JPH05331355A - Conductive paste - Google Patents

Abstract

PURPOSE:To obtain a conductive paste excellent in adhesion and migration and bleeding resistance even under high-temperature and high-pressure conditions and not causing the exudation of conductive powder by mixing a specified modified resin with a specified conductive composite powder and a porous filler. CONSTITUTION:The paste essentially consists of a modified resin comprising a bisphenol A novolac resin, an epoxy resin and a fluorine compound of formula I (wherein X is OH, NH2, COOH, a group of formula II or a group of formula III; and Y is H or NH2), a compound powder comprising a conductive powder and a fine silica powder and a porous filler. This paste is excellent in adhesion, migration resistance and bleeding resistance even under high-temperature and high-pressure conditions, does not cause the exudation of conductive powder and can give an electronic component of high reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste having excellent adhesiveness, bleeding resistance and migration resistance, which is used for assembly of semiconductor devices and adhesion of various parts.

[0002]

2. Description of the Related Art Generally, a conductive paste is composed of a thermosetting binder such as an epoxy resin and a conductive powder, and contains a small amount of a solvent to bond or coat various electronic parts.
It is applied to circuit formation by printing. The thermosetting resin of the binder is heat-cured by the curing agent to be insoluble in the organic solvent, and is given heat resistance, moisture resistance, weather resistance and the like.
As the curing agent for the binder epoxy resin, various kinds of polyamide resins, amines, melamines, acid anhydrides, boron trifluoride, amine complexes and the like are used.

[0003]

It is known that the solvent in the conductive paste causes bleeding at the interface with the adherend when these conductive pastes are bonded or dipping. During this bleeding, in particular, if the fine conductive powder in the conductive paste oozes out, migration becomes very likely to occur when a voltage is applied under conditions of high temperature and high humidity, and the reliability of electronic components is extremely reduced. There was a problem of lowering it.

The present invention has been made in view of the above circumstances, and is excellent in adhesiveness, improves bleeding resistance, prevents exudation of fine conductive powder, and can prevent migration. It is intended to provide a conductive paste.

[0005]

Means for Solving the Problems As a result of earnest studies to achieve the above object, the present inventor has found that the above object can be achieved by using a paste having a composition described later, and It has been completed. That is, the present invention relates to (A) (a) bisphenol A novolac resin (b) epoxy resin and (c) fluorine-containing compound represented by the general formula 2.

[0006]

[Chemical 2]

A conductive paste comprising a modified resin consisting of (B) a composite powder consisting of a conductive powder and a fine silica powder, and (C) a porous filler as essential components.

The present invention will be described in detail below.

The modified resin (A) used in the present invention is (a)
Bisphenol A novolac resin, (b) epoxy resin, and (c) fluorine-containing compound represented by the general formula 2.

The bisphenol A novolak resin (a) used in the present invention is a resin represented by the following general formula 3.

[0011]

[Chemical 3] (However, in the formula, m and n represent 0 or a positive integer.) Specific resins include, for example, Praiophen VH-4170.
(Manufactured by Dainippon Ink and Chemicals, Inc., etc.), and the softening point of PRIOFEN VH-4170 is 103 to 108 ° C,
The hydroxyl equivalent is about 118. The resin having such a structure improves the heat resistance, room temperature adhesive strength, hot adhesive strength and adhesiveness of the paste cured product or coating film in the composition of the present invention.

The epoxy resin (b) is, for example, Epicoat 827,828,834,1001,1002.
1007,1009 (Shell Chemical Co., trade name), DE
R330, 331, 332, 334, 335, 336,
337,383,660 (trade name, manufactured by Dow Chemical Co.), Araldite GY250, 260, 280, 60
71, 6084, 6097, 6099 (manufactured by Ciba Geigy, trade name), EPI-REZ510, 5101 (JO
NE DABNY, product name), Epicron 81
0,1000,1010,3010 (manufactured by Dainippon Ink and Chemicals, Inc., trade name), EP series manufactured by Asahi Denka Co., Ltd., and the like. Furthermore, when the average number of epoxy groups is 3 or more, for example, when a novolac epoxy resin is used, heat (350 ° C)
The adhesive strength of can be further improved. As these novolac epoxy resins, those having a molecular weight of 500 or more are suitable. Examples of industrially manufactured novolac epoxy resins include the following. Araldite EPN1138, 1139, EC
N1273, 1280, 1299 (Ciba Geigy,
Trade name), DEN431, 438 (trade name, manufactured by Dow Chemical Co., Ltd.), Epicoat 152, 154 (trade name, manufactured by Shell Chemical Co., Ltd.), ERR-0100, ERRB-044
7, ERLB-0488 (manufactured by Union Carbide Co., trade name), EOCN series (manufactured by Nippon Kayaku Co., trade name), etc., and these epoxy resins can be used alone or in combination of two or more. ..

