JPH0690883B2 - Conductive paste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a conductive paste that is compatible with the increase in size of semiconductor chips and the shortening of the assembly process. It has excellent hydrolyzability, has no voids, and has the advantage that it can be cured at high speed.

(Prior Art) The step of connecting a semiconductor chip such as an IC or LSI to a predetermined portion on a thin metal plate (lead frame) is one of the important steps that affects the long-term reliability of an integrated circuit. Conventionally, as the connection method, an Au-Si eutectic method has been mainstream in which the silicon surface of the chip is thermocompression bonded to the gold-plated surface on the lead frame.

However, in recent years, with the rise of precious metals, especially gold, resin-encapsulated semiconductor devices are rapidly shifting from the Au-Si eutectic method to the method using solder, the method using conductive paste, etc. is there.

(Problems to be solved by the invention) However, although some methods using solder have been put into practical use, it is pointed out that solder or solder balls may scatter and adhere to electrodes or the like, which may cause corrosion disconnection. Has been done. On the other hand, in the method of using a conductive paste, usually, an epoxy resin mixed with silver powder is used, and it has been partially put into practical use for about 10 years, but in terms of reliability, it is an Au-Si eutectic crystal. No satisfactory results were obtained compared to the eutectic method for forming alloys.
When using a conductive paste, it has advantages such as superior heat resistance compared to the soldering method, but on the other hand, the resin and its curing agent are not intended for bonding semiconductor elements. In many cases, the corrosion of the aluminum electrode was promoted to cause a disconnection failure, and the device reliability was inferior to that of the Au-Si eutectic method. Furthermore, with the recent increase in the size of semiconductor chips such as ICs, LSIs, and LEDs, the occurrence of chip cracks and the reduction in adhesive strength have become problems, and the shortening of the assembly process is required. Was strongly requested.

The present invention has been made in view of the above circumstances, and corresponds to the increase in the size of the semiconductor chip, the shortening of the assembly process, there is no corrosion disconnection of the wiring, adhesiveness, hydrolysis resistance, fast curing The purpose of the present invention is to provide a conductive paste which is excellent in reliability and has high reliability without generation of voids.

[Structure of the Invention] (Means for Solving the Problem) As a result of intensive studies conducted by the present inventors in order to achieve the above-mentioned object, the paste to be described later has adhesiveness, hydrolysis resistance, and
The present invention has been completed by finding out that it is a highly reliable conductive paste that is excellent in high-speed curing property and has few voids.

That is, the present invention includes (A) a modified resin composed of polyparahydroxystyrene and an epoxy resin, (B) a resin having a norbornene ring, (C) a silane coupling agent having a ureido group, and (D) a conductive powder. The conductive paste is characterized by containing, as an essential component.

The modified resin composed of polyparahydroxystyrene and an epoxy resin (A) used in the present invention is obtained by mixing or reacting polyparahydroxystyrene and an epoxy resin. The polyparahydroxystyrene used here is a resin represented by the following formula, For example, Maruka Linker M (trade name, manufactured by Maruzen Petrochemical Co., Ltd.)
Etc. This resin has a molecular weight of 3000 to 8000 and a hydroxyl group equivalent of about 120. As the epoxy resin, there are, for example, the following diepoxides of bisphenols that are industrially produced and can be effectively used in the present invention. Shrimp Court 827,828,834,100
1,1002,1007,1009 (Shell Chemical Co., Ltd., trade name), DER33
0,331,332,334,335,336,337,660 (trade name of Dow Chemical Co.), Araldite GY250,260,280,6071,6084,6097,6
099 (Ciba Geigy, trade name), EI-REZ510,5101
(JONE, manufactured by DABNEY, trade name), Epicron 810,1000,1
010,3010 (Dainippon Ink and Chemicals, Inc., trade name), EP series (Asahi Denka Co., Ltd., trade name), etc.

