JPH10144704A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain electrically conductive paste with improved thermal resistance, moisture resistance, and adhesion with gold plating when heated by introducing epoxy resin and phenol resin having a dicyclopentadienyl skeleton into a denatured resin. SOLUTION: A modified resin consisting of epoxy resin having a dicyclopentadienyl skeleton and phenol resin having a dicyclopentadienyl skeleton, and a solvent, a monomer or a mixture thereof are used. Silver powder, powder having a silver layer on the surface thereof, nickel powder, and carbon etc., are listed as an electrically conductive powder, and these can be used singly or by mixing two or more of them. Thus, an electrically conductive paste with improved thermal resistance, moisture resistance, and adhesion with gold plating when heated can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a technique for bonding a semiconductor chip on a thin metal plate (lead frame) using a conductive paste.

[0002]

2. Description of the Related Art LE on a thin metal plate (lead frame).
The step of physically and electrically bonding compound semiconductor chips such as D, IC, and LSI is one of the important steps that affect the long-term reliability of an element. Conventionally, as a joining method of such a compound semiconductor chip, there are a method of brazing using a low melting point alloy (solder or solder ball) and a method of bonding using a resin paste.

[0003] However, it has been pointed out that the method using solder may cause the solder or solder balls to scatter and adhere to electrodes and the like, causing corrosion and disconnection.

On the other hand, as a method of using a resin paste, a method of using an epoxy resin (conductive paste) containing silver powder as the resin paste has been partially put into practical use. The method using the conductive paste has advantages such as superior heat resistance as compared with the soldering method.

[0005] However, the resin in the paste and its hardener promote the corrosion of the aluminum electrode, which may also cause a disconnection failure.
The reliability was inferior to the eutectic method for producing the eutectic alloy of i.

Further, in recent years, gold plating has been often performed on bonding surfaces of electrodes and the like for the purpose of improving the electrical bonding reliability of semiconductor chips. However, since the gold-plated surface is chemically inert and has few surface-active groups, hydrogen bonding with the epoxy resin in the paste is not formed when bonding the semiconductor chip using the conductive paste, and sufficient adhesion is achieved. The strength cannot be obtained. For this reason,
The heat history during the assembly process and the mounting process has caused a problem that the semiconductor chip is separated from the lead frame.

[0007]

As described above, when a semiconductor chip is physically and electrically joined to a lead frame by using a conductive paste, depending on the type of material constituting the conductive paste, Resin and its curing agent may promote corrosion of the aluminum electrode, leading to disconnection failure.In the case of a semiconductor chip with a gold-plated bonding surface for electrodes, etc., sufficient adhesive strength with the lead frame is obtained. There was a problem that it was not easily peeled off.

The present invention has been made in view of the above circumstances, and has as its object to provide a semiconductor device which is excellent in heat resistance, moisture resistance, and hot adhesion to a gold-plated surface and has high reliability in an assembly process. Things.

[0009]

The inventor of the present invention has conducted intensive studies to achieve the above object, and as a result, has found that the above object can be achieved by using a conductive paste having a composition described later. Completed the invention.

That is, the semiconductor device of the present invention comprises:
Modified resin composed of epoxy resin having dicyclopentadienyl skeleton, phenol resin having dicyclopentadienyl skeleton, (Β) solvent, monomer or mixture thereof, and (C) conductive powder containing conductive powder as essential components The semiconductor chip is bonded and fixed to a lead frame by using a natural pace.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments in which the present invention is viewed will be described.

Examples of the epoxy resin having a dicyclopentadienyl skeleton used in carrying out the present invention include EXA7200 (trade name, manufactured by Dainippon Ink and Chemicals, Inc.). The epoxy resin having a dicyclopentadienyl skeleton can be used alone or as a mixture with another resin. As the resin to be mixed, a curable epoxy resin, a bisphenol A type epoxy resin,
Novolak type epoxy resin, glycidyl ester type epoxy resin, polyfunctional epoxy resin and the like can be mentioned. In this case, it is desirable to use an epoxy resin having an average number of epoxy groups of 3 or more, since the object of the present invention is to improve the adhesive strength when heated.

