JPH06336562A - Conductive paste - Google Patents

Abstract

PURPOSE:To obtain a highly conductive paste which gives a wiring board having low through-hole resistance even with low silver content, by mixing a silver powder and other metal powder with a nitrophenylhydrazine. CONSTITUTION:This conductive paste contains a silver powder, other metal powder and a nitrophenylhydrazine. It is desirable that the ratio of the silver powder to other metal powder is (10:1) to (1:5) by volume from the viewpoints of the resistance of conductor and the prevention of migration and that the amount of the nitrophenylhydrazine is 0.05-2.0wt.% based on the solids of the paste from the viewpoints of economy and the prevention of migration. It is desirable to use one of nitrophenylhydrazine and 3,5-dinitrophenylhydrazine or a mixture thereof. The content of the silver powder and other metal powder each is preferably 15-60wt.%, more preferably 20-60wt.%, based on the solids of the paste from the viewpoints of the resistance of conductor and economy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste for forming an electric circuit.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a wiring conductor of a printed wiring board, an electronic component or the like, a method of applying or printing a paste containing silver powder having excellent conductivity is generally known. .

[0003]

Since a conductive paste using silver powder has good conductivity, it is used as a wiring conductor or an electrode for printed wiring boards, electronic parts, etc., but these are used under a high temperature and high humidity atmosphere. When an electric field is applied, there is a drawback that electroplating of silver called migration occurs on wiring conductors and electrodes and the distance between electrodes or between wirings is shortened. 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 compound to the conductive paste have been studied, but it is sufficient. It was not possible to obtain such an effect.

Further, in order to obtain a conductor having good conduction resistance, it is necessary to increase the amount of silver powder blended, and the silver paste is expensive, so that the conductive paste is also expensive.

The present invention provides a conductive paste that does not have such drawbacks.

[0006]

The present invention relates to a conductive paste containing silver powder, metal powder other than silver powder, and nitrophenylhydrazines.

The silver powder in the present invention is not limited in its shape, but is preferably in the form of flakes or dendritic, and the aspect ratio is preferably about 3 or more, more preferably 10 or more. The particle diameter is 40 μm in the major axis.
The following is preferable since printability is not deteriorated. As the metal powder, a powder other than silver powder is used, and the smaller the particle diameter is, the more preferable. As the metal powder other than silver powder, it is preferable to use one of copper powder, nickel powder, zinc powder and tin powder or a mixture thereof.

From the viewpoint of resistance of the conductor and prevention of migration, the ratio of silver powder to metal powder is 10: 1 to 1: 5 by volume.
It is preferably (silver powder: metal powder). The amount of nitrophenylhydrazines is 0.05 to 2.0 in terms of prevention of migration and economy with respect to the solid content of the conductive paste.
It is preferably in the weight%. As the nitrophenylhydrazines, 3-nitrophenylhydrazine and 3,
It is preferable to use one of 5-dinitrophenylhydrazines or a mixture thereof.

In addition to the above materials, the conductive paste is an organic adhesive component such as liquid epoxy resin, phenol resin and unsaturated polyester resin, and if necessary, a solvent such as terpineol, ethyl carbitol and carbitol acetate, and fine graphite. Contains powder and the like. The content of the silver powder and the metal powder is preferably 15 to 60 wt% with respect to the solid content of the conductive paste in terms of the resistance of the conductor and economy.
More preferably, it is from about 60% by weight.

[0010]

EXAMPLES Examples of the present invention will be described below. Example 1 60 parts by weight of bisphenol A type epoxy resin (Oilized shell epoxy, trade name Epicoat 834) and 40 parts by weight of bisphenol A type epoxy resin (Oilized shell epoxy, trade name Epicoat 828) were dissolved by heating in advance. ,
Then, after cooling to room temperature, 5 parts by weight of 2 ethyl 4-methyl imidazole (manufactured by Shikoku Kasei), 1 part by weight of 3-nitrophenylhydrazine (manufactured by Wako Pure Chemical Industries, reagent), 20 parts by weight of ethylcarbitol (manufactured by Wako Pure Chemical Industries, reagent) Part and butyl cellosolve (manufactured by Wako Pure Chemical Industries, reagent) 20 parts by weight are added and uniformly mixed to form a resin composition, and 146 g of this resin composition is flaky silver powder (trade name TCG-1 manufactured by Tokuriki Kagaku Kenkyusho). 2
10g and copper powder (Fukuda Metal Foil Powder, trade name SPC4-
40 g of 8) was added and uniformly dispersed with a stirrer and a three-roll mill to obtain a conductive paste.

