JPS58103566A - Electrically conductive paint - Google Patents

Abstract

PURPOSE:To provide an electrically conductive paint which consists of Ag-In-Cu type conductive powder, resin and solvent and is low cost and excellent in electrical conductivity and migration characteristics. CONSTITUTION:Powdered alloy with a particle diameter of 0.05-10mu, consisting of 10-70wt% Ag, 1-20wt% In and balance Cu, is dipped in an organic solvent solution of 1,2,3-benzotriazole. Upon separation of the solvent and drying, electrically conductive powder surface coated with a thin film of a chelate compd. is obtained. Then the conductive power, a thermosetting resin (e.g. xylene resin) and a solvent (e.g. ethyl carbitol) are kneaded to produce an electrically conductive paint. The paint is applied to phenolic resin substrate, etc. by screen printing, etc. and is cured in the air under heating to form electrode and conducting path.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive paint, and an object of the present invention is to provide a conductive paint that is inexpensive, has excellent conductivity, and has excellent migration resistance.

Conventionally, this type of conductive paint contains A as a conductive powder.
Noble metal powders such as U, Ag, and Pd have been used. Generally, conductive powder is used to make phenolic resin,
Aq paint, which is made by kneading a thermosetting resin such as epoxy resin or xylene resin with a solvent such as ethyl calpitol, is applied to a phenolic resin substrate by a method such as screen printing, and then heated and cured to produce a variable resistor, etc. It has been used as an electrode for electronic circuits or as a printed wiring conductor for electronic circuits.

However, in recent years, as electronic devices have become smaller and thinner, there has been a strong demand for smaller electronic components. Due to the interaction with the DC electric field, a phenomenon in which Aq paint moves between electrodes, so-called migration, occurs, resulting in a short circuit, which is often a major cause of trouble.

In order to compensate for these drawbacks of Aq paint, Aq-P
Conductive paints using D powder are commercially available, but 1 is not perfect. In addition, conductive paint using Ag-Pd powder has an economical point of view, as the price of Pd is extremely high by 50% compared to the price of Aq, and in recent years the price of precious metals, especially Aq, has been rapidly increasing. This is extremely disadvantageous.

For the above-mentioned reasons, there is a desire for an inexpensive conductive paint with good migration resistance.

The present invention was made in view of these points, and as a result of research and study of alloy powders containing base metals, the inventors discovered a conductive powder made of Ag-In-Cu alloy powder. The inventors have discovered that the adhesive paint has excellent migration resistance and satisfies conductivity at a mediocre level.

Next, the configuration of the present invention will be explained in detail.

In the conductive paint according to the present invention, the conductive powder contains at least 10 to 70% by weight of Ag, 1 to 20% by weight of In, and the balance is Cu.
This is a conductive paint characterized by being made of alloy powder.

The desirable conditions for the conductive powder of this type of resin-curing conductive paint are: a) it has conductivity; b) it has thermal oxidation resistance during heat curing; Cu, which is a component of the alloy powder, is conductive. Although it is a metal with excellent properties, its thermal oxidation resistance and corrosion resistance are not good.
A large amount of oxide scale is generated on the surface of the U powder, and the cured paint film cannot have sufficient conductivity. Such defects of Cu powder can be improved by adding Aq as an alloying element. However, in terms of microclision resistance, since Cu is difficult to cause migration, ~-Cu-containing Cu tends to be improved compared to Ag powder, but sufficient migration resistance cannot be obtained.

This disadvantage of the more -Cu-containing Cu alloy can be greatly improved by further adding In as an alloying element. It is not clear why alloying brings about such an improvement in microclision resistance, but two reasons are that In itself is difficult to cause migration and that In is an extremely base metal compared to Aq. However, Aq-In-Cu
It is surmised that this alloy powder provides excellent microcrision resistance when used in conductive paints. In addition, the addition of In as an alloying element
It also tends to improve the thermal oxidation resistance of Cu-containing materials. this is,
From the viewpoint of conductivity, it is presumed that this is due to the semiconductor properties of In oxide. Furthermore, due to the environmental resistance of In itself, it is thought that the addition of In provides corrosion resistance effects. However, if the amount of In added exceeds an appropriate amount, the conductivity of the alloy powder itself decreases, making it impossible to obtain desirable characteristics.

The alloy composition in which Ag-I n -Cu alloy powder can find the above-mentioned advantages as a conductive powder for conductive paint is Aq
1o-70% by weight, In 1-20% by weight.

The remainder is Cu. The lower limit of the Aq amount is determined by the heat oxidation resistance of the alloy powder, and the upper limit is determined by economic efficiency. Also,! The lower limit of n1jk is the minimum amount at which the effect of its addition can be found, and the upper limit is the amount limited by the electrical conductivity of the alloy powder.

