at the time of mounting on a substrate is manufactured. It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation with significantly improved soldering stress resistance.

[0005]

The present invention provides (A) an aromatic compound having two or more epoxy groups, and (B) a phenolic resin curing agent represented by the formula (1) based on the total amount of the phenolic resin curing agent. Phenolic resin curing agent containing 30 to 100% by weight,

[0006]

Embedded image (L and m are integers of 1 or more, n is 0 or an integer of 1 or more,
l + m + n = 1 to 20, l + m divided by l + m + n
30% by weight or more, and the ratio of l to l + m + n is 7
Less than 0% by weight, R is the same or different atom or group selected from hydrogen, halogen, and alkyl group)

[0007] An epoxy resin composition for semiconductor encapsulation comprising (C) an inorganic filler and (D) a curing accelerator. Compared with the conventional epoxy resin composition, the epoxy resin composition has excellent reliability such as solder heat resistance and after solder treatment. It has the moisture resistance.

The aromatic compound having two or more epoxy groups used in the present invention includes, for example, a biphenyl type epoxy compound, a bisphenol type epoxy compound, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, and a triphenol methane type epoxy compound. And alkyl-modified triphenol methane type epoxy compounds. Particularly, when the amount of the inorganic filler as the epoxy resin composition is set to 80 to 90% by weight, 3, 3 ',
It is more preferable to use a relatively low molecular weight compound such as 5,5'-tetramethylbiphenyldiglycidyl ether and bisphenol type epoxy compound in terms of setting the melt viscosity.

The phenolic resin curing agent represented by the molecular structure of the formula (1) is obtained by polymerizing ortho-xylene and / or meta-xylene, ortho-xylene and / or meta-xylene and para-alkylene with a phenol by a Friedel-Crafts reaction. It is a resin curing agent obtained by this method, and has a lower elastic modulus at high humidity in a rubber region than a conventional phenol novolak resin, low moisture absorption, and excellent adhesion to a lead frame and a semiconductor element. Further, by using a phenolic resin curing agent of the formula (1) instead of the paraxylylene-modified phenolic resin curing agent represented by the formula (2) which is recently used as having excellent solder heat resistance,

[0010]

Embedded image

As the epoxy resin composition, an epoxy resin composition having high strength in a rubber region at a high temperature and excellent in solder heat resistance can be obtained. By adjusting the amount of the phenol resin curing agent represented by the formula (1), the solder heat resistance can be maximized by adjusting the amount. In order to obtain the effect of solder heat resistance, the phenol resin curing agent represented by the formula (1) should be used in an amount of 30 times the total phenol resin curing agent amount.
It is desirable to use at least 50% by weight, preferably at least 50% by weight. If the amount is less than 30% by weight, low water absorption and adhesion cannot be sufficiently obtained, and solder heat resistance is insufficient. Equation (1)
In the structural formulas, l and m are integers of 1 or more, n is 0 or an integer of 1 or more, and satisfy l + m + n = 1 to 20.
The ratio of l + m to l + m + n is preferably a modification ratio of 30% by weight or more in order to obtain the effect of solder heat resistance.
The characteristic of the l part is that the elastic modulus at high temperature is low and the soldering heat resistance is excellent as compared with the m part, but as a disadvantage, the curability is slightly inferior and the moldability tends to be reduced. Therefore, l + l +
The ratio to m + n is preferably less than 70% by weight.
On the other hand, when l + m + n exceeds 20, the fluidity is reduced and the moldability is deteriorated. Further, R in the structural formula of the formula (1) is preferably a large substituent from the viewpoint of water repellency, but is preferably a hydrogen atom because it inhibits the reactivity of the phenolic hydroxyl group.
When a phenol resin curing agent other than the phenol resin curing agent represented by the formula (1) is used in combination, it refers to all monomers, oligomers and polymers having a phenolic hydroxyl group. For example, a phenol novolak resin, a cresol novolak resin and the like can be mentioned.

The inorganic filler used in the present invention includes fused silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, silica powder obtained by pulverizing secondary aggregated silica powder or porous silica powder, alumina and the like. And fused silica powder is preferred from the viewpoints of thermal expansion coefficient, water resistance, impurities and the like. The amount of the inorganic filler is preferably from 70 to 95% by weight based on the total resin composition in view of solder heat resistance and fluidity. If it is less than 70% by weight, the water absorption increases and the solder heat resistance deteriorates. On the other hand, if it exceeds 95% by weight, the fluidity decreases and the moldability deteriorates. The curing accelerator used in the present invention may be any one that promotes the reaction between an epoxy group and a phenolic hydroxyl group, and those generally used as a sealing material can be widely used. -Diazabicycloundecene, triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like, and these may be used alone or as a mixture.