Examples of the phenol resin having a dicyclopentadienyl skeleton used in carrying out the present invention include DP @ -600M (trade name, manufactured by Nippon Petrochemical Co., Ltd.).

The modified resin (A) comprising an epoxy resin having a dicyclopentadienyl skeleton and a phenol resin having a dicyclopentadienyl skeleton is simply dissolved and mixed in a solvent (B) to be described later, a monomer or a mixture thereof. Alternatively, if necessary, the reaction may be partially controlled by controlling the heating reaction. In this reaction, a curing catalyst is used as necessary.

When mixing with another epoxy resin,
It is desirable that the compounding amount of (epoxy resin having a dicyclopentadienyl skeleton + phenol resin having a dicyclopentadienyl skeleton) be 40% by weight or more based on the solid content of the modified resin. When the compounding ratio is less than 40% by weight, there is no effect in improving the adhesiveness to the gold-plated surface when heated.

The solvent or monomer (B) used in carrying out the present invention dissolves the modified resin (A) and is used for adjusting and improving the working viscosity of the paste. As the solvent, for example, dioxane, hexane, toluene, methyl cellosolve, cyclohexanone,
Butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, diethylene glycol dimethyl ether, diacetone alcohol, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone and the like. These may be used alone or in two.
A mixture of more than one species can be used.

The monomers include n-butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, styrene oxide, phenyl glycidyl ether, cresyl glycidyl ether, p-sec-butylphenyl glycidyl ether,
Glycidyl methacrylate, t-butylphenyl glycidyl ether, diglycidyl ether, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,6-to Xandiol diglycidyl ether and the like. These can be used alone or in combination. Further, a mixture of a solvent and a monomer can be used. When a solvent is used, it is necessary to select a solvent having an appropriate boiling point according to the curing temperature, the curing time, and the working conditions.

Examples of the (C) conductive powder used in carrying out the present invention include silver powder, powder having a silver layer on its surface, copper powder, nickel powder, carbon and the like. These can be used in combination. The amount of the conductive powder is not particularly limited, but when importance is placed on the electrical characteristics, the ratio of (conductive powder / (solid content of modified resin / conductive powder)) is in the range of 80 to 95% by weight. It is desirable. The conductive paste used in the present invention contains the above-mentioned modified resin, conductive powder and solvent or monomer as essential components. However, as long as the object of the present invention is not adversely affected, and if necessary, a curing catalyst, an antifoaming agent, and a cup are used. A ring agent and other additives can be blended.

The conductive paste is prepared by thoroughly mixing the above-mentioned components according to a conventional method, and then dispersing, kneading,
It can be manufactured by performing a kneading treatment with a three-roll mill or the like, and then defoaming under reduced pressure.

The thus prepared conductive paste is filled in a syringe, discharged onto a lead frame by using a dispenser, and, for example, a compound semiconductor chip is joined by curing, followed by wire bonding and sealing with a resin sealant. Thus, a resin-sealed semiconductor device can be manufactured.

According to the present invention, by introducing an epoxy resin and a phenol resin having a dicyclopentadienyl skeleton into the modified resin, a conductive material having excellent heat resistance, moisture resistance, and adhesion when heated to gold plating is obtained. As a result, it is possible to realize a highly reliable semiconductor device having excellent corrosion resistance of an aluminum electrode or the like and sufficient bonding strength of a semiconductor chip.

[0022]

Next, embodiments of the present invention will be described. In the following Examples and Comparative Examples, “parts” means “parts by weight” unless otherwise specified.

(Example 1) A phenolic resin DPP having a dicyclopentadienyl skeleton as a curing agent was added to 100 parts of an epoxy resin EXA7200 having a dicyclopentadienyl skeleton (trade name, manufactured by Dainippon Ink and Chemicals, Inc.).
76 parts of -600M (trade name, manufactured by Nippon Petrochemical Co., Ltd.) in 176 parts of diethylene glycol diethyl ether at 85 ° C., 1
The dissolution reaction was performed for a time to obtain a viscous resin. To 30 parts of this resin, 0.20 part of imidazole 2-ethyl-4-methylimidazole as a curing catalyst, 0.02 part of an additive and 60 parts of silver powder
Parts, and further kneading treatment by three rolls,
The conductive paste (A) was produced by defoaming under reduced pressure.