As the fluorine-containing compound (c), those represented by the following general formula 4 are used.

[0014]

[Chemical 4]

This fluorine-containing compound is characterized by having a perfluoromethyl group, and is reacted with an epoxy resin or a bisphenol A novolak resin by the functional groups X and Y to be incorporated into a cured product to form a conductive paste. Provides bleeding resistance and migration resistance. The mixing ratio of this fluorine-containing compound is 1
It is desirable that the amount is 5 to 20 parts by weight with respect to 00 parts by weight.
If the blending amount is less than 5 parts by weight, the bleeding resistance and migration resistance are not effective, and if the blending amount exceeds 20 parts by weight, the coating film of the cured product becomes brittle and stress cannot be relaxed, and the adhesive is unreliable and not preferable ..

The bisphenol A novolac resin, the epoxy resin, and the fluorine-containing compound described above are used by dissolving and mixing with a solvent or by heating and partially binding them. A curing catalyst can also be used if necessary for the reaction. Furthermore, the working viscosity can be improved by dissolving in a solvent common to these resin components. As the solvent used here, dioxane, hexane, toluene, ethyl cellosolve, cyclohexanone,
Butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, diethylene glycol diethyl ether, dimethylformamide, N-methylpyrrolidone, diacetone alcohol, dimethylacetamide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, and the like. Can be used alone or in combination of two or more.

As the (B) composite powder used in the present invention,
The conductive powder and fine silica powder are used together. Examples of the conductive powder include silver powder, powder having a silver layer on the surface, copper powder, nickel powder, carbon and the like, and these may be used alone or in combination of two or more. Examples of the fine silica powder include Aerosil (trade name, manufactured by Nippon Aerogel Co., Ltd.) having an average particle diameter of 1 μm or less, and these can be used alone or in combination.

As the (C) porous filler used in the present invention, any porous filler can be used without particular limitation. Specific examples include talcite (trade name, manufactured by Kyowa Gas Chemical Co., Inc.), Ketjen Black (Ketje
Carbon black manufactured by n company, product name, Celite (Johns
Diatomaceous earth manufactured by Manville, trade name), etc.
These may be used alone or in combination of two or more.

The conductive paste of the present invention contains the above-mentioned modified resin, composite powder and porous filler as essential components, but as long as it does not defeat the purpose of the present invention, and if necessary, a defoaming agent and a coupling agent. , And other additives can be added. After thoroughly mixing the above-mentioned components in a conventional manner,
Further, a kneading process may be performed with a triple roll, and then defoaming under reduced pressure may be performed to produce a conductive paste. The conductive paste thus produced can be used for adhesion of various electronic components, coating, electrode formation by printing, circuit formation, and the like.

[0020]

[Function] The conductive paste of the present invention is bisphenol A.
Novolak resin, epoxy resin, modified resin composed of a fluorine-containing compound having a perfluoromethyl group of the general formula, a composite powder composed of a conductive powder and fine silica powder and a porous filler to achieve the object. is there. In particular, by incorporating the compound of the general formula into a modified resin and introducing a perfluoromethyl group, excellent heat resistance, chemical resistance, and water repellency of fluorine can be imparted, and the surface tension can be reduced. It is possible to improve the wettability with respect to the adhesive or the article to be coated, and as a result, the adhesiveness and adhesion of the conductive paste can be improved. Further, the compound can be reacted with a bisphenol A novolac resin or an epoxy resin to impart bleeding resistance and migration resistance.

[0021]

EXAMPLES The present invention will now 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 epoxy resin Epicoat 828 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), 63 parts of bisphenol A novolac resin, Priofen VH-4170 (trade name, manufactured by Dainippon Ink and Chemicals, Inc.), and General formula

[0023]

[Chemical 5] The compound BIS-AF-G (manufactured by Central Glass Co., Ltd., trade name) (15 parts) was dissolved in 386 parts of butyl cellosolve acetate at 100 ° C. for 1 hour to give a viscous resin.
26.8 parts of this resin, 1.2 parts of an amine complex of boron trifluoride as a catalyst, 0.05 parts of an additive, 69.4 parts of silver powder, 2.4 parts of Aerosil # 200 (manufactured by Nippon Aerogel Co., Ltd., trade name) as fine silica powder, talcite (Kyowa 0.1 part by a gas company was mixed to prepare a conductive paste.

