JPH03195721A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition having excellent thermal stress resistance applied to IC package in soldering, cracking resistance and water-vapor resistance comprising a specific epoxy resin, a specific curing agent of phenol resin, an inorganic filler and a curing promoter as essential components. CONSTITUTION:The objective composition comprising (A) an epoxy resin containing 30-100wt.%, preferably >=60wt.% based on total amounts of epoxy resins of a biphenyl type epoxy resin shown by formula I (R1 to R6 are H, halogen or alkyl); (B) a curing agent of phenol resin, containing 50-100%, preferably >=70% based on total amounts of curing agents of phenol resin of a trihydric curing agent of phenol resin shown by formula II (R1 to R11 are H, halogen or alkyl), (C) an inorganic filler (preferably fused silica powder) and (D) a curing promoter (e.g. diazabicycloundecene) as essential components.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the I/O during soldering in recent surface mounting.
The present invention relates to an epoxy resin composition for semiconductor encapsulation that has excellent resistance to heat stress applied to C packages.

[Conventional technology]

Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with thermosetting resins, but especially for integrated circuits, 0-talesol novolac epoxy resin, which has excellent heat resistance and moisture resistance, is used as a novolac type phenolic resin. A hardened epoxy resin is used.

However, in recent years, as integrated circuits have become more highly integrated, chips have become larger and larger, and packages have changed from the conventional DIP type to surface-mounted small, thin flat packages.
It is changing to SOP, SOJ, and PLCC.

That is, by enclosing a large chip in a small and thin package, problems such as the occurrence of cracks due to stress and a decrease in moisture resistance due to these cracks have been brought into focus.

Problems have arisen, such as the package cracking and the resin peeling off from the chip, resulting in deterioration of moisture resistance due to the sudden high temperature of over 200°C during the soldering process.

ing.

In order to solve these problems, soldering requires the addition of thermoplastic oligomers (Japanese Patent Laid-Open No. 62/1999) to alleviate the thermal shock caused by soldering.
-115849) and addition of various silicone compounds (JP-A-62-11585, 62-116654)
62-128162) and silicone modification (Japanese Unexamined Patent Publication No. 62-136860), but in both cases, soldering sometimes causes cracks in the package and does not have good reliability. However, it has not been 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 that has excellent resistance to heat stress during soldering, that is, resistance to soldering stress, biphenyl-type epoxy resin is used as the resin system (
The use of biphenyl-type epoxy resin improves adhesion with the lead frame and low water absorption, improves solder stress resistance, and particularly reduces crack generation. However, since the heat resistance is poor, the solder stress resistance is insufficient especially at high temperatures such as 250° C. or higher.

[Problem to be solved by the invention]

The present invention solves these problems by using a biphenyl-type epoxy resin as the epoxy resin, and in order to further improve heat resistance, using a trifunctional phenolic resin curing agent as the phenolic resin curing agent, which reduces soldering time. An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation that has extremely excellent heat stress resistance.

[Means to solve the problem]

The epoxy resin composition of the present invention is a biphenyl-type epoxy resin RI RsRy Rs having a structure represented by the following formula [I] as an epoxy resin (R and -Ra in the formula are selected from hydrogen, halogen, and an alkyl group). The trifunctional phenolic resin curing agent υn (RI- in the formula Ra+ is the same or different atom or group selected from hydrogen, halogen, alkyl group) from 50 to 100% by weight based on the total amount of phenolic resin curing agent.
It is characterized by comprising a phenolic resin curing agent, an inorganic filler, and a curing accelerator, and has extremely superior solder stress resistance compared to conventional epoxy resin compositions.

[For production]

The biphenyl type epoxy resin represented by the structure of formula (r) is a bifunctional epoxy resin having two epoxy groups in one molecule. Its characteristics include low melt viscosity and excellent fluidity during transfer molding. It also has features such as excellent adhesion to lead frames and low water absorption. In particular, it shows good results in solder stress resistance due to adhesion with lead frames and low water absorption. By setting the amount of biphenyl type epoxy resin to 311, the solder stress resistance can be maximized.

In order to obtain the effect of solder stress resistance, it is desirable to use the biphenyl type epoxy resin represented by formula [I] in an amount of 30% by weight or more, preferably 60% by weight or more of the total amount of epoxy resin. If it is less than 30% by weight, the adhesion to the lead frame and low water absorption will not be improved and the solder stress resistance will be insufficient. Furthermore, R5-R4 in the formula is preferably a methyl group, and R3-R are preferably hydrogen atoms.

When other epoxy resins are used in combination with the biphenyl-type epoxy resin represented by formula ('I), the epoxy resins used refer to all polymers having epoxy groups.

For example, bisphenyl type epoxy resin, Talesol novolac type epoxy resin, phenol novolac type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, etc.
Refers to functional epoxy resins, triazine core-containing epoxy resins, etc.

The trifunctional phenolic resin curing agent having the structure represented by formula (I[) is a phenolic resin curing agent having three hydroxyl groups in one molecule. Its characteristics are that the cured product with epoxy resin improves crosslinking density and heat resistance, that is, glass transition temperature. Therefore, soldering for recent surface mounting is suitable for resistance to solder stress over time.

By adjusting the amount of the trifunctional phenolic resin curing agent used, the solder stress resistance can be maximized. In order to achieve the effect of solder stress resistance, the trifunctional phenolic resin curing agent represented by formula (II) should be used in an amount of 50% by weight or more, preferably 7% by weight of the total amount of phenolic resin curing agent.
It is desirable to use 0% by weight or more. 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. Furthermore, Rt , Rt , R4 to R1 in the formula
, R1° and R8 are preferably hydrogen atoms, and 83% R@ and R9 are preferably methyl groups. In addition, a phenolic resin curing agent having less than two functional groups does not increase the crosslinking density, and tends to have poor heat resistance and low solder stress resistance.

