JPS6232158A - Electrically conductive paste - Google Patents

Abstract

PURPOSE:To obtain an electrically conductive paste which does not cause the breaking of wires due to corrosion and has excellent adhesion, by blending a modified resin, a monofunctional epoxysilane monomer, a norbornene ring- contg. resin and electrically conductive powder. CONSTITUTION:An electrically conductive paste contains a modified resin composed of poly-p-hydroxystyrene and an epoxy resin, a monofunctional epoxysilane monomer, a norbornene ring-contg. resin and electrically conductive powder. Examples of the monofunctional epoxysilane monomers are beta-(3,4- epoxycyclohexyl) ethyltri-methoxysilane and gamma-glycidoxypropyltrimethoxysilane. Even when said paste is cured by heating at 200 deg.C, lead from a is not stainned, a bond strength of 0.5kg/mm<2> or above, required for semiconductor pellet bending can be obtd. and a wire bonding strength of 4-5g can be obtd.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a conductive paste used in the assembly of semiconductor devices, and more specifically, to a conductive paste that can be used to increase the size of semiconductor pellets and shorten the Nahinburi process. , Concerning a fast-curing conductive paste that does not cause corrosion and disconnection of wiring and has excellent adhesive properties.

[Technical background of the invention and its problems] ICs and LSs are installed at predetermined parts on a thin metal plate (lead frame).
The process of connecting semiconductor pellets such as I is one of the important processes that affects the long-term reliability of the device. Conventionally, this connection method involves heating and pressing the silicon surface of the pellet to the gold-plated surface of the lead frame.
-8i eutectic method was the mainstream. However, with the rise in the price of precious metals, especially gold, in recent years, resin molded semiconductor devices are rapidly shifting from the Au3i method to methods using solder, conductive paste (adhesive), etc. be.

However, although some methods using solder have been put into practical use, it has been pointed out that the solder and solder balls may scatter and adhere to electrodes, etc., causing corrosion and disconnection. On the other hand, in the method of using conductive paste (adhesive), epoxy resin mixed with silver powder is usually used, and it has been partially put into practical use for about 10 years, but Au-3i Compared to the eutectic method for producing eutectic alloys, no results were found to be satisfactory. When using conductive paste (adhesive), it has advantages such as superior heat resistance compared to soldering, but on the other hand, resin and its hardener are made for bonding semiconductor elements. As a result, corrosion of the aluminum electrode is promoted, often causing disconnection defects, and the reliability of the device is inferior to that of the Al1-3i eutectic method. In recent years, with the increase in the size of semiconductor pellets such as IC/LSI and LED, the occurrence of pellet cracks and a decrease in adhesive strength have become a problem. There was a strong demand for the development of a sex paste.

[Object of the Invention] The object of the present invention was made in view of the above-mentioned circumstances and drawbacks, and it is possible to cope with the increase in the size of semiconductor pellets and the shortening of the assembly process, as well as to eliminate corrosion fronts of wiring and improve adhesiveness. The present invention aims to provide a fast-curing conductive paste that has excellent hydrolysis resistance and does not generate voids.

[Summary of the Invention] As a result of intensive research aimed at achieving the above object, the present inventors have found that a conductive paste having the composition described below has excellent adhesiveness and hydrolysis resistance, and has high speed curing without generating voids. This discovery led to the completion of the present invention. That is, the present invention is characterized by (A>modified resin consisting of polyvarahydroxystyrene and epoxy resin, (B) epoxysilane monofunctional monomer, (C) resin having a norbornene ring, and (Dollt-like powder and gold powder). It is a conductive paste.

Polyparahydroxystyrene, which is a modified resin composed of polyparahydroxystyrene and an epoxy resin used in the present invention, is a resin represented by the following formula.

An example of such a resin is Maruzen Resin M (trade name, manufactured by Maruzen Sekiyu Co., Ltd.). This resin has a molecular weight of 3,000 to 8,000 and a water m-based weight of about 120.

