JPH07179568A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain an epoxy resin composition containing respective specific epoxy resin, phenolic resin hardener and epoxy-modified silicone oil, having excellent soldering stress resistance and fluidity and suitable for the sealing of a semiconductor. CONSTITUTION:This composition contains (A) an epoxy resin containing 50-100wt.% of a biphenyl-type epoxy resin of formula I (R1 to R8 each is H, a halogen or an alkyl), (B) 70-93wt.% (based on the totai composition) of an inorganic filter (preferably fused silica powder), (C) a phenolic resin hardener containing 30-100wt.% of a flexible phenolic resin hardener of formula II (R is p-xylylene; (n) is 0-8), etc., (D) a cure accelerator (e.g. triphenyl phosphine) and (E) 0.1-3wt.% (based on the total composition) of an epoxy-modified silicone oil of formula III [R1 is group of formula IV or formula V; A is group of formula VI or formula VH (R is a 1-4C alkylene); the epoxy equivalent of the epoxy group of the group A is 140-500].

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 solder stress resistance and fluidity in surface mounting of 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, an O-cresol novolac type epoxy resin excellent in heat resistance and moisture resistance is used. An epoxy resin cured with a novolac type phenolic resin is used. However, in recent years, as the integration of integrated circuits has increased, 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, S.
It is changing to OJ and PLCC. In particular, in the soldering process, when exposed to a high temperature of 200 ° C. or more, the moisture resistance is deteriorated due to cracking of the package and peeling of the resin and the chip. In order to solve these problems, the epoxy resin represented by the formula (1) is used as the epoxy resin (JP-A-64-
No. 65116) has been studied. By using the epoxy resin represented by the formula (1), the viscosity of the resin system can be reduced. Therefore, by adding a larger amount of the inorganic filler, it is possible to reduce the thermal expansion and the moisture absorption after the composition is molded, and thus the solder resistance can be improved. The stress property was improved. However, as the filling amount of the inorganic filler was increased, the fluidity was sacrificed, and voids were easily generated in the package. However, silicone oil, which has been used for adjusting fluidity, can reduce voids in the package, but since solder resistance stress decreases, solderability stress and fluidity improvement cannot be achieved at the same time. .

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a resin composition having excellent crack resistance and fluidity when subjected to thermal stress due to a rapid temperature change in a soldering process. It is a thing.

[0004]

The epoxy resin composition of the present invention comprises (A) an epoxy resin represented by the following formula (1):

[0005]

[Chemical 6] (Wherein R _{1 to} R ₈ are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups)

An epoxy resin containing 50 to 100% by weight in the total amount of the epoxy resin, and 70 in the total amount of the resin composition (B).
To 93% by weight of inorganic filler, (C) flexible phenol resin curing agent represented by formula (2) and / or formula (3) having plural phenolic hydrogen groups in one molecule

[0007]

[Chemical 7] (R in the formula is paraxylylene, n = 0 to 8)

[0008]

[Chemical 8] (R in the formula is paraxylylene, dicyclopetadiene diphenol obtained by addition reaction of dicyclopetadiene and phenol, terpene diphenol obtained by addition reaction of terpenes and phenol, cyclopentadiene diphenol obtained by addition reaction of cyclopentadiene and phenol, and Cyclohexanone represents a residue of cyclohexanone diphenol obtained by addition-condensing phenol with two phenol moieties removed, and one of these is selected, and the value of n is 0 to
8)

30 to 1 in the total amount of curing agent for phenol resin
Phenolic resin curing agent containing 100% by weight, (D) curing accelerator and (E) epoxy-modified silicone oil of formula (4) and / or formula (5)

[0010]

[Chemical 9]

[0011]

[Chemical 10] (R in the formulas (4) and (5) is an alkylene group having 1 to 4 carbon atoms, 10 ≦ l + m + n + 2 ≦ 400, and the epoxy equivalent of the epoxy group represented by A is 140 to 500)

An epoxy resin composition for semiconductor encapsulation, comprising 0.1 to 3% by weight of the total composition,
It has extremely excellent solder stress resistance and fluidity as compared with conventional epoxy resin compositions.

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 an inorganic filler can be blended in the composition, a low thermal expansion and a low water absorption can be achieved, and an epoxy resin composition excellent in solder stress resistance can be obtained.
By adjusting the amount of the biphenyl type epoxy resin used, solder stress resistance can be maximized. To obtain the effect of solder stress resistance,
It is desirable to use the biphenyl type epoxy resin represented by the formula (1) in an amount of 50% by weight or more, preferably 70% by weight or more based on the total amount of the epoxy resin. If it is less than 50% by weight, low thermal expansion and low water absorption cannot be achieved, and the 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 refers to all polymers having an epoxy group. For example, it means a bisphenol type epoxy resin, a cresol novolac type epoxy resin, a phenol novolac type epoxy resin, a triphenol methane type epoxy resin, a triazine nucleus-containing epoxy resin and the like. These may be used alone or in combination.

