JPH10324792A - Electroconductive paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject paste by including a specific resin component, a prescribed sulfonium salt and specified electroconductive powder, showing quick curability and excellent moisture resistance, almost preventing the occurrence of void after curing and heat shrinkage, useful for bonding the chip mount of semiconductor apparatus. SOLUTION: This electroconductive paste comprises (A) a mixture of (i) a glycidyl ester of formula I (R is a bifunctional or polyfunctional organic group; (n) is 0-15; (m) is 2-4) and (ii) an alicyclic epoxy resin, (B) a sulfonium salt of formula II (X is CH3 , NO2 , H or a halogen; M is Sb, As or P) or formula III (R<1> and R<2> are each an alkyl, a halogen or H; R<3> is an ether or an ester; A<-> is SbF<5-> , AsF<6-> or CH3 SO4 <-> ) and (C) electroconductive powder. In the component A, the ratio of the component (i)/the component (ii) is 10/90 to 90/10 (by weight), the amount of the component B is 0.5-20 pts.wt. based on 100 pts.wt. of the component (ii). When the content of the component A and the component C is 100 pts.wt., the ratio of the component A/the component C is preferably in the range of 40/60 to 5/95.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste which is excellent in quick-curing property and moisture resistance and can be suitably used for bonding chip mounts and various electronic components in manufacturing semiconductor devices.

[0002]

2. Description of the Related Art In the manufacture of a semiconductor device, a process of connecting a semiconductor chip such as an IC or LS # to a predetermined portion on a metal thin plate (lead frame) is an important step that greatly affects the reliability over time of the semiconductor device. It is a process. Conventionally, as the connection method, a connection method by brazing using a low melting point alloy such as solder, a connection method using a conductive paste made of an epoxy resin mixed with silver powder, and the like have been adopted.

[0003]

However, a method of connecting by brazing using a low melting point alloy such as solder is as follows.
There has been a problem that the solder and the solder poles may scatter and adhere to the electrodes and the like, which may cause corrosion disconnection.

[0004] Further, the method of connecting using a conductive paste has a problem in that it is less reliable than the eutectic method of forming an Au-Si eutectic alloy on a silicon chip.
In other words, connection using a conductive paste is superior in heat resistance compared to connection by brazing using a low melting point alloy such as solder, but on the other hand, the conductive paste is a thermosetting resin, There is a problem that it takes time.

Further, when the conductive paste is cured in a short time, there is a problem that voids are generated in the adhesive layer formed from the conductive paste.

Further, as semiconductor devices such as ICs and LSs have become larger, there has been a problem that chip cracks and package cracks occur due to heat history during an assembly process and a mounting process.

[0007] The present invention has been made in view of the above-mentioned conventional problems, and provides a conductive paste which exhibits fast curing properties, has excellent moisture resistance, and substantially prevents generation of voids and heat shrinkage after curing. The purpose is to:

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies and as a result, by adding the following compounds,
It has been found that a conductive paste achieving the above object can be obtained.

That is, the conductive paste according to the present invention comprises (A) (a)

Embedded image (Wherein, R is a divalent or higher valent organic group, n is an integer of 0 to 15,
m is an integer of 2 to 4), a glycidyl ester represented by the formula:
(b) alicyclic epoxy resin, (B) general formula

Embedded image (Wherein, X represents CH ₃ , NO ₂ , H or halogen;
Represents Sb, As or P) or

Embedded image (Wherein, R ¹ and R ² represent an alkyl group, a halogen or H
And R ³ represents an ether or an ester, and A ⁻ represents SbF
_{^{5 -, AsF 6 -, PF}} 6 - or CH ₃ SO ₄ ^- sulfonium salt represented by the representative), and is characterized in that it contains (C) a conductive powder.

According to the present invention, the glycidyl ester shown in (A) and the epoxy group of the alicyclic epoxy resin are ring-opened by cationoid polymerization (cationic polymerization) with the sulfonium salt of (B). Upon curing, it can exhibit fast curing properties and exhibit excellent moisture resistance. In addition, the product obtained by the polymerization is a dense product having a three-dimensional network structure, and thus exhibits stable properties that are insoluble in a solvent and are infused by heating. Therefore, it is possible to produce a product in which the generation of voids after curing and the heat shrinkage are substantially prevented. Furthermore, when the conductive paste of the present invention is applied to the manufacture of a semiconductor device, since the above-described product is generated, a highly reliable semiconductor device can be manufactured.

