JPH0992026A - Complex conductive powder, conductive paste, manufacture of conductive paste, electric circuit, and manufacture of electric circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a complex conductive powder having a low specific resistance and a high conductivity by preparing complex conductive powders containing flat conductive powders and amorphous conductive powders. SOLUTION: This complex conductive powder is prepared from 95 to 50wt.% flat conductive powders and 5 to 50wt.% amorphous conductive powders. The flat conductive powders (e.g. scale-shaped) are made up of silver, a silver alloy, or a silver-covered conducting material, with an aspect ratio of 6 or more and an average particle diameter of about 25μm or less, and the amorphous conductive powders are made up of silver, a silver alloy, or reduced silver powders, with an aspect ratio of 5 or less and an average particle diameter of about 3 to 20μm. The complex conductive powder is formed into a conductive paste with the use of a liquefied epoxy resin or the like as a binder and terpineol or the like as a solvent, whereby it can be used in the formation of an electronic circuit such as a printed wiring board or electronic parts.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a composite conductive powder, a conductive paste, a method for manufacturing a conductive paste, an electric circuit and a method for manufacturing an electric circuit.

[0002]

2. Description of the Related Art Conventionally, as a method of forming an electric circuit (wiring conductor) such as a printed wiring board or an electronic component, electronic materials,
As described in October 1994, pages 42 to 46, a method of coating or printing a conductive paste containing silver powder having excellent conductivity is generally known.

A conductive paste containing silver powder is used for forming electric circuits and electrodes of printed wiring boards, electronic parts and the like because of its good conductivity. It is formed by using such a conductive paste. Volume resistivity of electrical circuit (specific resistance)
Is usually 50 to 100 μΩ · cm, and even excellent ones are only 30 to 40 μΩ · cm, and when the length of the printed circuit is as short as several cm, there is little trouble, but 10 cm
If it is above, the conduction resistance becomes high, and the problem is likely to occur.

In order to obtain a conductor having good conduction resistance, the amount of silver powder blended may be increased, but a specific resistance of 25 μΩ · cm or less cannot be stably obtained. Further, if the amount of silver powder is simply increased, disadvantages such as poor balance with other properties, for example, adhesion, occur.

Further, the method of etching a metal foil of silver, copper or the like has a drawback in that it is highly conductive and has a low specific resistance of several μΩ · cm, but it is expensive due to the complicated process. Also,
The conductive paste using silver powder has a drawback that when an electric field is applied in a hot and humid atmosphere, electroplating of silver called migration occurs on wiring conductors and electrodes, and electrodes or wirings are short-circuited. Several measures have been taken to prevent this migration, and measures such as applying a moisture-proof coating to the surface of the conductor or adding a corrosion inhibitor such as a nitrogen-containing compound to the conductive paste have been studied. The effect was not sufficient.

Further, in order to prevent migration, silver-palladium alloy powder may be used in place of silver powder, but such alloy powder is more expensive than silver powder and has a small size such as a hybrid IC. Although it has been put to practical use in wiring boards, it has not yet been put to practical use in substrates such as paper phenol substrates, glass epoxy substrates, and polyethylene terephthalate, which have large wiring boards. If silver-coated copper powder is used, migration can be improved, and if this is used, an inexpensive conductive paste can be obtained, but if the silver coating is uniformly and thickly coated, there is no effect of improving migration. Further, the plating method is an inexpensive method as a coating method. For example, silver plating of inexpensive spherical copper powder can be easily performed with less aggregation, but the conductive paste using this has a drawback of high resistance. It was

[0007]

The invention according to claim 1 is a conductive material for forming an electric circuit, which has a low specific resistance, a high conductivity, and a small change in the specific resistance even after a thermal shock test or a humidity / humidity load test. Provided is a composite conductive powder from which a paste is obtained. The inventions described in claims 2 to 7 are particularly excellent in conductivity among the inventions described in claim 1, and in addition to the invention described in claim 1, a composite conductive powder capable of obtaining a conductive paste having excellent oxidation resistance and heat resistance. I will provide a. The invention according to claims 8 to 10 provides a composite conductive powder which can be pressed to obtain a conductive paste having an anchor effect. The invention according to claim 11 provides a composite conductive powder, which has a low specific resistance, a high conductivity, and a conductive paste for forming an electric circuit, which is excellent in migration resistance.

According to the invention of claim 12, the specific resistance is low,
High conductivity, small change in resistivity even after thermal shock test or humidity / humidity load test, and improved contact probability between conductive powders, resulting in higher conductivity of electric circuits, especially for sheet-like base materials. Provided is a composite conductive powder which is capable of printing a circuit and obtaining a conductive paste that enhances conductivity when the printed circuit is pressed. The inventions according to claims 13 to 18 are particularly excellent in conductivity among the inventions according to claim 12, and in addition to the invention according to claim 12, a composite conductive powder capable of obtaining a conductive paste excellent in oxidation resistance and heat resistance. I will provide a. The invention described in claims 19 to 21 provides a composite conductive powder capable of obtaining a conductive paste having an anchor effect by pressurizing. The invention according to claim 22 provides a composite conductive powder, which has a low specific resistance, a high conductivity, and a conductive paste for forming an electric circuit, which is excellent in migration resistance.

The present invention provides a conductive paste for forming an electric circuit, which has a low specific resistance, a high conductivity, and a small change in the specific resistance even after a thermal shock test or a humidity / humidity load test. . The invention of claim 26 has a low specific resistance,
Provided is a conductive paste for forming an electric circuit, which improves the probability of contact between conductive powders, has a high electric circuit conductivity, and is excellent in migration resistance. The invention according to claim 27 is
Provided is an electric circuit having low specific resistance, high conductivity, and excellent migration resistance. The invention described in claim 28 provides an electric circuit excellent in forming a fine circuit in addition to the invention described in claim 27. The invention described in claim 29 provides a method for manufacturing an electric circuit having a low specific resistance, high conductivity, and excellent migration resistance. Claim 3
In addition to the invention described in claim 29, the invention described in 0 provides a method for manufacturing an electric circuit which is excellent in forming a fine circuit.

[0010]

The present invention relates to the following items. (1) Composite conductive powder containing flat conductive powder and irregular-shaped conductive powder. (2) The composite conductive powder according to (1) above, wherein the material of the flat conductive powder is silver, a silver alloy or a silver-coated conductor. (3) The composite conductive powder as described in (1) above, wherein the flat conductive powder is a flat silver-coated conductive powder. (4) The composite conductive powder according to (3) above, wherein the flat silver-coated conductor powder is silver-coated copper powder or silver-coated copper alloy powder. (5) The above-mentioned (3) or (4), which is a silver-coated copper powder in which the conductor covered with the flat silver-coated conductor powder is exposed.
The described composite conductive powder. (6) The composite conductive powder as described in any one of (1) to (5) above, wherein the material of the irregular-shaped conductive powder is silver or a silver alloy.

(7) The composite conductive powder as described in (6) above, wherein the irregular-shaped conductive powder is reduced silver powder. (8) The composite conductive powder as described in (6) above, wherein the irregular-shaped conductive powder is a conductive material having a hardness higher than that of silver or a silver alloy coated with silver. (9) A conductor having hardness higher than that of silver or silver alloy is Co or N
The composite conductive powder according to (8) above, which is i, Cr, Cu, W powder or an alloy powder thereof. (10) The composite conductive powder according to (9), wherein the conductor having a hardness higher than that of silver or silver alloy is copper powder or copper alloy powder. (11) The irregular-shaped conductive powder is silver-coated copper powder or silver-coated copper alloy powder in which the coated conductor is exposed, (8)
~ The composite conductive powder according to any one of (10).

(12) Composite conductive powder containing conductive powder having an aspect ratio of 6 or more and conductive powder having an aspect ratio of 5 or less. (13) The composite conductive powder as described in (12) above, wherein the material of the conductive powder having an aspect ratio of 6 or more is silver, a silver alloy, or a silver-coated conductor. (14) The composite conductive powder as described in (12) above, wherein the conductive powder having an aspect ratio of 6 or more is a silver-coated conductive powder having an aspect ratio of 6 or more. (15) The composite conductive powder according to (14), wherein the silver-coated conductor powder having an aspect ratio of 6 or more is silver-coated copper powder or silver-coated copper alloy powder. (16) The above-mentioned (14) or (15), wherein the silver-coated conductor powder having an aspect ratio of 6 or more is a silver-coated copper powder or a silver-coated copper alloy powder from which the coated conductor is exposed. Composite conductive powder.

(17) The composite conductive powder as described in any one of (12) to (16) above, wherein the material of the conductive powder having an aspect ratio of 5 or less is silver or a silver alloy. (18) The composite conductive powder as described in 17 above, wherein the conductive powder having an aspect ratio of 5 or less is reduced silver powder. (19) The composite conductive powder as described in (17) above, wherein the conductive powder having an aspect ratio of 5 or less is a conductive material having a hardness higher than that of silver or a silver alloy coated with silver. (20) A conductor having hardness higher than that of silver or silver alloy is Co or N
The composite conductive powder according to (19) above, which is i, Cr, Cu, W powder or an alloy powder thereof. (21) The composite conductive powder according to (19), wherein the conductor having a hardness higher than that of silver or silver alloy is copper powder or copper alloy powder. (22) The composite conductive powder as described in any of (19) to (21) above, wherein the irregular-shaped conductive powder is silver-coated copper powder in which the coated conductor is exposed.

