JPH051130A - Electroconductive paste - Google Patents

Abstract

PURPOSE:To provide a paste composed of respectively specified bismaleimide, epoxy compound and electroconductive powder, free from generation of voids, excellent in moisture resistance, hydrolysis resistance, adhesion and thermal resistance and useful for a semiconductor chip, etc. CONSTITUTION:The objective paste essentially composed of (A) preferably 80-90 pts.wt. bismaleimide of formula I (R<1> and R<2> are divalent hydrocarbon; R<3> and R<4> are univalent hydrocarbon; (n) is 1-5) derived from a diaminosiloxane, (B) preferably 10-20 pts.wt. epoxidized 1,2-polybutadiene of formula II and (C) an electroconductive powder such as silver powder having <=10mum average particle diameter. In addition, the mixture ratio of the component (C) to the resin component [the components (A)+(B)] is preferably (70/30) to (90/10) by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste having excellent moisture resistance, hydrolysis resistance, adhesiveness, heat resistance and the like.

[0002]

2. Description of the Related Art ICs and Ls are mounted on a predetermined portion of a lead frame.
The process of connecting semiconductor chips such as SI is one of the important processes that affect the long-term reliability of the device. Conventionally, as this connection method, Au-S has been used in which the silicon surface of the semiconductor chip is pressure-bonded to the gold-plated surface on the lead frame.
The eutectic method was the mainstream. However, Au-S has been used in resin-encapsulated semiconductor devices triggered by the recent surge of precious metals, especially gold.
The eutectic method is rapidly changing to a method using solder, a method using a conductive paste, or the like.

However, although some methods using solder have been put to practical use, it has been pointed out that solder or solder balls scatter and adhere to electrodes or the like, which causes corrosion breakage. On the other hand, in the method using the conductive paste, an epoxy resin mixed with silver powder is usually used.
Satisfactory results were not obtained as compared with the u-Si eutectic method. When using a conductive paste, it has advantages such as excellent heat resistance compared to the solder method, but on the other hand, since the resin and the curing agent are not made for bonding semiconductor elements, voids In addition, it was inferior to the Au-Si eutectic method in the reliability of the element because the generation, the moisture resistance and the hydrolysis resistance were inferior, the corrosion of the aluminum electrode was promoted and the disconnection failure was often caused. Further, with the increase in size of semiconductor chips such as IC, LSI, and LEDs, and the advent of various types of frames such as copper, chip cracks and decrease in adhesive strength occur, which has been a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and is excellent in moisture resistance, hydrolysis resistance, adhesiveness and heat resistance, and has voids and breakage due to corrosion of aluminum electrodes. It is an object of the present invention to provide a highly-reliable conductive paste which has less defects and less warp of a semiconductor chip and is compatible with an increase in size of a semiconductor chip.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventor has found that a resin composition having a composition described later achieves the above-mentioned object, and completed the present invention. It was done.

That is, the present invention provides (A) a bismaleimide derived from a diaminosiloxane represented by the general formula 3.

[0007]

[Chemical 3] (However, wherein R ¹ and R ² are divalent hydrocarbon radicals, R ³
And R ⁴ represents a monovalent hydrocarbon group, R ¹ and R ² , R ³
And R ⁴ may be the same or different, and n is 1 to
(B) represents an integer of 5) (B) an epoxidized product of 1,2 polybutadiene represented by Structural Formula 4 and

[0008]

[Chemical 4] (C) Conductive powder is a conductive paste, which is an essential component.

The present invention will be described in detail below.

The bismaleimide derived from the diaminosiloxane of the component (A) used in the present invention is a component for introducing an imide skeleton and a siloxane skeleton into a cured product, and the diaminosiloxane and maleic acid are condensed by a known method.
It can be easily produced by a dehydration cyclization reaction. Representative examples of such a diaminosiloxane include those shown in the following chemical formulas 5 and 6.

[0011]

[Chemical 5]

[0012]

[Chemical 6]

The epoxidized product of 1,2-polybutadiene (B) used for introducing a polybutadiene structure into the cured product of the present invention is an oligomer having a high reactivity containing an epoxy group and a vinyl group in the molecule, Its structure is estimated as

[0014]

[Chemical 7]

The epoxidized product is obtained by epoxidizing 1,2-polybutadiene by the hydrogen peroxide method, and specific compounds include BF-1000 (trade name, manufactured by Adeka Argus Chemical Co., Ltd.).

The above-mentioned (A) bismaleimide and (B)
The compounding ratio of the epoxidized product is preferably 50 to 95 parts by weight of the former and 5 to 50 parts by weight of the latter, more preferably 80 to 90 parts by weight of the latter and 10 to 20 parts by weight of the latter. To do.

Examples of the (C) conductive powder used in the present invention include silver powder, copper powder, nickel powder, powder having a metal layer on the surface, etc. These may be used alone or in combination of two or more. You can The average particle diameter of each of these conductive powders is preferably 10 μm or less. If the average particle size exceeds 10 μm, the composition does not become a paste and the coating performance deteriorates, which is not preferable.

Conductive powder and resin component [(A) + (B)]
It is desirable that the blending ratio of and is 70/30 to 90/10 by weight. When the conductive powder is less than 70 parts by weight, satisfactory conductivity cannot be obtained, and when it exceeds 90 parts by weight, workability is deteriorated, which is not preferable.

