JP2925905B2 - 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 is excellent in soldering stress resistance and fluidity in surface mounting of a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. In particular, in the case of integrated circuits, an O-cresol novolac type epoxy resin having excellent heat resistance and moisture resistance is used. An epoxy resin composition cured with a novolak type phenol resin is used.
However, in recent years, with the increase in the degree of integration of integrated circuits, chips have become larger and larger, and packages have become smaller and thinner flat packages, which are surface-mounted from the conventional DIP type.
It is changing to P, SOJ, PLCC. In particular, there has been a problem in that the device is suddenly exposed to a high temperature of 200 ° C. or more in the soldering process, and the moisture resistance is deteriorated due to cracking of the package and separation of the resin and the chip. In order to solve these problems, use of an epoxy resin represented by the formula (1) as an epoxy resin is disclosed in
No. 4-65116) 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 more inorganic filler, the composition can be solder-resistant because of its low thermal expansion and low moisture absorption after molding. The stress property was improved. However, with an increase in the amount of the inorganic filler, the fluidity was sacrificed and voids were likely to be formed in the package. However, with silicone oil which has been conventionally used for adjusting the fluidity, although the voids in the package can be reduced, the soldering resistance stress is reduced, so that the soldering stress and the improvement of the fluidity are not compatible.

[0003]

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

[0004]

According to the present invention, there is provided (A) an epoxy resin represented by the following formula (1):
Epoxy resin containing 0 to 100% by weight, (B) an inorganic filler containing 70 to 93% by weight in the total resin composition, and (C) a formula (2) having a plurality of phenolic hydroxyl groups in one molecule. A phenolic resin curing agent containing 30 to 100% by weight of a flexible phenolic resin curing agent in the total phenolic resin curing agent, (D) a curing accelerator, and (E) an epoxy of the formula (3) and / or (4) An epoxy resin composition for encapsulating a semiconductor, comprising a modified silicone oil in an amount of 0.1 to 3% by weight in a total resin composition, and having an excellent solder resistance as compared with a conventional epoxy resin composition. It has stress and fluidity.

Embedded image (R _{1 to} R ₈ in the formula are the same or different atoms or groups selected from hydrogen, halogen, and alkyl groups)

[0005]

Embedded image (R in the formula is paraxylylene, dicyclopentadiene diphenol obtained by addition reaction of dicyclopentadiene and phenol, terpene diphenol obtained by addition reaction of terpenes and phenol, cyclopentadiene diphenol obtained by addition reaction of cyclopentadiene and phenol, and cyclohexanone And cyclohexanone diphenol obtained by adding and condensing phenol, each of which represents a residue obtained by removing two phenol moieties, and one selected from these, and the value of n is from 0 to 8)

[0006]

Embedded image

[0007]

Embedded image (R in the formulas (3) and (4) 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)

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 a conventional polyfunctional epoxy resin, and transfer molding. Excellent fluidity at the time. Accordingly, a large amount of inorganic filler can be incorporated into the composition, and an epoxy resin composition having low thermal expansion and low water absorption, and 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. To achieve the effect of solder stress resistance,
It is desirable to use 50% by weight or more, preferably 70% by weight or more of the biphenyl type epoxy resin represented by the formula (1) in the total 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 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 (1), the epoxy resin used generally refers to any polymer having an epoxy group. For example, it refers to a bisphenol type epoxy resin, a cresol novolak type epoxy resin, a phenol novolak type epoxy resin, a triphenolmethane type epoxy resin, a triazine nucleus containing epoxy resin and the like. These may be used alone or as a mixture.

Examples of the inorganic filler include a fused silica powder, a crystalline silica powder, an alumina powder, a hydrated alumina powder, a silicon nitride powder, a calcium carbonate powder and the like, and a fused silica powder is particularly desirable. The compounding amount of the inorganic filler is preferably in the range of 70 to 93% by weight in the total resin composition. If it is less than 70% by weight, the amount of moisture absorption increases, and the coefficient of thermal expansion is too large to withstand thermal stress during mounting. On the other hand, if the content exceeds 93% by weight, the flow characteristics are deteriorated, which is not practical.

The phenolic resin curing agent represented by the structure of the formula (2) is a flexible phenolic resin curing agent having a relatively flexible structure in the R portion of the molecular structure, and is used as a novolak type phenolic resin curing agent. In comparison, it is possible to reduce the elastic modulus near the soldering temperature and to improve the adhesion to the lead frame and the semiconductor chip. Therefore, it is effective in preventing a reduction in stress generated at the time of a solder impact and a resulting peeling defect from a semiconductor chip or the like. By adjusting the amount of the phenol resin curing agent used, the solder stress resistance can be maximized. In order to obtain the effect of resistance to soldering stress, the flexible phenolic resin curing agent represented by the formula (2) is used in an amount of 30% by weight or more, preferably 50% by weight or more in the total phenolic resin curing agent. Is desirable. If the amount used is less than 30% by weight, low elasticity and insufficient adhesion to a lead frame, a semiconductor chip, etc. cannot be expected to improve solder stress resistance.

R in the formula (2) represents paraxylylene, dicyclopentadiene diphenol obtained by addition reaction of dicyclopentadiene and phenol, terpene diphenol obtained by addition reaction of terpenes with phenol, and cycloalkyl obtained by addition reaction of cyclopentadiene and phenol. This represents the residue of pentadiene diphenol excluding the two phenol moieties. Among these, there are p-xylylene, terpene diphenol obtained by addition reaction of terpenes and phenol, and dicyclopentadiene obtained by addition reaction of dicyclopentadiene and phenol. A residue in which two phenol moieties of phenol are removed is preferred. The value of n is 1-8. If n exceeds 8, the fluidity during transfer molding tends to decrease, and moldability tends to be poor. When other than the flexible phenol resin curing agent represented by the formula (2) is used in combination, a phenol novolak resin, a cresol novolak resin, a dicyclopentadiene-modified phenol resin and a phenol novolak and / or a cresol novolak resin are used. Copolymers and the like can be used.

The curing accelerator used in the present invention may be any one which promotes the reaction between an epoxy group and a phenolic hydroxyl group, and those generally used as a sealing material can be widely used. And tertiary amines such as benzyldimethylamine; imidazoles; and organic phosphorus compounds such as 1,8-diazabicycloundecene and triphenylphosphine. These may be used alone or as a mixture.

The silicone oil represented by the formulas (3) and (4) is an epoxy-modified silicone oil in which a part of the methyl substituent of dimethylsiloxane is substituted with a substituent having an epoxy group. Compared with a silicone oil having no silicone oil, an epoxy resin composition having excellent fluidity can be obtained without reducing solder stress resistance because of its excellent affinity with resin. By adjusting the amount of the epoxy-modified silicone oil used, the effect of improving solder stress resistance and fluidity can be maximized. As another advantage, this silicone oil has almost no effect on the spiral flow, one of the resin properties, when added, as compared with other silicone oils. In order to achieve both the anti-soldering stress and the improvement of the fluidity, the epoxy-modified silicone oil represented by the formula (3) and / or the formula (4) is added to the total resin composition in an amount of 0.1 to 0.1%.
It is desirable to use it in the range of 3% by weight. 0.1% by weight
If it is less than 3%, the fluidity cannot be improved, and external voids and the like are likely to be generated.
Solder stress resistance rapidly deteriorates. 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 when it exceeds 500, the solder stress resistance decreases. I will. Also, 10 ≦ l + m + n + 2 ≦ 400, and if it is less than 10, the heat resistance of the cured product will decrease, and if it exceeds 400, the solder stress resistance will decrease.

The epoxy resin composition of the present invention may contain, 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,
Additives such as a release agent such as a synthetic wax and a low stress agent such as a rubber 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 silicone oil, an inorganic filler, and other additives are sufficiently uniformly mixed by a mixer or the like. Alternatively, the mixture may be melt-kneaded with a hot roll or a kneader or the like, and cooled and pulverized to obtain a molding material. These molding materials are used for sealing, coating,
Insulation or the like can be applied.

[0015]

The present invention will be described in detail with reference to the following examples. The mixing ratio is by weight. Example 1 The following composition 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether (melting point 107 ° C., epoxy equivalent 191 g / eq) 8.40 parts by weight Curing agent represented by formula (5) (softening point 130 ° C, hydroxyl equivalent 174 g / eq) 2.80 parts by weight

Embedded image

Phenol novolak resin curing agent (hereinafter referred to as PN) (softening point 90 ° C., hydroxyl equivalent 103 g / eq) 2.80 parts by weight Silicone oil represented by formula (6) (epoxy equivalent 200 g / eq) 1.0 Parts by weight

Embedded image

84.0 parts by weight of fused silica powder 0.2 parts by weight of triphenylphosphine 0.3 parts by weight of carbon black 0.5 parts by weight of carnauba wax are mixed at room temperature with a mixer, and roll-kneaded at 80 to 90 ° C. After cooling, it was pulverized to obtain a molding material. The obtained molding material was tabletted, and a 6 mm × 6 mm chip was used for a solder crack test at 175 ° C., 70 kg / cm ² for 120 seconds using a low pressure transfer molding machine.
Sealed in 2pQFP. For the sealed test element, the following solder crack test and void observation were performed. Table 1 shows the results.

Evaluation method Spiral flow: The length of resin flowing in the mold when cured at a mold temperature of 175 ° C. and a pressure of 60 kg / cm ² according to EMMI-I-66. Solder crack test: Sealed test element at 85 ° C, 8
After treating for 168 hr and 336 hr in an environment of 5 RH and then performing IR reflow (240 ° C., 10 seconds), external cracks were observed with a microscope. External void observation: A package molded for a solder crack test was visually confirmed. Internal void observation: A package molded for a solder crack test was polished and observed.

Comparative Examples 1-3 Compounded according to Table 1 and obtained 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 void observation were performed using this molded product in the same manner as in Example 1. Table 1 shows the results. Comparative Example 2
The curing agent represented by the formula (7) (manufactured by Mitsui Toatsu Chemicals, Inc., trade name: Xylok, softening point 70 ° C., hydroxyl equivalent 174 g / eq) used in No. 3 has the following structure.

Embedded image

[0020]

[Table 1]

[0021]

According to the present invention, it is possible to obtain an epoxy resin composition having both solder stress resistance and flow characteristics free from voids, which cannot be obtained by the prior art. Due to sudden temperature changes,
Crack resistance when subjected to thermal stress does not deteriorate, and the moldability is very good. Therefore, when used for sealing, covering, insulating, and the like of electronic and electric components, it is suitable for products that require extremely high reliability, particularly in highly integrated large chip ICs mounted on surface mount packages. is there.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI H01L 23/31 (C08L 63/00 83:06) (58) Investigated field (Int.Cl. ⁶ , DB name) C08G 59/24 C08G 59 / 62 C08L 63/00-63/10 H01L 23/29 C08L 83/06

Claims (1)

(57) [Claims] 1. An epoxy resin containing 50 to 100% by weight of an epoxy resin represented by the following formula (1) in a total epoxy resin, and (B) 70 to 93% by weight in a total resin composition.
Inorganic filler containing (C) a phenolic resin containing 30 to 100% by weight of the total phenolic resin curing agent containing a flexible phenolic resin curing agent represented by the formula (2) having a plurality of phenolic hydroxyl groups in one molecule A semiconductor comprising 0.1 to 3% by weight of a total resin composition containing an agent, (D) a curing accelerator, and (E) an epoxy-modified silicone oil of the formula (3) and / or (4). Epoxy resin composition for sealing. Embedded image (R _{1 to} R ₈ in the formula are the same or different atoms or groups selected from hydrogen, halogen, and alkyl groups). (R in the formula is paraxylylene, dicyclopentadiene diphenol obtained by addition reaction of dicyclopentadiene and phenol, terpene diphenol obtained by addition reaction of terpenes and phenol, and cyclopentadiene diphenol obtained by addition reaction of cyclopentadiene and phenol. Represents a residue excluding the two phenol moieties, and one of them is selected from n values of 1 to 8) Embedded image (R in the formulas (3) and (4) 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)