The epoxy resin composition for encapsulation of the present invention comprises an epoxy resin, a phenolic resin curing agent, an inorganic filler and a curing accelerator as essential components. Various additions such as flame retardants such as epoxy resin, antimony trioxide and hexabromobenzene, coloring agents such as carbon black and red iron oxide, release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber There is no problem if an agent is appropriately compounded. In addition, in order to manufacture the epoxy resin composition for sealing of the present invention as a molding material, epoxy resin, phenol resin curing agent, inorganic filler, curing accelerator, and other additives are sufficiently and uniformly mixed by a mixer or the like. Thereafter, the mixture is further melt-kneaded with a hot roll or a kneader, cooled, and pulverized to obtain a molding material. These molding materials can be applied to sealing, coating, insulating and the like of electronic parts or electric parts.

Hereinafter, the present invention will be described specifically with reference to Examples. Example 1 An aromatic compound represented by the formula (3) (3,3 ', 5,5'
-Tetramethylbiphenyldiglycidyl ether) (melting point: 102 ° C, epoxy equivalent: 192 g / eq) 8.0 parts by weight

[0015]

Embedded image

A phenol resin curing agent represented by the formula (4) (softening point 70 ° C., hydroxyl equivalent 170)
2.2 parts by weight

[0017]

Embedded image (Mixture of l = 1, m = 1, n = 3)

A phenol resin curing agent represented by the formula (2) (softening point: 65 ° C., hydroxyl equivalent: 170) (weight of n = 1 is 0.6, n = 1 is 0.6, and n = 2 is 0.3) 4.8 parts by weight Fused silica powder (average particle size: 14 μm) 84.0 parts by weight Triphenylphosphine 0.2 part by weight Carnauba wax 0.5 part by weight Carbon black 0.3 part by weight at room temperature with a mixer The mixture was mixed, kneaded with a biaxial roll at 70 to 100 ° C., cooled and pulverized to obtain a molding material, which was tabletted to obtain an epoxy resin composition for semiconductor encapsulation. Using a low-pressure transfer forming machine (forming conditions: 175 ° C., 70 kg / cm ² , 120 seconds), this composition was molded into 52pQFP having a chip size of 6 × 6 mm,
The obtained molded article was post-cured at 175 ° C. for 8 hours and evaluated. Table 1 shows the evaluation results. Solder cracking test: Molded product (chip size 6 × 6m
m, 52pQFP) under an environment of 85 ° C. and 85% RH.
The treatment was carried out for 4, 48, 72 and 120 hours, then immersed in a solder bath at 260 ° C. for 10 seconds, and external cracks were observed with a microscope. Solder moisture resistance test: Molded product (chip size 6 × 6 mm, 5
2pQFP) is treated in an environment of 85 ° C. and 85% RH for 72 hours, then immersed in a solder bath at 260 ° C. for 10 seconds, and then subjected to a pressure cooker test (125 ° C., 100% RH) to measure the open defect of the circuit. did.

Examples 2 to 5 and Comparative Examples 1 to 3 According to the formulations shown in Table 1, a resin composition was obtained in the same manner as in Example 1.
Evaluation was performed in the same manner as in Example 1 .

Phenolic resin curing agent of formula (5) (softening point 65 ° C., hydroxyl equivalent 170)

Embedded image (Mixture of l = 1, m = 1)

[0021]

[Table 1]

[0022]

According to the present invention, the resistance to cracks when subjected to thermal stress due to a rapid temperature change in the soldering process is very excellent, and the reliability of the surface mounting package is improved, so that the industrial value is enormous. It is.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 59/24 C08G 59/62 C08L 63/02 H01L 23/29

Claims (3)

(57) [Claims] (A) an aromatic compound having two or more epoxy groups, and (B) a phenolic resin curing agent represented by the formula (1) in an amount of 30 to 100 with respect to the total amount of the phenolic resin curing agent.
Phenol resin curing agent containing 1% by weight (L and m are integers of 1 or more, n is 0 or an integer of 1 or more,
l + m + n = 1 to 20, l + m divided by l + m + n
30% by weight or more, and the ratio of l to l + m + n is 7
Less than 0% by weight, R is the same or different atom or group selected from hydrogen, halogen and alkyl group) (C) an epoxy resin for semiconductor encapsulation comprising an inorganic filler and (D) a curing accelerator Composition. 2. The method according to claim 1, wherein the aromatic compound is 3,3 ′, 5,5′-
The epoxy resin composition for semiconductor encapsulation according to claim 1, which is tetramethylbiphenyldiglycidyl ether. 3. The method according to claim 1, wherein R in the formula (1) is hydrogen.
Or the epoxy resin composition for semiconductor encapsulation according to claim 2.