(Example 2) 60 parts of an epoxy resin EXA7200 (trade name, manufactured by Dainippon Ink and Chemicals, Inc.) having a dicyclopentadienyl skeleton, and EOCN1 as an epoxy resin
For 40 parts of 03S (trade name, manufactured by Nippon Kayaku Co., Ltd.), 76 parts of phenolic resin DPP-600 (trade name, manufactured by Nippon Petrochemical Co., Ltd.) having a dicyclopentadienyl skeleton as a curing agent, and diethylene glycol diethyl ether 80 85 ° C in a mixed solvent of 1 part and 20 parts of butyl carbitol acetate, 1
The dissolution reaction was performed for a time to obtain a viscous resin. To 30 parts of this resin, 0.15 part of imidazole 2-ethyl-4-methylimidazole as a curing catalyst, 0.10 part of an additive and 60 parts of silver powder were mixed, and kneading treatment was further performed with a three-roll mill, followed by defoaming under reduced pressure. A conductive paste (Β) was produced.

COMPARATIVE EXAMPLE A commercially available epoxy resin-based conductive paste for solvent-type semiconductors (C) was obtained. Conductive paste obtained in Examples 1 and 2 and Comparative Example (Α)
(III) Using (C), a 1 × 1 mm silicon chip (solid gold plating on the back side) was bonded and fixed on a 200 μm-thick lead frame (copper-based) under the semiconductor element bonding conditions shown in Table 1 to complete the compound semiconductor device. Each was manufactured.

With respect to these compound semiconductor devices, adhesion strength, moisture resistance bias PC # and PC # tests were performed. Table 1 shows the results.

[0027]

[Table 1] The bonding strength test was conducted by bonding a 1 × 1 mm silicon chip (backside solid gold plating) on a 200 μm-thick lead frame (copper) under the semiconductor element bonding conditions shown in Table 1 and then 300 ° C.
The measurement was performed by measuring the adhesive strength in the shear direction on a heat block using a push-pull gauge.

The moisture resistance test was carried out in a moisture resistance test (PCT) in steam at a temperature of 121 ° C. and a pressure of 2 atm.
A moisture resistance test (bias PCT) was conducted in a steam at a pressure of 2 atm by applying an applied voltage of 1.5 V. Sixty semiconductor devices were subjected to the humidity resistance test, and the number of failures generated over time was counted. The defect was judged to be defective when the aluminum electrode constituting the semiconductor device was opened due to corrosion of the aluminum electrode or when the allowable value of the leak current increased by 500% or more.

As apparent from Table 1, Examples 1 and 2
It was confirmed that Sample No. 2 was superior in both adhesive strength and moisture resistance properties as compared with the Comparative Example.

[0030]

As apparent from the above description and Table 1, according to the present invention, heat resistance and moisture resistance are improved by introducing an epoxy resin and a phenol resin having a dicyclopentadienyl skeleton into the modified resin. A conductive paste with excellent heat resistance and adhesiveness to gold plating can be obtained, and as a result, a highly reliable semiconductor device with excellent corrosion resistance of aluminum electrodes etc. and sufficient bonding strength of semiconductor chips has been realized. It is possible to do.

[0031]

Claims (2)

[Claims] 1. A modified resin comprising (A) an epoxy resin having a dicyclopentadienyl skeleton, a phenol resin having a dicyclopentadienyl skeleton, (B) a solvent, a monomer or a mixture thereof, and (C) a conductive material. A semiconductor device comprising a semiconductor chip bonded and fixed to a lead frame by using a conductive paste containing conductive powder as an essential component. 2. The semiconductor device according to claim 1, wherein said semiconductor chip is a compound semiconductor chip.