JP2991846B2 - Epoxy 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 which has excellent soldering heat resistance during surface mounting of a highly integrated IC device.

[0002]

2. Description of the Related Art Most highly integrated IC devices are sealed by a resin sealing method using an epoxy resin sealing material which is excellent in reliability, cost and mass productivity. As an epoxy resin sealing material, a resin composition composed of an orthocresol novolak epoxy resin and a novolak type phenol resin having excellent heat resistance, moisture resistance, and moldability is used. However, with the recent high integration and multifunctionality,
Highly integrated IC packages tend to have smaller and thinner packages due to larger elements and more streamlined mounting, and are smaller and thinner than conventional DIP types in SOJ, SOP, and QF.
There is a rapid shift to P, TSOP type surface mount packages.

This means that the package itself is exposed to a high temperature of 215 to 260 ° C. at the time of soldering, unlike the conventional DIP type, and the surface mount type package in which a large chip is sealed in a small and thin package has a large stress. This causes cracking of the package resin and separation of the chip interface, which is a fatal problem for the reliability of the IC package. A highly reliable encapsulating resin composition suitable for encapsulating these surface mount packages is 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. No. 115850, 62
Japanese Patent Application Laid-Open No. 62-128162) and silicone modification (Japanese Patent Application Laid-Open No. 62-136860), all of which have cracks in the package during soldering and have excellent reliability. It was not possible to obtain an epoxy resin composition for semiconductor encapsulation.

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 stress resistance, a biphenyl type epoxy resin is used as a resin system (Japanese Patent Application Laid-Open No. 64-65116). Publication) has been studied, but the use of a biphenyl type epoxy resin improves the adhesion to the lead frame and low water absorption, and improves the solder stress resistance, and in particular, reduces the occurrence of cracks.
Since the heat resistance is inferior, the solder stress resistance is insufficient particularly at a high temperature such as 250 ° C. or higher.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation which has excellent solder heat resistance during soldering without deteriorating formability and reliability.

[0007]

The epoxy resin composition of the present invention comprises (A) a cocondensed novolak epoxy resin of orthocresol and β-naphthol represented by the following formula (1): Epoxy resin containing

[0008]

Embedded image (N = 1-6)

(B) The trifunctional phenol resin curing agent represented by the following formula (2) is added to the total phenol resin curing agent in an amount of 3
Phenolic resin curing agent containing 0-100% by weight

[0010]

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(Wherein R _{1 to} R ₁₁ are the same or different atoms or groups selected from hydrogen, halogen, and alkyl groups), (C) an inorganic filler, and (D) a curing accelerator. Epoxy resin composition for semiconductor encapsulation,
It has very good solder heat resistance as compared with the conventional epoxy resin composition.

The co-condensed novolak epoxy resin of ortho-cresol and β-naphthol represented by the formula (1) used in the present invention is an epoxidized product of a novolak resin obtained by co-condensing ortho-cresol and β-naphthol with formaldehyde. The amount of β-naphthol during the condensation is desirably 50% by weight or more. The epoxy resin of the formula (1) has the features of being excellent in low water absorption, having a small coefficient of linear expansion of the resin, and being excellent in releasability at the time of molding, and showing good results in solder heat resistance at the time of soldering. . By adjusting the amount of the ortho-cresol and β-naphthol co-condensed novolak epoxy resin, solder heat resistance can be maximized by adjusting the amount. In the formula, when n is 1 to 6 and exceeds 6, the fluidity at the time of molding decreases.

In order to obtain the effect of solder heat resistance, it is desirable to use ortho-cresol and β-naphthol cocondensed novolak epoxy resin in an amount of 30% by weight or more, preferably 60% by weight or more of the total epoxy resin amount. If it is less than 30% by weight, low water absorption and low coefficient of linear expansion cannot be sufficiently obtained, and solder heat resistance is insufficient.

When an epoxy resin other than ortho-cresol and β-naphthol co-condensed novolak epoxy resin is used in combination, the epoxy resin used generally refers to any polymer having an epoxy group. For example, trifunctional epoxy resins such as bisphenol type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, phenol novolak type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, and epoxy containing triazine nucleus. Refers to resin and the like.

The trifunctional phenol resin curing agent having the structure represented by the formula (2) is a phenol resin curing agent having three hydroxyl groups in one molecule. The feature is that the crosslink density of the reaction cured product with the epoxy resin is improved, and the heat resistance, that is, the glass transition temperature is improved. Therefore, it is suitable for resistance to solder stress during soldering for recent surface mounting.

By adjusting the amount of the trifunctional phenol resin curing agent used, the solder stress resistance can be maximized. In order to obtain the effect of resistance to soldering stress, the trifunctional phenolic resin curing agent represented by the formula (2) is used in an amount of 30% by weight or more based on the total amount of the phenolic resin curing agent.
Preferably, 70% by weight or more is used. If it is less than 30% by weight, the crosslinking density, that is, the heat resistance does not increase, and the solder stress resistance is insufficient. Further, R ₁ , R ₂ , R
_{4 ~R 7, R 10, R} 11 is a hydrogen _{atom, R 3, R 8, R} 9 is preferably a methyl group. Further, with a phenolic resin curing agent having two or less functions, the crosslinking density does not increase, and the heat resistance is poor, and the solder stress resistance tends to decrease.

