JPH04209687A - Conductive paste - Google Patents

Abstract

PURPOSE:To obtain a conductive paste which is excellent in adhesiveness and resistance moisture absorption, scarcely causes bleeding and migration, and has high reliability by mixing a specified modified resin, a conductive powder, a fine silica powder, a porous filler, and a water repellent. CONSTITUTION:A conductive paste obtained by mixing a modified resin made from poly-p-hydroxystyrene and an epoxy resin, a conductive powder, a fine silica powder, porous filler, and a water repellent. The modified resin to be used may be one made by merely dissolving and mixing poly-p-hydroxystyrene and an epoxy resin, and if necessary, thermally reacting them to partially combine with each other. Although they may be dissolved and mixed at once, it is desirable that first the poly-p-hydroxystyrene is dissolved. Also, by dissolving the constituent resins in a solvent common to them, working viscosity can be improved.

Description

[Detailed description of the invention]

[00011

[Industrial Field of Application] The present invention relates to a highly reliable conductive paste that has excellent adhesiveness and moisture absorption resistance, and is less likely to cause bleeding or migration. [0002] Conductive paste is generally composed of a binder such as an epoxy resin and conductive powder, and is used for bonding, coating, etc. of various electronic parts. As a hardener for the binder epoxy resin, polyamide resin,
A wide variety of materials are used, including amines, melamines, acid anhydrides, boron trifluoride, and amine complexes. It is known that when a conductive paste is bonded or coated (dipped), the solvent in the conductive paste causes bleeding at the interface with an adherend. In particular, during bleeding, migration tends to occur in the fine conductive powder in the conductive paste, resulting in an extremely low reliability of the conductive film. Further, the deterioration in reliability of the conductive film is largely caused by the moisture absorption characteristics of the conductive paste itself. [0003]

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and provides a highly reliable conductive paste with excellent adhesiveness and moisture absorption resistance, less occurrence of bleeding and migration. It is intended to. [0004]

[Means for Solving the Problems] As a result of intensive research aimed at achieving the above object, the present inventors discovered that a conductive paste having the composition described below can achieve the above object, and thus completed the present invention. It is something. [0005] That is, the present invention comprises: (A) modified resin made of polyparahydroxystyrene and epoxy resin, (B) conductive powder, (C) fine silica powder, (D) porous filler, and (E) water repellent. This is a conductive paste characterized by containing a chemical agent as an essential component. [0006] The present invention will be described in detail below. [0007] The modified resin (A) used in the present invention is (a
) polyparahydroxystyrene and (b') epoxy resin. (a) Polyparahydroxystyrene is a resin represented by chemical formula 1, and has a molecular weight of 3000
~8,000 and has a hydroxyl equivalent of about 120. [0008]

