JP3440446B2 - Conductive paste - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for assembling semiconductor devices and for bonding various parts, and has a low-temperature curing property, a fast curing property, and a storage stability. The present invention relates to a conductive paste having excellent adhesiveness and moisture resistance. 2. Description of the Related Art Generally, a conductive paste is composed of a binder such as an epoxy resin and a conductive powder, and is applied to bonding of various electronic parts, coating, circuit formation by printing, and the like. The binder is mainly a thermosetting resin, and is thermally cured by the curing agent to become insoluble in an organic solvent, and is imparted with heat resistance, moisture resistance, weather resistance, and the like. When an epoxy resin is used as the binder, various types of curing agents such as polyamide resins, amines, melamines, acid anhydrides, boron trifluoride, and amine complexes are used. [0003] However, when an epoxy resin composition containing an amine compound is inferior in storage stability, it is not stable and does not gel at a relatively low temperature in order to obtain an excellent low-temperature curability and fast-curing property. There is a strong demand for a so-called latent curing agent that cures quickly when heated. As the latent curing agent, a dispersion melting type is widely used, and examples thereof include dicyandiamide, dibasic hydrazide, melamine and derivatives thereof, and imidazole derivatives. However, dicyandiamide, dibasic hydrazide, melamine and their derivatives have excellent storage stability, but have the drawback that they require curing at high temperatures of 150 ° C or more for a long time, and imidazole derivatives have low-temperature curability and storage stability. It is difficult to balance with the above, and a satisfactory resin composition cannot be obtained. In recent years, a dispersion-melting type curing agent / catalyst and a microcapsule type curing agent / catalyst having both low-temperature curability and storage stability have been put on the market. All of these catalysts are soluble in a solvent or a reactive diluent. Therefore, a conductive paste containing a solvent or a reactive diluent component has a drawback of poor storage stability, and has not solved these problems. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has a low-temperature curing property, a fast curing property, and excellent storage stability. To provide a new conductive paste. The present inventors have made intensive studies to achieve the above object, and as a result, by using a paste having a latent curing agent or catalyst composition described later, It has been found that the object of the present invention can be achieved, and the present invention has been completed. That is, the present invention provides (A) (a) an epoxy resin, (b) a phenolic resin-based curing agent, and (c) a sulfonium salt represented by the following general formula (1) or (2). Formula 2 A conductive resin comprising (B) a conductive powder and (C) a solvent, a reactive diluent or a mixture thereof as essential components. Hereinafter, the present invention will be described in detail. The modified resin (A) used in the present invention comprises (a)
It comprises an epoxy resin, (b) a phenolic resin-based curing agent, and (c) a sulfonium salt represented by the general formula (2). As the epoxy resin (a) used for this, for example, Epicoat 827, 828, 834, 100
1,1002,1007,1009 (manufactured by Shell Chemical Company,
(Product name), DER330,331,332,334,3
35,336,337,383,660 (manufactured by Dow Chemical Company, trade name), Araldite GY250,260,
280, 6071, 6084, 6097, 6099 (trade name, manufactured by Ciba Geigy), EPI-REZ 510,5
101 (manufactured by JONE DABNEY, trade name), Epicron 810, 1000, 1010, 3010 (manufactured by Dainippon Ink and Chemicals, Inc.), EP series manufactured by Asahi Denka Co., Ltd., and the like. Furthermore, the average number of epoxy groups is 3 or more,
For example, by using a novolak epoxy resin, the adhesive strength when heated (at 350 ° C.) can be further improved. The molecular weight of these novolak epoxy resins is
500 or more is desirable. As the novolak epoxy resin, for example, Araldite EPN1138, 113
9, ECN1273, 1280, 1299 (Ciba-Geigy Co., trade name), DEN431, 438 (Dow Chemical Co., trade name), Epicoat 152, 154 (Shell Chemical Co., trade name), ERR-0100, ERRB-
0447, ERLB-0488 (manufactured by Union Carbide, trade name), EOCN series (manufactured by Nippon Kayaku Co., Ltd.) and the like, and these can be used alone or in combination of two or more kinds. Examples of (b) a phenolic resin curing agent as another component of the modified resin include XL225L (trade name, manufactured by Sumitomo Chemical Co., Ltd.), Resin M (trade name, manufactured by Maruzen Oil Co., Ltd.), V
H4170 (product name, manufactured by Dainippon Ink and Chemicals, Inc.), B
RG555-559, CKM-908,941,128
2,1634,2103,2400,2432,525
4, OTS467, CKS3592 (manufactured by Showa Polymer Co., Ltd.,
And the like, and these can be used alone or in combination of two or more. The phenolic resin-based curing agent improves the heat resistance, room temperature bonding strength, hot bonding strength, and adhesion of the cured paste or coating film. Further, (c) the other component in the modified resin
As the sulfonium salt, those represented by the aforementioned general formula 2 are used. Specific compounds of the sulfonium salt include, for example, [0013] Embedded image And the like, and these can be used alone or as a mixture. This sulfonium salt acts as a cationic polymerization catalyst on the epoxy resin. The compounding ratio of the sulfonium salt is 0.5 to 100 parts by weight of the epoxy resin.
It is desirable to mix 20 parts by weight. If the compounding amount is less than 0.5 part by weight, the curing speed is lowered without effecting the rapid curing property, and the curing is not practical. If the content exceeds 20 parts by weight, the storage stability of the paste becomes poor, and the Lewis acid remaining in the cured paste deteriorates the electrical properties under high humidity conditions and corrodes the base metal (electrolytic corrosion). It is not preferable because of lack of reliability. A modified resin obtained by dissolving and mixing the epoxy resin, phenolic resin-based curing agent and sulfonium salt, which are the above-described components, with a solvent or a reactive diluent, or by causing a heat reaction to partially bond the resin is used. The (B) conductive powder used in the present invention includes, for example, silver powder, copper powder, nickel powder, and powder having a metal layer on the surface. These may be used alone or as a mixture of two or more. be able to. The solvent (C), the reactive diluent, or a mixture thereof used in the present invention dissolves the modified resin (A) and controls and improves the working viscosity of the paste. Reactive diluents and mixtures thereof are used. Specific solvents include dioxane, hexane, toluene, methyl cellosolve, cyclohexane, butyl cellosolve, butyl cellosolve acetate,
Butyl carbitol acetate, diethylene glycol dimethyl ether, dimethylformamide, N-methylpyrrolidone, diacetone alcohol, dimethylacetamide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, and the like, alone or in combination of two or more It can be mixed and used. Examples of the reactive diluent include n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, styrene oxide,
Phenyl glycidyl ether, cresyl glycidyl ether, p-sec-butylphenyl glycidyl ether, glycidyl methacrylate, t-butyl phenyl glycidyl ether, diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, butanediol diglycidyl ether, Trimethylolpropane triglycidyl ether, 1,6-hexanediol diglycidyl ether and the like can be mentioned, and these can be used alone or in combination of two or more. Further, a solvent and a reactive diluent can be mixed and used. When a solvent is used, it is necessary to carefully consider the boiling point and select a solvent in accordance with conditions such as a curing temperature and a curing time. The conductive paste of the present invention comprises the above-mentioned modified resin, conductive powder and solvent, a reactive diluent or a mixture thereof as essential components. In addition, an antifoaming agent, a coupling agent, and other additives can be blended. This conductive paste can be produced by thoroughly mixing the above-described components according to a conventional method, further performing a kneading treatment using, for example, a three-roll mill, and then defoaming under reduced pressure. The conductive paste thus manufactured is used for bonding various electronic components, coating agents, forming electrodes by printing,
It can be used for circuit formation and the like. The purpose of the conductive paste of the present invention is achieved by using a modified resin, a conductive powder and a solvent, a reactive diluent or a mixture thereof as essential components. In particular, by incorporating a cationic polymerization type catalyst into the modified resin, a low-temperature curing and a rapid curing were enabled, and a one-pack type paste having excellent storage stability was able to be prepared. Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, “parts” means “parts by weight” unless otherwise specified. Example 1 100 parts of an epoxy resin Epicoat 1004 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.) and 13 parts of resin M, a phenolic resin-based curing agent (trade name, manufactured by Maruzen Oil Co., Ltd.), were treated with methyl cellosolve. A dissolution reaction was performed in 113 parts at 100 ° C for 1 hour to obtain a viscous resin. To 30 parts of this resin, 0.20 part of the sulfonium salt represented by Chemical Formula 4, 0.020 parts of an additive, and 60 parts of silver powder were mixed and kneaded with a three-roll mill to produce a conductive paste (A). Example 2 100 parts of an epoxy resin epicoat 1001 (trade name, manufactured by Yuka Shell Epoxy Co.), and a phenol resin-based curing agent V
H4170 (product name, manufactured by Dainippon Ink and Chemicals, Inc.) 24.8
Was dissolved in a mixed solvent of 299.5 parts of diethylene glycol dimethyl ether and 74.9 parts of toluene at 100 ° C. for 1 hour to obtain a viscous resin. In 36.9 parts of this resin,
Was mixed with 0.25 parts of a sulfonium salt, 0.12 parts of an additive and 60 parts of silver powder, and kneaded with a three-roll mill to produce a conductive paste (B). Example 3 100 parts of epoxy resin YL-980 (trade name, manufactured by Yuka Shell Epoxy Co.), CKS of phenol resin-based curing agent
8592 parts of 3592 (trade name, manufactured by Showa Polymer Co., Ltd.) were dissolved in 90.8 parts of allyl glycidyl ether at 100 ° C. for 1 hour to obtain a viscous resin. To 25.8 parts of this resin, 0.09 part of the sulfonium salt represented by Chemical Formula 3, 0.05 part of an additive, and 61 parts of silver powder were mixed, and kneaded with a three-roll mill to produce a conductive paste (C). Comparative Example A commercially available epoxy resin-based conductive paste (D) for a solvent-based semiconductor was obtained. Using the conductive pastes (A), (B), (C) and (D) obtained in Examples 1 to 3 and Comparative Example,
The adhesive strength, moisture resistance and storage stability were tested. The results are shown in Table 1. As shown in Table 1, the present invention was excellent, and the remarkable effects of the present invention were recognized. [Table 1] * 1: Measured with a differential scanning calorimeter (DSC) at a measurement condition of about 10 mg of sample and a heating rate of 10 ° C./min. * 2: Stored in a thermostat at 25 ° C, and the number of days until the viscosity doubles the initial viscosity was used as a measure of storage stability. * 3: 2.0 × on silver-plated lead frame (copper)
A 2.0 mm silicon chip was adhered, cured at a temperature of 150 ° C. × 1 h, and measured at 25 ° C. using a tension gauge. * 4: 2.0 × on silver-plated lead frame (copper)
Attach 2.0mm silicon chip, 121 ℃ × 100% R ・
After treatment at H × 2 atm × 24 hours, the measurement was carried out at 25 ° C. using a tension gauge. As is clear from the above description and Table 1, the conductive paste of the present invention has excellent adhesiveness and moisture resistance, and has low-temperature curability and quick-curing property. It also has excellent storage stability. By using this conductive paste, a highly reliable electronic component can be manufactured.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI H01L 23/29 H05K 1/09 23/31 H01L 23/30 H05K 1/09 (56) References JP-A-2-178319 (JP) , A) JP-A-4-11626 (JP, A) JP-A-5-230189 (JP, A) JP-A-7-278273 (JP, A) JP-A-4-214773 (JP, A) 5-36738 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 59/00-59/72 C09J 9/02 C09J 163/00-163/10 H01B 1/20-1 / 24 H01L 23/29 H01L 23/31 H05K 1/09

Claims (1)

(57) [Claims] (1) (A) (a) an epoxy resin, (b) a phenolic resin-based curing agent, (c) a sulfonium represented by the following general formula (1) or (2) Salt A conductive paste comprising, as essential components, a modified resin comprising (B) a conductive powder and (C) a solvent, a reactive diluent or a mixture thereof.