JPH0953001A - Electroconductive epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroconductive epoxy resin composition which can give a cured product excellent in thermal conductivity, electrical conductivity and stress characteristics and can be desirably used as a die bonding material in the semiconductor industries. SOLUTION: This electroconductive epoxy resin composition comprises an epoxy resin, a curing agent and an inorganic filler, wherein the inorganic filler comprises particles prepared by applying or sticking silver to the surface of a powder of an oxide, a composite oxide or a nitride of at least one metallic element selected from among Al, Si, B and Mg.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conductive epoxy resin composition which gives a cured product having excellent thermal conductivity, electrical conductivity and stress characteristics and can be suitably used as a die bond material in the semiconductor industry.

[0002]

2. Description of the Related Art
The conductive epoxy resin composition is typically filled with a large amount of silver as a filler, and therefore,
It has excellent thermal and electrical conductivity.

However, in the semiconductor industry, as the size of a chip increases, a conventional epoxy resin composition (die bond material) filled with a large amount of silver has a large expansion coefficient, so that a semiconductor element is considered in terms of stress characteristics. It is in a situation where it cannot be used because it has an adverse effect. Therefore, a material having a small expansion coefficient, excellent stress characteristics, and suitable as a die bond material is desired.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a conductive epoxy resin composition which gives a cured product having excellent thermal conductivity, electrical conductivity and stress characteristics.

[0005]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of extensive studies conducted by the inventor of the present invention, an epoxy resin composition containing an epoxy resin, a curing agent and an inorganic filler is obtained. In addition, Al, S as an inorganic filler
Thermal conductivity and electrical conductivity can be obtained by blending particles in which silver is coated or adhered on the surface of a metal oxide, complex metal oxide or metal nitride powder of at least one metal element selected from i, B and Mg. The inventors have found that a conductive epoxy resin composition that gives a cured product having excellent properties as well as excellent stress characteristics can be obtained, and completed the present invention.

Therefore, the present invention provides an epoxy resin composition containing an epoxy resin, a curing agent and an inorganic filler, wherein the inorganic filler is a metal of at least one metal element selected from Al, Si, B and Mg. Provided is a conductive epoxy resin composition, characterized in that particles of oxide, mixed metal oxide, or metal nitride powder are coated with or coated with silver.

The present invention will be described in more detail below. The conductive epoxy resin composition of the present invention contains an epoxy resin, a curing agent and an inorganic filler.

The epoxy resin used in the present invention may be any epoxy resin having two or more epoxy groups in one molecule, and in particular, bisphenol A type epoxy resin and bisphenol. Bisphenol type epoxy resin such as F type epoxy resin, phenol novolac type epoxy resin, novolac type epoxy resin such as cresol novolac type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, cyclopentadiene type epoxy resin, triphenolmethane type epoxy resin Examples of the resin include an aralkyl type epoxy resin, and among them, a liquid epoxy resin at room temperature (for example, 5 to 30 ° C.) is preferable.

When the composition of the present invention is used as a die-bonding material for semiconductor devices, the content of halogen ions or alkali metal ions extracted by the water content in the epoxy resin is 10 ppm or less, particularly 5 ppm or less. preferable. If the content of these ions exceeds 10 ppm, the reliability of the semiconductor element, particularly the moisture resistance may be adversely affected.

As the curing agent, for example, all acid anhydrides such as methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride and methylhymic acid anhydride can be used, and dicyandiamide, Carboxylic acid hydrazides such as adipic acid hydrazide and isophthalic acid hydrazide can be used.

When an acid anhydride is used as the curing agent, it is 0.3 to 0.
A desirable range is 7 moles, especially 0.4 to 0.6 moles. If the amount is less than 0.3 mol, the curability may be insufficient, and if it exceeds 0.7 mol, unreacted acid anhydride may remain and the glass transition temperature may be lowered.

When the carboxylic acid hydrazide is compounded as the curing agent, the compounding amount is 0.3 to 0.7 mol, particularly 0.4 to 0.6 mol, relative to 1 mol of the epoxy group in the epoxy resin. desirable. If this amount is less than 0.3 mol, the curability may be poor, and if it exceeds 0.7 mol,
Pot life may be shortened and workability may be poor, or storage stability may be poor.

It is preferable to add a curing accelerator to the composition of the present invention. Examples of the curing accelerator include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 2-
An imidazole derivative such as phenyl-4,5-dihydroxymethylimidazole can be used. In addition,
The imidazole derivative can be used as a curing accelerator for an acid anhydride-based curing agent and also as a curing agent for an epoxy resin.

When an imidazole derivative is used as a curing accelerator, it is 0.01 to 10 parts, especially 0.5 to 5 parts per 100 parts by weight of epoxy resin and curing agent (parts by weight, the same shall apply hereinafter). It is preferable that the blending amount is 0.01
If it is less than 10 parts, the curability may be poor, and if it exceeds 10 parts, the curability may be good but the storage stability may be deteriorated.

In addition to the above-mentioned components, the epoxy resin composition of the present invention contains silicone rubber, silicone oil, silicone-modified resin (for example, alkenyl group-containing epoxy resin or phenol resin and organohydrogenpolycarbonate) for the purpose of reducing the stress of the cured product. A copolymer obtained by a hydrosilylation addition reaction with siloxane) or a liquid polybutadiene rubber may be blended.

In the present invention, Al and S are used as the inorganic filler.
Conductive particles in which silver is coated or adhered to the surface of a metal oxide, a composite metal oxide, or a metal nitride powder of at least one metal element selected from i, B and Mg are used.

Specific examples of the metal oxides, composite metal oxides and metal nitrides include alumina, boron nitride, aluminum nitride, silicon nitride, fused silica, crystalline silica, magnesia and magnesium silicate. One or more selected from composite metal oxides such as Al-Si and Mg-Al (for example, alumina-silica (mullite phase), magnesia-alumina (spinel phase), etc.) are exemplified. Among these powders, alumina, boron nitride, aluminum nitride, and silicon nitride, which have a large thermal conductivity and a small thermal expansion coefficient, which can reduce the stress during curing, are particularly desirable.

In order to impart conductivity by coating or adhering silver on the above-mentioned metal oxide, composite metal oxide or metal nitride powder, 100 parts of metal oxide, composite metal oxide or metal nitride powder is added. On the other hand, it is desirable to use 30 to 150 parts, especially 40 to 100 parts of silver to coat the surface. If it is less than 30 parts, sufficient conductivity may not be imparted, and if it exceeds 150 parts, the amount of silver is large. The price will be too high and the coefficient of thermal expansion will also become large.

As a method for coating or adhering silver on the surface of the powder, a method of plating the surface of the particles by a wet method or a method such as hybridization can be adopted. As the coating or adhesion state of silver on the surface of particles, any of those in which the surfaces of all particles are coated or those in which silver is adhered in spots can be used. Above all, it is desirable to coat the entire surface of the particle with silver in order to impart high electrical conductivity.

The particle size distribution of the conductive particles coated or adhered with silver has an average particle size of 0.5 to 30 μm, particularly 1 to 1
It is preferably 0 micron and has a maximum particle size of 74 microns or less. If the average particle size is less than 0.5 μm, the viscosity may be high and the composition may not be filled in a large amount, and if it exceeds 30 μm, the coarse particle size may increase and the fine needle of the dispenser may be blocked.

The above metal oxide, composite metal oxide or metal nitride particles have a thermal conductivity of 5 W / mK or more, usually 5
˜200 W / mK, particularly preferably 10 to 160 W / mK, and if it is less than 5 W / mK, sufficient thermal conductivity cannot be obtained in the composition containing conductive particles coated or attached with silver, and stress characteristics are not obtained. May be inferior to.

Further, in the case of particles of silver alone, since silver has a large specific gravity, when it is dispersed in a resin, silver precipitates, but the conductive particles coated or attached with silver used in the present invention have a specific gravity of silver. Since it is lighter than that of (1), it also has an advantage of preventing sedimentation, and the specific gravity of the conductive particles to which silver is attached can be set in the range of 3 to 8.

The amount of the conductive particles coated or adhered with silver is usually 100 to 1000 parts, preferably 200 to 800 parts, and preferably 100 parts, per 100 parts of the total amount of the epoxy resin and the curing agent. If it does not satisfy the above condition, a satisfactory conductivity-imparting effect may not be obtained, and if it exceeds 1000 parts, the viscosity of the composition may increase and the workability may deteriorate.

In the composition of the present invention, in addition to the conductive particles coated or adhered with silver as an inorganic filler, conventionally known spherical silver powder or scaly silver powder for imparting further conductivity, You may add aluminum powder, gold powder, copper powder, nickel powder, etc. The shape of the conductive particles is not particularly limited, and a flake-shaped, dendritic-shaped, or spherical filler can be used alone or as a mixture. Also, silica,
Alumina, boron nitride, silicon nitride, aluminum nitride, etc. may be added for thermal conductivity and low expansion.
Further, ultrafine silica such as Aerosil may be added to impart thixotropy. The addition amount of these other inorganic fillers can be set to a normal amount within a range that does not impair the effects of the present invention, but 1 to 10 parts is preferable for 100 parts of the total amount of the epoxy resin and the curing agent. Is.

In addition, the composition of the present invention contains n-butyl glycidyl ether, phenyl glycidyl ether, styrene oxide, t-butyl phenyl glycidyl ether, and dicyclopentadiene diepoxide which are conventionally known for the purpose of decreasing the viscosity. Diluents can be added.

Further, silane coupling agents, titanium coupling agents, coupling agents such as aluminum coupling agents, coloring agents such as carbon black, nonionic surfactants, fluorochemical surfactants, silicone oils, etc. A wetting improver, a defoaming agent and the like can be added in some cases. In addition, the addition amount of these additives can be a usual amount as long as the effect of the present invention is not hindered.

The conductive epoxy resin composition of the present invention is prepared by, for example, stirring, dissolving, mixing, and dispersing an epoxy resin and a curing agent simultaneously or separately while optionally applying heat treatment,
It can be obtained by adding an inorganic filler to these mixtures, mixing, stirring and dispersing. The apparatus for mixing, stirring, dispersing, etc. is not particularly limited, but a lychee machine equipped with a stirring, heating device, three rolls, ball mill, planetary mixer, etc. can be used.

The epoxy resin composition of the present invention can be easily cured by heating, and the curing conditions are not particularly limited, but it is usually desirable to post-cure at 150 to 200 ° C. for 1 to 4 hours.

[0029]

The conductive epoxy resin composition of the present invention comprises
It has a smaller coefficient of thermal expansion than conventional conductive epoxy resin compositions using silver powder as a filler, has excellent stress characteristics, and is effective in reducing the influence of stress on semiconductor elements.

[0030]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. All parts in each example are parts by weight. [Examples 1 to 5, Comparative Examples 1 and 2] 90 parts of bisphenol A type epoxy resin (RE310: manufactured by Nippon Kayaku Co., Ltd.), 8 parts of dicyandiamide (DYCY: manufactured by Nippon Carbide Industry Co., Ltd.) as a curing agent, and a silane coupling agent. As γ-glycidoxypropyltrimethoxysilane (KBM403:
Shin-Etsu Chemical Co., Ltd.) 1 part, phenyl glycidyl ether (PGE-H: Nippon Kayaku Co., Ltd.) 10 parts, curing catalyst 2,
4,6-Tridimethylaminomethylphenol (DMP
-30: Kayaku Akzo Co., Ltd.), 0.8 parts of silver coating filler and silver powder (Silcoat AgC-GS: Fukuda Metal Co., Ltd.) shown in Table 1 were mixed at the ratios shown in Table 2, and three rolls were prepared. By uniformly kneading with, 7 types of epoxy resin compositions were obtained.

The following tests were conducted on these epoxy resin compositions. Table 2 shows the results. Test method: TMA, thermal expansion coefficient: TMA (thermo-mechanical analyzer) (trade name TAS manufactured by Rigaku Co., Ltd.) using a test piece of 5 × 5 × 15 mm
200), the value was measured when the temperature was raised at a rate of 5 ° C./min. CTE-1 is a linear expansion coefficient of 50 to 80 ° C, and CTE-2 is a linear expansion coefficient of 200 to 230 ° C. Viscosity: 2 at 4 rpm using a BH type rotational viscometer.
The viscosity at 5 ° C. was measured. Thermal conductivity: 50 mm × 10 mm × thickness 2 mm obtained by curing each composition at 175 ° C. for 4 hours
Insert the test piece in a sandwich form between the upper heaters, and make it adhere to the air pressure constantly, and the temperature difference between both sides of the test piece after reaching a steady state at 50 ° C, the thermal conductance is automatically calculated from the calorimeter output. Was calculated, and the thermal conductivity was calculated from the product of the value of the thermal conductance and the thickness of the test piece. Volume resistivity: 150 mm length × 20 mm width × obtained by curing each composition at 175 ° C. for 4 hours.
A test piece with a thickness of 1 mm was placed on an insulating plate, both ends were fixed with clips, and the volume resistivity was calculated by the following calculation formula based on the measured electric resistance value.

[0032]

[Equation 1]

Thermal shock defect rate: A conductive epoxy resin composition was uniformly applied onto a copper frame, and 10% was applied onto this resin.
A 0.6 mm thick silicone wafer cut into × 10 mm was placed and cured at 175 ° C. for 4 hours to obtain a test piece. This test piece was repeatedly subjected to a thermal cycle of -55 ° C for 1 minute to 160 ° C for 30 seconds, and the one in which cracks and peeling had occurred after 100 cycles was determined to be defective, and the defective rate was measured (20 tests).

From the results shown in Table 2, it was confirmed that the conductive epoxy resin composition of the present invention gives a cured product having excellent thermal conductivity, electrical conductivity and stress characteristics.

[0035]

[Table 1]

[0036]

[Table 2]

Front page continued (72) Inventor Kazuma Sumida 1 Hitomi, Oita, Matsuida-cho, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Toshio Shiobara In-person, Matsuida-cho, Usui-gun, Gunma Mi No. 1 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory

Claims (3)

[Claims] 1. An epoxy resin composition comprising an epoxy resin, a curing agent and an inorganic filler, wherein the inorganic filler is a metal oxide of at least one metal element selected from Al, Si, B and Mg, and a composite. A conductive epoxy resin composition, characterized in that the surface of a metal oxide or metal nitride powder is blended with particles coated or adhered with silver. 2. The conductive epoxy resin composition according to claim 1, wherein the inorganic filler has a thermal conductivity of 5 W / mK or more. 3. The conductive epoxy resin composition for die bond material according to claim 1 or 2.