Next, a paper phenol copper clad laminate (made by Hitachi Chemical Co., Ltd., trade name MCL-) having a thickness of 1.6 mm and a through hole having a diameter of 0.8 mm (φ) formed with the conductive paste obtained above. 437F) was printed with the test pattern shown in FIG. 1 and the through hole 1 was filled with the test pattern and heated at 60 ° C. for 30 minutes and 160 ° C. for 30 minutes to obtain a wiring board. In FIG. 1, 2 is a paper phenol copper clad laminate. Next, the resistance of the obtained wiring board was measured. As a result, the resistance of the through hole 1 excluding the resistance of the copper foil was 18 mΩ / hole, and the insulation resistance between adjacent through holes was 10 ⁸ Ω or more. As a result of the thermal shock test of the wiring board, the resistance of the through hole 1 was 2
It was 3 mΩ / hole. Moreover, as a result of performing a wet and medium load test on the wiring board, the insulation resistance between the through holes was 10 ⁸ Ω or more. The cold heat test conditions are 125 ° C. 30 minutes to −6.
100 cycles of 30 minutes at 5 ℃, 40 in the humidity load test
At 90 ° C. and 90% RH, a voltage of 50 V was applied between adjacent lines and held for 1000 hours.

Example 2 To 146 g of the resin composition obtained in Example 1, 200 g of the silver powder used in Example 1 and 80 g of copper powder were added, and the mixture was uniformly mixed and dispersed in the same manner as in Example 1 to obtain a conductive paste. Obtained. A wiring board was manufactured through the same steps as in Example 1 and the characteristics thereof were evaluated. As a result, the resistance of the through hole is 18 mΩ.
/ Hole, and the insulation resistance between through holes was 10 ⁸ Ω or more. As a result of a thermal shock test of the wiring board, the resistance of the through holes was 23 mΩ / hole, and the result of the wet and medium load test showed that the insulation resistance between the through holes was 10 ^8.
It was more than Ω.

Example 3 To 146 g of the resin composition obtained in Example 1, 700 g of the silver powder used in Example 1 and 150 g of copper powder were added and uniformly mixed and dispersed in the same manner as in Example 1 to obtain a conductive paste. Obtained. A wiring board was manufactured through the same steps as in Example 1 and the characteristics thereof were evaluated. As a result, the resistance of the through hole is 16m.
Ω / hole, and the insulation resistance between through holes was 10 ⁸ Ω or more. As a result of a thermal shock test of the wiring board, the resistance of the through holes was 23 mΩ / hole, and the result of the wet and medium load test showed that the insulation resistance between the through holes was 10 ^8.
It was more than Ω.

Example 4 To 146 g of the resin composition obtained in Example 1, 155 g of the silver powder used in Example 1 and 55 g of copper powder were added and uniformly mixed and dispersed in the same manner as in Example 1 to obtain a conductive paste. Obtained. A wiring board was manufactured through the same steps as in Example 1 and the characteristics thereof were evaluated. As a result, the resistance of the through hole is 20 mΩ.
/ Hole, and the insulation resistance between through holes was 10 ⁸ Ω or more. As a result of the thermal shock test of the wiring board, the resistance of the through holes was 25 mΩ / hole, and the result of the wet and medium load test showed that the insulation resistance between the through holes was 10 ⁸ Ω or more.

Example 5 146 g of a resin composition obtained in the same manner as in Example 1 except that 3,5-dinitrophenylhydrazine (manufactured by Wako Pure Chemical Industries, Ltd.) was used in place of 3-nitrophenylhydrazine. 200g of silver powder and zinc powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.9%) were pulverized to have a particle size of 5 to 10 μm.
80 g of the above was added and uniformly mixed and dispersed in the same manner as in Example 1 to obtain a 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 resistance of the through hole is 22 mΩ / hole,
The insulation resistance between the through holes was 10 ⁸ Ω or more. As a result of a thermal shock test of the wiring board, the resistance of the through holes was 31 mΩ / hole, and the result of the wet and medium load test showed that the insulation resistance between the through holes was 10 ⁸ Ω or more.

