JP2000143776A - Electroconductive paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition showing quick-curing properties, having excellent adhesiveness and moisture resistance, capable of preventing the occurrence of voids and heat shrinkage after curing, useful for producing a semiconductor apparatus, etc., by using a resin component blended in a specific ratio. SOLUTION: This composition comprises (A) (i) a glycidyl ester of formula I (R is a bifunctional or polyfunctional organic group; n is 0-15; m is 2-4), (ii) an alicyclic epoxy resin, (iii) a bisphenol type epoxy resin and (iv) an acrylate resin in the ratios of 10-50 pts.wt. of the component (iii) mixed based on 1000 wt.% of the components (i+ii), 10-50 pts.wt. the component (iv) mixed, (B) (v) a sulfonium salt of formula II (X is CH3, H or the like; M is Sb, As, etc.), or formula III (R1 and R2 are each alkyl, a halogen or the like; R3 is an alkyl or an acyl; A- is SbF6, AsF6 or the like) and (vi) an organic peroxide and (C) electroconductive powder as environmental components.

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 the production of semiconductor devices.

[0002]

2. Description of the Related Art In manufacturing a semiconductor device, a process of connecting a semiconductor chip such as an IC or an LSI to a predetermined portion on a thin metal plate (lead frame) is an important process which has a great influence on the long-term reliability of an element. One. Conventionally, as the connection method, a method of brazing using an alloy (solder) having a low melting point, and a method of connecting using a conductive paste made of an epoxy resin mixed with silver powder have been adopted.

[0003]

However, the connection method by brazing using a low melting point alloy such as solder has been put to practical use in part, but the solder and solder balls are scattered and adhere to electrodes and the like, and the corrosion is caused. It has been pointed out that it may cause disconnection.

[0004] On the other hand, the method of connecting using a conductive paste has a problem in that it is less reliable than the eutectic method of producing an Au-Si eutectic alloy in a silicon chip. That is, when connected using a conductive paste, the heat resistance is superior to the connection method by brazing using a low melting point alloy such as solder, but on the other hand, since the conductive paste is a thermosetting resin, There was a problem that time was required for curing.

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

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

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has a fast curing property, an excellent adhesive property and excellent moisture resistance, and a conductive property in which generation of voids after curing and heat shrinkage are substantially prevented. It is intended to provide a paste.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that the composition described below can achieve the above object, and have completed the present invention. is there. That is, the present invention relates to (A) (a) a glycidyl ester represented by the following general formula:

[0009]

Embedded image (Wherein, R represents a divalent or higher valent organic group, n represents an integer of 0 to 15, and m represents an integer of 2 to 4) (b) alicyclic epoxy resin and (c) bisphenol type [(A) + (b)] 1
The amount of the component (c) is 10 to 50 parts by weight with respect to 00 parts by weight.
(B) (1) a sulfonium salt represented by the following general formula (1) or (2) in which the amount of the component (d) is 10 to 50 parts by weight. When

[0010]

Embedded image (2) A conductive paste comprising an organic peroxide and (C) a conductive powder as essential components.

Hereinafter, the present invention will be described in detail.

The resin component (A) used in the present invention comprises (a)
A glycidyl ester, (b) an alicyclic epoxy resin, (c) a bisphenol type epoxy resin, and (d)
It is a blend with an acrylate resin.

Here, as the glycidyl ester (a), for example, glycidyl dimer acid can be suitably used. (B) Examples of the alicyclic epoxy resin include compounds having a cyclohexene oxide group, a tricyclodecene oxide group, a cyclopentene oxide group, or the like. (C) Examples of the bisphenol type epoxy resin include a bisphenol F type liquid epoxy resin and a bisphenol A type liquid epoxy resin. In addition, (d) the acrylate resin
Also called vinyl ester resin, is an addition reaction product of acrylic resin or methacrylic acid with epoxy resin,
Bisphenol A type epoxy acrylate resin and the like can be mentioned.

The mixing ratio of the glycidyl ester shown in (a) to the alicyclic epoxy resin of (b) is as follows:
/ (B) = 10/90 to 90/10 (parts by weight). When the glycidyl ester content is less than 10% by weight per 100 parts by weight, the reduction in stress after curing is impaired. For example, when a large semiconductor element is used for mounting on a metal plate, chip cracks and package cracks occur. It will be easier. Further, when the content of the alicyclic epoxy resin is less than 10% by weight per 100 parts by weight, it is difficult to obtain fast curability. Further, by adding 10 to 50 parts by weight of (c) a bisphenol type epoxy resin and (d) an acrylate resin to 100 parts by weight of the total of (a) glycidyl ester and (b) alicyclic epoxy resin. Adhesion can be improved.