(23) A conductive paste containing the composite conductive powder according to any one of the above (1) to (22), a binder and a solvent. (24) The composite conductive powder is 8 with respect to the solid content of the conductive paste.
The electrically conductive paste as described in (23) above, which is contained in an amount of 5 to 93% by weight. (25) The composite electroconductive powder according to any one of (1) to (11) above, a binder, and a solvent are contained, and the flat electroconductive powder is included in an amount of 95 to 50% by weight, and the irregular electroconductive powder in an amount of 5 to 50. The electrically conductive paste as described in (23) or (24) above, wherein the electrically conductive paste contains the weight percent. (26) The composite electroconductive powder according to any of (12) to (22) above, a binder, and a solvent are contained, and the aspect ratio is 95 to 50% by weight of the electroconductive powder having an aspect ratio of 6 or more. The conductive paste according to claim (23) or (24), which comprises 5 to 50% by weight of a conductive powder of 5 or less.

(27) An electric circuit formed on the surface of a substrate using the conductive paste according to any one of (23) to (26). (28) The specific resistance of the electric circuit formed on the surface of the base material is 2
The electric circuit as described in (27) above, which has a resistance of 5 μΩ · cm or less. (29) After forming a circuit pattern on the surface of the base material with the conductive paste according to any one of (23) to (26),
A method for manufacturing an electric circuit, which comprises pressurizing and curing. (30) The specific resistance of the electric circuit formed on the surface of the base material is 2
The method for producing an electric circuit as described in (29) above, wherein the electric circuit has a thickness of 5 μΩ · cm or less.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in the case of a combination of flat conductive powder and irregular conductive powder or a combination of conductive powder having an aspect ratio of 6 or more and conductive powder having an aspect ratio of 5 or less, contact between the conductive powders The probability can be improved, and the conductivity of the electric circuit can be increased. In particular, when the circuit is printed on a sheet-shaped substrate and the printed circuit is pressed, the conductivity can be increased.

In the present invention, the aspect ratio of the conductive powder means the ratio of the major axis and the minor axis of the particles of the conductive powder (major axis / minor axis). In the present invention, the particles of the conductive powder are mixed well in the curable resin having a low viscosity, and the resin is cured while allowing the particles to settle by standing, and the obtained cured product is cut in the vertical direction. The shape of the particles appearing on the cut surface is observed under magnification with an electron microscope, and the major axis / minor axis of each particle is obtained for at least 100 particles, and the average value thereof is defined as the aspect ratio. Here, the minor axis is defined as a combination of two parallel lines contacting the outside of the particle with respect to the particle appearing on the cut surface so as to sandwich the particle. Distance. On the other hand, the major axis is the two parallel lines perpendicular to the parallel line that determines the minor axis, and is the distance between the two parallel lines that are the longest among the combinations of the two parallel lines that contact the outside of the particle. is there. The rectangle formed by these four lines is sized to fit the particle exactly inside it. The specific method used in the present invention will be described later.

The flat conductive powder is a conductive powder composed of fine pieces having a substantially flat shape, and for example, there is a flaky conductive powder. Irregularly shaped conductive powder is a conductive powder having a shape other than flat, and is called spherical, cubic, tetrahedral, lumpy, roughly spherical, etc., powder with a projection on the surface such as sucrose. It refers to various conductive powders such as a body and a mixture thereof.
Examples of the conductive powder containing various shapes of conductive powder include reduced silver powder. A conductive powder having an aspect ratio of 6 or more and a conductive powder having an aspect ratio of 5 or less can be used for each of the flat conductive powder and the irregular-shaped conductive powder.

In many cases, the conductive powder having an aspect ratio of 6 or more corresponds to a flat conductive powder, and in addition to this, there is a shape called a dendritic shape (also called a dendrite shape). Can be used. As the conductive powder having an aspect ratio of 6 or more, an aspect ratio of 7 or more is preferable, an aspect ratio of 8 or more is more preferable, and an aspect ratio of 10 or more is further preferable, in that a highly conductive paste can be obtained. Therefore, from the viewpoint of both the shape and the aspect ratio, the flat conductive powder having an aspect ratio of 7 or more is more preferable in terms of high conductivity, the viscosity of the conductive paste, and the like, and the flat conductive powder having an aspect ratio of 8 or more is more preferable. A flat conductive powder having an aspect ratio of 10 or more is most preferable.

The average particle size of the particles of the flat conductive powder or the conductive powder having an aspect ratio of 6 or more is preferably 25 μm or less from the viewpoint of not impairing printability.
Those having a size of 20 μm or less are more preferable, and those having a size of 10 μm or less are still more preferable. The average particle size here is
It can be measured by a laser scattering type particle size distribution measuring device. In the present invention, the measurement was performed using a master sizer (manufactured by Malvern) as the device.

As the conductive powder having an aspect ratio of 5 or less,
Many of the above-mentioned irregularly shaped conductive powders correspond to the above. As the conductive powder having an aspect ratio of 5 or less, an aspect ratio of 4 or less is preferable in that a highly conductive paste can be obtained,
The aspect ratio is more preferably 3 or less, further preferably 2.5 or less.

The average particle size of the irregular-shaped conductive powder or the conductive powder having an aspect ratio of 5 or less is 3 to 2 in terms of excellent printability.
The range of 0 μm is preferable, and the range of 3 to 10 μm is more preferable. Here, the average particle size can be measured by a laser scattering type particle size distribution measuring device in the same manner as described above. In the present invention, the measurement was performed using a master sizer (manufactured by Malvern) as the device.

The material of each conductive powder is preferably silver or silver alloy in terms of conductivity and oxidation resistance. As the silver alloy, it is preferable to use an alloy with palladium (for example, about 1 to 5% by weight in a silver alloy), platinum (for example, about 1% by weight in a silver alloy), or the like. Further, one of the methods for producing the above-mentioned silver powder is an in-liquid reduction method, and since the silver powder produced by this method is a fine powder having an average particle size of several μm, it is widely used as an industrial production method. There is. This in-liquid reduction method is a method in which silver is dissolved in an acid, neutralized with an alkali, and then reduced with a reducing agent such as formalin or starch to obtain a fine powder. There, the powder obtained by this is called reduced silver powder, the shape of which is
It is close to lumpy but has an irregular shape instead of a constant shape. This reduced silver powder can be used as an irregularly shaped conductive powder or a conductive powder having an aspect ratio of 5 or less in the present invention. Each conductive powder may be a silver-coated conductive powder in which a conductor other than silver or a silver alloy is coated with silver or a silver alloy.

The irregular-shaped conductive powder may be silver-coated conductor powder as described above, but the conductor to be coated is preferably a conductor having a hardness higher than that of silver or silver alloy. As such a conductor, for example, Co, Ni, C
Metal powders such as r, Cu and W or alloy powders thereof can be used, but among these, it is preferable to use copper powder or copper alloy powder. It is preferable to use this because when the electric circuit is pressurized, the irregular-shaped conductive powder bites into the flat silver powder or the silver alloy powder to increase the conductivity of the electric circuit. As the above-mentioned copper alloy powder, for example, alloy powders of copper and tin, copper and zinc, etc. are used.

To coat the surface of the irregular-shaped conductive powder or the conductive powder having an aspect ratio of 5 or less with silver, there are methods such as displacement plating, electroplating, and electroless plating. Since the adhesion between the conductive powder and silver described below is high and the running cost is low, it is preferable to perform the coating by the displacement plating method. The amount of silver coated on the surface of the irregular-shaped conductive powder or the conductive powder having an aspect ratio of 5 or less is less than that of the irregular-shaped conductive powder or the conductive powder having an aspect ratio of 5 or less from the viewpoints of cost and the effect of suppressing electrolytic corrosion. 3-
The range of 50% by weight is preferable, and the range of 3 to 20% by weight is more preferable.

It is preferable to use any of the above-mentioned silver-coated conductor powders because it has excellent migration resistance. As the silver-coated conductor powder, one in which a part of the conductor is exposed (abbreviated as exposed-cover conductor powder) can be used. The exposed coated conductor powder can be used for each of the flat conductor powder or the conductor powder having an aspect ratio of 6 or more and the irregularly shaped conductor powder or the conductor powder having an aspect ratio of 5 or less. The exposed area of the conductive powder is preferably 50% or less in order to obtain good conductivity, and 2
0% or less is more preferable.

Since the spherical silver-coated copper powder or silver-coated copper alloy powder after displacement plating has few contact points, the resistance tends to increase. Therefore, the spherical silver-coated copper powder or silver-coated copper alloy powder after displacement plating may be impacted to change the shape of the particles to a flat shape or an aspect ratio of 6 or more. Specifically, it can be deformed by a method such as a ball mill or a vibration mill.

