JPH064814B2 - Paste for mounting semiconductor pellets - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a paste used for assembling (assembling) a semiconductor device, and more particularly to increasing the size of a semiconductor pellet and shortening the assembly process. The present invention relates to a rapid-curing paste which is improved as described above and has excellent adhesiveness without corrosion breakage of wiring.

[Technical Background of the Invention and Problems Thereof] In the process of assembling a semiconductor device, the process of mounting and electrically connecting a semiconductor pellet such as an IC or an LSI on a predetermined portion of a metal thin plate (lead frame) is a long-term reliability of the device. It is one of the important processes that affect sex. Conventionally, as this connection method, an Au-Si eutectic method has been mainstream, in which the silicon surface of the semiconductor pellet is thermocompression bonded to the gold-plated surface on the lead frame. However, in recent years, with the surge of precious metals, especially gold, resin-molded semiconductor devices have
The Au-Si eutectic method is rapidly changing to a method using solder, a method using a conductive paste, or the like.

However, although the method using solder has been partially put into practical use, it has been pointed out that solder or solder balls may scatter and adhere to electrodes or the like, which may cause corrosion breakage. On the other hand, in the method using the conductive paste, an epoxy resin mixed with silver powder is usually used, and it has been partially put into practical use for about 10 years, but in terms of reliability, an Au-Si eutectic alloy is used. No satisfactory results were obtained compared to the eutectic method used. When a conductive paste is used, it has advantages such as excellent heat resistance as compared with the soldering method, but on the other hand, since the resin or the curing agent is not made for bonding semiconductor elements, In many cases, it promotes corrosion of the aluminum electrode and causes a disconnection failure.
It was inferior to the Si eutectic method. Further, this method has an advantage that it can greatly contribute to productivity improvement, but in the case of MOSIC, it is necessary to connect the back surface of the pellet to the frame in order to draw out the sub-electrode from the bonding pad on the semiconductor pellet. Notwithstanding, expensive silver paste is used, and there is a drawback that the cost becomes high.

[Object of the Invention] The present invention has been made in order to solve the above-mentioned drawbacks, and its purpose is to cope with an increase in the size of a semiconductor pellet and a shortening of the assembly process, and to prevent the wiring from corroding and breaking, and to improve the adhesiveness. Another object of the present invention is to provide a paste that is excellent in hydrolysis resistance, does not generate voids, is fast curable, and can contribute to cost reduction.

[Summary of the Invention] As a result of intensive studies to achieve the above object, the present inventors have achieved the above object by using a filler having good thermal conductivity without using silver powder. The inventors have completed the present invention by finding that an excellent paste that can contribute to cost reduction can be obtained. That is, the present invention is characterized by including (A) a modified or mixed resin composed of polyparahydroxystyrene and an epoxy resin, (B) epoxysilane (C) a thermally conductive filler, and used for mounting a semiconductor pellet. It is a paste.

The modified or mixed resin (A) used in the present invention is a modified resin obtained by reacting polyparahydroxystyrene and an epoxy resin, or a resin obtained by mixing polyparahydroxystyrene and an epoxy resin (including this mixed resin. And will be referred to as modified resin below). One of the components, polyparahydroxystyrene, is a resin represented by the following formula.

An example of such a resin is Marzen Resin M (trade name, manufactured by Maruzen Oil Co., Ltd.). This resin has a molecular weight of 3
000 to 8,000 and a hydroxyl group equivalent of 120.
Further, as an epoxy resin which is another component of the modified resin, there is, for example, the following bisphenol diepoxide. Epicoat 827,828,834,100
1,1002,1004,1007,1009 (manufactured by Shell Chemical Co., trade name), DER330,331,332
334, 335, 336, 337, 660, 661, 6
62,667,668,669 (trade name, manufactured by Dow Chemical Co.), Araldite GY250, 260, 280, 6
071, 6084, 6097, 6099 (trade name, manufactured by Ciba-Geigy), EPI-REZ510, 5101 (J
Ones Dabney, trade name), Epicron 810, 1000, 1010, 3010 (Dainippon Ink and Chemicals, trade name) and Asahi Denka EP series. 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 at the time of heating (350 ° C.) can be further improved. As these novolac epoxy resins, those having a molecular weight of 500 or more are suitable. Examples of such novolac epoxy resin are as follows. Araldite EPN1138, 1139, E
CN1273, 1280, 1299 (manufactured by Ciba Geigy, trade name), DEN431, 438 (manufactured by Dow Chemical Co., trade name), Epicoat 152, 154 (manufactured by Shell Chemical Co., trade name), ERR-0100, ERRB-044
7, ERLB-0488 (trade name, manufactured by Union Carbide Co., Ltd.), EOCN series manufactured by Nippon Kayaku Co., Ltd., and the like.

Examples of the (B) epoxysilane used in the present invention include β- (3.4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane and the like. These are used alone or in combination of two or more.

The mixing ratio of the (A) modified or mixed resin composed of polyparahydroxystyrene and an epoxy resin and the (B) epoxysilane is preferably in the vicinity of an equivalent amount. If the blending ratio deviates greatly from the equivalent, one of them becomes unreacted at the time of curing and the adhesive strength at heating and the weight loss upon heating increase, which is not preferable. When blending the modified or mixed resin (A) polyparahydroxystyrene and epoxy resin used in the present invention and (B) epoxysilane, (A)
Although the component (B) is added and dissolved and mixed, the (A) modified or mixed resin, polyparahydroxystyrene, and the epoxy resin may be simply dissolved and mixed, or if necessary, partially heated by reaction with each other. It may be a combination. Further, the working viscosity can be improved by dissolving the modified resin in a common solvent. And, if desired, a curing catalyst can also be used. Solvents for viscosity adjustment used here include dioxane, hexanone,
Examples include benzene, toluene, solvent naphtha, industrial gasoline, cellosolve acetate, ethyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. These may be used alone or in combination of two or more. To do.

