JP2954412B2 - 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 resistance to soldering stress and moisture during surface mounting of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, semiconductor devices such as integrated circuits, transistors and diodes are sealed with a thermosetting resin. In particular, in the case of integrated circuits, ortho-cresol novolak epoxy resin having excellent heat resistance and moisture resistance is made of a novolak type. An epoxy resin composition cured with a phenol resin is used.

However, in recent years, there has been a remarkable tendency to increase the size of chips and reduce the size and thickness of packages due to the high integration, multifunctionality, and rationalization of semiconductor devices. The ratio of SOJ, SOP, QFP, and the like, which are mountable packages, is increasing. A surface mount type package in which a large chip is enclosed in a small and thin package has a sudden
When exposed to a high temperature of 50 ° C. or more, a large stress is applied to the package, and a phenomenon such as cracking of the package or separation of the interface between the chip and the sealing resin occurs, which is a serious problem in the reliability of the semiconductor device. Therefore, development of a highly reliable sealing composition suitable for sealing these surface mount packages is urgent.

In order to solve these problems, addition of thermoplastic oligomers (Japanese Patent Application Laid-Open No. 62-15849) and addition of various silicone compounds (Japanese Patent Application Laid-Open No. 115850, 62-
Nos. 116654 and 62-128162) and silicone modification (Japanese Patent Application Laid-Open No. 62-136860). However, cracks occur in the package at the time of soldering, resulting in excellent reliability. 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 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 reduces the occurrence of cracks.
At the above high temperature, the solder stress resistance is still insufficient.

[0006]

An object of the present invention is to provide a resin composition for semiconductor encapsulation which is excellent in soldering stress resistance without deteriorating reliability against such a problem.

[0007]

The epoxy resin composition of the present invention comprises, as an epoxy resin (A), 1,6-bis (2,3-epoxypropoxy) naphthalene represented by the formula (1), Epoxy resin containing 30 to 100% by weight with respect to

[0008]

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(B) A phenolic resin curing agent containing a trifunctional phenolic resin curing agent represented by the formula (2) in an amount of 50 to 100% by weight based on the total amount of the phenolic resin curing agent.

[0010]

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(Wherein the value of n is 1 to 4 and R _{1 to} R ₇ are the same or different atoms or groups selected from hydrogen, halogen and lower alkyl group). (C) Inorganic filler and (D) It is a resin composition for semiconductor encapsulation containing a curing accelerator as an essential component and has extremely excellent solder stress resistance as compared with conventional epoxy resins.

The epoxy resin represented by the formula (1) used in the present invention is 1,6-bis (2,3-epoxypropoxy) naphthalene, which exhibits a semi-solid property at room temperature and a molding temperature (175 ° C.) In this case, the viscosity is very low, so that the amount of the filler added can be greatly increased. From this, in addition to the characteristics of the resin body that is excellent in low water absorption, the coefficient of linear expansion of the resin is small, and excellent in mold release property during molding, the resin composition highly filled with a filler has a water absorption rate and a linearity. It has the characteristic that the coefficient of expansion is smaller and the impact strength is excellent, and shows good results in the resistance to soldering stress during soldering. By adjusting the amount of the 1,6-bis (2,3-epoxypropoxy) naphthalene used, the solder stress resistance can be maximized.

In order to obtain the effect of solder stress resistance,
1,6-bis (2,3-epoxypropoxy) naphthalene is used in an amount of 30% by weight or more, preferably 60% by weight of the total epoxy resin.
It is desirable to use not less than weight%. If the content is less than 30% by weight, low water absorption and low coefficient of linear thermal expansion cannot be sufficiently obtained, and solder stress resistance is insufficient. When an epoxy resin other than 1,6-bis (2,3-epoxypropoxy) naphthalene is used in combination, the epoxy resin used refers to all polymers 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 triazine nucleus containing epoxy resin And so on.

The trifunctional phenolic resin curing agent having the structure represented by the formula (2) is a phenolic resin curing agent having three or more hydroxyl groups in one molecule, wherein the value of n is from 1 to 4, R ₁
To R ₇ are the same or different atoms or groups selected from hydrogen, halogen, and lower alkyl groups, and when n exceeds 4, the fluidity during molding is poor. The number of carbon atoms in the lower alkyl group is 1 to 4, and if it exceeds 4, the fluidity during molding is poor. Further, R ₁ , R ₃ , R _{5 to} R ₇ in the formula are a hydrogen atom, R ₂ , R
₄ is preferably a methyl group. The feature is that the crosslink density of the reaction cured product with the epoxy resin is improved, and the glass transition temperature is improved. Therefore, it is suitable for soldering stress during soldering for recent surface mounting.

By adjusting the amount of the trifunctional phenolic resin curing agent used, solder stress resistance can be maximized. In order to achieve the effect of resistance to soldering stress, it is desirable to use the trifunctional phenolic resin curing agent represented by the formula (2) 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 does not increase and the solder stress resistance is insufficient.