The mixing ratio of the flat conductive powder and the irregular conductive powder or the conductive powder having an aspect ratio of 6 or more and the conductive powder having an aspect ratio of 5 or less is such that the flat conductive powder or the aspect ratio is 6
It is preferable that the above-mentioned conductive powder is in the range of 5 to 50% by weight with respect to 95 to 50% by weight of the irregular-shaped conductive powder or the conductive powder having an aspect ratio of 5 or less in order to enhance the conductivity. Conductive powder with an aspect ratio of 6 or more is 80 to 60
It is more preferable that the irregularly shaped conductive powder or the conductive powder having an aspect ratio of 5 or less is in the range of 20 to 40% by weight based on the weight%.

The conductive paste contains these composite conductive powders, a binder and a solvent. In this conductive paste, the content of the composite conductive powder is 85 to 85 in terms of the resistance, economy and adhesiveness of the conductor with respect to the solid content of the conductive paste.
It is preferably 93% by weight, more preferably 87 to 90% by weight.

A liquid epoxy resin, a phenol resin, an unsaturated polyester resin or other organic adhesive component is used as the binder, and terpineol, ethyl carbitol, carbitol acetate, butyl cellosolve or the like is used as the solvent. To be In addition to the above materials, the conductive paste is added with a hardening agent for organic adhesive components such as 2-ethylmethylimidazole and, if necessary, a corrosion inhibitor such as benzothiazole and benzimidazole, and fine graphite powder, and uniformly mixed. Obtained. The content of the binder and the solvent is 7 to 15 wt% of the binder and 10 of the solvent with respect to the conductive paste in terms of conductivity, adhesiveness and printability.
Is preferably in the range of ~ 35 wt% and the binder is 7
It is more preferable that the range is -12 wt% and the solvent is 15-25 wt%. In addition, the content of the curing agent is preferably 0.5 to 10 parts by weight, more preferably 1 to 8 parts by weight with respect to 100 parts by weight of the binder in terms of workability. The corrosion inhibitor and the fine graphite powder are added as needed, but if added, the content of the corrosion inhibitor is 0.
It is preferably in the range of 1 to 3 parts by weight. The fine graphite powder is preferably in the range of 1 to 10% by weight with respect to the conductive paste.

The method for forming the electric circuit is not particularly limited, and a known method, for example, a conductive paste can be formed by screen printing or a drawing machine controlled by a computer. As the substrate, a polyethylene terephthalate film, a polyimide film, a polyamideimide film, a paper phenol laminate, an epoxy resin glass cloth substrate laminate, a polyimide resin glass cloth substrate laminate, or the like is used.

In the present invention, the specific resistance of the electric circuit is preferably 25 μΩ · cm or less, more preferably 15 μΩ · cm.
cm or less, and if it exceeds 25 μΩ · cm, conductivity tends to decrease, resulting in a large voltage drop in the electric circuit.
It becomes difficult to make a fine electric circuit. Note that it is particularly preferable that the specific resistance of the electric circuit be 10 μΩ · cm or less, since the electric circuit can be used for an electric circuit having a long wire such as a fine and coil-shaped planar antenna. The specific resistance of the electric circuit of 25 μΩ · cm or less can be achieved by forming a circuit pattern on the surface of the base material with the above-mentioned conductive paste, and then pressing it with a press to densify the circuit pattern. As a pressing method, a method of applying pressure using a surface plate, a method of pressing with a roll, or the like is applied, as long as the contact efficiency between powders in a conductive layer formed of a conductive paste can be increased. Note that the binder in the conductive layer is preferably softened during pressing, and if the binder is in a semi-cured state or hardened, it is preferably heated and softened before use. The binder may be cured after pressing or during pressing.

[0033]

EXAMPLES Examples of the present invention will be described below. Example 1 Bisphenol A type epoxy resin (oiled shell epoxy)
Co., Ltd., trade name Epikote 834 60 parts by weight and bisphenol A type epoxy resin (Yukaka Shell Epoxy Co., Ltd.)
Manufactured by trade name Epikote 828) 40 parts by weight in advance by heating, and then cooled to room temperature, and then 5 parts by weight of 2 ethyl 4-methylimidazole (manufactured by Shikoku Chemicals Co., Ltd.), 20 parts by weight of ethyl carbitol and butyl cellosolve. 20 parts by weight were added and mixed uniformly to obtain a resin composition.

Next, a flaky silver powder having an aspect ratio of 8 and an average long diameter of 8 μm (trade name: T, manufactured by Tokuriki Kagaku Kenkyusho)
CG-1) 210 parts by weight (79.2% by weight) and a silver powder having an aspect ratio of 2.3 and a major axis having an average particle diameter of 7 μm (manufactured by Rare Metallic Co., Ltd.) (hereinafter, referred to as silver powder having an aspect ratio of 2.3). 55 parts by weight (20.8% by weight) was added, and then this was added to 145 parts by weight of the resin composition obtained above, and the mixture was uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. Obtained. The content of the composite silver powder of the flaky reduced silver powder and the silver powder having an aspect ratio of 2.3 was 80% by weight based on the solid content of the conductive paste.

Then, using the conductive paste obtained above, a silver conductor circuit 1 shown in FIG. 1 was printed on a polyethylene terephthalate film having a thickness of 125 μm in the air at 60 ° C. for 30 minutes and further at 145 ° C. A heat treatment was performed under the condition of 30 minutes to obtain a wiring board. In FIG. 1, 2 is a polyethylene terephthalate film. Then, the specific resistance of the obtained wiring board was measured and found to be 52 μΩ · cm.
As a result of the thermal shock test of the wiring board, the rate of change in specific resistance was 5%. Further, as a result of performing a wet and medium load test on the wiring board, the rate of change in specific resistance was 8%. The cooling and heating test conditions were 100 cycles of 125 ° C. for 30 minutes to −65 ° C. for 30 minutes, and the humidity and medium load test was 100 ° C. at 40 ° C. and 90% RH.
Hold for 0 hours.

The specific measuring method of the aspect ratio in this embodiment is shown below. 8 g of base material (No.20-8130) of low-viscosity epoxy resin (manufactured by Buehler) and curing agent (No.2
0-8132) 2 g were mixed, and 2 g of the conductive powder was mixed and well dispersed therein, and then vacuum degassing was performed at 30 ° C., and then 6 to 8
The particles were allowed to settle and harden by standing at 30 ° C. for a time. Then, the obtained cured product was cut in the vertical direction, the cut surface was magnified 2000 times with an electron microscope, and the 100 appeared on the cut surface.
The major axis / minor axis was determined for each particle, and the average value thereof was defined as the aspect ratio.

Example 2 Example 1 except that 400 parts by weight (80% by weight) of the flaky silver powder used in Example 1 and 100 parts by weight (20% by weight) of silver powder having an aspect ratio of 2.3 were blended. A conductive paste was obtained through the same steps as. The content of the composite silver powder of the flaky reduced silver powder and the silver powder having an aspect ratio of 2.3 was 85% by weight based on the solid content of the conductive paste. A wiring board was manufactured through the same steps as in Example 1 and the characteristics thereof were evaluated. As a result, the specific resistance of the wiring board was 43 μΩ · cm. As a result of conducting a thermal shock test of the wiring board,
The rate of change in resistivity was 4%, and the result of the wet and medium load test showed that the rate of change in resistivity was 7%.

Example 3 320 parts by weight (80% by weight) of the flaky silver powder used in Example 1 and 80 parts by weight of silver powder having an aspect ratio of 2.3 (2
A conductive paste was obtained through the same steps as in Example 1 except that 0% by weight) was blended. The content of the composite silver powder of the flaky reduced silver powder and the silver powder having an aspect ratio of 2.3 was 86% by weight based on the solid content of the conductive paste. A wiring board was manufactured through the same steps as in Example 1 and the characteristics thereof were evaluated. As a result, the specific resistance of the wiring board was 39 μΩ · cm. As a result of a thermal shock test of the wiring board, the rate of change in resistivity was 5%, and the result of the wet / medium load test showed a rate of change in resistivity of 6%.

Example 4 The wiring board obtained in Example 3 was heated and pressed with a hot press at a temperature of 100 ° C. and a pressure of 10 MPa to densify the silver conductor circuit and evaluate its characteristics. As a result, the specific resistance of the densified wiring board was 22 μΩ · cm. Further, as a result of a thermal shock test of the densified wiring board, the rate of change in resistivity was 5%, and the result of the wet / medium load test showed a rate of change in resistivity of 4%.

Comparative Example 1 400 parts by weight of the flaky reduced silver powder used in Example 1 was added to 145 parts by weight of the resin composition obtained in Example 1 to give Example 1.
A conductive paste was obtained by uniformly mixing and dispersing in the same manner as in. A wiring board is manufactured through the same steps as in Example 1 below.
Its characteristics were evaluated. As a result, the specific resistance of the wiring board is 62.
It was μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change of the specific resistance was 10%, and the result of the wet and medium load test showed the rate of change of the specific resistance to be 9%.

