JPS63192293A - Method of forming conductive film on insulating substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention is directed to the use of conductive films for electrical wiring such as printed circuit boards, thermal heads, image sensors, and liquid crystal display devices in order to reduce costs. It is proposed to create a membrane.

"Conventional technology" Conventional printed circuit boards are produced by pasting fI foil onto an insulating substrate such as glass epoxy, and forming electrical wiring by wet etching using a single step of well-known photolithography. Ta.

In the case of a device such as a thermal head, a conductive metal such as Au is deposited on the entire surface of an insulating ceramic substrate by ion blasting, etc., and wet etching is performed similarly using photolithography. The method used was to form electrical wiring using a method.

``Problems to be solved by the invention'' In order to reduce costs, it is possible to form wiring patterns directly using conductive ink using printing methods such as screen printing, but it is difficult to improve adhesion and conductivity. In order to do this, it was necessary to bake the conductive ink at a high temperature. For this reason, there is a problem in that low-cost substrates such as glass substrates and glass epoxy substrates that are distorted or carbonized at the high temperatures necessary for sintering the conductive ink cannot be used.

"Means for solving the problem" In the method of forming a conductive film using conductive ink,
Only the metal part to be fired requires heating, not the insulating substrate.

Therefore, the present invention is characterized in that firing is performed by heating only the conductor layer using Joule heat caused by eddy current loss. However, by heating only the conductor part, a new problem arises in that thermal distortion occurs in the board due to the difference in thermal expansion between the conductor part and the board part. After heating to a temperature approximately 50° C. lower than the temperature at which thermal strain or carbonization occurs as a physical property, only the conductor layer was further heated by high-frequency induction heating to sinter the conductor layer.

An explanation will be given below based on examples.

"Example" FIG. 1 shows a firing apparatus used in the present invention.

The insulating substrate (1) used in this example is soda glass having a strain point of 511°C. Conductive ink used (2)
is conductive using an ink with a composition ratio of 55% by weight of silver powder with an average particle size of 0.1 μm, 30% by weight of glass flift with a low melting point (480°C), and 15% by weight of linseed oil. A wiring pattern having a width of 50 μm and a thickness of 10 μm was printed on a soda glass substrate using an offset printing method. After that, the infrared lamp (3) is heated using the baking device shown in Figure 1.
The heating temperature of the substrate heating was increased to 460℃, and the electrode part (4
), only the conductor portion was heated to 550° C., which is necessary for firing, using a high-frequency induction heating method.

In this case, the appropriate frequency of the high frequency to be applied is 20011 Hz or more, and in this example, 500 Hz was used.

By using this high frequency induction heating method, the temperature of the soda glass substrate itself did not rise much, and only the conductive portion could be heated to 550° C., which is necessary for sintering.

"Effect" By using infrared heating and high-frequency induction heating together, thermal distortion and carbonization of the substrate can be avoided, and costs can be reduced when forming a conductive film on a substrate with an insulating surface. Ta.

Furthermore, poor adhesion of the conductive film due to thermal strain between the conductive film and the substrate can be solved.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of the sintering apparatus used in the present invention.

Claims (1)

[Claims] 1. On an insulating substrate or a substrate having an insulating surface, 1.
In a method of forming a conductive film using a solvent having a total composition ratio of 20% by weight or more of conductive metal powder of more than 1 type, heating the substrate after applying the solvent having the metal powder on the substrate; A method for forming a conductive film on an insulating substrate, characterized in that high-frequency induction heating is performed on the coated material at the same time as or after the substrate heating step. 2. A method for forming a conductive film on an insulating substrate according to claim 1, wherein the heating temperature during substrate heating is below the thermal strain point of the substrate.