Furthermore, 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 when heated (350 ° C) can be further improved. The molecular weight of these novolac epoxy resins is
500 or more is suitable. Examples of such novolac epoxy resins industrially produced include the following. Araldite EPN1138,1139, ECN
1273,1280,1299 (Ciba-Geigy product name), DEN43
1,438 (trade name, manufactured by Dow Chemical Company), Epicoat 152,1
54 (manufactured by Shell Chemical Co., Ltd., trade name), ERR-0100, ERRB-044
7, ERLB-0488 (made by Union Carbide, product name), EO
There are CN series (manufactured by Nippon Kayaku Co., Ltd., etc.). These epoxy resins can be used alone or in combination of two or more.

The polyparahydroxystyrene and the epoxy resin may be simply dissolved and mixed, or they may be heated to react with each other to partially bond each other,
The working viscosity can be improved by dissolving these component resins in a common solvent. If necessary for the reaction, a curing catalyst may be used.

The resin having a norbornene ring (B) used in the present invention includes a petroleum resin and the like, which is a general-purpose resin obtained from a C _{5 to} C ₉ fraction of petroleum. As commercially available products, for example, Celoxide 4000 (manufactured by Daicel, trade name), Tatsuki Roll 1000 (manufactured by Sumitomo Chemical Co., Ltd.), Kraton 1500,1
000,1300 (manufactured by Nippon Zeon Co., Ltd., trade name) may be mentioned, and these may be used alone or in admixture of two or more. The compounding ratio of the resin having a norbornene ring is 10 to 30 with respect to the total resin content.
It is desirable to blend the composition in a weight percentage. If the blending amount is less than 10% by weight, there is no effect in improving the adhesive strength, and if the blending amount exceeds 30% by weight, the reactivity tends to be poor, which is not preferable.

When polyparahydroxystyrene, an epoxy resin, and a resin having a norbornene ring are simply dissolved and mixed in a solvent, they may be added at the same time and dissolved, but first, the polyparahydroxystyrene is dissolved in the solvent, and then the epoxy resin is added. It is preferable to dissolve and mix the resin and the resin having a norbornene ring. Solvents used here include dioxane, hexane, benzene, toluene, solvent naphtha, industrial gasoline, cellosolve acetate, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc. These are used alone or in combination of two or more.

The silane coupling agent having a ureido group (C) used in the present invention is a coupling agent that imparts particularly rapid curing property to the conductive paste of the present invention. Examples of the silane coupling agent having a ureido group (C) include γ-ureidoethyltrimethoxysilane and γ-ureidopropyltrimethoxysilane, which may be used alone or in combination of two or more. The compounding ratio of the silane coupling agent having an ureido group is 0.01 with respect to 100 parts by weight of the conductive powder.
It is preferable to blend 5 to 5 parts by weight. More preferably 0.
Add from 05 to 1.0 parts by weight. If the blending amount is less than 0.01 parts by weight, sufficient rapid curing property cannot be obtained, and if it exceeds 5 parts by weight, voids of the conductive paste increase, which is not preferable.

Examples of the (D) conductive powder used in the present invention include silver powder and metal powder having a silver layer on the surface.

The conductive paste used in the present invention contains a modified resin composed of polyparahydroxystyrene and an epoxy resin, a resin having a norbornene ring, and a silane coupling agent having a ureido group as essential components, but it does not meet the purpose of the present invention. Other additives may be added and blended as necessary within the range not to be met. The manufacturing method of this conductive paste is
The above-mentioned modified resin according to a conventional method, a resin having a norbornene ring, a silane coupling agent having an ureido group, a conductive powder and other components are sufficiently mixed and then further kneaded by, for example, a three-roll mill, After that, degassing is performed under reduced pressure to manufacture. The conductive paste thus manufactured is filled in a syringe and discharged onto a lead frame using a dispenser and used for high-speed bonding of semiconductor chips or the like.