When other phenolic resin curing agents are 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, phenol novolak resins, cresol novolak resins, dicyclopentadiene-modified phenol resins, co-condensates of dicyclopentadiene-modified phenol resins with phenol novolak and cresol novolak resins, para-xylene-modified phenol resins, 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. Examples thereof include powder, alumina, and the like, and particularly preferred is a mixture with fused silica powder, spherical silica powder, and fused silica powder. The amount of the inorganic filler is desirably 70 to 90% by weight in the total resin composition in view of the balance between solder stress resistance and moldability.

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 for sealing materials can be widely used. For example, triphenylphosphine (TPP), tributylphosphine, tri (4-
Organic phosphine compounds such as methylphenyl) phosphine, tertiary amines such as tributylamine, triethylamine, benzyldimethylamine, trisdimethylaminomethylphenol, diazabicycloundecene (DBU), 2-methylimidazole, 2-phenylimidazole, Imidazole compounds such as -ethyl-4-methylimidazole. These can be used alone or in combination of two or more.

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 coloring agent such as carbon black, and carnauba wax are optionally used. , Release agents such as synthetic waxes, flame retardants such as brominated epoxy and antimony trioxide, coupling agents such as γ-glycidoxypropyl trimethoxysilane, silicone rubber, and low stress agents such as polybutadiene. Additives may be appropriately compounded.

In order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent,
A curing accelerator, a filler, and other additives can be sufficiently homogeneously mixed by a mixer or the like, then further melt-mixed 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.

[0021]

The present invention will be described in detail with reference to the following examples. The mixing ratio is by weight.

Example 1 1,6-bis (2,3-epoxypropoxy) naphthalene (epoxy equivalent 150 g / eq) 7.3 parts by weight orthocresol novolak epoxy resin (epoxy equivalent 200 g / eq, softening point 65 ° C.) 4 5.9 parts by weight Phenol resin curing agent represented by formula (3) (hydroxyl equivalent 109 g / eq, softening point 100 ° C.) 5.5 parts by weight

[0023]

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(R ₁ , R ₃ , R ₅ -R ₇ are hydrogen atoms, R
_2, R ₄ is a methyl group, a mixture the value of n represents 1-3, the ratio, n = 1, 2, 3 is 3: 2: 1. Phenol novolak resin curing agent (hydroxyl equivalent: 104 g / eq, softening point: 95 ° C) 2.3 parts by weight Fused silica powder 79.0 parts by weight Triphenylphosphine 0.2 parts by weight Carbon black 0.3 parts by weight Carnauba wax 0. 5 parts by weight were mixed at room temperature with a mixer, kneaded at 70 to 100 ° C. with a biaxial roll, cooled and pulverized to obtain a molding material. This composition was transferred to a low-pressure transfer molding machine (molding conditions: 17).
(5 ° C., 70 kg / cm ² , 120 seconds), and the obtained molded article was post-cured at 175 ° C. for 8 hours and evaluated. Table 1 shows the test results.

Evaluation method * 1 Spiral flow Using a mold for measuring spiral flow according to EMMI-I-66, 15 g of a sample was molded at a molding temperature of 175 ° C., a molding pressure of 70 kg / cm ² , and a molding time of 2 minutes. * 2 Solder stress test 52pQFP (chip size 36mm ² , package thickness 2.
05mm) After treating 20 pieces for 24 hours and 72 hours in an atmosphere of 85 ° C. and 85% RH, 1 piece was placed in a solder bath at 260 ° C.
It shows the number of molded articles immersed for 0 seconds and having cracks. * 3 Solder moisture resistance test 16pSOP (package size 7.2 × 11.5 × 1.95) mounted with A1 simulation device (chip size 3.0 × 3.5mm)
mm ^t ) at 85 ° C. in an atmosphere of 85% RH for 72 hours, then immersed in a solder bath at 260 ° C. for 10 seconds, and then subjected to a pressure cooker test (125 ° C., 100% RH) to open the circuit. The number was measured.

Examples 2 to 5 Compounded according to Table 1, and an epoxy resin composition was obtained in the same manner as in Example 1. The same test as in Example 1 was performed using this composition. Table 1 shows the results.

Comparative Examples 1-4 Compounded according to Table 1, an epoxy resin composition was obtained in the same manner as in Example 1. The same test as in Example 1 was performed using this composition. Table 1 shows the results.

[0028]

[Table 1]

[0029]

The epoxy resin composition for encapsulating a semiconductor according to the present invention is extremely excellent in solder stress resistance and moisture resistance, and thus is suitable as a resin composition for encapsulating a surface mount package.

Claims (1)

(57) [Claims] (1) 1,6-bis (2,3-epoxypropoxy) represented by the formula (1) as an epoxy resin:
An epoxy resin containing naphthalene in an amount of 30 to 100% by weight based on the total amount of the epoxy resin. (B) A phenolic resin curing agent containing a trifunctional phenolic resin curing agent represented by the formula (2) as a phenolic resin curing agent in an amount of 50 to 100% by weight based on the total amount of the phenolic resin curing agent. (Wherein the value of n is 1-4, R ₁ -R ₇ are hydrogen, halogen,
The same or different atoms or groups selected from lower alkyl groups) An epoxy resin composition for semiconductor encapsulation comprising (C) an inorganic filler and (D) a curing accelerator as essential components.