Examples of the inorganic filler include fused silica powder, crystalline silica powder, alumina powder, hydrated alumina powder, silicon nitride powder, calcium carbonate powder and the like, and fused silica powder is particularly desirable. The compounding amount of the inorganic filler is 70-
A range of 93% by weight is preferred. If it is less than 70% by weight, the amount of moisture absorption increases, and the coefficient of thermal expansion is large, so that it cannot withstand thermal stress during mounting. On the other hand, if it exceeds 93% by weight, the flow characteristics deteriorate and it is not practical.

The phenol resin curing agent represented by the structures of the formulas (2) and (3) is a flexible phenol resin curing agent having a relatively flexible structure at the R portion in the molecular structure, and is a novolac type phenol. As compared with a resin curing agent or the like, it is possible to lower the elastic modulus in the vicinity of the soldering processing temperature and improve the adhesive force between the lead frame and the semiconductor chip. Therefore,
This is effective in reducing the stress generated at the time of solder impact and preventing the defective peeling from the semiconductor chip or the like. By adjusting the amount of the phenol resin curing agent used, solder stress resistance can be maximized. In order to obtain the effect of resistance to solder stress, the flexible phenol resin curing agent represented by the formula (2) and / or the formula (3) is added in an amount of 30% by weight based on the total amount of the phenol resin curing agent.
Above, it is desirable to use 50% by weight or more.
If the amount used is less than 30% by weight, the elasticity is low and the adhesion to the lead frame, semiconductor chip, etc. is insufficient, and improvement in solder stress resistance cannot be expected.

Further, R in the formula (2) is paraxylylene,
The value of n is 0-8. If n exceeds 8, the fluidity at the time of transfer molding tends to deteriorate, and the moldability tends to deteriorate. R in the formula (3) is paraxylylene, dicyclopetadiene diphenol obtained by addition reaction of phenol with dicyclopetadiene, terpene diphenol obtained by addition reaction of terpenes with phenol, cyclopentadiene obtained by addition reaction of cyclopentadiene with phenol. Represents residues of diphenol and cyclohexanone diphenol obtained by addition-condensing cyclohexanone with phenol, excluding two phenol moieties, and among these, terpene diphenol obtained by addition reaction of paraxylylene, terpenes and phenol, and dicyclopeta A residue obtained by removing two phenol moieties of dicyclopetadiene diphenol obtained by addition reaction of diene and phenol is preferable. The value of n is 0-8. n
When it exceeds 8, the fluidity at the time of transfer molding tends to deteriorate, and the moldability tends to deteriorate. When other compounds are used in combination with the flexible phenol resin curing agents represented by the formulas (2) and (3), those used are phenol novolac resin, cresol novolac resin, dicyclopentadiene modified phenol resin and phenol novolac. And / or a copolymer with a cresol novolac resin or the like can be used.

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 phenolic hydroxyl group, and those generally used for sealing materials can be widely used. , Tertiary amines such as benzyldimethylamine, imidazoles, organic phosphorus compounds such as 1.8-diazabicycloundecene and triphenylphosphine, and the like, and they may be used alone or in combination.

The silicone oil represented by the formulas (4) and (5) is an epoxy-modified silicone oil obtained by substituting a part of the methyl substituents of dimethylsiloxane with a substituent having an epoxy group. When compared with a silicone oil that does not have it, an epoxy resin composition having good fluidity can be obtained without reducing solder stress resistance because of its excellent affinity with a resin. By adjusting the amount of the epoxy-modified silicone oil used, the effects of improving solder stress resistance and fluidity can be maximized. As another advantage, this silicone oil has almost no effect on the spiral flow, which is one of the resin characteristics, when added, as compared with other silicone oils. In order to achieve both resistance to soldering stress and improvement of fluidity, it is preferable to use the epoxy-modified silicone oil represented by the formulas (4) and (5) in the range of 0.1 to 3% by weight in the total composition. desirable. If it is less than 0.1% by weight, the fluidity cannot be improved and external voids and the like tend to occur. On the contrary, if it exceeds 3% by weight, the fluidity is good, but the solder stress resistance deteriorates sharply. Further, the equivalent of the epoxy group represented by A in the formula is in the range of 140 to 500, and when the epoxy equivalent is less than 140, the heat resistance of the cured product decreases, and
If it exceeds, the solder stress resistance will be reduced. Also,
10 ≦ l + m + n + 2 ≦ 400, and if this is less than 10, the heat resistance of the cured product will decrease, and if it exceeds 400, the solder stress resistance will decrease.

In the epoxy resin composition of the present invention, if necessary, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony trioxide, hexabromobenzene, a coloring agent such as carbon black and red iron oxide, a natural wax,
A release agent such as a synthetic wax and an additive such as a low stress agent such as rubber may be appropriately mixed. To produce the encapsulating epoxy resin composition of the present invention as a molding material, the epoxy resin, the curing agent, the curing accelerator, the silicone oil, the inorganic filler, and other additives are sufficiently uniformly mixed by a mixer or the like. Further, it can be melt-kneaded with a hot roll, a kneader or the like, and cooled and pulverized to obtain a molding material. These molding materials are used to seal and cover electronic or electrical components,
Insulation etc. can be applied.