The sulfonium salt of (1) in (B) used in the present invention is represented by the above formula (4). The sulfonium salt is activated when heated, generates a cationic species or a Lewis acid, and causes ring-opening polymerization of the epoxy resins by cationoid polymerization (cationic polymerization). The compounding ratio of the sulfonium salt is (A) the resin component 10
It is desirable to add 0.5 to 20 parts by weight to 0 part by weight. If the amount of the sulfonium salt is less than 0.5 part by weight based on 100 parts by weight of the resin component (A), it is difficult to exhibit the effect of quick-curing and the curing speed is reduced, resulting in poor practicality. If the sulfonium salt exceeds 20 parts by weight with respect to 100 parts by weight of the resin component (A), 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 are deteriorated, and the wiring made of a thin metal plate or aluminum is corroded (electrically eroded), and the reliability is lacking. .

The organic peroxide (2) of (B) used in the present invention acts as a radical polymerization initiator for the acrylate resin (d) of (A). The mixing ratio is (A)
Of (d) 100 parts by weight of the acrylate resin
It is desirable to mix up to 20 parts by weight. If the compounding amount is less than 0.5 part by weight, the quick-curing property is lost, and if it exceeds 20 parts by weight, the resin is deteriorated due to the reaction heat at the time of polymerization, and the electric characteristics are reduced. Become.

As the conductive powder (C) used in the present invention, for example, metal powders such as silver powder, copper powder and nickel powder can be preferably used, and these can be used alone or in combination of two or more kinds. Can be. The powder is not limited to metal powder as long as it has electrical conductivity, and may be, for example, a powder having a metal layer only on the surface. The shape of the conductive powder is not particularly limited, but the particle size of the conductive powder is preferably 50 μm or less. If the particle diameter 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 (C) conductive powder to the (A) resin component is based on the case where the contents of the (A) resin component and (C) conductive powder in the conductive paste are 100 parts by weight. , (A) / (C) = 40 / 60-5 / 95
(Parts by weight). (C) When the amount of the conductive powder 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 adhesiveness are reduced. 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 the epoxy group, an antifoaming agent, a coupling agent, and other various additives are used. It can be blended as needed as long as it does not violate the purpose of the invention. Specific solvents include cellosolve acetate, ethyl cellosolve, 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, and these may be used alone or in combination of two or more. It can be mixed and used. 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-butylphenyl) glycidyl ether, diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, butanediol diglycidyl ether, trimethylolpropane triglycidyl ether, 1,6-hexanediol diglycidyl ether, and the like. These can be used alone or in combination of two or more. Further, examples of the coupling agent include γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane.

The conductive paste of the present invention comprises (A) a resin component described above, (B) (1) a sulfonium salt,
After sufficiently mixing (2) the organic peroxide of (B), the (C) conductive powder, and other additives according to a conventional method, a kneading treatment is further performed by a disperse, a kneader, a three-roll mill, or the like. It can be manufactured by defoaming. The conductive paste thus manufactured can be suitably used for manufacturing semiconductor devices and bonding various electronic components and the like.
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. When the conductive paste according to the present invention is cured, it is usually 120 to 20.
It is easily carried out by heating at 0 ° C. for 10 seconds to 120 seconds.

[0020]

The conductive paste of the present invention is a cationoid polymerizable resin (glycidyl ester,
Alicyclic epoxy resin, bisphenol type epoxy resin)
The object is achieved by using a radical polymerizable resin (acrylate resin), a conductive powder and other additives. That is, the glycidyl ester of the resin component, the alicyclic epoxy resin, and the epoxy group of the bisphenol-type epoxy resin are ring-opened and bonded by cationoid polymerization (cationic polymerization) using a sulfonium salt, so that they exhibit fast curing properties upon curing. Demonstrates excellent adhesion and moisture resistance. Further, the acrylate resin is polymerized by radical polymerization, but the radical polymerizable resin has a high reaction heat at the time of polymerization, and therefore promotes the ring-opening polymerization of the cationoid polymerizable resin. Adhesion and moisture resistance can be exhibited. In addition, the product obtained by the polymerization is a dense product having a three-dimensional network structure, so that it is insoluble in a solvent,
In addition, it exhibits infusible and stable properties 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. further,
When the conductive paste of the present invention is applied to the manufacture of a semiconductor device, since the above-described products are generated, a highly reliable semiconductor device can be manufactured.

[0021]

Next, the present invention will be described specifically 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 20 parts of PG207S (trade name, manufactured by Toto Kasei Co., Ltd.) as glycidyl ester, 40 parts of celloxide 2081 (trade name, manufactured by Daicel Chemical Industries, Ltd.) as alicyclic epoxy resin, and bisphenol-type epoxy resin Y
L983U (product name, manufactured by Yuka Shell Epoxy Co., Ltd.)
20 parts, KAYARAD R- as acrylate resin
712 (trade name, manufactured by Nippon Kayaku Co., Ltd.), 2 parts of SI-80L (trade name, manufactured by Sanshin Chemical Industry Co., Ltd.) as a sulfonium salt, and Perhexa 3M as an organic peroxide
(Nippon Yushi Co., Ltd., trade name) 0.5 part, 1 part of γ-glycidoxypropyltrimethoxysilane as a coupling agent, and 412 parts of silver powder were sufficiently mixed, and then kneaded with a three-roll mill. Thus, a conductive paste was obtained.

