JP2823633B2 - Epoxy resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application field] The present invention
The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent heat stress resistance to an IC package.

[Conventional technology]

Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. Especially for integrated circuits, 0-cresol novolak epoxy resin, which has excellent heat resistance and moisture resistance, is cured with a novolak type phenol resin. Epoxy resin is used.

However, in recent years, chips have become larger and larger as integrated circuits have become more highly integrated.
It is changing to SOP, SOJ, PLCC.

That is, by encapsulating a large chip in a small and thin package, problems such as generation of cracks due to stress and deterioration of moisture resistance due to these cracks have been greatly highlighted.

In particular, there has been a problem that when the temperature is rapidly increased to 200 ° C. or more in the soldering process, the moisture resistance is deteriorated due to cracking of the package and separation of the chip from the resin.

Development of a highly reliable sealing resin composition suitable for sealing these large chips has been desired.

In order to solve these problems, thermoplastic oligomers were added to alleviate the thermal shock during soldering (Japanese Patent Laid-Open No.
No. 1-115849), addition of various silicone compounds (Japanese Patent Application Laid-Open No. 62-11585, Japanese Patent Application Laid-Open No. 62-116654 and Japanese Patent Application Laid-Open No. 62-128162), and further, silicone modification (Japanese Patent Application Laid-Open No. 62-136860). However, in any case, cracks occurred in the package at the time of soldering, and it was not possible to obtain a highly reliable 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, use of a biphenyl type epoxy resin as a resin system (Japanese Patent Application Laid-Open No. 64-11616), etc. However, although the use of a biphenyl-type epoxy resin has improved the adhesion to the lead frame and the low water absorption, the solder stress resistance has been improved, and the occurrence of cracks has been particularly reduced. At a high temperature such as ℃ or more, the solder stress resistance is insufficient.

[Problems to be solved by the invention]

The present invention solves such a problem by using a biphenyl type epoxy resin as an epoxy resin and further using a trifunctional phenol resin curing agent as a phenol resin curing agent to further improve heat resistance. It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation having extremely excellent stress properties.

[Means for solving the problem]

The epoxy resin composition of the present invention is a biphenyl type epoxy resin having a structure represented by the following formula [I] as an epoxy resin. (R _{1 to} R ₈ in the formula are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups) An epoxy resin and a phenol resin curing agent containing 30 to 100% by weight based on the total epoxy resin amount Represented by the following formula [II]
Functional 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) and a phenol resin curing agent containing 50 to 100% by weight based on the total amount of the phenol resin curing agent. Characterized by consisting of an inorganic filler and a curing accelerator, compared to conventional epoxy resin compositions,
It has extremely excellent solder stress resistance.

(Operation)

The biphenyl type epoxy resin represented by the structure of the formula [I] is a bifunctional epoxy resin having two epoxy groups in one molecule. Features include low melt viscosity and excellent fluidity during transfer molding. It also has features such as excellent adhesion to a lead frame and low water absorption. In particular, the results show that the solder stress resistance is better than the adhesion to the lead frame and low water absorption. By adjusting the amount of the biphenyl-type epoxy resin used, soldering stress can be maximized. In order to obtain the effect of resistance to soldering stress, the biphenyl type epoxy resin represented by the formula [I] is required to be 30% by weight of the total epoxy resin amount.
It is desirable to use at least 60% by weight. If the content is less than 30% by weight, the adhesion to the lead frame and the low water absorption are not improved, and the solder stress resistance is insufficient. Furthermore,
R _{1 to} R ₄ are preferably a methyl group, and R _{5 to} R ₈ are preferably a hydrogen atom.

When another epoxy resin is used in addition to the biphenyl-type epoxy resin represented by the formula [I], the epoxy resin used generally refers to any polymer having an epoxy group.

For example, biphenyl type epoxy resin, cresol novolak type epoxy resin, phenol novolak type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, etc.
It refers to a functional epoxy resin, a triazine nucleus-containing epoxy resin and the like.

The trifunctional phenol resin curing agent having a structure represented by the formula [II] is a phenol resin curing agent having three hydroxyl groups in one molecule. The feature is that the cured product with the epoxy resin improves the crosslink density and the heat resistance, that is, the glass transition temperature. 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 exhibit the effect of resistance to soldering stress, it is desirable to use the trifunctional phenolic resin curing agent represented by the formula [II] in an amount of 50% by weight or more, preferably 70% by weight or more of the total amount of the phenolic resin curing agent. If it is less than 50% by weight, the crosslinking density, that is, the heat resistance does not increase, and the solder stress resistance is insufficient. Further, in the formula, R ₁ , R ₂ , R _{4 to} R ₇ , R ₁₀ and R ₁₁ are preferably elementary atoms, and R ₃ , R ₈ and R ₉ are preferably methyl groups. 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 [II], the phenolic resin curing agent used generally refers to any polymer having a phenolic hydroxyl group. For example, phenol novolak resins, cresol novolak resins, dicyclopentadiene-modified phenol resins, copolymers of dicyclopentadiene-modified phenol resins with phenol novolak and cresol novolak resins, and para-xylene-modified phenol resins can be used.

Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary aggregated silica powder, porous silica powder, silica powder obtained by grinding secondary aggregated silica powder or porous silica powder, alumina And the like, and a fused silica powder is particularly preferred.

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 for a sealing material can be widely used. Bicycloundecene (DBU),
Triphenylphosphine (TPP), dimethylbenzylamine (BDMA), 2-methylimidazole (2MZ), or the like is used alone or in combination of two or more.

The epoxy resin composition for sealing of the present invention is an epoxy resin,
A curing agent, an inorganic filler and a curing accelerator are essential components, but if necessary, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony trioxide, hexabromobenzene, carbon black, red iron oxide, etc. And various additives such as a release agent such as natural wax and synthetic wax, and a low stress additive such as silicone oil and rubber.

Further, in order to produce the epoxy resin composition for sealing of the present invention as a molding material, epoxy resin, a curing agent, a curing accelerator, a filler, and other additives are sufficiently uniformly mixed by a mixer or the like, Furthermore, it can be 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.

Example 1 The following composition, 16 parts by weight of a biphenyl type epoxy resin represented by the formula [III] Orthocresol novolak epoxy resin 4 parts by weight Trifunctional phenol resin represented by the formula [IV] 8 parts by weight Phenol novolak resin 2 parts by weight Fused silica powder 68.8 parts by weight Triphenylphosphine 0.2 parts by weight Carbon black 0.5 parts by weight Carnauba wax 0.5 parts by weight is mixed at room temperature with a mixer, kneaded at 70 to 100 ° C with a biaxial roll, and cooled. A post-crushed molding material was used.

The obtained molding material is tableted, and a low pressure transfer molding machine is used to seal a 6 × 6 mm chip in a 52p package for solder crack testing under the conditions of 175 ° C., 70 kg / cm ² , and 120 seconds. One 3 x 6 mm chip for testing
Sealed in a 6pSOP package.

The sealed test element was subjected to the following solder crack test and solder moisture resistance test.

Solder crack test: Sealed test element at 85 ° C, 85%
After 48 hours and 72 hours treatment in an RH environment, and then immersed in a 250 ° C. solder bath for 10 seconds, external cracks were observed with a microscope. Solder moisture resistance test: Sealed test element at 85 ° C
Treated for 72 hours in an environment of 85% RH, then placed in a 250 ° C solder bath
After immersion for 0 seconds, pressure cooker test (125 ° C, 100
% RH) and the open failure of the circuit was measured.

 The test results are shown in Table 1.

Examples 2 to 6 Compounded according to the formulation shown in Table 1 to obtain a molding material 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 and a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. The test results are shown in Table 1.

Comparative Examples 1 to 6 Compounded according to the formulation shown in Table 1 to obtain a molding material 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 and a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. Test results first
It is shown in the table.

[Effect of the Invention] According to the present invention, it is possible to obtain an epoxy resin composition having adhesion to a lead frame, low water absorption and heat resistance, which could not be obtained by the conventional technique, so that a rapid Excellent in crack resistance when subjected to thermal stress due to temperature change, and also excellent in moisture resistance, especially when used for sealing, covering, insulating, etc. of electronic and electric parts, especially surface mount package This is suitable for a product that requires very high reliability in a highly integrated large chip IC mounted on a device.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI H01L 23/31 (58) Investigated field (Int.Cl. ⁶ , DB name) C08G 59/22 C08G 59/62 C08L 63/02 H01L 23 / 29

Claims (1)

(57) [Claims] 1. A biphenyl type epoxy resin represented by the following formula [I]: An epoxy resin containing 30 to 100% by weight (R _{1 to} R ₈ in the formula are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups) based on the total epoxy resin amount. (B) trifunctional phenol resin curing agent represented by the following formula [II] A phenol resin curing agent containing (wherein R _{1 to} R ₁₁ are the same or different atoms or groups selected from hydrogen, halogen, and alkyl groups) in an amount of 50 to 100% by weight based on the total amount of the phenol resin curing agent. (C) an inorganic filler and (D) a curing accelerator. An epoxy resin composition for encapsulating a semiconductor, comprising as an essential component.