Example 2 100 parts of Epicoat 1001 (manufactured by Yuka Shell Epoxy Co., Ltd., trade name) of epoxy resin, 24 parts of Priofen VH-4170 (manufactured by Dainippon Ink and Chemicals Co., Ltd.) of bisphenol A novolac resin, and General formula

[0025]

[Chemical 6] 10 parts of the compound BIS-A-AF (trade name, manufactured by Central Glass Co., Ltd.) was dissolved in 290 parts of diethylene glycol diethyl ether at 100 ° C. for 1 hour to give a viscous resin. To 26.8 parts of this resin, 1.2 parts of amine complex of boron trifluoride as a catalyst, 0.12 parts of additive, and 69.4 silver powder
Parts, 2.4 parts of Aerosil # 200 (manufactured by Nippon Aerosil Co., Ltd., trade name) as fine silica powder and 0.1 part of Ketjen Black (manufactured by Ketjen Co., Ltd.) were mixed to prepare a conductive paste.

Example 3 100 parts of epoxy resin EOCN103S (manufactured by Nippon Kayaku Co., Ltd.), 26 parts of bisphenol A novolac resin Praiophen VH-4170 (manufactured by Dainippon Ink and Chemicals, Inc.) and general formula

[0027]

[Chemical 7] 15 parts of the compound BIS-AF (trade name of Central Glass Co., Ltd.) represented by
A viscous resin was obtained by performing a dissolution reaction in 151 parts at 100 ° C for 1 hour. Imidazole compound 2 as a catalyst in 30 parts of this resin
pH-CN (manufactured by Shikoku Chemicals Co., Ltd.) 0.1 part, additive 0.1 part, silver powder 65 parts, Aerosil # 200 as fine silica powder (manufactured by Nippon Aerosil Co., Ltd.) 0.8
Part, talcite (manufactured by Kyowa Gas Co., Ltd., trade name) 0.1 part and butyl cellosolve acetate 4 parts were mixed to prepare a conductive paste.

Comparative Example A commercially available epoxy resin-based solvent-type conductive paste for semiconductors was obtained.

The conductive pastes obtained in Examples 1 to 3 and Comparative Example were evaluated for adhesive strength, accelerated migration test, migration resistance and bleeding property. The results are shown in Table 1, and the present invention was excellent in all cases, and the remarkable effect of the present invention was recognized.

[0030]

[Table 1] * 1: 2.0 × on a silver-plated lead frame (copper-based)
A 2.0 mm silicon element was adhered and measured using a tension gauge at a temperature of 25 ° C. * 2: 2.0 × on a silver-plated lead frame (copper-based)
A 2.0 mm silicon element is bonded and 121 ° C x 100% R.S. H
After the treatment of × 2atm × 24 hours, the temperature was measured at 25 ° C using a tension gauge. * 3: Conductive paste is screen-printed on a slide glass, surface resistance after curing is measured, and converted to volume resistivity. * 4: As shown in Fig. 1, the conductive paste 2 is screen-printed on the slide glass 1 so that a discontinuous portion 3 having a width of 5 mm and a thickness of 20 µm and a width of 2 mm is provided in the middle, and the width of 2 m is obtained.
Distilled water 4 was added dropwise to the m 3 discontinuous portion 3, a DC voltage of 5 V was applied, and the time until the current leaked was measured. * 5: Test piece of * 4 temperature 60 ℃, humidity 95%, applied voltage D
It was observed at a predetermined time under the condition of C30V, and the time when migration first occurred was measured. * 6: The test piece of * 2 was observed 24 hours after PCT and before measuring the adhesive strength. ○: No bleed, △: Slight bleed, ×:
There is remarkable bleeding.

[0031]

As is clear from the above description and Table 1, the conductive paste of the present invention has excellent adhesiveness, migration resistance and bleeding resistance even under high temperature and high humidity conditions, and exudes conductive powder. There is no good. By using this conductive paste, a highly reliable electronic component can be manufactured.

[Brief description of drawings]

FIG. 1 is a plan view of a test piece used for an accelerated migration test and a migration resistance test.

[Explanation of symbols]

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

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // H05K 3/32 B 9154-4E

Claims (1)

[Claims] 1. (A) (a) Bisphenol A novolac resin (b) Epoxy resin and (c) Fluorine-containing compound represented by the general formula: A conductive paste comprising a modified resin consisting of (B), a composite powder consisting of a conductive powder and a fine silica powder, and (C) a porous filler as essential components.