When another phenolic resin curing agent is used in addition to the trifunctional phenolic resin curing agent represented by the formula (2), the phenolic resin curing agent used generally refers to any polymer having a phenolic hydroxyl group. For example, a phenol novolak resin, a cresol novolak resin, a dicyclopentadiene-modified phenol resin, a co-condensate of a dicyclopentadiene-modified phenol resin with phenol novolak and a cresol novolak resin, a para-xylene-modified phenol resin, and the like can be used.

The inorganic filler used in the present invention includes fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, secondary aggregated silica powder or silica obtained by pulverizing porous silica powder. Powder, alumina and the like, and a fused silica powder is particularly preferable. The amount of the inorganic filler is 70 to 90% by weight in the total resin composition in consideration of the balance between solder stress resistance and moldability.
Is preferred.

The curing accelerator used in the present invention may be any one which promotes the reaction between the epoxy resin and the phenolic hydroxyl group, and those generally used as sealing materials can be widely used. For example, organic phosphine compounds such as triphenylphosphine (TPP), tributylphosphine and tri (4-methylphenyl) phosphine, tributylamine, triethylamine, dimethylbenzylamine (BDMA), trisdimethylaminomethylphenol, and diazabicycloundecene (DBU) ) And imidazole compounds such as 2-methylimidazole, 2-phenylimidazole and 2-ethyl-4-methylimidazole. These can be used alone or 2
It is used by mixing more than one kind.

The epoxy resin composition for encapsulation of the present invention comprises an epoxy resin, a curing agent, an inorganic filler and a curing accelerator as essential components. In addition to this, a silane coupling agent and a brominated epoxy resin may be used if necessary. And various additives such as flame retardants such as 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 it is appropriately blended.

In order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent,
After a curing accelerator, a filler, and other additives are sufficiently and uniformly mixed by a mixer or the like, the mixture is further melt-kneaded by 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.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Example 1 Composition below Orthocresol and β-naphthol co-condensed novolak epoxy resin (n is a mixture of 1 to 6, epoxy equivalent 225, softening point 84 ° C) 15 parts by weight Phenolic resin curing agent represented by the following formula (3) (OH equivalent: 145, softening point: 220 ° C) 9 parts by weight

[0023]

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75 parts by weight of fused silica powder 0.2 parts by weight of triphenylphosphine 0.3 parts by weight of carbon black 0.5 parts by weight of carnauba wax are mixed at room temperature with a mixer, and kneaded at 70-100 ° C. with a biaxial roll. After cooling, a molding material was obtained. The obtained molding material is tableted, and a low pressure transfer molding machine is used to enclose a 6 × 6 mm chip in a 52p package for a solder crack test at 175 ° C., 70 kg / cm ² for 120 seconds, and for a solder moisture resistance test. A 3 × 6 mm chip was sealed in a 16pSOP package. The sealed test element was subjected to the following solder crack test and solder moisture resistance test. Table 1 shows the test results.

Solder crack test: The sealed test element was subjected to 48 hours and 72 hours under an environment of 85 ° C. and 85% RH.
After the treatment, it was immersed in a solder bath at 260 ° C. for 10 seconds, and external cracks were observed with a microscope. Solder moisture resistance test: Sealed test element at 85 ° C, 85
% RH environment and then immersed in a solder bath at 260 ° C. for 10 seconds, followed by a pressure cooker test (12
5 ° C., 100% RH), and the open failure of the circuit was measured.

Examples 2 to 5 Compounded according to Table 1 and obtained molding materials in the same manner as in Example 1. A sealed molded product for a test was obtained from this molding material, and a solder crack test was performed using this molded product in the same manner as in Example 1. Table 1 shows the test results.

Comparative Examples 1 to 4 Compounded according to Table 1, and a molding material was obtained in the same manner as in Example 1. Using this molded product, a solder crack test was performed in the same manner as in Example 1. Table 1 shows the results.

[0028]

[Table 1]

[0029]

According to the present invention, an epoxy resin having heat resistance and low water absorption, which could not be obtained by the prior art, can be obtained. Therefore, solder is used as a sealing material for a surface-mounted highly integrated IC package. When used for encapsulation, coating, insulation, etc. of electronic and electrical components, it has a particularly high integration
Suitable for surface mount package for C.

Claims (1)

(57) [Claims] (A) An epoxy resin containing 30 to 100% by weight of a co-condensed novolak epoxy resin of ortho-cresol and β-naphthol represented by the following formula (1), based on the total epoxy resin amount: (N = 1-6) (B) A phenol resin curing agent containing a trifunctional phenol resin curing agent represented by the following formula (2) in an amount of 30 to 100% by weight based on the total amount of the phenol resin curing agent. (Wherein R _{1 to} R ₁₁ are the same or different atoms or groups selected from hydrogen, halogen, and alkyl group), (C) an inorganic filler, and (D) a curing accelerator. Epoxy resin composition for use.