[0009] Specific examples thereof include Maruka J-Linker M (manufactured by Maruzen Petrochemical Co., Ltd., trade name). [00101(b) The epoxy resin is not particularly limited for the purpose of this invention, and examples include those that are industrially produced and can be effectively used in the present invention, such as Epicote 827, 828, 834, and 1001. ,1002
．． 1007.1009 (manufactured by Shell Chemical Co., Ltd., product name)
,DER330,331,332,334,335,3
36,337,660 (manufactured by Dow Chemical Company, trade name),
Araldite GY250, 260, 280, 6071,
6084.6097.6099 (manufactured by Ciba Geigy,
Product name), EPI-REZ510.5101 (J
one manufactured by Dabney, product name), Ebicuron 81
0,1000,1010.3010 (manufactured by Dainippon Ink and Chemicals, trade name), EP series (manufactured by Asahi Denka Co., Ltd., trade name), and the like. Furthermore, by using an epoxy resin having an average number of epoxy groups of 3 or more, such as a novolak epoxy resin, the adhesive strength at high temperature (350° C.) can be further improved. As these novolak epoxy resins, those having a molecular weight of 500 or more are suitable. Examples of industrially produced novolac epoxy resins include Araldite EPN1138 and 1139.
, ECN1273, 1280.1299 (manufactured by Ciba Geigy, trade name), DEN431,438 (manufactured by Dow Chemical Company, trade name) Epicote 152,154 (manufactured by Shell Chemical Company, trade name), ERR-0100, ERRB
-0447, ERLB-0488 (manufactured by Union Carbide Co., Ltd., trade name), EOCN series (manufactured by Nippon Koyaku Co., Ltd., trade name), etc., and these can be used alone or in a mixture of two or more. [00111 The modified resin used in the present invention may be obtained by simply dissolving and mixing polyparahydroxystyrene and an epoxy resin, or may be partially bonded by heating reaction if necessary. When carrying out the reaction, a curing catalyst can be used if necessary. [0012] When dissolving and mixing polyparahydroxystyrene and epoxy resin, they may be added and dissolved at the same time, but first dissolve polyparahydroxystyrene in a solvent, and then dissolve the epoxy resin. Preferably, they are mixed. Furthermore, the working viscosity can be improved by dissolving these component resins in a common solvent. Solvents used here include dioxane, hexane, benzene, toluene, solvent naphtha, industrial gasoline,
Examples include cellosolve acetate, butyl acetate, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, butyl carpitol acetate, diethylene glycol diethyl ether, dimethyl formamide, dimethyl acetamide, N-methyl pyrrolidone, etc., and these may be used alone or in a mixture of two or more. . [0013] Examples of the conductive powder (B) used in the present invention include silver powder, silver-plated copper powder, copper powder, nickel powder, carbon, etc., and these can be used alone or in a mixture of two or more kinds. . [00141 The fine silica powder (C) used in the present invention includes, for example, Aeroseal (manufactured by Nippon Aeroseal Co., Ltd., trade name) with an average particle size of 1 μm or less, and these may be used alone or in a mixture of two or more. can do. [00151 Examples of the porous filler (D) used in the present invention include talcite, Ketchien black, and celite, and these can be used alone or in combination of two or more. [0016] The water repellent (E) used in the present invention includes fluorocarbon-based, silicone-based, etc.
Examples include TL450, 610, 500F, KT400M (manufactured by Kitamura Co., Ltd., trade name), TSL8241, 8185 (manufactured by Toshiba Silicone Co., Ltd., trade name), and these can be used alone or in a mixture of two or more kinds. [00171 The conductive paste of the present invention contains a modified resin made of polyparahydroxystyrene and an epoxy resin, a conductive powder, a fine silica powder, a porous filler, and a water repellent as essential components, but this is contrary to the purpose of the present invention. Antifoaming agents and other additives may be added and blended as necessary, within the range that is not included. After the above-mentioned components are sufficiently mixed according to a conventional method, the mixture is further kneaded using three rolls, and then defoamed under reduced pressure to produce a conductive paste. [0018] The conductive paste thus produced can be used for adhesion, covering, coating, etc. of various electronic components. [0019]

[Function] The conductive paste of the present invention has a modified resin, a conductive powder, a fine silica powder, a porous filler, and a water repellent as essential components, so that bleeding is extremely reduced and moisture absorption resistance is good. As a result, adhesion was excellent and migration could be prevented. [00201

[Examples] Next, the present invention will be specifically explained by examples, but the present invention is not limited by these examples. In addition, in the following examples and comparative examples, “
"Parts" means "parts by weight" unless otherwise specified. [00211 Example 1 37.5 parts of epoxy resin Epikote 1001 (manufactured by Shell Chemical Co., Ltd., trade name) and 10 parts of parahydroxystyrene Marukalinker M (manufactured by Maruzen Petrochemical Co., Ltd., trade name) were mixed with diethylene glycol diethyl ether. 100°C in 103 parts. A dissolution reaction was carried out for 1 hour to obtain a viscous modified resin. To 22 parts of this resin, 1.0% boron trifluoride amine complex was added as a catalyst.
0 parts, 0.03 parts of additives, 57 parts of silver powder, 2.0 parts of Aeroseal #200 (manufactured by Japan Aeroseal Co., Ltd., trade name) as fine silica powder, 0.1 part of talcite as porous filler, repellent A conductive paste was prepared by mixing 0.5 part of KTL-500F (manufactured by Kitamura Co., Ltd., trade name) and 50 parts of butyl acetate as a liquid agent. [0022] Example 2 15.8 parts of epoxy resin Epikote 828 (manufactured by Shell Chemical Co., Ltd., trade name) and 10 parts of parahydroxystyrene Marcarin Power-M (manufactured by Maruzen Petrochemical Co., Ltd., trade name),
A dissolution reaction was carried out in 56 parts of butyl cellosolve acetate at 100° C. for 1 hour to obtain a viscous modified resin. This resin 2
In the second part, 1.0% of an amine complex of boron trifluoride was added as a catalyst.
57 parts of silver powder, 2.5 parts of Aeroseal #200 (mentioned above) as fine silica powder, 0.1 part of talcite as porous filler, and KTL6100 (as water repellent).
A conductive paste was prepared by mixing 5 parts of Kitamura Co., Ltd. (trade name) and 50 parts of butyl acetate. [0023] Example 3 66 parts of epoxy resin EOCN103S (manufactured by Nippon Koyaku Co., Ltd., trade name) and 34 parts of parahydroxystyrene Marcalin-M (described above) were mixed in 1-117 parts of butylcarpitol acetate. A dissolution reaction was carried out at 100°C for 1 hour to obtain a viscous modified resin. To 22 parts of this resin, 1.0 part of an amine complex of boron trifluoride as a catalyst, 57 parts of silver powder, 2.0 parts of Aerosil #200 (mentioned above) as fine silica powder, and 0.0 parts of talcite as a porous filler. 1 part, 0.5 part of TSL8241 (manufactured by Toshiba Silicone Corporation, trade name) as a water repellent, and 50 parts of butyl acetate to prepare a conductive paste. [0024] Comparative Example A commercially available epoxy resin-based solvent-based conductive paste for semiconductors was obtained. [0025] The conductive pastes obtained in Examples 1 to 3 and Comparative Examples were tested for adhesion and moisture absorption, and a bleed test,
We performed an accelerated migration test and obtained the results, so Table 1
However, the present invention exhibited excellent characteristics, and the effects of the present invention could be confirmed. [0026] [Table 1] (Unit) *1: 2. Omm
X 2. Omm silicon chips were bonded at 200℃ for 60 minutes and measured using a tension gauge at a temperature of 25℃. *2: △ mark: There was some bleeding,
× mark: Very large amount of bleeding *3: As shown in Fig. 1, the conductive paste 2 is applied on the slide glass plate 1 with a width of 5 mm and a thickness of 20 μm, with a discontinuous part 3 of 2 mm width in the middle. Distilled water 4 was dropped onto a discontinuous portion 3 having a width of 2 mm by screen printing, a DC voltage of 8 V was applied, and the time until current leakage was measured. [0027]

[Effects of the Invention] As is clear from the above explanation and Table 1, the conductive paste of the present invention has excellent adhesion, moisture absorption resistance, and migration resistance, and is highly reliable with less occurrence of bleeding. By using conductive paste, reliable electronic components can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a test piece with electrodes used in an accelerated migration test.

[Explanation of symbols]

1...Slide glass 2... Conductive paste 3...Discontinuous part 4... Distilled water.

Claims (1)

[Claims] Claim 1: (A) modified resin made of polyparahydroxystyrene and epoxy resin, (B) conductive powder, (C) fine silica powder, (D) porous filler, and (E) water repellent as essential components. A conductive paste characterized by the following characteristics: