JPH0595178A - Production of circuit board - Google Patents

Abstract

PURPOSE:To manufacture a circuit board on which a high-density wiring pattern that cannot be provided only by printing is formed. CONSTITUTION:Among the wiring patterns to be formed on an insulating board 1, for a pattern 2a which ensures wiring width and intervals by printing, the pattern is formed by printing using conductive ink. For a pattern that cannot ensure the wiring width and interval by printing, the pattern is formed by printing by conductive ink as a solid pattern 2b with the pattern 2a or as an approximate pattern which is approximate to the wiring pattern to be formed. Then, the solid pattern 2b or the approximate pattern is irradiated with excimer laser beams 4 through a mask 3 which has the wiring pattern to be formed. Thus, the conductive ink is partially removed and the desirable wiring pattern is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a circuit board used for a keyboard of an electronic desk calculator, a flexible wiring board of a liquid crystal display device, or the like.

[0002]

2. Description of the Related Art Conventionally, a circuit board of a membrane switch used for a keyboard of an electronic desk calculator or the like, and a flexible wiring board for connecting a display panel of a liquid crystal display device and a printed circuit board on which a control circuit is mounted are known. ,
A desired circuit is printed on an insulating substrate by a silk printing method using a conductive ink.

FIG. 2 is a diagram showing an example of a wiring pattern 10 on a circuit board of a membrane switch in a keyboard of an electronic desk calculator or the like manufactured by the silk printing method.

As the conductive ink used in the above-mentioned manufacturing method, conductive particles (hereinafter referred to as conductive filler) having a diameter of about 5 to 40 μm, such as carbon, nickel, silver and palladium, are used as an epoxy adhesive resin. A paste-like ink obtained by kneading with a urethane adhesive resin or the like is used.

[0005]

By the way, in the above-mentioned conventional method for manufacturing a circuit board, since the paste-like ink containing various conductive fillers is used as the conductive ink, a high-density wiring pattern is formed. However, the minimum limit of the line width and the line interval can be set to only about 300 μm.

[0006] Therefore, an object of the present invention is to provide a method for manufacturing a circuit board capable of forming a high-density wiring pattern which cannot be obtained only by printing.

[0007]

According to the present invention, in a wiring pattern to be formed on an insulating substrate, a pattern portion in which a line width and a line interval can be secured by printing is formed by printing a conductive ink and printed. For the pattern portion where the line width and the line interval cannot be secured, the solid pattern portion or the similar pattern portion is formed by printing conductive ink as an approximate pattern portion similar to the wiring pattern to be formed together with the pattern portion. For by irradiating the excimer laser light through a mask having a wiring pattern to be formed,
A method for manufacturing a circuit board is characterized in that the conductive ink is partially removed to form a desired wiring pattern.

[0008]

According to the present invention, of the wiring pattern to be formed on the insulating substrate, the pattern portion that cannot be formed with desired accuracy by printing is printed as a solid pattern portion or an approximate pattern portion by printing conductive ink, Unwanted portions of the solid pattern portion and the approximate pattern portion are removed by irradiation of excimer laser light through a mask to form a desired high-density wiring pattern.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a process chart showing a method of manufacturing a circuit board according to an embodiment of the present invention.

In the first step of this manufacturing method, as shown in FIG.
As shown in FIG. 3, a temporary wiring pattern 2 partially different from the wiring pattern to be formed on the insulating substrate 1 made of glass, ceramic or the like has a thickness of about 3 to 20 μm by silk printing using conductive ink. Printed, dried and cured.

In this case, the tentative wiring pattern 2 includes the pattern portion 2a which can be accurately formed by silk printing among the wiring patterns to be finally formed and the silk printing among the wiring patterns to be finally formed. The solid pattern portion 2b is formed in place of the pattern portion that cannot be formed with desired accuracy.

That is, the pattern portion 2a is a portion where the line width and the line interval can be accurately secured by silk printing, and the solid pattern portion 2b prints the entire predetermined solid area including the wiring pattern to be formed with conductive ink. It is the part that I did.

As the above-mentioned conductive ink, a paste made by kneading a conductive filler of carbon, nickel, silver or the like having a diameter of about 5 to 40 μm with an epoxy adhesive resin, a urethane adhesive resin or the like is used. ..

In the second step, the solid pattern portion 2b of the temporary wiring pattern 2 thus formed is irradiated with the excimer laser light 4 through the mask 3 as shown in FIG. 1 (B). .. In this case, the mask 3 is formed with a negative image pattern corresponding to a desired wiring pattern to be formed in the solid pattern portion 2b.

As a result, as shown in FIG. 1C, in the solid pattern portion 2b, the ink portion which is out of the desired wiring pattern is removed by the irradiation of the excimer laser beam 4, and the solid pattern portion 2b is formed by printing. It becomes a high-precision wiring pattern that cannot be done. That is, the circuit board 6 in which the high-definition wiring pattern 5 is formed on the insulating substrate 1 as a whole can be obtained. Area 7 surrounded by a chain double-dashed line in FIG.
Indicates a portion where the printing ink is removed by the irradiation of the excimer laser light 4.

When the printing ink is removed by irradiating the excimer laser beam 4, a film thickness of about 0.2 to 0.3 μm can be removed per one pulse of the laser beam, and 3 to 2
When the printing ink having a film thickness of about 0 μm is removed, it can be dealt with by increasing the number of laser light irradiation pulses according to the film thickness.

The accuracy of the line width and the line interval of the wiring pattern obtained by the irradiation of the excimer laser light 4 is the accuracy of the projected image projected onto the insulating substrate 1 through the mask 3 and the accuracy of the adhesion of the mask 3 to the insulating substrate 1. In any case, the line width and the line interval can be formed up to about 50 μm.

Further, in the above embodiment, the solid pattern portion 2b of the wiring pattern portion which cannot be formed with desired accuracy by printing.
However, the present invention is not limited to this, but the approximate pattern portion in which the contour of the wiring pattern portion to be finally formed is somewhat enlarged is formed by printing, and the unnecessary ink portion is formed from this approximate pattern portion. It may be removed by the excimer laser beam 4 to obtain a required wiring pattern.

[0019]

As described above, according to the method of manufacturing a circuit board of the present invention, in the wiring pattern to be formed on the insulating substrate, the pattern portion where the line width and the line interval can be secured by printing is made conductive. Formed by printing a conductive ink, and for a pattern portion where the line width and line spacing cannot be secured by printing, it is formed by printing a conductive ink as a solid pattern portion or an approximate pattern portion similar to the wiring pattern to be formed together with the pattern portion. By irradiating the solid pattern portion or the approximate pattern portion with an excimer laser beam through a mask having a wiring pattern to be formed, the conductive ink is partially removed to form a desired wiring pattern. Circuit board with a high-density wiring pattern that cannot be obtained only by printing It can be produced.

[Brief description of drawings]

FIG. 1 is a diagram showing steps of a method for manufacturing a circuit board according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a wiring pattern of a circuit board manufactured by a silk printing method.

[Explanation of symbols]

 1 Insulating Substrate 2 Temporary Wiring Pattern 2a Pattern Part 2b Solid Pattern Part 3 Mask 4 Excimer Laser Light

Claims (1)

[Claims] 1. A wiring pattern to be formed on an insulating substrate, a pattern portion of which a line width and line spacing can be secured by printing is formed by printing conductive ink, and the line width and line spacing are secured by printing. The unpatternable part is formed by printing conductive ink together with the pattern part as a solid pattern part or an approximate pattern part similar to the wiring pattern to be formed, and the wiring to be formed for the solid pattern part or the approximate pattern part. A method of manufacturing a circuit board, which comprises irradiating an excimer laser beam through a mask having a pattern to partially remove the conductive ink to form a desired wiring pattern.