Comparative Example 2 A wiring board was obtained through the same steps as in Example 1 except that the conductive paste obtained in Comparative Example 1 was used. Next, the wiring board was heated and pressed under the same conditions as in Example 4 using a hot press to densify the silver conductor circuit, and its characteristics were evaluated. As a result, the specific resistance of the densified wiring board was 58 μΩ · cm. As a result of a thermal shock test conducted on the densified wiring board, the rate of change in resistivity was 10%, and the result of the wet / medium load test showed a rate of change in resistivity of 9%.

Example 5 Ni powder having an aspect ratio of 2 and an average long diameter of 3 μm (manufactured by Kojundo Chemical Co., Ltd.) was degreased with an acidic cleaner (manufactured by Nippon MacDermid, trade name L-5B), washed with water, and 20 g of AgCN was added.
/ H ₂ O 1 liter and NaCN 40 g / H ₂ O 1 liter, electroless plating was performed so that the amount of silver was 15% by weight based on the above Ni powder, and the silver-coated Ni was washed with water and dried. Got the powder.

Next, a flaky silver powder having an aspect ratio of 8 and an average long diameter of 8 μm (trade name: T, manufactured by Tokuriki Kagaku Kenkyusho)
CG-1) 210 parts by weight (91.3% by weight) and 20 parts by weight (8.7% by weight) of the silver-coated Ni powder obtained above were blended, and this was then added to the resin composition obtained in Example 1. 145
It was added to parts by weight and uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. The content of the composite conductive powder of the flaky silver powder and the silver-coated Ni powder was 61.3% by weight based on the solid content of the conductive paste. A wiring board was manufactured through the same steps as in Example 1 and the characteristics thereof were evaluated. As a result, the specific resistance of the wiring board was 43 μΩ · cm. As a result of a thermal shock test of the wiring board, the rate of change in specific resistance was 5%, and the result of the wet and medium load test showed a rate of change in specific resistance of 8%.

Example 6 400 parts by weight of the flaky silver powder used in Example 5 (88.
9% by weight) and 50 parts by weight (11.1% by weight) of the silver-coated Ni powder obtained in Example 5 were mixed, and a conductive paste was obtained through the same steps as in Example 5. The content of the composite conductive powder of the flaky silver powder and the silver-coated Ni powder was 73.4% by weight based on the solid content of the conductive paste. Example 5 below
A wiring board was manufactured through the same steps as above, and its characteristics were evaluated. As a result, the specific resistance of the wiring board was 43 μΩ · cm. As a result of a thermal shock test of the wiring board, the rate of change in resistivity was 4%, and the result of the wet / medium load test showed a rate of change in resistivity of 7%.

Example 7 320 parts by weight of the flaky silver powder used in Example 5 (91.
4% by weight) and 30 parts by weight (8.6% by weight) of the silver-coated Ni powder obtained in Example 5 were blended to obtain a conductive paste through the same steps as in Example 5. The content of the composite conductive powder of the flaky silver powder and the silver-coated Ni powder was 70.7% by weight based on the solid content of the conductive paste. A wiring board was manufactured through the same steps as in Example 5 and the characteristics thereof were evaluated. As a result, the specific resistance of the wiring board was 38 μΩ · cm. As a result of a thermal shock test of the wiring board, the rate of change in resistivity was 5%, and the result of the wet / medium load test showed a rate of change in resistivity of 6%.

Example 8 320 parts by weight of the flaky silver powder used in Example 5 (80.
0% by weight) and 80 parts by weight (20.0% by weight) of the silver-coated Ni powder obtained in Example 5 were blended to obtain a conductive paste through the same steps as in Example 5. The content of the composite electroconductive powder of the flaky silver powder and the silver-coated Ni powder was 89.9% by weight based on the solid content of the electroconductive paste. Example 5 below
A wiring board was produced through the same steps as in. Then, the printed circuit was densified by heating and pressing the wiring board with a hot press under the conditions of a temperature of 100 ° C. and a pressure of 10 MPa, and its characteristics were evaluated. As a result, the specific resistance of the densified wiring board is 20 μΩ ・
It was cm. Further, as a result of a thermal shock test of the densified wiring board, the rate of change in resistivity was 5%, and the result of the wet / medium load test showed a rate of change in resistivity of 4%.

Example 9 A flaky silver powder A (manufactured by Tokuriki Kagaku Kenkyusho, trade name TCG-1) having an aspect ratio of 8 and an average long diameter of 8 μm was used in an attritor (manufactured by Mitsui Mining Co., Ltd.). Crushed, flaky silver powder B4 with aspect ratio of 11 and average particle size of 20 μm
00 parts by weight (66.7% by weight) and an aspect ratio of 2.
Silver powder with an average particle size of 3 and 7 μm (made by Rare Metallic Co., Ltd.)
200 parts by weight (hereinafter referred to as silver powder having an aspect ratio of 2.3) (33.3% by weight) was blended, and this was added to 145 parts by weight of the resin composition obtained in Example 1 and stirred. The mixture was uniformly mixed and dispersed by a machine and a triple roll to obtain a conductive paste. The ratio of the scaly silver powder B to the silver powder having an aspect ratio of 2.3 was 6.67: 3.33 in a volume ratio (scaly silver powder B: silver powder having an aspect ratio of 2.3). The composite conductive (silver) powder was contained in an amount of 85.1% by weight based on the solid content of the conductive paste.

Next, the conductive paste obtained above was printed on the test pattern shown in FIG.
A circuit board 6 having a 5 μm circuit 4 formed thereon was obtained. Board 3
Is a polyethylene terephthalate film (thickness: 125
μm) and heat curing conditions are 60 ° C. for 30 minutes + 145 ° C.
It took 45 minutes. The specific resistance of the obtained circuit board 6 is 42 μΩ.
・ It was cm. As a result of the thermal shock test of the circuit board 6, the rate of change in specific resistance was 5%. Further, as a result of performing a humidity and medium load test on the circuit board 6, the rate of change in specific resistance was 8%. The cold heat test conditions are 125 ° C. for 30 minutes
100 cycles of −65 ° C. for 30 minutes were performed, and the humidity and humidity load test was held at 40 ° C. and 90% RH for 1000 hours. On the other hand, on the upper surface of the chip mounting portion 5 of the circuit board 6, the IC chip 8 in which the test circuit 7 is formed on the silicon substrate 9 shown in FIG.
As shown in Fig. 2, an anisotropic conductive sheet (manufactured by Hitachi Chemical Co., Ltd., trade name Anisolm 82) is placed so that the test circuit 7 is on the lower side.
01) (not shown) and placed and connected. The average value of the connection resistance including the anisotropic conductive sheet was 45 mΩ, and the maximum value was 63 mΩ.

Example 10 350 parts by weight of the flaky silver powder B used in Example 9 (50
%) And 350 parts by weight (50% by weight) of silver powder having an aspect ratio of 2.3 were added to 145 parts by weight of the resin composition obtained in Example 1 and then uniformly mixed in the same manner as in Example 9. A conductive paste was obtained by mixing and dispersing. The ratio of the flaky silver powder B to the silver powder having an aspect ratio of 2.3 was 5: 5 by volume ratio (scaly silver powder B: silver powder having an aspect ratio of 2.3). The composite conductive (silver) powder was contained in an amount of 43.2% by volume (86.9% by weight) based on the solid content of the conductive paste. A circuit board was manufactured through the same steps as in Example 9 below, and the characteristics thereof were evaluated. As a result, the specific resistance is 41μ.
Ω · cm. As a result of the thermal shock test of the circuit board, the rate of change of the specific resistance was 4%, and the result of the wet and medium load test showed the rate of change of the specific resistance to be 7%. Further, as in Example 9, the average value of the connection resistance when the test circuit was connected using the anisotropic conductive sheet was 40 mΩ, and the maximum value was 55 mΩ.

Example 11 650 parts by weight of the flaky silver powder used in Example 9 (72.
2% by weight) and 250 parts by weight (27.8% by weight) of silver powder having an aspect ratio of 2.3 were added to 145 parts by weight of the resin composition obtained in Example 1, and the same method as in Example 9 was performed. Were uniformly mixed and dispersed to obtain a conductive paste. The volume ratio of the flaky silver powder B to the silver powder having an aspect ratio of 7.2 was 7.22: 2.78 (scaly silver powder B: silver powder having an aspect ratio of 2.3). Composite conductivity (silver)
The powder is 49.5% by volume (8% with respect to the solid content of the conductive paste).
9.6% by weight). A circuit board was manufactured through the same steps as in Example 9 below, and the characteristics thereof were evaluated. As a result, the specific resistance was 39 μΩ · cm. As a result of the thermal shock test of the circuit board, the rate of change in specific resistance was 5%, and the result of the wet and intermediate load test showed a rate of change in specific resistance of 6%. Furthermore, as in Example 9, the average value of the connection resistance when the test circuit was connected using the anisotropic conductive sheet was 38.
mΩ, and the maximum value was 58 mΩ.

