JPH02244506A - Electroconductive paste - Google Patents

Abstract

PURPOSE:To obtain conductive paste with high adhesiveness by forming it from epoxy compound, hardening agent, epoxy resin benzophenon series imido group, and conductive powder. CONSTITUTION:Novolac epoxy resin having a mean epoxy group of no less than three and a molecular weight of no less than 500 is used to epoxy compound, and th adhesion strength at 350 deg.C is enhanced to a great extent. Commercially available novolac epoxy resin may be used solely or in a mixture. It may be diluted with monofunctional epoxy compound with low viscosity. A hardening agent employed may be usually used imidasol type or phenol type compound. Epoxy resin having benzophenon series imido group shall have both epoxy group and benzophenon group in one compound and contains 5-80wt.% of the total amount of resin components. Conductive powder used shall be of Ag, Cu, etc., having a mean particle dia. of 10mum or less, and its mix proportion with resin components preferably be 30/70 through 10/90. The viscosity is adjusted with organic solvent, and a hardening catalyst, etc., may be added.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is a conductive paste used in the assembly of semiconductor devices, etc. This invention relates to a conductive paste with improved adhesiveness to accommodate shortening.

(Prior Art) In the manufacture of semiconductor devices, the process of connecting semiconductor chips such as ICs and LSIs to predetermined portions on a thin metal plate (lead frame) is one of the important processes that affects the long-term reliability of semiconductor devices. It is one.

Conventionally, the mainstream connection method has been the Al1-3i eutectic method in which the silicon surface of the semiconductor chip is pressure-bonded to the gold-plated surface of the lead frame. In recent years, with the rise in the price of precious metals, especially gold, resin-encapsulated semiconductor devices have changed from the Au-8i eutectic method to methods using solder.
There is a rapid shift to methods using conductive paste. However, although some methods using solder have been put into practical use, it has been pointed out that the solder and solder balls scatter and adhere to electrodes and the like, causing corrosion and disconnection.

On the other hand, the method using conductive paste, which uses epoxy resin mixed with silver powder, etc., has been put into practical use for about 10 years, and has advantages such as superior heat resistance compared to the soldering method.

(Problems to be Solved by the Invention) On the other hand, the method using conductive paste has the disadvantage that the resin and curing agent used are not made for bonding semiconductor chips, so impurities contained in the paste may cause This often promoted corrosion of the aluminum electrode and caused disconnection defects, and the reliability of the device was still inferior to that of the Au-3i eutectic method. , In addition, in recent years, IC/LS
With the increase in the size of semiconductor chips such as I and LEDs and the appearance of various frames such as Cu materials, the adhesive strength of chips has become a problem, and there is a demand for the development of conductive base l- with high adhesive strength. Ta.

The present invention was made in view of the above circumstances and drawbacks, and
The purpose is to provide a conductive base with improved adhesiveness that is compatible with larger semiconductor chips, shorter assembly processes, and the use of Cu material frames.

[Structure of the Invention] (Means for Solving Problems) As a result of intensive research to achieve the above object, the present inventors have found that the above object can be achieved by using a paste with a specific composition. The present invention has been completed by discovering that the present invention is possible. That is, the present invention provides a conductive paste comprising (A) an epoxy compound, (B) a curing agent, (C) an epoxy resin having a benzophenone imide group, and (D) a conductive powder. It is.

The present invention will be explained in detail below.

Among the industrially produced epoxy compounds (A) that can be effectively used in the present invention, there are the following. For example, Epicote 827, 828, 8
31i, 1001, 1002゜1007.1009 (
Shell Chemical Co., Ltd., trade name), DER330, 331, 33
2,334,335°336.337,660 (manufactured by Dow Chemical Company, trade name), Araldite GY250,
260°28O, 607m, 6084.6097609
9 (manufactured by Ciba Geigy, product name), EPI-REZ5
10 5101 (manufactured by JONE DABNEY, product name), Ebikuron 810°1000.1010.301
0 (manufactured by Dainippon Ink Chemical Co., Ltd., trade name), E manufactured by Asahi Denka Co., Ltd.
Examples include the P series. Furthermore, the epoxy compound has an average number of erodible groups of 3 or more and a molecular weight of 50.
For example, by using a novolac epoxy resin that satisfies these conditions, the adhesive strength at high temperatures (350"C) can be further improved. Examples of novolac epoxy resins include Araldite, for example. EPN-1138, 1139゜ECN1273
, 1280.1299 (manufactured by Ciba Kaigy Co., Ltd., product name)
, DEN431,438 (manufactured by Dow Chemical Company, trade name), Epicote 152°154 (manufactured by Shell Chemical Company, trade name), ERR-0100, ERRB-0447, ER
LB0488 (manufactured by Union Carbide, product name)
, the EOCN series manufactured by Nippon Kapaku Co., Ltd., and the like.

These epoxy compounds may be used alone or in combination of two or more. Furthermore, the above epoxy compound may be diluted with a monofunctional low viscosity epoxy compound.

As the curing agent (B) used in the present invention, any curing agent that can be used as a curing agent for ordinary epoxy resins can be used. Examples of these curing agents include imidazole compounds, phenol compounds, and polyamine acid anhydrides, which may be used alone or in combination of two or more.

