JPS58103565A - Electrically conductive paint - Google Patents

Abstract

PURPOSE:To provide an electrically conductive paint which consists of Ag-Be-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, 0.1-3wt% Be 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 powder, 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 Au as conductive powder.
Noble metal powders such as , Af, and Pd have been used. Generally, AP is used as the conductive powder, and ζphenol resin,
Ar paint mixed with a thermosetting resin such as epoxy resin or xylene resin and a solvent such as ethelcalpitol 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. electrode,
It has also been used 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. The interaction between the moisture inside and the DC electric field causes a phenomenon in which Ar paint transfers between electrodes, so-called migration, which results in short circuits and is often a major cause of trouble.

In order to compensate for these drawbacks of Ar paint, A2-P
Conductive paints using d-powder are commercially available, but they are still not perfect. In addition, conductive paint using AP-Pd powder is extremely expensive in terms of economy, as the price of Pd is extremely high compared to the price of AP, and in recent years the prices of precious metals, especially 82, have been rapidly increasing. It is disadvantageous.

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

The present invention has been made in view of these points, and as a result of research and study on alloy powders whose main components are base metals, the inventors have developed a conductive powder using Af-Be-Cu alloy powder as a conductive powder. It has been discovered that the paint has excellent migration resistance and satisfies a considerable level of conductivity.

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

The conductive paint according to the present invention is characterized in that the conductive powder is an AP-Be-Cu alloy powder containing at least A210-70% by weight, Be 0.1-3% by weight, and the balance being Cu. It is a conductive paint.

Desired conditions for the conductive powder of this type of resin-curing conductive paint include a1 conductivity and b1 thermal oxidation resistance during heat curing.

Cu, which is one component of the alloy powder, is a metal with excellent electrical conductivity, but it cannot be said to have good thermal oxidation resistance and corrosion resistance. Therefore, a large amount of oxidized scale is often generated on the surface of the Cu powder due to the heating during the paint curing process, making it impossible to obtain sufficient electrical conductivity of the cured paint film. C like this
The disadvantages of U powder can be improved by adding AP as an alloying element.

However, in terms of migration resistance, since Cu is difficult to cause migration, At
-Cu alloy powder tends to be improved compared to He2 powder, but sufficient migration resistance cannot be obtained. Such drawbacks of At-Cu alloy powder can be greatly improved by further adding Be as an alloying element. It is not clear why alloying brings about such an improvement in migration resistance, but the fact that Be itself is difficult to cause migration and that Be is an extremely base metal compared to A2 makes Aft - Be-Cu
It is presumed that the alloy powder has excellent migration resistance when used as a conductive paint. In addition, the addition of aS as an alloying element
-It also tends to improve the heat oxidation resistance of the Cu alloy powder. This is presumably because Be oxide prevents excessive oxidation of the alloy powder. Furthermore, due to the environmental resistance of Be itself, it is thought that the addition of Be provides corrosion resistance effects. However, if the daily amount of Be exceeds an appropriate amount, desirable characteristics cannot be obtained because the conductivity of the alloy powder itself decreases, mechanical processability decreases, and pulverization becomes difficult.

The alloy composition in which At-Be-Cu alloy powder can find the above-mentioned advantages as a conductive powder for conductive paint is Al1
F10-70 weight ratio, Be 0.1-3% by weight, balance Cu
It is. The lower limit of At is determined by the thermal oxidation resistance of the alloy powder, and the upper limit is determined by economic efficiency.

Well, the lower limit of the amount of Be is the minimum at which the effect of its addition can be found! , the upper limit is the amount restricted from the production of alloy powder.

As described above, the conductive paint using Af-Be-Cu alloy powder can be found to have practically sufficient performance in terms of conductivity and migration property.

However, in general, the corrosion resistance of Cu and Cu-based alloys is not necessarily good in excessively corrosive environments, and the alloy powder of the present invention does not necessarily have satisfactory corrosion resistance when left in such an atmosphere. isn't it. However, such drawbacks are caused by the following: 1.
This problem can be solved by a process (hereinafter referred to as benzotriazole treatment) in which 2.3-benzotriazole is immersed in a solution of an organic solvent such as acetic acid, and then the solution is separated and dried. 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 anticorrosion effect.

According to the present invention, At-Be-Cu alloy powder or
AP-Be-Cu alloy powder treated with benzotriazole is kneaded with a thermosetting resin and a solvent to form a conductive paint. This conductive paint is applied to a phenolic resin substrate or the like by a method such as screen printing in the same way as ordinary A1 paint, and then heated and cured in the atmosphere to be used as electrodes or conductive paths. The particle size of alloy powder is 0.06-10
The range of μ is preferably about 0.6 to 5 μ. 10μ
If it is more than that, the printability during screen printing will deteriorate and the sheet resistance after final heat curing will increase.

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

The AV-Be-Cu alloy powder according to the present invention was produced as follows. In accordance with the alloy composition according to the invention, A
Each material of t-Be-Cu was weighed, and the total amount was 19 (Be was added by the Cu-Be master alloy).

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 in water. The particle size of the obtained alloy powder was approximately 6 to 100 μm, but this was powdered again using a mechanical crusher to obtain an average particle size of 2 μm.

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 towns with acetone 100mA! dissolved in
10 tons of alloy powder was immersed in this solution and sufficiently dispersed. After that, the alloy powder and the solution were separated, and the alloy powder was dried.

The alloy powder 22 obtained by the above method or the alloy powder 22 treated with benzotriazole was kneaded with xylene IUJ11f and ethyl carpitol 0.22 using a Hubermala.

For kneading with a Hubermala, the load was 100 bond, 40
Rotation was repeated four times.

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

The results of measuring the resistance value between both ends of the above printed pattern,
Furthermore, the results of measurements after being left in a constant temperature and humidity chamber at 40 C and 95% RH for 120 hours are shown in the following table.

The table also shows the results when commercially available A2 powder and Cu powder were used as conductive powder.

(Left below) In addition, as a migration resistance test, the paint prepared above was placed on a phenolic resin substrate with gaps of 0 and 5.
After screen printing a mm pattern and curing it by heating, 0.2 ml of pure water was dropped into the gap, a DC voltage of 3V was applied to the gap, and the current flowing through the gap was measured. The current values 2 hours after voltage application were about 10μ8 in all cases. On the other hand, when a similar test was conducted on a paint using A1 powder as conductive powder, a short circuit was observed in the fish in which A2 transfer was observed in the gap 1 minute after voltage application. Therefore, it can be said that the conductive paint according to the present invention has extremely superior migration resistance compared to conventional At paint.

As is clear from the above description and table, the conductive paint according to the present invention has sufficient properties to be put to practical use, although it is somewhat inferior in terms of conductivity and corrosion resistance compared to conventional At paint. It has particularly excellent migration resistance and can be produced economically at a much lower cost than conventional At paints, so it has great industrial value.

Claims (2)

[Claims] (1) Conductive powder consisting of conductive powder, resin, and solvent, characterized in that the conductive powder is an alloy powder containing at least 10 to 70% by weight of A, 0.1 to 3% by weight of Be, and the balance consisting of Cu. sex paint. (2) The alloy powder is obtained by immersing the powder in a solution of 1.2.3-benzotriazole in an organic solvent, separating it from the solution, and drying it. Conductive paint described in ).