Example 12 700 parts by weight of the flaky silver powder B used in Example 9 (5
8.3% by weight) and an aspect ratio of 2.3 silver powder 500
145 parts by weight of the resin composition used in Example 1 was added to a mixture of 4 parts by weight (41.7% by weight), and uniformly mixed and dispersed in the same manner as in Example 9 to obtain a conductive paste. The ratio of the flake-shaped silver powder B to the silver powder having an aspect ratio of 2.3 is 5.83: 4.17 (flake-shaped silver powder B:
The silver powder had an aspect ratio of 2.3. The composite conductive (silver) powder was contained in an amount of 56.6% by volume (91.9% by weight) based on the solid content of the conductive paste. A circuit board was prepared through the same steps as in Example 9 except that the heating and curing conditions were 60 ° C. for 30 minutes and 110 ° C. for 1 hour, and then the circuit board was heated and pressed under the conditions of 100 ° C. and 9.8 MPa with a hot press. The circuit was densified to evaluate its characteristics. As a result, the specific resistance was 9.
It was 1 μΩ · cm. As a result of the thermal shock test of the circuit board, the rate of change of the specific resistance was 5%, and the result of the wet and medium load test was that the rate of change of the specific resistance was 4%. Furthermore, as in Example 9, the average value of the connection resistance when connecting using the anisotropic conductive sheet was 32 mΩ, and the maximum value was 42 m.
Ω.

Comparative Example 3 600 parts by weight of the flaky silver powder B used in Example 9 was added to 145 parts by weight of the resin composition obtained in Example 1, and the mixture was uniformly mixed in the same manner as in Example 9 below. Dispersed to obtain a conductive paste. A circuit board was manufactured through the same steps as in Example 9 below, and the characteristics thereof were evaluated. As a result, the specific resistance is 46 μΩ.
・ It was cm. As a result of the thermal shock test of the circuit board, the rate of change in resistivity was 10%, and the result of the wet and medium load test showed a rate of change in resistivity of 9%. Furthermore, as in Example 9, the average value of the connection resistance when connecting using the anisotropic conductive sheet was 1.05Ω, and the maximum value was 12 mΩ.
Met.

Example 13 380 parts by weight of the flaky silver powder B used in Example 9 (6
Silver powder 220 having an aspect ratio of 2.3)
A mixture containing 1 part by weight (36.7% by weight) was added to 145 parts by weight of the resin composition obtained in Example 1, and the mixture was uniformly mixed and dispersed in the same manner as in Example 9 to obtain a conductive paste. . The volume ratio of the flaky silver powder B to the silver powder having an aspect ratio of 6.33: 3.67 (scaly silver powder B:
The silver powder had an aspect ratio of 2.3. The composite conductive (silver) powder was contained in an amount of 39.5% by volume (85.1% by weight) based on the solid content of the conductive paste. A circuit board was manufactured through the same steps as in Example 9 below, and the characteristics thereof were evaluated.
As a result, the specific resistance was 43 μΩ · cm. As a result of the thermal shock test of the circuit board, the rate of change in resistivity was 5
%, And the rate of change in specific resistance was 8% as a result of the wet and medium load test. Further, as in Example 9, the average value of the connection resistance when the test circuit was connected using the anisotropic conductive sheet was 42 mΩ, and the maximum value was 60 mΩ.

Example 14 380 parts by weight of the flaky silver powder B used in Example 9 (5
4.2% by weight) and an aspect ratio of 2.3 silver powder 320
145 parts by weight of the resin composition obtained in Example 1 was added with a mixture of 4 parts by weight (45.8% by weight), and uniformly mixed and dispersed in the same manner as in Example 9 to obtain a conductive paste. The ratio of the flaky silver powder B to the silver powder having an aspect ratio of 2.3 was 5.42: 4.58 by volume (scaly silver powder B: silver powder having an aspect ratio of 2.3). The composite conductive (silver) powder was contained in an amount of 43.2% by volume (86.9% by weight) based on the solid content of the conductive paste. A circuit board was manufactured through the same steps as in Example 9 below, and the characteristics thereof were evaluated.
As a result, the specific resistance was 43 μΩ · cm. As a result of the thermal shock test of the circuit board, the rate of change in resistivity was 4
%, And the rate of change in specific resistance was 7% as a result of the wet and medium load test. Further, as in Example 9, the average value of the connection resistance when the test circuit was connected using the anisotropic conductive sheet was 38 mΩ, and the maximum value was 52 mΩ.

Example 15 600 parts by weight of the flaky silver powder B used in Example 9 (6
6.7 wt%) and an aspect ratio of 2.3 silver powder 300
145 parts by weight of the resin composition obtained in Example 1 was added with the mixture of 3 parts by weight (33.3% by weight), and uniformly mixed and dispersed in the same manner as in Example 9 to obtain a conductive paste. The ratio of the scaly silver powder B to the silver powder having an aspect ratio of 2.3 was 6.67: 3.33 in a volume ratio (scaly silver powder B: silver powder having an aspect ratio of 2.3). The composite conductive (silver) powder was contained in an amount of 49.5% by volume (89.6% by weight) based on the solid content of the conductive paste. A circuit board was manufactured through the same steps as in Example 9 below, and the characteristics thereof were evaluated.
As a result, the specific resistance was 35 μΩ · cm. As a result of the thermal shock test of the circuit board, the rate of change in resistivity was 5
%, And the rate of change in specific resistance was 6% as a result of the wet and medium load test. Furthermore, as in Example 9, the average value of the connection resistance when the test circuit was connected using the anisotropic conductive sheet was 36 mΩ, and the maximum value was 56 mΩ.

Example 16 650 parts by weight of the flaky silver powder B used in Example 9 (5
4.2% by weight) and an aspect ratio of 2.3 silver powder 550
145 parts by weight of the resin composition used in Example 1 was added to the resin composition used in Example 1, and uniformly mixed and dispersed in the same manner as in Example 9 to obtain a conductive paste. The volume ratio of the flaky silver powder B to the silver powder having an aspect ratio of 2.32: 4.58 (scaly silver powder B:
The silver powder had an aspect ratio of 2.3. The composite conductive (silver) powder was contained in an amount of 56.6% by volume (91.9% by weight) based on the solid content of the conductive paste. Thereafter, a circuit board is manufactured through the same steps as in Example 9, and then 1 by a hot press.
The circuit was densified by heating and pressurizing under the conditions of 00 ° C. and 9.8 MPa, and its characteristics were evaluated. As a result, the specific resistance is 8.7 μΩ.
・ It was cm. As a result of the thermal shock test of the circuit board, the rate of change of the specific resistance was 5%, and the result of the wet and medium load test was that the rate of change of the specific resistance was 4%. Furthermore, as in Example 9, the average value of the connection resistance when connecting using the anisotropic conductive sheet was 30 mΩ, and the maximum value was 40 mΩ.

Example 17 A flaky silver powder having an aspect ratio of 8 and an average long diameter of 8 μm (manufactured by Tokuriki Kagaku Kenkyusho, trade name TCG-1) 450
150 parts by weight (75% by weight) and 150 parts by weight (25% by weight) of silver powder (produced by Rare Metallic Co., Ltd.) having an aspect ratio of 2.3 and an average major axis diameter of 7 μm (hereinafter, referred to as silver powder having an aspect ratio of 2.3). ) Was blended and then added to 145 parts by weight of the resin composition obtained in Example 1 and uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. The content of the flaky silver powder and the silver powder having an aspect ratio of 2.3 was 39.5% by volume (85.1% by weight) based on the solid content of the conductive paste.

After manufacturing a wiring board through the same steps as in Example 1, the wiring board was heated and pressed by a hot press at a temperature of 110 ° C. and a pressure of 10 MPa for 2 minutes, and then 145
It was cured at 30 ° C. for 30 minutes to form an electric circuit having a dense circuit pattern. The specific resistance of this electric circuit was measured and found to be 13 μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change in specific resistance was 5%. Moreover, as a result of performing a humidity and medium load test on the wiring board, the rate of change in specific resistance was 7%. The cooling test conditions are 125 ° C for 30 minutes-
100 cycles of 65 ° C. for 30 minutes, 4 in humidity and medium load test
It was kept at 0 ° C. and 90% RH for 1000 hours.

Example 18 550 parts by weight of the flaky silver powder used in Example 17 (8
4.6% by weight) and an aspect ratio of 2.3 silver powder 100
Example 17 except that parts by weight (15.4% by weight) were blended.
A conductive paste was obtained through the same steps as. The content of the flaky silver powder and the silver powder having an aspect ratio of 2.3 was 41.4% by volume (86.1% by weight) based on the solid content of the conductive paste. A wiring board was manufactured through the same steps as in Example 17, and an electric circuit was further formed to evaluate the characteristics. As a result, the specific resistance of the electric circuit was 10 μΩ · cm. As a result of conducting a thermal shock test of the wiring board,
The rate of change in resistivity was 4%, and the result of the wet and medium load test showed that the rate of change in resistivity was 7%.