Epoxy resins used in the modified resin include dieboxides of bisphenols such as those listed below, which are industrially produced and can be effectively used in the present invention. Epicoat 827, 828 manufactured by Shell Chemical Co., Ltd.
,834.1001゜1002.1004,1007.
1009, manufactured by Dow Chemical Company, DER330, 331,
332°334.335,336,337,660°6
61.662, 667.668, 669, manufactured by Ciba Geigy, Araldai 1~GY250.260°280.6
071.6084.6097゜6099, JONES
DABNEY EPI-REZ510, 5101,
Manufactured by Dainippon Ink Chemical Co., Ltd., Ebikuron 810.100
0.1010°3010 (all product names) and Asahi Denkasha! There is a uEP series. By using, for example, a novolac epoxy resin having an average number of epoxy groups of 3 or more as the epoxy resin, the adhesive strength under heat (350° C.) can be further improved. Suitable novolak epoxy resins have a molecular weight of 8,500 or more. Examples of industrially produced novolak epoxy resins include the following: Manufactured by Ciba Geigy, Araldai, EP
N1138°1139, ECN1273.1280.1
299, manufactured by Dow Chemical Company, DEN431.438, manufactured by Shell Chemical Company, Epicote 152, 154, manufactured by Union Carbide Company, ERR-0100, ERRB-0447
, ERLB-0488, EOCN series manufactured by Nippon Kayaku Co., Ltd., etc.

Examples of the epoxysilane monofunctional monomer (B) used in the present invention include β-(3,4 epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxyprobyltrimethoxysilane, γ-glycidoxybrobylmethyl Examples include di-earthoxysilane, which may be used alone or in combination
Use by mixing more than one species. Polyparahydroxystyrene, epoxy resin, and epoxysilane monofunctional monomer are blended in approximately equivalent amounts. If the blending ratio deviates significantly from the equivalent range, one of the components will remain unreacted during curing.
This is not preferable because the adhesive strength and heat loss during heating increase.

Examples of the resin having a norbornene ring (C) used in the present invention include petroleum resins, which are general-purpose resins obtained from 05 to C3 fractions of petroleum. For example, commercially available Celloxide 4000 (manufactured by Daicel Corporation, trade name), Takki Roll 1000 (manufactured by Sumitomo Chemical Co., Ltd., trade name), Finton 1500° 1000, 1300 (manufactured by Nippon Zeon Co., Ltd.,
(trade name), and these may be used alone or in combination of two or more. The blending ratio of the resin having a norbornene ring is
It is desirable to mix 0.5 to 15% by weight based on the total amount of the modified resin consisting of polyvarahydroxystyrene and epoxy resin and the epoxysilane monofunctional monomer. If the amount is less than 0.5% by weight, it is not effective in improving adhesive strength, and if it exceeds 15% by weight, the reactivity tends to be poor, which is not preferable.

When blending (A> modified resin consisting of polyvarahydroxystyrene and epoxy resin, (B) epoxysilane monofunctional monomer, and (C) resin having a norbornene ring used in the present invention, simply add each component and a solvent. However, it is preferable to first dissolve the modified resin in an epoxysilane monofunctional monomer and then mix the resin having a norbornene ring.Also, the modified resin can be prepared by simply dissolving the polyvarahydroxystyrene and the epoxy resin. They may be melted and mixed, or if necessary, they may be partially bonded to each other by a heating reaction, and the working viscosity can be improved by dissolving these modified resins in a common solvent. A curing catalyst may also be used if necessary.The solvents used here for viscosity adjustment include dioxane,
hexanone, benzene, toluene, solvent naphtha,
Examples include industrial gasoline, vinegar mtrosolve, ethyl cellosolve, butyl cellosolve acetate, butyl carpitol acetate tylacetamide, N-methylpyrrolidone, etc., and these may be used alone or in combination of two or more.

As the conductive powder (D) used in the present invention, for example, silver powder or the like is used.

The conductive paste of the present invention contains a modified resin made of polyvarahydroxystyrene and an epoxy resin, an epoxysilane monofunctional monomer, and a resin having a norbornene ring.
Antifoaming agents, coupling agents and other additives can be added as necessary.