Example 6 The same procedure as in Example 1 was repeated except that 0.5 parts by weight of 3-nitrophenylhydrazine used in Example 1 and 3,5-dinitrophenylhydrazine used in Example 5 were each used. 70 g of the silver powder used in Example 1 and nickel powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 9
0.99%) was pulverized to have a particle size of 5 to 10 μm and added in an amount of 150 g to uniformly mix and disperse in the same manner as in Example 1 to obtain a 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 resistance of the through holes was 20 mΩ / hole, and the insulation resistance between the through holes was 10 ⁸ Ω or more. As a result of a thermal shock test of the wiring board, the resistance of the through holes was 30 mΩ / hole, and the result of the wet and medium load test showed that the insulation resistance between the through holes was 10 ⁸ Ω or more.

Example 7 To 146 g of the resin composition obtained in Example 1, 155 g of the silver powder used in Example 1 and tin powder (manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 9
9.9%) was pulverized to have a particle size of 5 to 10 μm, and 55 g was added and uniformly mixed and dispersed in the same manner as in Example 1 to obtain a 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 resistance of the through holes was 26 mΩ / hole, and the insulation resistance between the through holes was 10 ⁸ Ω or more. As a result of the thermal shock test of the wiring board, the resistance of the through hole was 3
It was 8 mΩ / hole, and the insulation resistance between through holes was 10 ⁸ Ω or more as a result of the wet and medium load test.

Comparative Example 1 To 145 g of the resin composition obtained in the same manner as in Example 1 except that nitrophenylhydrazines were not added, 1000 g of the silver powder used in Example 1 was added, and the same procedure as in Example 1 was performed. Was mixed and dispersed into a conductive paste. Example 1 below
A wiring board was manufactured through the same steps as above, and its characteristics were evaluated. As a result, the resistance of the through holes was 18 mΩ / hole, and the insulation resistance between the through holes was 10 ⁸ Ω or more. As a result of the thermal shock test of the wiring board, the resistance of the through hole was 24 mΩ / hole, and the result of the wet and medium load test showed that the insulation resistance between the through holes was two 10 ⁷ Ω among the five wiring boards. There was something that was falling on the table.

COMPARATIVE EXAMPLE 2 170 g of the silver powder used in Example 1 was added to 145 g of the resin composition obtained by the same method as in Example 1 except that nitrophenylhydrazines were not added, and the same procedure as in Example 1 was performed. Was mixed and dispersed into a 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 resistance of the through holes was 20 mΩ / hole, and the insulation resistance between the through holes was 10 ⁸ Ω or more. As a result of a thermal shock test of the wiring board, the resistance of the through hole was 35 mΩ / hole, which was 1.5 times the resistance before the thermal shock test. Further, according to the results of the humidity and medium load test, the insulation resistance between the through holes was reduced to the order of 10 ⁷ Ω among the 5 wiring boards.

[0020]

EFFECT OF THE INVENTION The conductive paste according to the present invention is a highly conductive paste having a low through-hole resistance in a wiring board even if the content of silver is low, and the insulation resistance between the through-holes after a wet and medium load test. The amount of silver used can be reduced by using at least one type of silver powder and metal powder, and the migration of silver can be suppressed by using at least one type of metal powder and nitrophenylhydrazines. In addition, the conductive paste is excellent in characteristics.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a conductive paste is printed on a paper phenol copper clad laminate and the through holes are filled.

[Explanation of symbols]

 1 Through hole 2 Paper phenol copper clad laminate

Claims (2)

[Claims] 1. A conductive paste containing silver powder, metal powder other than silver powder, and nitrophenylhydrazines. 2. The metal powder is one or a mixture of copper powder, nickel powder, zinc powder and tin powder, and the nitrophenylhydrazines are 3-nitrophenylhydrazine and 3,3.
The conductive paste according to claim 1, which is one of 5-dinitrophenylhydrazine or a mixture thereof.