JPH06107772A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide the subject composition containing a specific epoxy resin, a curing agent, an inorganic filler and a cure accelerator as essential components and having excellent soldering stress resistance in the surface mounting of semiconductor devices. CONSTITUTION:The objective composition contains (A) 30-100wt.% (preferably 50-100wt.%) of an epoxy resin of formula I (R1 to R8 are H, halogen or alkyl) based on the total epoxy compound, (B) 30-100wt.% (preferably 50-100wt.%) of a naphthol resin curing agent of formula II ((n) is 0-3) based on the total curing agent, (C) preferably 70-90wt.% of an inorganic filler and (D) a cure accelerator such as diazabicycloundecene as essential components.

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 a thermosetting resin. Especially in integrated circuits, O-cresol novolac epoxy resin which is excellent in heat resistance and moisture resistance is used as a novolak. An epoxy resin cured with a type phenolic resin is used. However, in recent years, as the integration of integrated circuits has become higher, the size of the chip has gradually increased, and the package is a small and thin flat package surface-mounted from the conventional DIP type, SOP,
It has changed to SOJ and PLCC. That is, a large chip is enclosed in a small and thin package, and problems such as cracks caused by stress and deterioration of moisture resistance due to these cracks have been greatly highlighted. In particular, when exposed to a high temperature of 200 ° C. or more in the soldering process, moisture resistance is deteriorated due to cracking of the package and peeling of the resin and the chip. It has been desired to develop a highly reliable encapsulating resin composition suitable for encapsulating these large chips. In order to solve these problems, use of an epoxy resin represented by the following formula (1) as an epoxy resin (Japanese Patent Laid-Open No. 64-65116) has been studied.

[0003]

[Chemical 3]

By using the epoxy resin represented by the formula (1), it is possible to reduce the viscosity of the resin system. Therefore, by adding a larger amount of fused silica powder, the composition can have low thermal expansion and low water absorption after molding. The solder stress resistance was improved. However, an increase in elastic modulus due to the addition of a large amount of fused silica powder is one of the harmful effects, and further improvement in solder stress resistance is required.

[0005]

The present invention uses an epoxy resin represented by the formula (1) as an epoxy resin to solve the above problems and reduces the elastic modulus, water absorption amount, and thermal expansion coefficient of a molded product. In addition, the use of a naphthol resin curing agent represented by the formula (2) as a curing agent provides a semiconductor encapsulating epoxy resin composition in which the solder stress resistance of a semiconductor package during substrate mounting is significantly improved. is there.

[0006]

In the epoxy resin composition of the present invention, a biphenyl type epoxy resin having a structure represented by the following formula (1) is used as an epoxy resin in the total amount of epoxy resin.

[0007]

[Chemical 4]

On the other hand, an epoxy resin containing 30 to 100% by weight and a naphthol resin curing agent represented by the following formula (2) as a curing agent are used with respect to the total amount of the curing agent.

[0009]

[Chemical 5]

An epoxy resin composition for semiconductor encapsulation, which contains a curing agent, an inorganic filler and a curing accelerator, which are contained in an amount of 30 to 100% by weight, as essential components.

The biphenyl type epoxy resin represented by the structure of the formula (1) is a bifunctional epoxy resin having two epoxy groups in one molecule and has a lower melt viscosity than the conventional polyfunctional epoxy resin and is transfer molded. Excellent fluidity over time. Therefore, a large amount of fused silica powder of the composition can be blended, low thermal expansion and low water absorption can be achieved, and an epoxy resin composition having excellent solder stress resistance can be obtained.

By adjusting the amount of the biphenyl type epoxy resin used, the solder stress resistance can be maximized. In order to obtain the effect of resistance to soldering stress, the biphenyl type epoxy resin represented by the formula (1) is used in an amount of 30% by weight or more, preferably 50% by weight of the total epoxy resin amount.
It is desirable to use more than weight%. If it is less than 30% by weight, low thermal expansion and low water absorption cannot be obtained, and solder stress resistance is insufficient. Further, in the formula, R _{1 to} R ₄ are preferably methyl groups, and R _{5 to} R ₈ are preferably hydrogen atoms.

When another epoxy resin is used in combination with the biphenyl type epoxy resin represented by the formula (1), the epoxy resin to be used is a general polymer having an epoxy group. For example, bisphenol type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin and triphenol methane type epoxy resin, trifunctional epoxy resin such as alkyl modified triphenol methane type epoxy resin, triazine nucleus-containing epoxy resin, etc. Say.

By using the curing agent represented by the molecular structure of the formula (2), as compared with the conventional phenol novolac resin curing agent, the elastic modulus lowers near the soldering temperature and the adhesion to the lead frame and the semiconductor chip is improved. Since the force is improved and the naphthalene structure is introduced in the molecule, low thermal expansion and low water absorption can be obtained. Therefore, it is effective for reducing the generated stress against the thermal shock at the time of soldering and preventing the defective peeling from the semiconductor chip or the like due to it.