The epoxy resin (C) having a benzophenone imide group used in the present invention has an evoz3i- group and a benzophenone group in the - compound, and for example, one having the following structural formula can be used.

These epoxy resins having a benzophenone imide group can be used alone or in a mixture of two or more. The blending ratio of the epoxy resin having benzophenone imide groups is based on the total amount of resin components excluding the conductive powder [(A
) The content is desirably 5 to 80% by weight based on 10 (B) and (C)].

If the amount is less than 5% by weight, it is not effective in improving adhesive strength, and if it exceeds 80% by weight, the reactivity tends to be poor, which is not preferable.

Examples of conductive powders used in the present invention (D>) include silver powder, copper powder, nickel powder, and inorganic or organic powders having a metal layer on the surface. It is preferable that these conductive powders have an average particle size of 10 μm or less. If the average particle size exceeds 10 μm, it will be impossible to fill the powder with high density, and it will not form into a paste or will not be coated properly. This is because performance deteriorates.The blending ratio of the binder, which is a resin component, and the conductive powder is preferably 30/70 to 10/90 in terms of heavy lid ratio.If the conductive powder is less than 70 parts by weight, Sufficient conductivity cannot be obtained, and if it exceeds 90 parts by weight, workability and adhesion deteriorate, which is not preferable.

For the conductive paste of the present invention, an organic solvent can be used as necessary to adjust the viscosity.

Examples of the solvents include methyl cellosolve, ethyl cellosolve, butyl cellosolve and their acetates, diethylene glycol diethyl ether, and the like.

The conductive paste of the present invention contains an epoxy compound, a hardening agent,
The essential ingredients are an epoxy resin having a benzophenone imide group and a conductive powder, but if necessary, an antifoaming agent,
Coupling agents, curing catalysts, and other additives may be added and blended.

The conductive paste can be manufactured by blending and thoroughly mixing the above-mentioned components according to a conventional method, and then kneading the mixture using, for example, three rolls, followed by degassing under reduced pressure. The conductive paste produced in this way can be used for bonding semiconductor chips, joining semiconductor parts, and the like.

(Example) Next, the present invention will be explained by Examples, but the present invention is not limited by these Examples. In the following Example 01 and Comparative Examples, r part j is " Parts by weight.

Example l Epoxy compound EP4400 (manufactured by Jiryuka Co., Ltd., trade name)
7.6 parts, marcarinic power of parahydroxystyrene - M
(manufactured by Marukubi Petrochemical Co., Ltd., trade name) 5.6 parts, 062 parts of an epoxy resin having a benzophenone imide group, 10.4 parts of γ-glycidoxyprobyltrimethoxysilane, and 4.0 parts of diethylene glycol diethyl ether. 1
A dissolution reaction was carried out at 00°C for 1 hour to obtain a viscous brown resin composition. To 2768 parts of this resin composition, 2P HZ-CN (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name) was added as a catalyst.
0.006 part and 70 parts of silver powder were mixed to produce conductive paste <A).

Example 2 20.0 parts of the epoxy compound Epicote 828 (manufactured by Shell Chemical Co., Ltd., trade name), 0.1 part of an epoxy resin having a benzophenone imide group, and 4.0 parts of diethylene glycol diethyl ether were dissolved and reacted at 100°C for 1 hour. A viscous brown resin composition was obtained. A conductive paste (B) was prepared by mixing 27.8 parts of this resin composition with 006 parts of 2Pf (Z-CN (described above)) as a catalyst and 70 parts of silver powder.

Real square nail f row 3 Epoxy compound Epicote 828 (supra) io.

10.
0 parts, 0.1 parts of epoxy resin having a benzophenone imide group, and 4.0 parts of butyl cellosolve at 100°C.
A dissolution reaction was carried out for 1 hour to obtain a viscous brown resin composition. 2PH was added as a catalyst to 27.8 parts of this resin composition.
A conductive paste (C) was prepared by mixing 0.006 parts of 2-CN (mentioned above) and 70 parts of silver powder.

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

Conductive bases produced in Examples 1 to 3 and comparative examples (
Using A), (B), (C), and (D), the semiconductor chip was bonded and cured to a 42A L frame and a Cu lead frame. An adhesive strength test was conducted on this, and the results are shown in Table 1 along with the adhesive conditions. The adhesive strength of the present invention was inferior, confirming the remarkable effects of the present invention.

Table 1 (Units) *1: 4111 on a silver-plated lead frame
A silicon chip of Ix 121m was bonded and measured using a push-pull gauge at each temperature.

[Effect of the Invention 1] As is clear from the above explanation and Table 1, the conductive base of the present invention has remarkable adhesion properties, especially adhesion properties under heat, and is difficult to adhere to large chips and assemble. It is possible to manufacture a highly reliable semiconductor device that can accommodate shortening.

Claims (1)

[Scope of Claims] 1. A conductive paste characterized by having as essential components (A) an epoxy compound, (B) a curing agent, (C) an epoxy resin having a benzophenone imide group, and (D) a conductive powder. .