Example 19 900 parts by weight of the flaky silver powder used in Example 17 (8
Silver powder 200 having an aspect ratio of 2.3)
Example 17 except that parts by weight (18.2% by weight) were blended.
A conductive paste was obtained through the same steps as. The content of the flaky silver powder and the silver powder having an aspect ratio of 2.3 was 55% by volume (91.5% by weight) based on the solid content of the conductive paste. A wiring board was manufactured through the same steps as in Example 17, and an electric circuit was further formed to evaluate the characteristics. As a result, the specific resistance of the electric circuit was 8.2 μΩ · cm. As a result of conducting a thermal shock test of the wiring board,
The rate of change in resistivity was 5%, and the result of the wet and medium load test showed that the rate of change in resistivity was 6%.

Example 20 The wiring board obtained in Example 19 was heated and pressed with a hot roll at a speed of 30 cm / min at a temperature of 125 ° C. and a pressure of 980 N / cm, and then cured at 145 ° C. for 30 minutes. Then, an electric circuit having a dense circuit pattern was formed. The specific resistance of this electric circuit was measured and found to be 8.3 μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change in resistivity was 5%, and the result of the wet / medium load test showed a rate of change in resistivity of 4%.

Example 21 410 parts by weight of the flaky silver powder used in Example 17 (6
6.7 wt%) and silver powder 205 having an aspect ratio of 2.3
Example 17 except that parts by weight (33.3% by weight) were blended.
A conductive paste was obtained through the same steps as. The content of the flaky silver powder and the silver powder having an aspect ratio of 2.3 was 40% by volume (85.4% by weight) based on the solid content of the conductive paste. A wiring board was obtained through the same steps as in Example 17 below. Next, the wiring board obtained above was heated and pressed for 2 minutes at a temperature of 100 ° C. and a pressure of 5 MPa with a hot press, and then cured at 145 ° C. for 30 minutes to form an electric circuit with a dense circuit pattern. When the specific resistance of this electric circuit was measured, it was 12 μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change in specific resistance was 5%. Further, as a result of performing a wet and medium load test on the wiring board, the rate of change in specific resistance was 8%. The cooling test condition is 125
100 cycles of 30 ° C. to −65 ° C. for 30 minutes were performed, and the humidity and medium load test was held at 40 ° C. and 90% RH for 1000 hours.

Example 22 600 parts by weight of the flaky silver powder used in Example 17 (80
Wt%) and 150 parts by weight (20% by weight) of silver powder having an aspect ratio of 2.3 were added, and a conductive paste was obtained through the same steps as in Example 17. The content of the flaky silver powder and the silver powder having an aspect ratio of 2.3 was 45% by volume (87.7% by weight) based on the solid content of the conductive paste. Hereinafter, a wiring board was manufactured through the same steps as in Example 17, then an electric circuit was formed through the same steps as in Example 21, and the characteristics thereof were evaluated. As a result, the specific resistance of the electric circuit was 10 μΩ · cm. As a result of a thermal shock test of the wiring board, the rate of change in resistivity was 4%, and the result of the wet / medium load test showed a rate of change in resistivity of 7%.

Example 23 800 parts by weight of the flaky silver powder used in Example 17 (7
2.7% by weight) and 300 parts by weight of amorphous silver powder (27.
(3 wt%) except that the conductive paste was obtained through the same steps as in Example 17. The content of the composite silver powder of the flaky silver powder and the silver powder having an aspect ratio of 2.3 was 54.5% by volume (91.3% by weight) based on the solid content of the conductive paste. A wiring board was manufactured through the same steps as in Example 17, and an electric circuit was further formed to evaluate the characteristics. As a result, the specific resistance of the electric circuit was 8.5 μΩ · cm. As a result of conducting a thermal shock test of the wiring board,
The rate of change in resistivity was 5%, and the result of the wet and medium load test showed that the rate of change in resistivity was 6%.

Example 24 The wiring board obtained in Example 23 was heated and pressed with a hot roll at a speed of 30 cm / min at a temperature of 125 ° C. and a pressure of 980 N / cm, and then cured at 145 ° C. for 30 minutes. An electric circuit having a dense circuit pattern was formed. When the specific resistance of this electric circuit was measured, it was 8.4 μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change in resistivity was 5%, and the result of the wet / medium load test showed a rate of change in resistivity of 4%.

Example 25 550 parts by weight of the flaky silver powder used in Example 17 (8
4.6% by weight), aspect ratio 3 and average particle size 5μ
m Ni powder 100 parts by weight (15.4% by weight) was added,
Then, this was added to 145 parts by weight of the resin composition obtained in Example 1 and uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. The content of the flaky silver powder and Ni powder was 4 with respect to the solid content of the conductive paste.
It was 2.5 volume% (86.6 weight%). A wiring board was obtained through the same steps as in Example 17 below.

Then, the wiring board obtained above was hot-pressed by
After heating and pressurizing for 2 minutes at a temperature of 110 ° C. and a pressure of 10 MPa, it was cured at 145 ° C. for 30 minutes to form an electric circuit having a dense circuit pattern. When the specific resistance of this electric circuit was measured, it was 12 μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change in specific resistance was 7%. Further, as a result of performing a wet and medium load test on the wiring board, the rate of change in specific resistance was 6%. The cooling test condition is 12
100 cycles of 30 minutes from 5 ° C. to 30 minutes at −65 ° C. were carried out, and the humidity load test was held at 40 ° C. and 90% RH for 1000 hours.

Example 26 650 parts by weight of the flaky silver powder used in Example 17 (8
6.7% by weight) and 100 parts by weight of Ni powder (13.3% by weight) were added, and a conductive paste was obtained through the same steps as in Example 17. The content of the flaky silver powder and the Ni powder was 45.5% by volume (8%) with respect to the solid content of the conductive paste.
8% by weight). A wiring board was manufactured through the same steps as in Example 17, and an electric circuit was formed through the same steps as in Example 25, and the characteristics thereof were evaluated. as a result,
The specific resistance of the electric circuit was 10 μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change in resistivity was 4
%, And the rate of change in specific resistance was 5% as a result of the wet and intermediate load test.

Example 27 900 parts by weight of the flaky silver powder used in Example 17 (8
(7.4% by weight) and 130 parts by weight (12.6% by weight) of Ni powder having a surface plated with 10% by weight of silver were blended to obtain a conductive paste through the same steps as in Example 17.
The content of the flaky silver powder and the Ni powder was 53.5% by volume (91% by weight) based on the solid content of the conductive paste. A wiring board was manufactured through the same steps as in Example 17, and an electric circuit was formed through the same steps as in Example 25, and the characteristics thereof were evaluated. As a result, the specific resistance of the electric circuit was 8.2 μΩ · cm. As a result of performing a thermal shock test on the wiring board, the rate of change in resistivity was 5%, and the result of the wet / medium load test showed a rate of change in resistivity of 5%.

Example 28 The wiring board obtained in Example 27 was heated and pressed with a hot roll at a rate of 30 cm / min at a temperature of 125 ° C. and a pressure of 980 N / cm, and then cured at 145 ° C. for 30 minutes. Then, an electric circuit having a dense circuit pattern was formed. The specific resistance of this electric circuit was measured and found to be 8.5 μΩ · cm. As a result of performing a thermal shock test on the wiring board, the rate of change in resistivity was 5%, and the result of the wet / medium load test showed a rate of change in resistivity of 5%.

Example 29 410 parts by weight of the flaky silver powder used in Example 17 (6
6.7% by weight) and 205 parts by weight of Ni powder (33.3% by weight) were added, and a conductive paste was obtained through the same steps as in Example 17. The content of flaky silver powder and Ni powder is 41.5% by volume based on the solid content of the conductive paste.
(86.1% by weight). A wiring board was obtained through the same steps as in Example 17 below. Next, the wiring board obtained above was heated and pressed for 2 minutes at a temperature of 100 ° C. and a pressure of 5 MPa by a hot press, and then cured at 145 ° C. for 30 minutes to form an electric circuit having a dense circuit pattern. When the specific resistance of this electric circuit was measured, it was 12.5 μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change in specific resistance was 5%. Further, as a result of performing a wet and medium load test on the wiring board, the rate of change in specific resistance was 6%. The cold heat test conditions are 125 ° C. for 30 minutes to −65 ° C. for 30 minutes.
Cycling was performed, and the humidity and medium load test was held at 40 ° C. and 90% RH for 1000 hours.

Example 30 700 parts by weight of the flaky silver powder used in Example 17 (8
(7.5% by weight) and 100 parts by weight of Ni powder (12.5% by weight) were added, and a conductive paste was obtained through the same steps as in Example 17. The content of the flaky silver powder and Ni powder was 54.0% by volume based on the solid content of the conductive paste.
(91.1% by weight). Hereinafter, a wiring board was manufactured through the same steps as in Example 17, then an electric circuit was formed through the same steps as in Example 29, and the characteristics thereof were evaluated. As a result, the specific resistance of the electric circuit was 9.5 μΩ · cm.
As a result of the thermal shock test of the wiring board, the rate of change of the specific resistance was 4%, and the result of the wet and medium load test showed the rate of change of the specific resistance to be 5%.