When using other phenolic resin curing agents in addition to the trifunctional phenolic resin curing agent represented by formula (II), the phenolic resin curing agent used refers to any polymer having a phenolic hydroxyl group, such as phenol novolak resin, cresol novolac, etc. Resins, dicyclopentadiene-modified phenolic resins, copolymers of dicyclopentadiene-modified phenolic resins with phenol novolak and cresol novolak resins, varaxylene-modified phenolic resins, and the like can be used.

Inorganic fillers used in the present invention include fused silica powder,
Examples include spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, porous silica powder, silica powder obtained by pulverizing secondary agglomerated silica powder or porous silica powder, alumina, etc., and fused silica powder is particularly preferred.

The curing accelerator used in the present invention may be one that promotes the reaction between the epoxy group and the phenolic hydroxyl group, and a wide variety of those commonly used in sealing materials can be used, such as diaza. Bicycloundesene (DBU),
Triphenylphosphine (TPP), dimethylbenzylamine (BDMA) and 2methylimidazole (2MZ)
etc. may be used alone or in combination of two or more.

The epoxy resin composition for sealing of the present invention contains an epoxy resin, a curing agent, an inorganic filler, and a curing accelerator as essential components,
In addition, if necessary, silane coupling agents, brominated epoxy resins, antimony dioxide, flame retardants such as hexabromobenzene, carbon blanks, coloring agents such as red iron, mold release agents such as natural wax and synthetic wax, and silicone oil. There is no problem in appropriately blending various additives such as low stress additives such as rubber and the like.

In addition, in order to produce the epoxy resin composition for sealing of the present invention as a molding material, an epoxy resin, a curing agent, a curing accelerator,
After the filler and other additives are thoroughly and uniformly mixed using a mixer or the like, the mixture can be further melt-kneaded using a hot roll or a niegoo, cooled, and then pulverized to obtain a molding material. These molding materials can be applied to sealing, covering, insulating, etc. electronic or electrical components.

Example 1 The following composition, biphenyl-type epoxy resin 16 represented by the formula (I[[]
Part by weight ffC H3 Orthocresol novolac epoxy resin 4 parts by weight Trifunctional phenolic resin represented by formula (IV) 8 parts by weight Phenol novolac resin Fused silica powder Triphenylphosphine carbon black Carnauba wax are mixed at room temperature with a mixer, 2 parts by weight 68.8 parts by weight 0.2 parts by weight 0.5 parts by weight 0.5 parts by weight The mixture was kneaded with twin-screw rolls at 70 to 100°C, cooled, and then pulverized to give a molding material.

The obtained molding material was made into tablets, and 52 6×6 country chips were molded for solder crank test using a low-pressure transfer molding machine at 175°C, 170 kg/d, and 120 seconds.
It is sealed in a P package, and also 3x for solder moisture resistance test.
A 611Iffl chip was sealed in a 16p SOP package.

The following solder crack test and solder moisture resistance test were conducted on the sealed test device.

Solder crack test: sealed test element at 85°C1
Treated for 48 hours and 72 hours in an environment of 85% RH,
Thereafter, the external crank was immersed in a solder bath at 250°C for 10 seconds, and then observed under a microscope. Solder moisture resistance test: The sealed test element was heated at 85°C and 85% RH for 72 hours.
R treatment, then immersed in a 250°C solder bath for 10 seconds, and then subjected to a pressure cooker test (125°C 1100%R).
H) was performed to measure open defects in the circuit.

The test results are shown in Table 1.

Examples 2 to 6 Molding materials were obtained in the same manner as in Example 1 by blending according to the formulations in Table 1. A sealed molded product for testing was obtained using this molding material, and a solder crank test and a solder moisture resistance test were conducted in the same manner as in Example 1 using this molded product. Test results first
Shown in the table.

Comparative Examples 1 to 6 Molding materials were obtained in the same manner as in Example 1 by blending according to the formulations in Table 1. A sealed molded product for testing was obtained using this molding material, and a solder crank test and a solder moisture resistance test were conducted in the same manner as in Example 1 using this molded product. The test results are shown in Table 1.

〔Effect of the invention〕

According to the present invention, it is possible to obtain an epoxy resin composition that has adhesion to lead frames, low water absorption, and heat resistance, which could not be obtained using conventional techniques. It has excellent crack resistance when subjected to stress, and also has good moisture resistance, so when used for sealing, covering, and insulating electronic and electrical components, it is especially suitable for use in surface mount packages. It is suitable for products that require high performance in highly integrated large chip ICs.

Claims (1)

[Claims] (1) (A) Biphenyl-type epoxy resin represented by the following formula [I] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [ I ] (R_1 to R_8 in the formula are selected from hydrogen, halogen, and alkyl groups) (same or different atoms or groups)
An epoxy resin containing 30 to 100% by weight based on the total amount of epoxy resin. (B) Trifunctional phenolic resin curing agent represented by the following formula [II] ▲ Numerical formula, chemical formula, table, etc. are available ▼ [II] (In the formula, R_1 to R_1_1 are the same selected from hydrogen, halogen, and alkyl group) or different atoms or groups) from 50 to 100% by weight based on the total amount of phenolic resin curing agent. (C) an inorganic filler, and (D) a curing accelerator. An epoxy resin composition for semiconductor encapsulation which has as an essential component.