JP3305097B2 - 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 resistance to soldering stress in surface mounting of semiconductor devices.

[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 an integrated circuit, an ortho-cresol novolac type epoxy resin having excellent heat resistance and moisture resistance is replaced with phenol. An epoxy resin composition cured with a novolak resin and blended with an inorganic filler such as fused silica or crystalline silica as a filler is used. However, in recent years, the chip has been gradually increased in size with the increase in the integration degree of the integrated circuit, and the package has been changed to the conventional DIP.
Small and thin QFP, SO surface mounted from type
P, SOJ, TSOP, TQFP, PLCC have been changed. That is, a large chip is sealed in a small and thin package, and cracks are generated due to thermal stress. Problems such as a decrease in moisture resistance due to these cracks are greatly highlighted. 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 or separation of the resin and the chip. Therefore,
The development of a highly reliable resin composition for semiconductor encapsulation suitable for encapsulating these large chips has been desired.

[0003]

SUMMARY OF THE INVENTION The present invention solves such a problem by using an epoxy resin represented by the formula (1) as an epoxy resin to improve adhesion to a lead frame and a semiconductor chip. An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation in which a molded article has a low stress due to a low elastic modulus at a high temperature, thereby significantly improving the solder stress resistance of a semiconductor package when mounted on a substrate.

[0004]

The present invention relates to (A) an epoxy resin represented by the following formula (1):

[0005]

Embedded image (R in the formula is the same or different atom or group selected from hydrogen, halogen, and an alkyl group having 1 to 10 carbon atoms)

[0006] 30 to 100 with respect to the total amount of epoxy resin
It is an epoxy resin composition for semiconductor encapsulation containing, as essential components, an epoxy resin containing by weight, (B) a phenol resin curing agent, (C) an inorganic filler, and (D) a curing accelerator. In comparison, it has solder crack resistance and moisture resistance after soldering as excellent reliability.

The epoxy resin represented by the molecular structure of formula (1) is an epoxy resin obtained by glycidyl etherification of a phenol resin obtained by polymerizing meta-xylene and phenols by a Friedel-Crafts alkylation reaction. Compared with the conventional orthocresol novolak epoxy resin, the cured product has a low elastic modulus at a high temperature exceeding the glass transition temperature and has excellent adhesion to metals such as a lead frame. Therefore, it is possible to reduce the thermal stress at the time of surface mounting soldering, and to obtain an epoxy resin composition having excellent solder crack resistance. R in the formula (1) is the same or different atom or group selected from hydrogen, halogen, and an alkyl group having 1 to 10 carbon atoms, and among them, a hydrogen atom is preferable. When an alkyl group having more than 10 carbon atoms is selected, the curability tends to decrease. n is from 0 to 20, but when it exceeds 20, the fluidity is poor. Preferred n is 0
It is 10. By adjusting the amount of the epoxy resin used, solder crack resistance can be maximized. In order to obtain the effect of solder crack resistance, it is desirable to use the epoxy resin represented by the formula (1) in an amount of 30% by weight or more, preferably 50% by weight or more based on the total amount of the epoxy resin. If it is less than 30% by weight, a low elastic modulus at high temperature and adhesiveness cannot be obtained, and solder crack resistance is insufficient. When an epoxy resin other than the epoxy resin represented by the formula (1) is used in combination, the epoxy resin used refers to all monomers, oligomers and polymers having an epoxy group. For example, a biphenyl-type epoxy compound, a bisphenol-type epoxy compound, a phenol novolak-type epoxy resin, a cresol novolak-type epoxy resin, a triphenolmethane-type epoxy compound, an alkyl-modified triphenolmethane-type epoxy compound, and a triazine nucleus-containing epoxy resin. .

The phenolic resin curing agent used in the present invention comprises:
Phenol novolak resin, cresol novolak resin, dicyclopentadiene-modified phenol resin, paraxylylene-modified phenol resin, terpene-modified phenol resin, triphenolmethane compound, etc. ,
Terpene-modified phenolic resins and mixtures thereof are preferred. The amount of these curing agents is preferably such that the number of epoxy groups in the epoxy compound and the number of hydroxyl groups in the curing agent match.

The curing accelerator used in the present invention may be any as long as it promotes a curing reaction between an epoxy group and a hydroxyl group.
What is generally used for a sealing material can be widely used. For example, 1,8-diazabicycloundecene, triphenylphosphine, dimethylbenzylamine, 2-methylimidazole, or the like is used alone or in combination of two or more. Examples of the inorganic filler used in the present invention include fused silica powder, spherical silica powder, crystalline silica powder, secondary agglomerated silica powder, porous silica powder, alumina and the like, particularly spherical silica powder, and fused silica powder and spherical silica powder. Mixtures with silica powder are preferred. The amount of the inorganic filler is preferably 80 to 90% by weight based on the total amount of the epoxy resin composition from the viewpoint of solder crack resistance. If it is less than 80% by weight, the solder crack resistance is disadvantageous. If it exceeds 90% by weight, the fluidity is insufficient.

The epoxy resin composition of the present invention comprises an epoxy resin, a phenolic resin curing agent, an inorganic filler and a curing accelerator as essential components. In addition to this, if necessary, a silane coupling agent, a brominated epoxy resin, Various additives such as flame retardants such as antimony trioxide and hexabromobenzene, coloring agents such as carbon black and red iron oxide, release agents such as natural wax and synthetic wax, and low stress additives such as silicone oil and rubber are appropriately used. It is safe to mix.
In addition, in order to manufacture the epoxy resin composition for encapsulation of the present invention as a molding material, epoxy resin, phenol resin curing agent, curing accelerator, inorganic filler, and other additives are sufficiently and uniformly mixed by a mixer or the like. After that, the mixture is further melt-kneaded with a hot roll or a kneader, cooled and pulverized to obtain a sealing material. These molding materials are used for coating electric or electronic components such as transistors and integrated circuits,
It can be applied to insulation, sealing, and the like.

Hereinafter, the present invention will be described specifically with reference to Examples. Example 1 The following composition: 7.6 parts by weight of an epoxy resin represented by the formula (2) (softening point: 50 ° C., epoxy equivalent: 240 g / eq)

[0012]

Embedded image (The value of n is a mixture showing 0 to 3, and the weight ratio is 0.7 for n = 1, 0.7 for n = 1, and 0.4 for n = 2.
5, n = 3 is 0.35. )

Orthocresol novolak type epoxy resin (softening point 58 ° C., epoxy equivalent 200 g / eq) 1.9 parts by weight Phenol novolak resin curing agent (softening point 65 ° C., hydroxyl equivalent 105 g / eq) 4.3 parts by weight Melting Silica powder (average particle size 10 μm, specific surface area 2.0 m ² / g) 35 parts by weight Spherical silica powder (average particle size 30 μm, specific surface area 2.5 m ² / g) 50 parts by weight Triphenylphosphine 0.2 part by weight Carbon 0.5 parts by weight of black 0.5 parts by weight of carnauba wax was 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. The molding material obtained by the pulverization is tabletted, and is 175 ° C., 70 kg / cm ² , 120 with a low-pressure transfer molding machine.
Under the condition of seconds, a chip of 6 × 6 mm was sealed in 52 pQFP for a solder crack test, and a chip of 3 × 6 mm was sealed in 16 pSOP for a solder moisture resistance test. The sealed test element was subjected to the following solder crack test and solder moisture resistance test.

Evaluation method Solder crack test: A sealed test element was heated at 85 ° C. for 8 hours.
The treatment was performed for 24 hours, 48 hours, 72 hours, and 120 hours in an environment of 5% RH, and then immersed in a solder bath at 260 ° C. for 10 seconds, and then external cracks were observed with a microscope. Solder moisture resistance test: Sealed test element at 85 ° C, 85
% RH environment for 72 hours, and then immersed in a solder bath at 260 ° C. for 10 seconds, followed by a pressure cooker test (1
(25 ° C., 100% RH), the open defect of the circuit was measured, and the result was represented by the average life (hour) of the solder moisture resistance. Table 1 shows the test results. Examples 2 and 3 The components were blended according to the formulation shown in Table 1, and a molding material was 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 a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. Table 1 shows the test results. Comparative Examples 1 and 2 Compounded according to the formulation shown in Table 1, and a molding material was 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 a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. Table 1 shows the test results. Comparative Example 3 Instead of the epoxy resin of the formula (2) in Example 1, an epoxy resin of the following formula (3) (softening point 55 ° C., epoxy equivalent 2
Except for using 45 g / eq), a molding material was obtained in the same manner as in the formulation of Table 1. A sealed molded product for a test was obtained from this molding material, and a solder crack test and a solder moisture resistance test were performed using this molded product in the same manner as in Example 1. Table 1 shows the test results.

[0015]

Embedded image (The value of n is a mixture showing 0 to 3, and the weight ratio of n = 0 to 1 is 0.8 for n = 1 and 0.4 for n = 2.
5, n = 3 is 0.4. )

[0016]

[Table 1]

[0017]

According to the present invention, it is possible to realize a resin-sealed semiconductor package which is excellent in solder crack resistance and moisture resistance and has good moldability and can be surface-mounted.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 23/31 (56) References JP-A-3-258829 (JP, A) JP-A-5-222156 (JP, A) JP-A-5-99767 (JP, A) JP-A-5-97966 (JP, A) JP-A-3-14819 (JP, A) JP-A-60-112813 (JP, A) JP-A-5-194708 ( JP, A) JP-A-7-196568 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 59/20-59/32 C08G 59/62 C08L 63/00-63 / 04 H01L 23/29

Claims (2)

(57) [Claims] (A) an epoxy resin represented by the following formula (1): (R in the formula is the same or different atom or group selected from hydrogen, halogen, and alkyl group having 1 to 10 carbon atoms) epoxy resin containing 30 to 100% by weight based on the total epoxy resin amount, (B ) Phenolic resin curing agent, (C)
An epoxy resin composition for semiconductor encapsulation, comprising an inorganic filler and (D) a curing accelerator as essential components. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein R in the formula (1) is hydrogen.