Example 31 750 parts by weight of the flaky silver powder used in Example 17 (8
3.3 wt%) and 150 wt parts (16.7 wt%) of Ni powder having a surface plated with 10 wt% silver were blended to obtain a conductive paste through the same steps as in Example 17.
The content of the composite conductive powder of the flaky silver powder and the silver powdered Ni powder was 50.50 with respect to the solid content of the conductive paste.
It was 0% by volume (89.7% by weight). Example 17 below
A wiring board was prepared through the steps similar to those of Example 29.
An electric circuit was formed through the same steps as above, and its characteristics were evaluated. As a result, the specific resistance of the electric circuit was 8.3 μΩ · cm. As a result of conducting a thermal shock test of the wiring board,
The rate of change in resistivity was 5%, and the result of the wet and medium load test showed that the rate of change in resistivity was 4%.

Example 32 The wiring board obtained in Example 31 was heated and pressed with a hot roll at a speed of 30 cm / min at a temperature of 125 ° C. and a pressure of 980 N / cm, and then cured at 145 ° C. for 30 minutes. An electric circuit having a dense circuit pattern was formed. When the specific resistance of this electric circuit was measured, it was 8.4 μΩ · cm. As a result of the thermal shock test of the wiring board, the rate of change of the specific resistance was 4%, and the result of the wet and medium load test showed the rate of change of the specific resistance to be 4%.

Example 33 Spherical copper powder having an average particle size of 6.2 μm (Japan atomized
Co., Ltd., SF-Cu) 25 wt% silver by displacement plating method
After coating, the shape is deformed by rotating with a zirconia ball in a ball mill for 30 minutes under the condition of 60 rpm,
A flaky silver-coated copper powder having an average major axis diameter of 10.3 μm, an aspect ratio of 6 and an average exposed area of copper of 3 to 18% and a mean of 7% was obtained. Separately from the above, the same copper powder as above was coated with 25% by weight of silver by the displacement plating method, and then the glass ball and the ball mill were operated at 60 rpm for 2 minutes.
The shape is deformed by rotating for 0 minutes, the average diameter of major axis is 7.5 μm, the aspect ratio is 2 and the exposed area of copper is 2 to 2.
An irregularly shaped silver-coated copper powder with an average of 3% was obtained in the range of 7%. Next, 410 parts by weight of scaly silver-coated copper powder (66.
7% by weight) and 205 parts by weight of irregularly shaped silver-coated copper powder (3
(3.3 wt%) was added to 145 parts by weight of the resin composition obtained in Example 1, and the mixture was uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. The content of the flaky silver-coated copper powder and the irregular-shaped silver-coated copper powder was 86% by weight based on the solid content of the conductive paste. The exposed area of copper was determined as follows. That is, a SEM photograph of silver-coated copper powder is taken with a scanning electron microscope (SEM), 20 particles of the silver-coated copper powder are randomly selected from this, and surface analysis of silver and copper is performed by an X-ray microanalyzer. The exposed area of copper was calculated from the area ratio of the area covered with silver and the area exposed with copper, the average value was calculated, and this average value was used as the covered area. Also in the following examples and comparative examples, the copper coating area was calculated by the same method as described above.

Thereafter, using the conductive paste obtained above, a silver conductor circuit 1 shown in FIGS. 1 and 5 was printed on a polyethylene terephthalate film having a thickness of 125 μm, and the product was printed at 80 ° C. for 30 minutes in the atmosphere. Further, a press heated to 100 ° C. was used to heat and pressurize at a pressure of 5 MPa for 2 minutes, and then heat treatment was performed at 145 ° C. for 30 minutes to obtain an electric circuit. The size of A in FIG. 5 is 100 μm. Then, the specific resistance of the obtained electric circuit shown in FIG. 1 was measured and found to be 11.5 μΩ · cm. As a result of a thermal shock test of the electric circuit, the rate of change in specific resistance was 5%.
Further, as a result of performing a wet and medium load test of the comb-shaped electric circuit shown in FIG. 5, the insulation resistance between the wirings was 10 ⁸ Ω or more.
In addition, the cooling / heating test condition is 100 cycles of 125 ° C. 30 minutes to −65 ° C. 30 minutes, and the humidity medium load test is 40 ° C. 90% RH.
Apply a voltage of 50V between the lines that are adjacent to each other in 2000
Hold for hours.

Example 34 700 parts by weight (87.5% by weight) of the flaky silver-coated copper powder obtained in Example 33 and 100 parts by weight of the irregularly-shaped silver-coated copper powder obtained in Example 33 (12. 5% by weight) was added to 145 parts by weight of the resin composition obtained in Example 1 and uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. The content of the flaky silver-coated copper powder and the irregular-shaped silver-coated copper powder was 89% by weight based on the solid content of the conductive paste. Then, an electric circuit was produced through the same steps as in Example 33, and the characteristics thereof were evaluated. As a result, the specific resistance of the electric circuit was 9.5 μΩ · cm. Moreover, as a result of conducting a thermal shock test of the electric circuit, the rate of change in specific resistance is 4%,
The insulation resistance between the wirings was 10 ⁸ Ω or more in the humidity and humidity load test of the comb-type electric circuit.

Example 35 750 parts by weight (83.3% by weight) of the flaky silver-coated copper powder obtained in Example 33 and the surface of the copper powder used in Example 33 were subjected to displacement plating to obtain 10 parts by weight of silver. % After coating, Example 3
The average particle diameter of the major axis obtained through the same process as in No. 3 is 6.0 μ.
m, an aspect ratio of 2, and an exposed area of copper in the range of 3 to 13%, the resin composition obtained in Example 1 with 150 parts by weight (16.7% by weight) of irregular shaped silver-coated copper powder having an average of 7%. 145
It was added to parts by weight and uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. The content of the flaky silver-coated copper powder and the irregular-shaped silver-coated copper powder was 89% by weight based on the solid content of the conductive paste. Hereinafter, an electric circuit was produced through the same steps as in Example 33 except that the press was performed under the conditions of 20 MPa, and the characteristics thereof were evaluated.
As a result, the specific resistance of the electric circuit was 8.3 μΩ · cm. As a result of the thermal shock test of the electric circuit, the rate of change of the specific resistance was 5%, and in the wet and medium load test of the comb-shaped electric circuit, the insulation resistance between the wirings was 10 ⁸ Ω or more.

Example 36 An electric circuit was produced using the conductive paste obtained in Example 35 through the same steps as in Example 33, and then heated and pressed under the conditions of a hot roll, a temperature of 100 ° C. and a pressure of 10 MPa to print. The circuit was densified and its characteristics were evaluated. As a result, the specific resistance of the densified electric circuit was 8.4 μΩ · cm. As a result of conducting a thermal shock test on the densified electric circuit,
The rate of change of the specific resistance was 4%, and the insulation resistance between the wirings was 10 ⁸ Ω or more in the wet and medium load test of the comb-type electric circuit.

Comparative Example 4 To 145 parts by weight of the resin composition obtained in Example 1, 400 parts by weight of the flaky silver-coated copper powder obtained in Example 33 was added, and the mixture was homogenized with a stirrer and a triple roll mill. Was mixed and dispersed into a conductive paste. Next, an electric circuit was produced through the same steps as in Example 33 except that the heating and pressing step with a press was omitted, and the characteristics thereof were evaluated. As a result, the specific resistance of the electric circuit is 6
It was 2 μΩ · cm. As a result of a thermal shock test of the electric circuit, the rate of change of the specific resistance was 10%, and in the wet and medium load test of the comb-shaped electric circuit, the insulation resistance between the wirings was 10 ⁸
It was more than Ω.

Comparative Example 5 145 parts by weight of the resin composition obtained in Example 1 had a flaky silver powder having an aspect ratio of 8 and a long diameter of 8 μm (trade name: TCG-1 manufactured by Tokuriki Kagaku Kenkyusho). Was added to 400 parts by weight and uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. Next, an electric circuit was produced through the same steps as in Example 33 except that the heating and pressing step with a press was omitted, and the characteristics thereof were evaluated. As a result, the specific resistance of the electric circuit was 62 μΩ · cm. Moreover, as a result of the thermal shock test of the electric circuit, the rate of change of the specific resistance is 10%,
In the wet / humidity load test of the comb-shaped electric circuit, the insulation resistance between the wirings decreased to 10 ⁸ Ω or less after the test time of 370 hours, and silver migration occurred between the wirings.

Comparative Example 6 145 parts by weight of the resin composition obtained in Example 1 was coated with silver on the surface before being transformed into the scaly pieces obtained in Example 33 with copper powder (exposed area of copper was less than 1%. Then, about 0%) was added in an amount of 400 parts by weight, and the mixture was uniformly mixed and dispersed with a stirrer and a triple roll to obtain a conductive paste. Next, an electric circuit was produced through the same steps as in Example 33 except that the heating and pressing step with a press was omitted, and the characteristics thereof were evaluated. As a result, the specific resistance of the electric circuit was 65 μΩ · cm. As a result of the thermal shock test of the electric circuit, the change rate of the specific resistance is 12%.
In the wet / humidity load test of the comb-shaped electric circuit, the insulation resistance between the wirings decreased to 10 ⁸ Ω or less after a test time of 530 hours, and silver migration occurred between the wirings.