[0020]

The present invention will be described in detail with reference to the following examples. The mixing ratio is parts by weight. Example 1 The following composition 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether (softening point 107 ° C., epoxy equivalent 191 g / eq) 8.09 parts by weight The curing agent represented by the formula (2) (Mitsui Toatsu Chemical Co., Ltd., trade name Zyloc) (softening point 70 ° C., hydroxyl equivalent 174 g / eq) 1.97 parts by weight Curing agent represented by the formula (6) (softening point 130 ° C., hydroxyl equivalent 174 g / eq) 1.97 parts by weight

[0021]

[Chemical 11]

Phenol novolac resin curing agent (hereinafter referred to as PN) (softening point 90 ° C., hydroxyl group equivalent 103 g / eq) 1.97 parts by weight Silicone oil represented by the formula (7) (epoxy equivalent 200 g / eq) 1 part by weight

[0023]

[Chemical 12]

Fused silica powder 84.0 parts by weight Triphenylphosphine 0.2 parts by weight Carbon black 0.3 parts by weight Carnauba wax 0.5 parts by weight are mixed with a mixer at room temperature and roll-kneaded at 80 to 90 ° C., After cooling, it was pulverized to obtain a molding material. The obtained molding material is made into a tablet, and 1
52p of 6mm x 6mm chip for solder crack test under the condition of 75 ° C, 70kg / cm ² and 120 seconds.
Sealed in QFP. The sealed test element was subjected to the following solder crack test and void observation. The evaluation results are shown in Table 1.

Evaluation method Spiral flow: According to EMMI-I-66, the length of resin flow in the mold when cured at a mold temperature of 175 ° C. and a pressure of 60 kg / cm ² . Solder crack test: sealed test element at 85 ° C, 8
After 168 hr and 336 hr treatments in an environment of 5RH, and then IR reflow treatment (240 ° C, 10 seconds) treatment, external cracks were observed with a microscope. External void observation: A package molded for a solder crack test was visually confirmed. Observation of internal voids: A package molded for a solder crack test was cross-section polished and observed. Examples 2 to 16 Compounding was carried out according to Tables 1, 2 and 3 and a molding material was obtained in the same manner as in Example 1. A sealed molded product for testing was obtained from this molding material, and a solder crack test and void observation were performed using this molded product in the same manner as in Example 1. The test results are shown in Tables 1, 2 and 3. The silicone oil of the formula (8) used in Example 16 has the following structure.

[0026]

[Chemical 13]

Comparative Examples 1 to 6 Compounding was carried out according to Tables 1, 2 and 3 and a molding material was obtained in the same manner as in Example 1. A sealed molded product for testing was obtained from this molding material, and a solder crack test and void observation were performed using this molded product in the same manner as in Example 1. The test results are shown in Tables 1, 2 and 3. The silicone oil represented by the formula (9) used in Comparative Example 5 has the following structure and has an epoxy equivalent of 700.

[0028]

[Chemical 14]

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

According to the present invention, it is possible to obtain an epoxy resin composition which has both soldering stress resistance and void-free flow characteristics, which cannot be obtained by the prior art. Due to sudden temperature changes,
The crack resistance does not deteriorate when heat stress is applied, and the moldability becomes very good. Therefore, when it is used for encapsulation, coating, insulation, etc. of electronic and electric parts, it is particularly suitable for a product that requires extremely high reliability in a highly integrated large chip IC mounted in a surface mount package. is there.

Claims (1)

[Claims] 1. An epoxy resin represented by the following formula (1): An epoxy resin containing 50 to 100% by weight in the total amount of epoxy resin, wherein R _{1 to} R ₈ are the same or different atoms or groups selected from hydrogen, halogen and alkyl groups, and (B) total resin. Inorganic filler containing 70 to 93% by weight in the amount of composition, (C) flexible phenol resin curing represented by formula (2) and / or formula (3) having a plurality of phenolic hydrogen groups in one molecule Agent [Chemical Formula 2] (R in the formula is paraxylylene, n = 0 to 8) (R in the formula is paraxylylene, dicyclopetadiene diphenol obtained by addition reaction of dicyclopetadiene and phenol, terpene diphenol obtained by addition reaction of terpenes and phenol, cyclopentadiene diphenol obtained by addition reaction of cyclopentadiene and phenol, and Cyclohexanone represents a residue of cyclohexanone diphenol obtained by addition-condensing phenol with two phenol moieties removed, and one of these is selected, and the value of n is 0 to
8) A phenol resin curing agent containing 30 to 100% by weight in the total amount of the phenol resin curing agent, (D) a curing accelerator, and (E) an epoxy-modified silicone oil of formula (4) and / or formula (5) 4] [Chemical 5] (R in the formulas (4) and (5) is an alkylene group having 1 to 4 carbon atoms, 10 ≦ l + m + n + 2 ≦ 400, and the epoxy equivalent of the epoxy group represented by A is 140 to 500)
An epoxy resin composition for semiconductor encapsulation, comprising 0.1 to 3% by weight of the total composition.