By adjusting the amount of the naphthol resin curing agent of the formula (2) used, solder stress resistance can be maximized. In order to bring out the effect of resistance to solder stress, it is desirable to use the naphthol resin curing agent represented by the formula (2) in an amount of 30% by weight or more, more preferably 50% by weight or more, based on the total amount of the curing agent. If the amount used is less than 30% by weight, low water absorption, low elasticity, etc. and insufficient adhesion to the lead frame and semiconductor chip, and improvement in solder stress resistance cannot be expected. Further, the value of n in the formula is preferably in the range of 1 to 6, and when the value of n exceeds 3, the fluidity at the time of transfer molding tends to decrease and the moldability tends to deteriorate. R _{1 to} R ₄ in the formula are preferably hydrogen atoms.

When a curing agent other than the naphthol resin curing agent represented by the formula (2) is used in combination, it generally means all polymers having a phenolic hydroxyl group.
For example, phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin,
A copolymer of a dicyclopentadiene-modified phenol resin and a phenol novolac or cresol novolac resin, a para-xylene-modified phenol resin, or the like can be used.

As the inorganic filler used in the present invention, fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, porous silica powder, secondary agglomerated silica powder or silica obtained by pulverizing porous silica powder is used. Examples thereof include powder and alumina, and fused silica powder, spherical silica powder, and a mixture of fused silica powder and spherical silica powder are particularly preferable. In addition, the compounding amount of the inorganic filler is 70 to 9 relative to the total amount of the composition in view of the balance between solder stress resistance and moldability.
0% by weight is preferred.

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 sealing materials can be widely used. Zabicyclo undecene (DBU),
Triphenylphosphine (TPP), dimethylbenzylamine (BDMA) and 2-methylimidazole (2M
Z) and the like are used alone or in combination of two or more.
The epoxy resin composition for sealing of the present invention has an epoxy resin, a curing agent, an inorganic filler and a curing accelerator as essential components,
In addition to these, silane coupling agents, brominated epoxy resins, flame retardants such as antimony trioxide and hexabromene, colorants such as carbon black and red iron oxide, mold release agents such as natural wax and synthetic wax, and silicones as required. Various additives such as low stress additives such as oil and rubber may be appropriately blended.

To produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent,
An inorganic filler, a curing accelerator, and other additives are sufficiently and uniformly mixed with a mixer or the like, and then melt-kneaded with a hot roll, a kneader, or the like, cooled, and then pulverized to obtain a molding material. These molding materials can be applied to sealing, coating, insulating, etc. of electronic parts or electric parts.

[0020]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 7.6 parts by weight of an epoxy resin represented by the following composition (3) (softening point 110 ° C., epoxy equivalent 190)

[0021]

[Chemical 6]

Orthocresol novolac epoxy resin (softening point 65 ° C., epoxy equivalent 200) 5.0 parts by weight Naphthol resin curing agent represented by the formula (4) (softening point 76 ° C., hydroxyl equivalent 120) 4.5 parts by weight

[0023]

[Chemical 7]

(Where n = 0 is 1, n = 1 is 0.2,
n = 2 is 0.1 and n = 3 is <0.1. ) Phenol novolac resin curing agent (softening point 90 ° C, hydroxyl equivalent 104) 2.9 parts by weight fused silica powder 78.8 parts by weight triphenylphosphine 0.2 parts by weight carbon black 0.5 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 × 6 mm chip is sealed in a 52p package for solder crack test under conditions of 175 ° C., 70 kg / cm ² and 120 seconds with a low-pressure transfer molding machine, and solder is also used. 3 x 6 for humidity resistance test
The mm chip was encapsulated in a 16p SOP package. The following solder crack test and solder moisture resistance test were performed on the sealed test element. Solder crack test: sealed test element at 85 ° C, 8
Treated in an environment of 5% RH for 48 hours and 72 hours, then 2
After immersing in a solder bath at 60 ° C. for 10 seconds, external cracks were observed with a microscope. Solder moisture resistance test: Sealed test element at 85 ° C for 8
It is treated for 72 hours in an environment of 5% RH and then immersed in a solder bath at 260 ° C for 10 seconds, and then a fresher cooker test (1
At 25 ° C. and 100% RH), open circuit failure was measured. The test results are shown in Table 1.

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

Comparative Examples 1 to 4 Compounding was carried out according to the formulation shown in Table 1 and molding materials were obtained in the same manner as in Examples. Using this molding material, a molded product sealed for testing was obtained, and a solder crack test and a solder moisture resistance test were carried out in the same manner as in Example 1 using this molded product. The test results are shown in Table 1.

[0027]

[Table 1]

[0028]

As described above, according to the present invention, an epoxy resin composition having a solder stress resistance which could not be obtained by the prior art can be obtained. Has very good crack resistance and good moisture resistance, so when used for encapsulation, coating, insulation, etc. of electronic and electrical parts, especially highly integrated large chip IC mounted in surface mount package It is suitable for products that require extremely high reliability.

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Claims (1)

[Claims] 1. An epoxy resin represented by the following formula (1): An epoxy resin containing 30 to 100% by weight with respect to the total amount of epoxy resin, (B) a naphthol resin curing agent represented by the following formula (2): An epoxy resin composition for semiconductor encapsulation, which comprises as an essential component a curing agent containing 30 to 100% by weight with respect to the total amount of curing agent, (C) an inorganic filler, and (D) a curing accelerator.