[0083]

The composite conductive powder according to claim 1 is a conductive paste for forming an electric circuit, which has a low specific resistance, high conductivity, and a small change in specific resistance even after a thermal shock test or a humidity / humidity load test. can get. The composite conductive powders according to claims 2 to 7 are particularly excellent in conductivity among the composite conductive powders according to claim 1, and in addition to the composite conductive powder according to claim 1, a conductive paste having excellent oxidation resistance and heat resistance. Is obtained. The composite conductive powder according to claims 8 to 10 is pressed to obtain a conductive paste having an anchor effect. With the composite conductive powder according to claim 11, a conductive paste for forming an electric circuit, which has a low specific resistance, high conductivity, and excellent migration resistance, can be obtained.

The composite conductive powder according to claim 12 has a low specific resistance, high conductivity, a small change in specific resistance even after a thermal shock test or a humidity / humidity load test, and improves the contact probability between conductive powders. However, the conductivity of the electric circuit is increased, and in particular, a conductive paste can be obtained that enhances the conductivity when the circuit is printed on a sheet-shaped substrate and the printed circuit is pressed. Claim 13-
The composite conductive powder according to claim 18 is particularly excellent in conductivity among the composite conductive powder according to claim 12, and in addition to the composite conductive powder according to claim 12, a conductive paste having excellent oxidation resistance and heat resistance can be obtained. The composite conductive powder according to claims 19 to 21,
By applying pressure, a conductive paste having an anchor effect is obtained. With the composite conductive powder according to claim 22, a conductive paste for forming an electric circuit, which has a low specific resistance, high conductivity, and excellent migration resistance, can be obtained.

The conductive paste according to claims 23 to 25 is
It is suitable for forming an electric circuit having a low specific resistance, high conductivity, and a small change in specific resistance even after a thermal shock test or a humidity / humidity load test. The conductive paste according to claim 26 is suitable for forming an electric circuit which has a low specific resistance, improves the probability of contact between conductive powders, has a high electric circuit conductivity, and is excellent in migration resistance. The electric circuit according to claim 27 has a low specific resistance, high conductivity, and excellent migration resistance. The electric circuit according to claim 28 is excellent in forming a fine circuit in addition to the electric circuit according to claim 27. According to the method for producing an electric circuit as claimed in claim 29, an electric circuit having a low specific resistance, high conductivity and excellent migration resistance can be produced. A method of manufacturing an electric circuit according to claim 30,
In addition to the method of manufacturing an electric circuit according to claim 29, an electric circuit excellent in forming a fine circuit can be manufactured.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a silver conductor circuit is printed on a polyethylene terephthalate film.

FIG. 2 is a plan view of a circuit board according to an embodiment of the present invention.

FIG. 3 is a plan view of an IC chip.

FIG. 4 is a schematic view showing a state where an IC chip is mounted on a chip mounting portion of a circuit board.

FIG. 5 is a plan view showing a state in which a silver conductor circuit is printed in a comb shape on a polyethylene terephthalate film.

[Explanation of symbols]

 1 silver conductor circuit 2 polyethylene terephthalate film 3 substrate 4 circuit 5 chip mounting part 6 circuit board 7 test circuit 8 IC chip 9 silicon substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application No. 7-140495 (32) Priority date Hei 7 (1995) June 7 (33) Country of priority claim Japan (JP) (31) Priority Claim Number Japanese Patent Application No. 7-181473 (32) Priority Date July 7 (1995) July 18 (33) Country of priority claim Japan (JP) (72) Inventor Riichi Ono 3-3 Ayukawacho, Hitachi City, Ibaraki Prefecture No. 1 in Sakuragawa Sangyo Co., Ltd. (72) Inventor Yoshikatsu Mikami 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Inside Hitachi Chemical Co., Ltd. (72) Inventor Kuji Dogawachi 1150 Goshomiya, Shimodate-shi, Ibaraki Prefecture Hitachi Chemical Co., Ltd., Yuki Plant (72) Inventor Hiroshi Wada 1380 Nishihara, Ashikaga, Hitachinaka City, Ibaraki Prefecture 1 Hitachi Chemical Co., Ltd., Yamazaki Plant

Claims (30)

[Claims] 1. A composite conductive powder containing flat conductive powder and irregular-shaped conductive powder. 2. The composite conductive powder according to claim 1, wherein the material of the flat conductive powder is silver, a silver alloy or a silver-coated conductor. 3. The composite conductive powder according to claim 1, wherein the flat conductive powder is a flat silver-coated conductive powder. 4. The composite conductive powder according to claim 3, wherein the flat silver-coated conductor powder is silver-coated copper powder or silver-coated copper alloy powder. 5. The composite conductive powder according to claim 3, which is a silver-coated copper powder in which the conductor covered with the flat silver-coated conductor powder is exposed. 6. The composite conductive powder according to claim 1, wherein the material of the irregular-shaped conductive powder is silver or a silver alloy. 7. The composite conductive powder according to claim 6, wherein the irregular-shaped conductive powder is reduced silver powder. 8. The composite conductive powder according to claim 6, wherein the irregular-shaped conductive powder is a conductive material having a hardness higher than that of silver or a silver alloy coated with silver. 9. A conductor having a hardness higher than that of silver or a silver alloy is C.
The composite conductive powder according to claim 8, which is o, Ni, Cr, Cu, W powder or an alloy powder thereof. 10. The composite conductive powder according to claim 9, wherein the conductor having a hardness higher than that of silver or silver alloy is copper powder or copper alloy powder. 11. The composite conductive powder according to claim 8, wherein the irregular-shaped conductive powder is silver-coated copper powder or silver-coated copper alloy powder in which the coated conductor is exposed. 12. A composite conductive powder containing conductive powder having an aspect ratio of 6 or more and conductive powder having an aspect ratio of 5 or less. 13. The composite conductive powder according to claim 12, wherein the material of the conductive powder having an aspect ratio of 6 or more is silver, a silver alloy, or a silver-coated conductor. 14. The composite conductive powder according to claim 12, wherein the conductive powder having an aspect ratio of 6 or more is silver-coated conductive powder having an aspect ratio of 6 or more. 15. The composite conductive powder according to claim 14, wherein the silver-coated conductor powder having an aspect ratio of 6 or more is silver-coated copper powder or silver-coated copper alloy powder. 16. The silver-coated conductor powder having an aspect ratio of 6 or more is silver-coated copper powder or silver-coated copper alloy powder in which the coated conductor is exposed. Composite conductive powder. 17. The composite conductive powder according to claim 12, wherein the material of the conductive powder having an aspect ratio of 5 or less is silver or a silver alloy. 18. The composite conductive powder according to claim 17, wherein the conductive powder having an aspect ratio of 5 or less is reduced silver powder. 19. The composite conductive powder according to claim 17, wherein the conductive powder having an aspect ratio of 5 or less is obtained by coating a conductor having a hardness higher than that of silver or a silver alloy with silver. 20. The composite conductive powder according to claim 19, wherein the conductor having a hardness higher than that of silver or silver alloy is Co, Ni, Cr, Cu, W powder or alloy powder thereof. 21. The composite conductive powder according to claim 19, wherein the conductor having a hardness higher than that of silver or silver alloy is copper powder or copper alloy powder. 22. The composite conductive powder according to claim 19, wherein the irregular-shaped conductive powder is a silver-coated copper powder in which the coated conductor is exposed. 23. A conductive paste containing the composite conductive powder according to claim 1, a binder and a solvent. 24. The conductive paste according to claim 23, wherein the composite conductive powder is contained in an amount of 85 to 93% by weight based on the solid content of the conductive paste. 25. The composite conductive powder according to any one of claims 1 to 11, a binder and a solvent are contained, and 5 to 50 weight% of irregular conductive powder to 95 to 50 weight% of flat conductive powder. 25. The conductive paste according to claim 23 or 24, wherein the conductive paste contains 20%. 26. Aspect ratio of 5 to 95% by weight of the electroconductive powder containing the composite electroconductive powder according to any one of claims 12 to 22, a binder and a solvent and having an aspect ratio of 6 or more. 25. The conductive paste according to claim 23 or 24, which contains 5 to 50% by weight of the following conductive powder. 27. An electric circuit formed on the surface of a substrate using the conductive paste according to claim 23. 28. The electric circuit according to claim 27, wherein the electric circuit formed on the surface of the substrate has a specific resistance of 25 μΩ · cm or less. 29. A method of manufacturing an electric circuit, comprising forming a circuit pattern on the surface of a base material with the conductive paste according to claim 23, and then pressing and curing the circuit pattern. 30. The method for producing an electric circuit according to claim 29, wherein the electric circuit formed on the surface of the substrate has a specific resistance of 25 μΩ · cm or less.