In the present invention, (A) is a resin component and is a mixture of the glycidyl ester shown in (a) and the alicyclic epoxy resin of (b). Here, as the glycidyl ester shown in (a), for example, glycidyl dimer acid can be suitably used, and as the alicyclic epoxy resin in (b), for example, a cyclohexene oxide group, a tricyclodecene oxide And compounds having a cyclopentene oxide group or the like. In addition, the glycidyl ester shown in (a)
The mixing ratio of (b) with the alicyclic epoxy resin is (a) / (b) = 10
It is desirable to be in the range of / 90 to 90/10 (parts by weight).
If the glycidyl ester is less than 10% by weight per 100 parts by weight, low stress after curing is impaired. For example, chip cracks and package cracks occur when used for mounting large semiconductor elements on thin metal plates. It will be easier. In addition, 10% by weight of alicyclic epoxy resin
%, It is difficult to obtain quick-curing properties.

The sulfonium salt of the formula (B) represented by the above general formula generates a cation or a Lewis acid by heating and causes the epoxy groups to be ring-opened to each other by cationoid polymerization (cationic polymerization). The ratio of the sulfonium salt is desirably 0.5 to 20 parts by weight based on 100 parts by weight of the alicyclic epoxy resin. When the amount of the sulfonium salt is less than 0.5 with respect to 100 parts by weight of the alicyclic epoxy resin, it is difficult to exhibit the effect of quick-curing and the curing speed is reduced, so that the practicality is poor. If the sulfonium salt exceeds 20 parts by weight with respect to 100 parts by weight of the alicyclic epoxy resin, Lewis acid remains in the product formed by curing the conductive paste. When used for mounting on a thin plate, the electrical characteristics of the semiconductor element under high humidity conditions tend to be degraded, or the wiring made of a thin metal plate or aluminum tends to corrode (electrolytic corrosion).

Further, as the conductive powder, for example, metal powders such as silver powder, copper powder and nickel powder can be suitably used, and these can be used alone or in combination of two or more. Further, the powder is not limited to metal powder as long as it has conductivity, for example,
Powder having a metal layer only on the surface may be used. Although the shape of the conductive powder is not particularly limited, the particle size of the conductive powder is preferably 50 μm or less. If the particle size of the conductive powder exceeds 50 μm, the conductivity of the conductive powder becomes unstable. The particle size is defined as the diameter of a sphere having the same volume. Further, the mixing ratio of the resin component (A) and the conductive powder (C) is as follows when the content of the resin component (A) and the conductive powder (C) in the conductive paste is 100 parts by weight. A) / (C) = 40 / 60-5 /
It is desirable to be in the range of 95 (parts by weight). When the amount of the conductive powder (C) is less than 60 parts by weight, it is difficult to obtain sufficient conductivity, and when the amount exceeds 95 parts by weight, workability and adhesion deteriorate.

In the present invention, for example, a solvent for adjusting the viscosity of the conductive paste, a diluent having reactivity to ring-opening polymerization of an epoxy group, an antifoaming agent, a coupling agent and other various types Additives can be added as needed. Examples of the solvent include cellosolve acetate, ethyl cellosolve, butyl cellosolve, butyl cellosolve acetate, butyl carbitol acetate, diethylene glycol dimethyl ether, diacetone alcohol, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, γ-butyllactone, and 1,3-dimethyl-2. -Imidazolidinone, etc., and these can be used alone or as a mixture of two or more. Further, as a diluent, 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-butyl Phenyl glycidyl ether, diglycidyl ether, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,6-hexanediol diglycidyl ether, etc. These can be used alone or in combination of two or more.

Further, examples of the coupling agent include γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane.
-Methacryloxypropyltrimethoxysilane.

The conductive paste according to the present invention is, for example,
After sufficiently mixing the above-mentioned components, the mixture can be easily obtained by further performing a kneading treatment with a disperser, kneader, three-roll mill or the like, and then defoaming under reduced pressure. The conductive paste thus obtained can be suitably used for manufacturing semiconductor devices and bonding various electronic components. For example, when used in the manufacture of a semiconductor device, after filling a conductive paste into a syringe or the like, discharging it onto a thin metal plate using a dispenser, mounting the semiconductor element on the thin metal plate via the conductive paste, The conductive paste is cured by heating for a short time. Incidentally, in curing the conductive paste according to the present invention, usually,
It is easily carried out by heating at 120 ° C. to 200 ° C. for 10 seconds to 120 seconds.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, one embodiment of the electrostatic image developing toner according to the present invention will be described, but the present invention is not limited to these embodiments. In the following Examples and Comparative Examples, “parts” means “parts by weight” unless otherwise specified.

Example 1 First, the following compounds were prepared.

Glycidyl ester (Toto Kasei Co., Ltd .: YD171) 50 parts Alicyclic epoxy resin (Daicel Chemical Industries, Ltd .: Celloxide 2081) 50 parts Sulfonium salt (Sanshin Chemical Industry Co., Ltd .: SI-80L) 2 parts Cup Ring agent (γ-glycidoxypropyltrimethoxysilane) 1 part Silver powder 412 parts Next, these were sufficiently mixed, and further kneaded with a three-roll mill to obtain a conductive paste.

Example 2 The following compounds were prepared.

Glycidyl ester (Toto Kasei Co., Ltd .: YD171) 30 parts Alicyclic epoxy resin (Daicel Chemical Industries, Ltd .: Celoxide 2083) 70 parts Sulfonium salt (Sanshin Chemical Industry Co., Ltd .: SI-100L) 2 parts Cup Ring agent (γ-methacryloxypropyltrimethoxysilane) 1 part Silver powder 412 parts Next, these were sufficiently mixed, and further kneaded with a three-roll mill to obtain a conductive paste.

Comparative Example A solventless conductive paste (for semiconductors) based on an epoxy resin was prepared. In addition,
The solvent-free conductive paste contains an imidazole-based curing agent and an imidazole-based accelerator.

Next, using the conductive pastes obtained in Examples 1 and 2 and Comparative Example, the semiconductor chip and the thin metal plate (lead frame) are bonded and cured, and the bonding strength, the amount of warpage of the chip, and the amount of voids are determined. Characteristic tests were performed on the occurrence and pot life. Note that these characteristic tests were performed under the following conditions. In other words, the bonding strength is determined by placing a 2 mm square silicon chip on a Cu frame via a conductive paste, curing the conductive paste on a 180 ° C heat block for a predetermined time (15 to 120 seconds), and then immediately breaking it. (Peeling). The amount of warpage of the chip was determined by placing a 4 × 12 mm silicon chip on a 200 μm thick Cu frame via a conductive paste and curing it in an oven heated to 180 ° C. for 2 hours. It was measured using a surface roughness meter. Furthermore, the presence or absence of voids was visually observed after placing a 8 mm square glass chip on a Cu frame via a conductive paste, curing the conductive paste on a 180 ° C heat block for 2 minutes, . The pot life is determined by leaving the obtained conductive paste in an environment at 25 ° C and 50% humidity.
Every 6 hours, a part thereof was sampled, and a test similar to the above-described adhesive strength was performed to measure a period until the adhesive strength was deteriorated. Table 1 shows the measurement results.

[0024]

[Table 1] As is clear from Table 1, in Examples 1 and 2 and Comparative Example, when the time required for curing was the same, the conductive paste obtained in Examples 1 and 2 was the same as the conductive paste obtained in Comparative Example. Adhesive strength is higher than that of the conductive paste. When the time required for curing is 120 sec, the adhesive strength in the comparative example is 9.11 N. However, in Example 1 and Example 2, when the time required for curing is 30 sec in Example 1 and Example 2, The value that has been reached. Therefore, it can be understood that the conductive paste obtained in Example 1 and Example 2 requires a shorter time for curing than the conductive paste of Comparative Example, and exhibits high adhesive strength in a short time. Further, since the amount of warpage of the chips in Examples 1 and 2 is less than half the amount of warpage of the chips in the comparative example, the conductive pastes of Examples 1 and 2 are stable against heat. It was understood that it was hardly affected by heat history. Furthermore, the conductive pastes of Example 1 and Example 2 have a short curing time and easily exhibit high adhesive strength, but do not generate voids in the cured product and are stable to the environment. This was understood from the presence or absence of voids and the pot life.

[0025]

As described above in detail, according to the conductive paste of the present invention, the glycidyl ester and the epoxy group of the alicyclic epoxy resin are ring-opened by cationoid polymerization (cation polymerization) with a sulfonium salt. Since the bonding is performed, it is possible to provide a conductive paste that exhibits fast curing properties and is excellent in moisture resistance.

According to the conductive paste of the present invention,
The product obtained by the polymerization is a dense product having a three-dimensional network structure, so that it exhibits a stable property of being insoluble in a solvent and of being infused by heating. Therefore, it is possible to provide a conductive paste that produces a product in which generation of voids after curing and thermal shrinkage are substantially prevented.

Further, according to the conductive paste of the present invention, since the above-described characteristics are exhibited, it is possible to manufacture a highly reliable semiconductor device by applying the conductive paste to, for example, manufacturing of a semiconductor device.

[0028]

Claims (1)

[Claims] 1. A conductive paste containing the following compound: (A) (a) a general formula: (Wherein, R is a divalent or higher valent organic group, n is an integer of 0 to 15,
m is an integer of from 2 to 4), (b) an alicyclic epoxy resin, (B) a general formula: (Wherein, X represents CH ₃ , NO ₂ , H or halogen;
Represents Sb, As or P) or (Wherein, R ¹ and R ² represent an alkyl group, a halogen or H
And R ³ represents an ether or an ester, and A ⁻ represents SbF
^{_{5 -, AsF 6 -, PF}} 6 - or CH ₃ SO ₄ ^- sulfonium salt represented by the representative), and, (C) conductive powder.