As described above, the conductive paint using A92In-Cu alloy powder can be found to have practically sufficient performance in terms of conductivity and migration resistance. However, in general, the corrosion resistance of Cu and Cu-based alloys is not necessarily good in an excessively corrosive environment, and the alloy powder of the present invention may not necessarily have satisfactory corrosion resistance when left in such an atmosphere. do not have. However, these drawbacks can be overcome by a process in which alloy powder is immersed in a solution of 1,2,3-hensitriazole dissolved in an organic solvent such as acetone, and then the solution is separated and dried (hereinafter referred to as benzotriazole treatment). ). It is presumed that the benzotriazole treatment described above forms a thin chelate compound film on the surface of the alloy powder, thereby exerting an anticorrosive effect.

According to the present invention, Ag-In-Cu alloy powder or Ag-In7C treated with benzotriazole
A conductive paint is made by kneading U alloy powder with a thermosetting resin and a solvent. This conductive paint is applied to a phenol resin substrate or the like by a method such as screen printing in the same manner as ordinary Aq paint, and then heated and cured in the atmosphere to be used as an electrode or a conductive path.

The particle size of the alloy powder is in the range of 0.05 to 10 μm, preferably about 0.5 to 6 μm. When the thickness exceeds 10μ, printability during screen printing deteriorates, and sheet resistance after final heat curing increases.

Next, examples will be described in detail in order to make the present invention more concrete.

Ag-I n -Cu alloy powder according to the present invention was produced as follows. A according to the alloy composition according to the invention
Weigh the container materials of g, In, and Cu, and calculate the total amount by IK(
It was set to 1. This was dissolved in nitrogen gas and further pulverized by a molten metal spray method. Nitrogen gas was used as a spray medium and the mixture was cooled by being put into water. The particle size of the obtained alloy powder is 6~1o
Although the particle size was approximately 0μ, it was again pulverized using a mechanical pulverizer to have an average particle size of 2μ.

For some of the alloy powder obtained by the above method,
Benzotriazole treatment was performed. The benzotriazole treatment was performed according to the following procedure. 1°2.3-benzotriazole (10%) was dissolved in 100tttl of acetone, and the alloy powder (10y) was immersed in this solution and thoroughly dispersed.

After this, the alloy powder and the solution were separated and the alloy powder was dried.

The alloy powder 2y1 obtained by the above method or the alloy powder 2y treated with benzo)IJ azole was kneaded with xylene resin 'F 1 ethylcarpitol 0.2F using a Hubermala.

The crosstalk caused by Hoover Mara has a load of 100 pounds and 40
Rotation was repeated four times.

The conductive paint prepared above was printed in a predetermined shape on a phenol resin substrate using a screen printing method, and then cured by heating at 190° C. for 10 minutes in the atmosphere.

The results of measuring the resistance value between both ends of the above printed pattern,
The following table shows the measurement results after being left in a constant temperature and humidity chamber at 40° C. and 96% RH for 120 hours. For reference, the table also shows the results when commercially available Ag powder and Cu powder were used as conductive powder.

(Margin 2 below) Also, as a migration resistance test, the paint prepared above was placed on a phenolic resin substrate with a gap of 0.5m +
After screen printing the pattern and heating and curing, 0.2 ml of pure water was dropped into the gap and a DC voltage of 3V was applied to the gap, and the current flowing through the gap was measured. The current values after 2 hours are all 10.
It was about μ8.

On the other hand, when a similar test was conducted on a paint using conductive Ag powder, Aq migration was observed in the gap 1 minute after voltage application, resulting in a short circuit. Therefore, it can be said that the conductive paint according to the present invention has extremely superior micretion resistance compared to conventional Aq paint.

As is clear from the above description and table, the conductive paint according to the present invention has a
Although it is somewhat inferior in terms of conductivity and corrosion resistance, it exhibits sufficient properties for practical use, and is particularly excellent in microclision resistance, and economically, it is extremely inexpensive compared to conventional Aq paint. It has great industrial value because it can be produced in many different ways.

Claims (2)

[Claims] (1) The conductive powder is an alloy powder comprising a conductive powder, a resin, and a solvent, and the conductive powder contains at least 10 to 70% by weight of Ag, 1 to 20% by weight of In, and the balance is Cu. conductive paint. (2) The alloy powder is immersed in a solution of 1,2,3-benzotriazole dissolved in an organic solvent, and then the solution is separated.
The conductive paint according to claim 1, wherein the conductive paint is dried.