JPH05175373A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To improve the moldability, reliability, and the properties of solder resistance at the time of soldering by arranging a specific epoxy resin, a specific phenol resin setting agent, a fused silica, and a triphenylphosphine as essential ingredients. CONSTITUTION:A co-condensation novolak epoxy resin of orthocresol and beta-naphthol represented by the formula I is contained in 30 to 100weight% of the total amount of the epoxy resin. Also, a co-condensation phenol resin setting agent of paraxylene and beta-naphthol represented by the formula II is contained in 30 to 100weight% of the total amount of the phenol resin setting agent. These elements and an inorganic filler and a setting accelerating agent are arranged as essential ingredients. Thus, it is possible to obtain an epoxy resin composition for semiconductor sealing excellent in the properties of solder heat resistance at the time of soldering without deteriorating its formability and reliability.

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 is excellent in resistance to solder stress in surface mounting semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as diodes, transistors, and integrated circuits have been sealed with thermosetting resin. Especially in integrated circuits, orthocresol novolak epoxy resin, which has excellent heat resistance and moisture resistance, is used as a novolak type. An epoxy resin cured with a phenol resin is used. However, in recent years, as the integration of integrated circuits has become higher and higher, the size of the chip has gradually increased, and the package has changed from the conventional DIP type to a surface-mounted small and thin flat package, SO.
It is changing to P, SOJ, PLCC. In other words, a large chip is to be enclosed in a small and thin package, and cracks are generated due to stress, and problems such as deterioration of moisture resistance due to these cracks have been greatly highlighted. Especially in the soldering process,
The above-mentioned problems are caused by being exposed to a high temperature of ℃ or more. Development of a highly reliable encapsulating resin composition suitable for encapsulating these large chips has been desired.

In order to solve these problems, addition of a thermoplastic oligomer (Japanese Patent Laid-Open No. 62-15849) and various silicone compounds (Japanese Patent Laid-Open No. 62-15849) for the purpose of mitigating thermal shock during soldering. -11850 publication,
62-116654, 62-128162), and further silicone modification (JP-A-62-1368).
No. 60), but cracks occur in the package during soldering, and it has not been possible to obtain a highly reliable epoxy resin composition for sealing.

On the other hand, in order to obtain an epoxy resin composition for semiconductor encapsulation which is excellent in heat stress resistance during soldering, that is, solder stress resistance, use of a biphenyl type epoxy resin as a resin system (JP-A-64-65116). However, the use of biphenyl type epoxy resin improves the adhesion to the lead frame and the low water absorption, and improves the solder stress resistance, especially cracking is reduced, but In particular, at a high temperature of 250 ° C. or higher, the solder stress resistance is insufficient because of poor properties.

[0005]

SUMMARY OF THE INVENTION The present invention provides an epoxy resin composition for semiconductor encapsulation which is excellent in solder heat resistance during soldering without deteriorating moldability and reliability.

[0006]

The epoxy resin composition of the present invention comprises (A) a co-condensed novolac epoxy resin of orthocresol and β-naphthol represented by the following formula (1) in an amount of 30 to 30 with respect to the total amount of epoxy resin. Epoxy resin containing 100% by weight,

[0007]

[Chemical 3]

(B) A phenol resin curing agent containing a para-xylene and β-naphthol co-condensation 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,

[0009]

[Chemical 4]

An epoxy resin composition for semiconductor encapsulation, which comprises (C) an inorganic filler and (D) a curing accelerator as essential components,
It has extremely excellent solder heat resistance as compared with conventional epoxy resin compositions.

The co-condensed novolac epoxy resin of orthocresol and β-naphthol of the formula (1) used in the present invention is an epoxidized novolak resin obtained by co-condensing orthocresol and β-naphthol from formaldehyde, and the co-condensation thereof. At this time, the amount of β-naphthol is preferably 60% by weight or more, and the compound mainly has the structure of formula (1).
Here, n is 1 to 6, and if it exceeds 6, the fluidity at the time of molding becomes poor.

The resin of the formula (1) has excellent low water absorption, a small linear expansion coefficient of the resin, excellent releasability during molding, and good solder heat resistance during soldering. Orthocresol and β
-The amount of naphthol co-condensed novolak epoxy resin used can be adjusted to maximize solder heat resistance. In order to obtain the effect of soldering heat resistance, it is preferable to use the co-condensed novolac epoxy resin of orthocresol and β-naphthol in an amount of 30% by weight or more, preferably 60% by weight or more based on the total amount of epoxy resin. Thirty
If it is less than wt%, low water absorption and low linear expansion coefficient cannot be sufficiently obtained, and solder heat resistance is insufficient.

When an epoxy resin other than the co-condensed novolak epoxy resin of orthocresol and β-naphthol is used in combination, the epoxy resin used means all polymers having an epoxy group. For example, it means a bisphenol type epoxy resin, a cresol novolac type epoxy resin, a biphenyl type epoxy resin, a phenol novolac type epoxy resin, a triphenylmethane type epoxy resin, a triazine ring-containing epoxy resin and the like.

The para-xylene and β-naphthol co-condensation phenol resin curing agent having the structure represented by the formula (2) is characterized in that a cured product obtained by reaction with an epoxy resin has toughness and low water absorption. In particular, it has excellent toughness at high temperature during soldering, and has a remarkable effect on solder heat resistance during soldering at 250 to 260 ° C. Here, n in the formula (2) is 1 to
In case of 6, when it exceeds 6, the fluidity at the time of molding becomes poor.

To obtain the effect of solder heat resistance, the formula (2) is used.
It is desirable to use the para-xylene and β-naphthol co-condensed phenolic resin curing agent represented by the above formula in an amount of 30% by weight or more, preferably 60% by weight or more based on the total phenolic resin curing agent.
If it is less than 30% by weight, the toughness at the time of heating becomes insufficient and the solder heat resistance at the time of soldering cannot be sufficiently obtained. Further, when other one is used in combination with the para-xylene and the β-naphthol co-condensation phenol resin curing agent, it means the entire polymer having a phenolic hydroxyl group. For example, a phenol novolac resin, a cresol novolac resin, a co-condensation product of a dicyclopentadiene-modified phenol resin with a phenol novolac resin or a cresol novolac resin can be used.

Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, silica powder obtained by crushing porous silica powder, alumina, etc., and particularly fused silica. Powders, spherical silica powders and mixtures of fused silica powders and spherical silica powders are preferred. In addition, as the compounding amount of the inorganic filler,
From the standpoint of balance between solder stress resistance and moldability, it is desirable that the total resin composition contains 70 to 90 parts by weight.

Further, the curing accelerator used in the present invention may be any one as long as it accelerates the reaction between the epoxy group and the hydroxyl group, and those generally used for the sealing material can be widely used. For example, organic phosphine compounds such as triphenylphosphine (TPP), tributylphosphine, tri (4-methylphenyl) phosphine, tributylamine,
Tertiary amines such as triethylamine, benzyldimethylamine, trisdimethylaminomethylphenol, 1,8-diazabicyclo [5,4,0] -7-undecene (DBU), 2-methylimidazole, 2-phenylimidazole, 2-ethyl. Examples thereof include imidazole compounds such as 4-methylimidazole. These may be used alone or in combination of two or more.

In addition to the above, the composition of the present invention may optionally contain a coloring agent such as carbon black, a release agent such as carnauba wax and synthetic wax, a flame retardant such as brominated epoxy and antimony trioxide, and γ-. A coupling agent such as glycidoxypropyltrimethoxysilane and a rubber component such as silicone rubber and polybutadiene can be added.

The epoxy resin composition of the present invention is prepared by uniformly mixing an epoxy resin, a curing agent, an inorganic filler, a curing accelerator, and other additives with a mixer or the like, and then heating the mixture with a general kneading device such as a roll or an extruder. A molding material can be obtained by melt-kneading, cooling and pulverizing.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples. The mixing ratio is parts by weight.

Example 1 A co-condensed novolak epoxy resin of orthocresol and β-naphthol represented by the following formula (1) (a mixture of n = 1 of 1 and n = 2 of 0.3 by weight ratio, epoxy equivalent) 228, softening point 83 ° C) 4.5 parts by weight

[0022]

[Chemical 5]

Orthocresol novolac epoxy resin (epoxy equivalent 200, softening point 65 ° C.) 10.5 parts by weight Para-xylene and β-naphthol co-condensed phenol resin represented by the following formula (2) Curing agent (n = 1 by weight) 1 to 1, n = 2 is 1.4, n = 3 is 0.4, n = 4 is 0.1, hydroxyl equivalent is 231, softening point is 113 ° C.) 3.0 parts by weight

[0024]

[Chemical 6]

Phenol novolac resin (hydroxyl equivalent 105, softening point 95 ° C.) 6.0 parts by weight fused silica powder 75.0 parts by weight triphenylphosphine 0.2 parts by weight carbon black 0.3 parts by weight carnauba wax 0.5 parts by weight The parts were mixed at room temperature with a mixer, kneaded with a biaxial roll at 70 to 100 ° C., cooled and pulverized to obtain a molding material. The obtained molding material is made into a tablet, and a 6 x 6 mm chip is encapsulated in a 52p package for a solder crack test under conditions of 175 ° C, 70 kg / cm ² and 120 seconds on a low-pressure transfer molding machine, and also for a solder moisture resistance test. A 3 × 6 mm chip was encapsulated in a 16 pSOP package. The sealed test element was subjected to the following solder crack test and solder moisture resistance test.

Solder crack test: The sealed test element was subjected to an environment of 85 ° C. and 85% RH for 48 hours and 72 hours.
After processing, 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 ℃, 85%
It is treated for 72 hours in an environment of RH, then immersed in a solder bath at 260 ° C for 10 seconds, and then subjected to a pressure cooker test (12
The circuit was opened at 5 ° C. and 100% RH, and the open circuit failure was measured. The test results are shown in Table 1.

Examples 2 to 5 Compounding was carried out according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. A molded product in which a test element was sealed with this molding material was obtained, and a solder crack test and a solder moisture resistance test were conducted using this molded product in the same manner as in Example 1. The test results are shown in Table 1.

Comparative Examples 1 to 5 Compounding was carried out according to the formulation shown in Table 1, and a molding material was obtained in the same manner as in Example 1. A molded product in which a test element was sealed with this molding material was obtained, and a solder crack test and a solder moisture resistance test were conducted using this molded product in the same manner as in Example 1. The test results are shown in Table 1.

[0029]

[Table 1]

[0030]

As described above, according to the epoxy resin composition of the present invention, the moldability is not deteriorated and the solder stress resistance is improved as compared with the usual epoxy resin.
No cracks occur during soldering. Furthermore, since it has low water absorption, solder moisture resistance is also significantly improved. As is clear from these, the present composition is useful as a semiconductor encapsulating material excellent in moldability, reliability, and resistance to soldering stress during soldering.

Continuation of front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08G 59/62 NJU 8416-4J C08K 3/36 NKX 7167-4J C08L 63/00 NJW 8830-4J

Claims (1)

[Claims] 1. An epoxy resin comprising (A) an orthocresol and β-naphthol co-condensed novolac epoxy resin represented by the following formula (1) in an amount of 30 to 100% by weight based on the total amount of epoxy resin: (N = 1 to 6) (B) Phenolic resin curing containing a para-xylene and β-naphthol co-condensed phenolic 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 phenolic resin curing agent. Agent, (N = 1 to 6) An epoxy resin composition for semiconductor encapsulation, which comprises (C) an inorganic filler and (D) a curing accelerator as essential components.