The (C) thermally conductive filler used in the present invention is required to contain no ionic impurities such as alkali metal ions and halogen ions. For this reason, a filler that does not contain ionic impurities is selected. Remove ionic impurities by washing with water / solvent or ion exchange agent. The thermal conductivity of the filler is desirably ^{10k / Wm -1 K -1 (0} ℃) or more, preferably 20k / ^{Wm -1} K
^-1 or more is good. Examples of such fillers include metal powders such as copper, aluminum, magnesium, iron and tin, crystalline carbons such as graphite, carborundum, boron carbide, boron nitride, aluminum nitride, non-oxides such as titanium nitride. Ceramic powder, oxides of beryllium, magnesium, aluminum, titanium, silicon and the like, which are used alone or as a mixed system of two or more kinds.

The compounding ratio of the resin composed of the total of the modified resin and the epoxysilane and the filler is preferably in the range of total resin / filler = 10/90 to 40/60. It is preferably in the range of 15/85 to 30/70. If the amount of the filler exceeds 90 parts, the viscosity of the paste will be high and the workability will be poor, and if it is less than 60 parts, the strength to withstand the bonding temperature cannot be obtained, which is not preferable.

The paste of the present invention contains a modified resin, epoxy silane, and a heat conductive filler, but it is possible to add an antifoaming agent, a coupling agent and other additives if necessary. Further, the paste is manufactured by thoroughly mixing the above-mentioned modified resin, epoxysilane and heat conductive filler according to a conventional method, further kneading with, for example, three rolls, and then defoaming under reduced pressure. The paste thus produced is used for bonding the semiconductor pellet and the lead frame.

[Examples of the Invention] Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" means "parts by weight" unless otherwise specified.

Example 1 Epoxy resin EP4400 (trade name, manufactured by Asahi Denka Co., Ltd.)
7.6 parts, parahydroxystyrene Marzene Resin M
(Maruzen Petrochemical Co., Ltd., trade name) 5.6 parts, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane 10.4 parts of epoxysilane, and 4.0 parts of diethylene glycol diethyl ether at 100 ° C., 1 A time-dependent dissolution reaction was performed to obtain a yellow viscous resin. To 27.8 parts of this resin, 0.006 parts of 2PHZ-CN (manufactured by Shikoku Kasei Co., Ltd.) as a catalyst and 70 parts of alumina powder were added and sufficiently mixed to prepare a paste (A).

Example 2 7.6 parts of EP4400 of epoxy resin (supra), Marzene resin M of parahydroxystyrene (supra) 5.6.
Part, 10.4 parts of γ-glycidoxypropylmethyldiethoxysilane of epoxysilane, and 4.0 parts of diethylene glycol diethyl ether were subjected to a dissolution reaction at 100 ° C. for 1 hour to obtain a yellow viscous resin. To 27.8 parts of this resin, 0.006 parts of 2PHZ-CN (described above) and 70 parts of alumina powder were added as a catalyst and sufficiently mixed to prepare a paste (B).

Example 3 7.6 parts of EP4400 of epoxy resin (supra), Marzene resin M of parahydroxystyrene (supra) 5.6.
Part, 10.4 parts of γ-glycidoxypropyltrimethoxysilane of epoxysilane, and 4.0 parts of diethylene glycol diethyl ether were subjected to a dissolution reaction at 100 ° C. for 1 hour to obtain a yellow viscous resin. To 27.8 parts of this resin, 0.006 parts of 2PHZ-CN (described above) and alumina powder 7 as a catalyst
0 part was added and mixed well to produce paste (C).

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

The semiconductor pellets and the lead frame were adhesively cured using the pastes (A), (B) and (C) of Examples 1 to 3 and the conductive paste (D) of the comparative example. These were tested for adhesive strength, presence of voids, and hydrolyzable CI ions. The results are shown in Table 1, and the remarkable effect of the present invention was confirmed. In the adhesive strength test, a 4 × 4 mm silicon element was bonded onto a silver-plated lead frame (42 alloy), and the strength at temperatures of 25 ° C. and 350 ° C. was measured using a push-pull gauge. For the test of hydrolyzable CI ion, each paste was cured under the adhesion conditions shown in Table 1, then pulverized to 100 mesh and 180 ° C x 2
The amount of CI ions subjected to the time heating extraction was measured.

[Advantages of the Invention] The paste of the present invention does not generate voids due to a small amount of solvent scattered, has excellent adhesiveness, particularly adhesiveness at the time of heating, and has excellent hydrolysis resistance. It is a paste that cures at high speed without any defects such as defects and defects in leak current due to moisture. If this paste is used, a highly reliable large-sized pellet semiconductor device can be manufactured, the assembly process can be significantly shortened, and no expensive silver powder is used, so the cost of MOS and IC can be reduced. It is possible to measure, which is very useful in industry.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication H01B 1/22 A 7244-5G

Claims (1)

[Claims] 1. A paste containing (A) a modified or mixed resin composed of polyparahydroxystyrene and an epoxy resin, (B) epoxysilane (C) a thermally conductive filler, and used for mounting a semiconductor pellet. .