The conductive paste of the present invention is prepared by thoroughly mixing the above-mentioned modified resin, epoxysilane monofunctional monomer, norbornene ring-containing resin, and conductive powder according to a conventional method, and then kneading the paste using, for example, a three-roll mill. Manufactured by degassing under reduced pressure. After bonding the semiconductor pellet and the lead frame using the conductive paste produced in this way, wire A7 bonding is performed, and then the semiconductor pellet is sealed to produce an IC and an LSI. The semiconductor device obtained in this way has no contamination on the lead frame surface even when the conductive paste is heat-cured at 200°C, and the adhesive strength is higher than the value of 0.5 klJ/ml12 required for semiconductor pellet adhesion, and wire bonding. Similarly, the strength can be 19 times higher than the value of 4 to 5 g.

[Examples of the Invention] Next, the present invention will be explained by examples, but the present invention is not limited by these examples. Examples and comparative examples. Unless otherwise specified, ``bu'' means ``emperor's department.''

Example 1 Epoxy resin EP4400 (manufactured by Layaseika Co., Ltd., trade name)
7.6 parts, parahydroxystyrene Maruzen Resin M
(manufactured by Maruzen Oil Co., Ltd., trade name) 5.6 parts, Celoxide 4000, a resin having a norbornene ring (manufactured by Daicel Corporation, trade name) 0.2 parts, γ-glycidoxypropyltrimethoxysilane 10.4 parts, A dissolution reaction of 4.0 parts of diethylene glycol diethyl ether was carried out at 100° C. for 1 hour to obtain a viscous brown resin. 2PHZ-CN (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name) as a catalyst was added to 27.8 parts of this resin.
．． 006 parts and 70 parts of silver powder were mixed to produce a conductive paste (A).

Example 2 7.6 parts of epoxy resin EP4400 (listed above), 5.6 parts of rose hydroxystyrene Marzen Resin M (listed above), 1.0 part of Celoxide 4000 (listed above), β-(3
, 4epoxycyclohexyl)ethyltrimethoxysilane and 4.0 parts of diethylene glycol diethyl ether were dissolved and reacted at 100° C. for 1 hour to obtain a viscous brown resin. 21.8 parts of this resin and 2P as a catalyst
A conductive paste (B) was prepared by mixing 0.006 parts of H2-CN (described above) and 70 parts of silver powder.

Example 3 Epoxy resin EP4400 (above) 7.6 parts, rose hydroxystyrene Maruzen Resin M (above) 5.6 parts
parts, 1.5 parts of celloxide 4000 (previously mentioned), 10.4 parts of γ-glycidoxypropylmethyljethoxysilane, and 4.0 parts of diethylene glycol diethyl ether.
A dissolution reaction was carried out at 00°C for 1 hour to obtain a yellow viscous resin. 2PH2-CN was added to 27.8 parts of this resin as a catalyst.
(Supra) 0.006 parts and 70 parts of silver powder were added and thoroughly mixed to produce a conductive paste (C).

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

Conductive pastes obtained in Examples 1 to 3113 and comparative examples (
A), (B), (C) and (D) were used to bond and cure the semiconductor pellet and the lead frame. Regarding these, adhesive strength, presence or absence of voids,
A test for hydrolyzable c1 ions was conducted. The results are shown in Table 1, and it was possible to confirm the remarkable effects of the present invention.

Table 1 *1: A 4 mm x 4 mm silicon element was adhered onto a silver-plated lead frame (4270), and measurements were taken at each temperature using a push-pull gauge.

*2: MO of CI ions obtained by curing the conductive paste under the adhesive conditions shown in Table 1, crushing it into 100 meshes, and performing heating extraction at 180°C for 2 hours [Effect of the invention] The conductive paste of the present invention , because there is little scattered solvent, no voids occur, and the adhesive properties are excellent, especially when hot.
The paste also has excellent hydrolysis resistance, has no defects such as disconnection due to corrosion of the wiring metal, or defects due to leakage current due to moisture, and is a fast-curing paste. If this conductive paste is used, it is possible to manufacture highly reliable large-sized pellet semiconductor devices, and the assembly process can be greatly shortened, which is very useful industrially.

Claims (1)

[Claims] 1. Contains (A) a modified resin consisting of polyparahydroxystyrene and an epoxy resin, (B) an epoxysilane monofunctional monomer, (C) a resin having a norbornene ring, and (D) a conductive powder. A conductive paste featuring: