JPH10162646A - Conductive resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase conductivity and improve migration resistance by containing conductive powder composed of specific quantities of silver and copper, copper alloy powder having the higher silver concentration on the grain surface than the average silver concentration of grains, and one or more kinds of other conductive powder selected from silver powder, silver alloy powder, and silver-plated copper powder. SOLUTION: The conductive powder combined with copper alloy powder and other conductive powder and having high surface silver concentration is used to manufacture a conductive resin composition. In a conductive paste containing a binder resin of 5-40 pts.wt. against the conductive powder of 100 pts.wt., the conductive powder contains the copper alloy powder of 30-95 pts.wt. expressed by a general formula Agx Cuy [0.001<=x<=0.6, 0.4<=y<=0.999 (atomic percentage)] and having the higher silver concentration on the grain surface than the average silver concentration of grains. At least one or more kinds of other conductive powder of 5-70 pts.wt. selected from silver powder, silver alloy powder, and silver-plated copper powder is contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a conductive resin composition having excellent conductivity and migration resistance.

[0002]

2. Description of the Related Art With the rapid progress of electronics, various conductive resin compositions have been proposed as conductors and used for various electronic devices, electronic components and electronic circuits. Various conductive powders are used as the conductive material in the conductive resin composition depending on the application. For example, silver and silver alloys and silver plating powder are used for applications requiring high conductivity, copper powder is used for applications requiring ion migration resistance and high-frequency characteristics, and applications where withstand voltage is required Uses nickel powder. Further, in order to improve the ion migration resistance and the oxidation resistance, Japanese Patent Laid-Open No.
A copper alloy powder as described in -268381 has been proposed.

[0003]

Known conductive resin compositions using silver powder, silver alloy powder, and silver plating powder as the conductive powder particles have the following disadvantages. That is, when using silver powder, silver alloy powder, and silver plating powder,
Although the conductivity is high and the conductivity is hardly deteriorated by oxidation, silver ion migration is easily caused.

[0004]

SUMMARY OF THE INVENTION In view of these points, the present invention has been studied in order to obtain a conductive resin composition having excellent conductive stability and excellent migration resistance. Is high, a conductive resin composition prepared using a conductive powder obtained by combining a copper alloy powder and other conductive powders has been found to be able to solve the above-described problems, and has reached the present invention. . That is, the present invention is as follows. 1. In a conductive paste containing 5 to 40 parts by weight of a binder resin with respect to 100 parts by weight of the conductive powder, the conductive powder has a general formula of Ag _x Cu _y (0.001 ≦ x ≦ 0.
6,0.4 ≦ y ≦ 0.999 (atomic ratio)), and contains 30 to 95 parts by weight of a copper alloy powder having a silver concentration on the surface of the particle higher than the average silver concentration of the particle. A conductive resin composition comprising 5 to 70 parts by weight of at least one selected from silver powder, silver alloy powder, and silver-plated copper powder as the conductive powder. 2. The conductive resin composition, wherein the shape of the copper alloy powder is spherical, scale-like, or a mixture thereof. 3. The conductive resin composition, wherein the shape of the conductive powder other than the powder is a dendrite, a sphere, a flake, a grain, a cone, a needle, or a mixture thereof. 4. A conductive resin composition comprising 0.5 to 5 parts by weight of an oxide remover and an antioxidant with respect to 100 parts by weight of the copper alloy powder.

The copper alloy powder used in the present invention has a general formula A
g _x Cu _y (0.001 ≦ x ≦ 0.6, 0.4 ≦ y ≦ 0.
999 (atomic ratio), but when x is less than 0.001, sufficient oxidation resistance cannot be obtained, and when x exceeds 0.6, electromigration resistance is insufficient. Moreover, the copper alloy powder produced by the inert gas atomization method in the range of 0.001 ≦ x ≦ 0.6 has a silver concentration on the surface of the powder higher than the average silver concentration. The silver concentration at and near the surface of the powder can be determined by an X-ray photoelectron spectrometer as a surface concentration at a depth of about 50 A from the surface. To determine the average silver concentration, the sample was dissolved in concentrated nitric acid and
A CP (high frequency inductively coupled plasma emission analyzer) can be used. The copper alloy powder of the present invention has a silver concentration on the powder surface higher than the average silver concentration, but preferably has a silver concentration on the powder surface of at least 1.4 times the average silver concentration, more preferably 2. 5 times or more.

The copper alloy powder is used in an amount of 30 to 95 parts by weight, preferably 50 to 85 parts by weight, based on 100 parts by weight of the conductive powder used in the present invention. 30
When the amount is less than part by weight, the migration resistance is lowered, and when the amount is more than 95 parts by weight, it is not necessary. The average particle size of the copper alloy powder of the present invention can be measured with a laser diffraction type particle size distribution meter. In particular, the submicron particle size distribution tends to cause errors due to poor dispersion or measuring equipment. Can be determined from the image analysis.

The copper alloy powder used in the present invention is produced by an atomizing method, preferably an inert gas atomizing method using nitrogen gas, argon gas, hydrogen gas or the like, and most preferably a gas atomizing method using an inert gas containing helium gas. is there. The following method is an example of the inert gas atomizing method. First, a mixture or alloy of copper and silver is melted in an inert gas or vacuum in a crucible using high frequency induction heating. After melting, the melt is spouted from the crucible tip into an inert gas atmosphere. A high-speed air stream generated by adiabatically expanding the compressed inert gas at the same time as the jetting is jetted toward the melt to produce a copper alloy powder. In a particularly preferred helium gas atomization, the active gas such as oxygen gas is 0.1% or less, more preferably 0.0% or less.
It is desirable that it be 1% or less. The helium gas may have a high purity, but a mixed gas in which a part of the helium gas is replaced with a nitrogen gas has a preferable gas composition. A helium-nitrogen mixed gas having a helium gas mixture ratio of 10 to 99% by volume can produce a copper alloy powder having a particularly suitable particle size distribution, and can form a conductive circuit having a high packing density. It is extremely useful industrially to use a helium-nitrogen mixed gas at a suitable ratio in consideration of the production cost, particle size distribution, and paste characteristics.

As the particle shape, a spherical shape, a scale-like shape and a mixture thereof are used. A scaly powder is more preferable because a mixture of the scaly powder and the spherical powder makes the surface of the conductive resin composition flat. The shape of the scaly powder preferably has a diameter / thickness of 3 or more. The shape and particle size were measured using a scanning electron microscope, and the average value of the measured values of 100 powders in the visual field was used.

In order to obtain a flaky powder, the copper alloy powder of the present invention is preferably mechanically deformed by a known method. For example,
A method such as a stamp mill, a ball mill, and a vibration ball mill is preferable. Among them, it is preferable to use a vibrating ball mill. The copper alloy powder used in the present invention is not particularly limited as long as the properties are not impaired. For example, Al, Zn, Sn, Pb, Si, Mn, Ni, Fe,
Bi, Mo, Cr, Ir, Nb, Sb, B, P, Mg,
Li, C, Na, Ba, Ti, In, Au, Pd, P
Metals such as t, Rh, Ru, Zr, Hf, Y, and La, semimetals, and compounds thereof may be added.

The conductive powder other than the copper alloy powder used in the present invention is at least one selected from silver powder, silver plating powder, and silver alloy powder. The silver powder and silver alloy powder used in the present invention need not be atomized powder, but may be, for example, electrolytic copper powder or chemically reduced copper powder. The silver alloy powder used in the present invention is an alloy with at least one selected from palladium and platinum. The alloy ratio to silver is preferably from 0.1% by weight to 30% by weight, particularly preferably from 0.5% by weight to 20% by weight.

The silver-plated copper powder used in the present invention may be prepared by either electrolytic plating or electroless plating. The weight percent of silver used for plating is preferably 1% to 10%, particularly preferably 3% to 7%. The particle diameter of the silver powder, silver alloy powder, and silver plating powder used in the present invention is 0.1.
Those having a thickness of 1 to 100 µm are preferred, and those having a thickness of 0.1 to 50 µm are particularly preferred. The shape may be a resin, a sphere, a flake, a grain, a cone, a needle, or a mixture thereof.

To the conductive powder of the present invention, at least one selected from carbon powder, copper powder and nickel powder may be added as long as the required conductivity does not decrease. The amount of the conductive powder is preferably 0.1 to 50% by weight, particularly preferably 1 to 30%. The binder resin used in the present invention has a good dispersibility of the conductive powder, a sufficient strength of the conductive resin composition is obtained, and any structure may be used as long as the binder resin does not hinder the conductivity. Absent. The glass transition point of the binder resin is -50
It is preferable that the temperature is in the range of -300 ° C. Specifically, it is at least one selected from thermoplastic resins, thermosetting resins, and electron beam curable resins.
For example, an acrylic resin, an alkyd resin, a vinyl acetate resin, a polyurethane resin, a polyester resin, a polyvinyl butyral resin, a polycarbonate resin, a styrene resin, and a combination of at least one of them are exemplified. Among them, polyester resin, vinyl acetate resin, polyurethane resin and acrylic resin are particularly preferable.

Examples of the thermosetting resin include an epoxy resin, a phenol resin, a melamine resin, an alkyd resin, a polyurethane resin, a polyester resin, an acrylic resin, a polyimide resin, and a combination of at least one of these modified resins. Among them, one type of epoxy resin, phenolic resin, and melamine resin, or a combination of two or more types is preferable.

The amount of the binder resin used in the present invention is 5 to 40 parts by weight with respect to 100 parts by weight of the conductive powder, and more preferably 5 parts by weight or more when the conductive powder in the conductive resin composition is bound. A sufficient amount of resin to be obtained is obtained. When the amount is 40 parts by weight or less, a conductive resin composition having a good balance between conductivity and mechanical strength is obtained. As a method for forming the conductive resin composition of the present invention, a conductive powder is mixed with a binder solution dissolved in a solvent to form a conductive paste, which is then applied by a screen printing method, a dipping method, etc., and dried or cured. It is preferable to use a method of forming by carrying out.

For the present invention, the following oxide remover:
It is more preferable to add an antioxidant. The amount of the oxide remover and antioxidant used in the present invention is 0.5 to 10 parts by weight based on 100 parts by weight of the conductive powder. If the amount is less than 0.5 part by weight, the effect of improving conductivity and dispersibility is insufficient, and if it exceeds 10 parts by weight, the strength of the coating film is reduced.

As the oxide removing agent, one or more selected from fatty acids, dicarboxylic acids, oxycarboxylic acids and metal salts thereof, and metal chelating agents can be used. Specifically, as the saturated fatty acid, for example, propionic acid,
Butyric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid. Unsaturated fatty acids include acrylic acid, oleic acid, elaidic acid, sorbic acid, linoleic acid, arachidonic acid, and stearic acid. Examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. . Examples of the oxycarboxylic acid include glycolic acid, lactic acid, hydroxyacrylic acid, oxybutyric acid, glyceric acid, tartaric acid, citric acid, salicylic acid, mandelic acid, tropic acid, oxyphenylacetic acid, resorcinic acid, and ascorbic acid. Moreover, those metal salts can be used. Examples of metal chelating agents include triethanolamine, diethanolamine and derivatives thereof, trifluoroacetylacetone, hexafluoroacetylacetone,
Trifluorobenzoylacetone, benzoylacetone, acetylacetone and derivatives thereof, phenylpyridylketoxime, propylpyridylketoxime and derivatives thereof can be used.

As antioxidants, phenol compounds,
Organic titanium compounds, pyrazolidinone compounds, aldehyde compounds, imidazole compounds, and organic phosphorus compounds can be used. As the phenol compound, monovalent, 2
A trivalent phenol and its derivative can be used. For example, phenol, p-aminophenol, cresol, 3,5-xylenol, carvacrol, thymol, naphthol, methylhydroxynaphthalene, catechol, resorcin, hydroquinone, t-butylhydroquinone, chlorohydroquinone, phenylhydroquinone,
Methylhydroquinone, 1,2,4-benzenetriol, pyrogallol, phloroglysin.

As the organic titanium compound, R1-Ti-
(R2) 3 (wherein R1 is an alkoxy group having 1 to 3 carbon atoms,
R2 is a carboxylic acid ester having 2 to 20 carbon atoms. For example, isopropyl triisostearoyl titanate,
Isopropyltrioctanoyl titanate. Examples of pyrazolidinone compounds are phenidone and phthalazinone.

As a substrate to which the conductive resin composition of the present invention is applied, a known substrate can be used. Specifically, paper phenol resin substrate, polyimide substrate, polyester resin substrate, BT resin substrate, polysulfone resin substrate, polyether sulfone resin substrate, polyetherimide resin substrate, polybutadiene resin substrate, glass polyimide resin substrate, flexible substrate, etc. Organic substrate is used.

[0020]

The present invention will be specifically described below with reference to examples and comparative examples. Preparation of Copper Alloy Powder (Copper Alloy Powder A) 316 g of copper particles and 15 g of silver particles were melted in a graphite crucible using high frequency induction heating. The atmosphere was replaced with helium gas for operation. After heating to 1600 ° C, pressure 30k against melt falling from crucible tip
/ G helium gas was spouted from a nozzle (18 nozzles with a nozzle diameter of 1.2 mm and mounted in a circle) around the circumference to produce a copper-silver alloy powder. The obtained powder was collected by a cyclone, and the particle size distribution and the surface silver concentration of the copper-silver alloy powder were measured by an X-ray photoelectron spectrometer. Ag3d is used for the measurement of silver concentration in order to compare peaks having similar photoelectron energies.
_5/2 (Kα line of Al) and Cu3p (Kα line of Mg) were selected and determined as the surface concentration at a depth of about 50 A from the surface, and the ratio of this value to the average silver concentration determined by ICP was defined as the silver concentration ratio. . The silver concentration ratio was 4.5, the average particle size was 9.6 μm, and the maximum particle size was 60 μm. The particle size distribution was determined by measuring the particle size from the SEM photograph image.

A part of the obtained copper alloy powder was classified to a particle size of 5 μm or less by air current classification, and then spread by a vibration ball mill. This is designated as copper alloy scale powder A. The particle size distribution of the copper alloy scale powder was determined by measuring the particle size of the long diameter from the SEM photograph image. (Copper alloy powder B) 264 g of copper particles and 67 g of silver particles were treated in exactly the same manner as described above to produce a copper alloy powder. When the silver concentration ratio of the obtained powder was measured by the same method as described above, it was 3.0. The average particle size was 8.5 μm, and the maximum particle size was 58 μm. A part of the obtained copper alloy powder was classified into particles having a particle size of 10 μm or less by an air flow spheroid, and spread by a vibration ball mill. This is designated as copper alloy scale powder B.

Various tests described in the examples were performed as follows. (1) Conductivity measurement A conductive paste was prepared, and two lines each having a width of 1 mm and a length of 100 mm were formed on a glass epoxy substrate at 0.5 mm intervals by screen printing (film thickness: 15 μm).
Test board. This is dried by heating at 120 ° C. for 20 minutes, and the conductivity of each line is measured by a four-terminal method. (2) Evaluation of migration resistance A direct current of 100 V was applied to a pair of adjacent lines of the test substrate manufactured in the same manner as in (1), and the test substrate was maintained at 60 ° C. and a constant temperature and humidity of 90% for 120 hours. Measure the insulation resistance of (Measurement voltage 50 V, logarithmic display) (Example 1) Copper alloy powder A 60 g, silver scale powder (apparent density 1.75 g / cm ³ , tap density 3.23 g / c)
m ³ ) 40 g, polyester resin 10 g, vinyl acetate resin 3 g, epoxy resin 2 g, benzyl alcohol 15
g, triethanolamine 1 g and stearic acid 1 g
This roll was kneaded to prepare a conductive paste. When the conductivity was measured by the method (1), a good value of 3.5Ω was obtained. When the migration was measured by the method (2), the insulation resistance was a good value of> 12 (LogΩ). (Example 2) 85 g of copper alloy scale powder B, 15 g of silver powder (apparent density 3.8 g / cm ³ ), polyurethane resin 2
g, resol type phenol resin 8 g, butyral resin 0.5 g, catechol 1.0 g, acetylacetone 1.
5 g and 9 g of benzyl alcohol are kneaded with three rolls,
A conductive paste was produced. Increase the curing temperature to 150
A test substrate was prepared in exactly the same manner as in (1) except that the temperature was 30 ° C. and the conductivity was measured, and the conductivity was measured. When the migration was measured in the same manner as in (2), the insulation resistance was a good value of 13 (LogΩ). (Example 3) Copper alloy powder A 80 g, silver platinum alloy powder (platinum 0.5%, tap density 4.3 g / cm ³ ) 2
0 g, resol type phenol resin 8 g, epoxy resin 1
g, triethanolamine 1 g, stearic acid 0.8
g and benzyl alcohol (5 g) were kneaded with three rolls to prepare a conductive paste. The curing temperature is 150 ° C, 3
A test substrate was prepared in exactly the same manner as in (1) except that the time was set to 0 minutes, and the conductivity was measured. As a result, a good value of 4.3 Ω was obtained. When migration was measured in the same manner as in (2), the insulation resistance was a good value of 14 (LogΩ). (Example 4) 60 g of copper alloy powder B, 40 g of silver-plated copper powder (silver content 5%, apparent density 3.5 g / cm ³ ), 7 g of resole-type phenol resin, and 0.1 g of polyvinyl butyral resin.
Five rolls, 0.5 g of maleic acid, 1 g of isopropyl triisostearoyl titanate, and 10 g of dipropylene glycol monoisopropyl ether were kneaded with three rolls to prepare a conductive paste. The curing temperature is 150 ° C, 3
A test substrate was prepared in exactly the same manner as in (1) except that the time was set to 0 minutes, and the conductivity was measured. The result was a good value of 4.0Ω. When the migration was measured in the same manner as in (2), the insulation resistance was a good value of 12 (LogΩ). (Example 5) Copper alloy flake powder B 70 g, silver palladium alloy powder (palladium 1%, tap density 4.5 g / cm ³ )
30 g, polyester resin 5 g, bisphenol F-type epoxy resin resin 10 g, 2-ethyl-4-methylimidazole 1.0 g, stearic acid 0.7 g, and benzyl alcohol 9 g were kneaded with three rolls to prepare a conductive paste. A test substrate was prepared in exactly the same manner as in (1) except that the curing temperature was changed to 170 ° C. for 20 minutes, and the conductivity was measured. As a result, a good value of 3.8 Ω was obtained. (2)
When the migration was measured in the same manner as described above, the insulation resistance was a good value of 12 (LogΩ). (Comparative Example 1) Silver scale powder (apparent density 1.75 g / c)
m ³ , tap density 3.23 g / cm ³ ) 100 g, polyester resin 10 g, vinyl acetate resin 3 g, epoxy resin 2 g, benzyl alcohol 15 g, triethanolamine 1 g, and stearic acid 1 g are kneaded with three rolls, and a conductive paste is prepared. Was prepared. When the conductivity was measured by the method (1), a good value of 3.3Ω was obtained. When the migration was measured by the method (2), the insulation resistance was a low value of 9 (LogΩ). (Comparative Example 2) Silver-plated copper powder (silver content 5%, apparent density 3.
5 g / cm ³ ) 100 g, resol type phenol resin 7
g, 0.5 g of polyvinyl butyral resin and 10 g of propylene glycol monoisopropyl ether were kneaded in a three-roll mill to prepare a conductive paste. A test substrate was prepared in the same manner as in (1) except that the curing temperature was changed to 150 ° C. for 30 minutes, and the conductivity was measured.
Was a good value. When migration was measured in the same manner as in (2), the insulation resistance was a low value of 9 (LogΩ). (Comparative Example 3) 100 g of silver palladium alloy powder (palladium 1%, tap density 4.5 g / cm ³ ), 5 g of polyester resin, bisphenol F type epoxy resin resin 10
g, 2-ethyl-4-methylimidazole 1.0 g
This roll was kneaded to prepare a conductive paste. A test substrate was prepared in exactly the same manner as in (1) except that the curing temperature was 170 ° C. for 20 minutes, and the conductivity was measured. As a result, a good value of 3.7 Ω was obtained. When the migration was measured in the same manner as in (2), the insulation resistance 9 (Lo) was measured.
gΩ).

As is clear from the above, the conductive resin composition of the present invention has excellent conductivity and migration resistance.

[0024]

The present invention provides a conductive resin composition having excellent conductivity and exhibiting excellent migration resistance. The conductive resin composition of the present invention can be used for printed wiring boards used for audio products and home electric appliances.

Claims (4)

[Claims] In a conductive paste containing 5 to 40 parts by weight of a binder resin with respect to 100 parts by weight of a conductive powder, the conductive powder has a general formula of Ag _x Cu _y (0.001 ≦
x ≦ 0.6, 0.4 ≦ y ≦ 0.999 (atomic ratio)), and contains 30 to 95 parts by weight of a copper alloy powder having a silver concentration on the particle surface higher than the average silver concentration of the particles. In addition, at least one selected from silver powder, silver alloy powder, and silver-plated copper powder is used as the other conductive powder in an amount of 5-7.
A conductive resin composition containing 0 parts by weight. 2. A conductive resin composition, wherein the shape of the copper alloy powder is spherical, scaly, or a mixture thereof. 3. The conductive resin composition, wherein the conductive powder other than the copper alloy powder is in the form of a tree, a sphere, a flake, a grain, a cone, a needle, or a mixture thereof. . 4. A conductive resin composition comprising 0.5 to 5 parts by weight of an oxide remover and an antioxidant with respect to 100 parts by weight of the copper alloy powder.