(Examples) 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 37.5 parts of Epoxy resin Epicoat 1001 (manufactured by Shell Chemical Co., Ltd.), 10 parts of polyparahydroxystyrene Marcalinker M (manufactured by Maruzen Petroleum Co., Ltd.), and Quinton 1300 (Norbornene ring resin) Made by Zeon,
A viscous resin was obtained by dissolving 10 parts of the product (trade name) in 103 parts of diethylene glycol diethyl ether at 100 ° C. for 1 hour. In 22 parts of this resin, an amine complex of BF ₃ was used as a catalyst.
A conductive paste (I) was prepared by mixing 1.0 part, 0.03 part of γ-glycidoxypropyltrimethoxysilane, and 57 parts of silver powder.

Example 2 Epoxy resin Epicoat 828 (manufactured by Shell Chemical Co., Ltd., trade name) 15.8 parts, polyparahydroxystyrene marcalinker M (previously described) 10 parts, and Norbornene ring-containing resin Tatsukiro 1000 (manufactured by Sumitomo Chemical Co., Ltd., A viscous resin was obtained by performing a dissolution reaction of 10 parts (trade name) in 56 parts of butyl cellosolve acetate at 100 ° C for 1 hour. In 22 parts of this resin,
A conductive paste (II) was manufactured by mixing 1.0 part of an amine complex of BF ₃ as a catalyst, 0.03 part of γ-glycidoxypropyltriethoxysilane, and 57 parts of silver powder.

Example 3 Epoxy resin EOCN103S (manufactured by Nippon Kayaku Co., trade name) 66 parts,
Parahydroxystyrene Marker Linker M (supra) 34
Part, and Quinton 1700, a resin having a norbornene ring
Six parts (manufactured by Nippon Zeon Co., Ltd.) were dissolved in 117 parts of butyl carbitol acetate at 100 ° C. for 1 hour to give a viscous resin. 22 parts of this resin was mixed with 1.0 part of an amine complex of BF ₃ as a catalyst, 0.03 part of γ-glycidoxypropyltrimethoxysilane, and 57 parts of silver powder to prepare a conductive paste (III).

Comparative Example A commercially available epoxy resin-based conductive paste (IV) for a semiconductor was obtained.

Conductive pastes (I) obtained in Examples 1 to 3 and Comparative Example,
Using (II), (III) and (IV), a large-sized semiconductor chip of 4 × 4 mm and a lead frame are bonded at 170 ° C. and 300 ° C. for a predetermined time shown in Table 1 for a predetermined time. Then, the adhesive was cured to manufacture a semiconductor device. About the obtained semiconductor device, the adhesive strength, the presence or absence of voids,
The results of hydrolysis tests were shown in Table 1, and the remarkable effects of the present invention were confirmed. Each test was conducted as follows.

The adhesive strength was measured using a push-pull gauge at room temperature and a temperature of 350 ° C. after bonding a 4 × 4 mm silicon chip on a lead frame (42 alloy) plated with silver having a thickness of 200 μm. For hydrolyzability, the conductive paste is hardened under the same conditions as the semiconductor chip bonding conditions, then crushed to 100 mesh and heat extracted at 180 ° C for 2 hours.
The amounts of l-ions and Na-ions were measured by ion chromatography.

[Effects of the Invention] As is clear from the above description and Table 1, the conductive paste of the present invention is excellent in adhesiveness, hydrolysis resistance, and fast curing property, and has no wiring corrosion or voids and is reliable. It has high quality. By using this conductive paste, it is possible to cope with an increase in the size of a semiconductor chip and a shortening of the assembly process.

Claims (1)

[Claims] 1. A modified resin comprising (A) polyparahydroxystyrene and an epoxy resin, (B) a resin having a norbornene ring, (C) a silane coupling agent having a ureido group, and (D) a conductive powder. An electrically conductive paste characterized by comprising as an essential component.