Example 2 20 parts of PG207S (trade name, manufactured by Toto Kasei Co., Ltd.) as a glycidyl ester, 50 parts of celloxide 2083 (trade name, manufactured by Daicel Chemical Industries, Ltd.) as an alicyclic epoxy resin, and bisphenol type epoxy resin G
L62 (manufactured by Daicel Chemical Industries, Ltd., trade name) 20
Part, BE3700 (Daicel
UCB Co., Ltd., 10 parts, SI-100L as sulfonium salt (manufactured by Sanshin Chemical Industry Co., Ltd., 2 parts), Perhexa 3M as organic peroxide
After sufficiently mixing 0.5 part (manufactured by NOF CORPORATION, trade name), 1 part of γ-methacryloxypropyltrimethoxysilane as a coupling agent, and 412 parts of silver powder,
Further, the mixture was kneaded with three rolls to obtain a conductive paste. Comparative Example A commercially available epoxy resin-based conductive paste for a semiconductor without solvent was prepared. The solventless 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, a semiconductor chip and a metal thin plate (lead frame) are bonded and cured to obtain an adhesive strength,
Characteristic tests were performed on the amount of chip warpage, the presence or absence of voids, and the pot life. Note that these characteristic tests were performed under the following conditions.

Adhesive strength: A 2 mm square silicon chip is placed on a Cu frame via a conductive paste,
After the conductive paste was cured on a heat block at a predetermined temperature for 15 seconds to 120 seconds, the paste was immediately destroyed (peeled).

Chip warpage: A silicon chip of 4 mm × 12 mm was placed on a 200 μm thick Cu frame via a conductive paste, and cured in an oven heated to 180 ° C. for 2 hours. It was measured using a roughness meter.

Presence / absence of voids: An 8 mm square glass chip is placed on a Cu frame via a conductive paste.
After the conductive paste was cured on a heat block at 180 ° C. for 2 minutes, it was visually observed.

Pot life: The obtained conductive paste was left in an environment of 25 ° C. and 50% humidity, and a part thereof was sampled every 6 hours. The period until deterioration was measured.

As described above, the results are shown in Table 1. The present invention was excellent in each case, and remarkable effects of the present invention were recognized.

[0030]

[Table 1]

As is clear from Table 1, when the curing time is the same in Examples 1 and 2 and Comparative Example, the conductive paste obtained in Examples 1 and 2 The adhesive strength is higher than that of the obtained conductive paste. In addition, the time required for curing is 1
In the case of 20 sec, the adhesive strength is 14.8 in the comparative example.
The adhesive strength is N, which is the value which has already been reached when the time required for curing is 30 seconds in Examples 1 and 2. Therefore, it can be understood that the conductive paste obtained in Example 1 and Example 2 requires less 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 was less than half the amount of warpage of the chips in the comparative example, the conductive paste obtained in Examples 1 and 2 was exposed to heat. It was understood that this was stable against heat and was not easily 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.

[0032]

As apparent from the above description and Table 1, according to the conductive paste of the present invention, the cationoid polymerizable resin (glycidyl ester, alicyclic epoxy resin and bisphenol type epoxy resin) with sulfonium salt is used. When used in combination with a radically polymerizable resin (acrylate resin), it is possible to provide a conductive paste that exhibits fast curing properties and has excellent moisture resistance. Further, according to the conductive paste of the present invention, the product obtained by polymerization is a dense product having a three-dimensional network structure, so that it is insoluble in a solvent, and is insoluble and stable by heating. It will show its properties. 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. By using this conductive paste, highly reliable semiconductor devices and electronic components can be manufactured.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C09J 163/00 C09J 163/00 F term (reference) 4J002 CD022 CD053 CD101 CD204 DA078 DA078 EK007 EV296 FD118 FD146 FD147 GQ02 4J036 AA06 AD01 AG03 AG04 AJ08 EA02 EA04 FA02 GA03 JA15 4J040 DF042 EC062 EC091 EC261 HA066 HB41 HD18 JB02 JB10 KA32 LA09 MA02 MA10 NA19

Claims (1)

[Claims] (A) (a) a glycidyl ester represented by the following general formula: (Wherein, R represents a divalent or higher valent organic group, n represents an integer of 0 to 15, and m represents an integer of 2 to 4) (b) alicyclic epoxy resin and (c) bisphenol type [(A) + (b)] 1
The amount of the component (c) is 10 to 50 parts by weight with respect to 00 parts by weight.
(B) (1) a sulfonium salt represented by the following general formula (1) or (2), in which the amount of the component (d) is 10 to 50 parts by weight. And (2) A conductive paste comprising an organic peroxide and (C) a conductive powder as essential components.