After sufficiently mixing the above-mentioned components, for example, a kneading process is performed with, for example, a three-roll mill, and then defoaming under reduced pressure to produce a conductive paste. The conductive paste of the present invention may use an organic solvent as necessary for adjusting the viscosity. As the organic solvent, dioxane, hexane, cellosolve acetate, ethyl cellosolve,
Butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, isophorone and the like,
These may be used alone or in combination of two or more. Further, this conductive paste is cured without using a curing agent, but an imidazole-based derivative, a maleation catalyst, or the like can also be used.

The conductive paste thus manufactured is filled in a syringe, discharged onto a lead frame by using a dispenser, and after bonding semiconductor elements, wire bonding is performed and sealing is performed with a resin sealing material to obtain a semiconductor device. Can be manufactured. Even when heated at 280 ° C (corresponding to the wire bonding temperature of the element), this semiconductor device has extremely small warpage deformation of the large chip, the adhesive strength is the strength required for bonding the semiconductor chip, and the moisture absorption is also small. It was a thing.

[0021]

The present invention will be described below with reference to examples.
The invention is not limited by these examples. In the examples and comparative examples, "parts" means "parts by weight" unless otherwise specified.

Example 1 A reaction vessel equipped with a stirrer, a thermometer and a Dean-Stark azeotropic distillation trap was charged with 100 parts of the diaminosiloxane shown in Chemical formula 8 and 80 parts of maleic anhydride, while nitrogen gas was being bubbled through. The temperature was raised. After reacting for 3 hours at a temperature of 100 ° C in the vessel, water produced by the xylol reflux method at 180 ° C was removed to the outside of the system. After reacting for 2 hours in this state, xylol was removed from the system by distillation under reduced pressure and cooled to synthesize a pale yellow bismaleimide derived from diaminosiloxane.

[0023]

[Chemical 8]

The epoxidized product BF-1000 (trade name, manufactured by Adeka Argus Chemical Co., Ltd.) was added to 85 parts of this bismaleimide.
A thermosetting resin composition was manufactured by adding 15 parts and 0.1 part of an antioxidant and stirring well until uniform.

Using the thermosetting resin composition thus obtained, the components shown in Table 1 were kneaded three times with a three-roll mill to produce the conductive paste of Example 1.

Example 2 100 parts of the diaminosiloxane shown in Chemical formula 9 was reacted with 70 parts of maleic anhydride in the same manner as in Example 1 to synthesize a pale yellow bismaleimide derived from diaminosiloxane.

[0027]

[Chemical 9]

Epoxy compound BF-1000 (trade name, manufactured by ADEKA ARGUS CHEMICAL CO., LTD.) Is added to 90 parts of this bismaleimide.
A thermosetting resin composition was manufactured by adding 10 parts and 0.1 part of an antioxidant and stirring well until uniform.

Using the thermosetting resin composition thus obtained, the components shown in Table 1 were kneaded three times with a three-roll mill to produce the conductive paste of Example 2.

Example 3 100 parts of the diaminosiloxane shown in Chemical formula 10 was reacted with 40 parts of maleic anhydride in the same manner as in Example 1 to synthesize a pale yellow bismaleimide derived from diaminosiloxane.

[0031]

[Chemical 10]

To 85 parts of this bismaleimide, the epoxidized product BF-1000 (trade name, manufactured by Adeka Argus Chemical Co., Ltd.)
A thermosetting resin composition was produced by adding 15 parts and 0.1 part of an antioxidant and stirring well until uniform.

Using the thermosetting resin composition thus obtained, the components shown in Table 1 were kneaded three times with a three-roll mill to produce the conductive paste of Example 3.

Comparative Example A commercially available epoxy resin-based solvent-type conductive paste was obtained.

Using the conductive pastes obtained in Examples 1 to 3 and Comparative Example, a semiconductor chip and a lead frame were bonded and cured to manufacture a semiconductor device. These semiconductor devices were tested for adhesive strength, chip warpage, hydrolysis and moisture resistance. The results are shown in Table 2, and in all cases, the remarkable effect of the present invention was recognized.

The adhesive strength was measured by adhering a 4 × 12 mm silicon chip onto a lead frame having a thickness of 200 μm under the semiconductor element adhesive conditions shown in Table 2 and using a push-pull cage at a temperature of 350 ° C. The warp of the chip was measured by measuring the surface of the chip after curing with a surface roughness meter and indicated by the distance between the center and the end of the chip. For the hydrolyzability, the conductive paste is cured under the conditions for bonding semiconductor elements, then pulverized to 100 mesh and then heated at 180 ° C.
The amount of chloride ions extracted by heating for 2 hours was measured by ion chromatography. In the humidity resistance test, the amount of moisture absorption was measured in water vapor at a temperature of 121 ° C and a pressure of 2 atm.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

As is clear from the above description and Table 2, the conductive paste of the present invention has a moisture resistance, a hydrolysis resistance,
It is excellent in adhesiveness and heat resistance, has few voids, disconnection defects and warpage due to corrosion of aluminum electrodes, and is highly reliable in response to the increase in size of semiconductor chips.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H01L 21/52 E 9055-4M H05K 3/32 B 9154-4E

Claims (1)

Claims: (A) a bismaleimide derived from a diaminosiloxane represented by the general formula 1, (However, wherein R ¹ and R ² are divalent hydrocarbon radicals, R ³
And R ⁴ represents a monovalent hydrocarbon group, R ¹ and R ² , R ³
And R ⁴ may be the same or different, and n is 1 to
(B represents an integer of 5) (B) an epoxidized product of 1,2-polybutadiene represented by the structural formula 2 and (C) A conductive paste comprising a conductive powder as an essential component.