JPH06232526A - Printed wiring board with key contact - Google Patents

Abstract

PURPOSE:To prevent generation of oozing between the electrodes, of key contact point pattern caused by conductive paste when the key contact point patterns are screen printed using conductive paste. CONSTITUTION:In this printed wiring board with a key contact point pattern consisting of conductive paste located at least on a part of the printed wiring board which constitutes a conductor pattern on an insulating substrate, a separation line 2 is printed simultaneously with a screen between the electrodes 1a and 1b of the key contact point pattern 1 before screen printing the key contact point pattern 1. The oozing of the conductor paste is prevented by the thickness of the printed separation line 2, and defective insulation can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board having key contacts.

[0002]

2. Description of the Related Art A key contact pattern made of a conductive paste is provided at a desired position between conductor circuits formed on an insulating substrate for the purpose of connecting or disconnecting the conductor circuits.

A conventional key contact pattern is, for example, as shown in FIGS. 3 and 4, electrodes 10a and 10b.
Form an intricate skewered shape (not limited to a square shape and a skewered shape) and form a square shape as a whole.

This key contact pattern is provided for the electrode 1 in order to improve the conduction efficiency when connecting the conductor circuits 14.
Screen printing is performed by making the distances 0a and 10b very close to each other.

In the step of providing the key contact pattern 10 on the surface of the substrate 13, first, the conductor circuit 14 is formed on the surface of the substrate 13, and the other parts except for the portion of the conductor circuit 14 connected to the key contact pattern are required. Solder resist 15 on the part
To provide. Next, the symbol mark is printed (not shown).

After that, the key contact pattern connecting portion of the conductor circuit 14 (the portion where the solder resist 15 is not applied)
Is completed by printing so that the connecting portions 16a and 16b of the electrodes 10a and 10b overlap.

[0007]

However, the conventional key contact pattern 10 has electrodes 10a and 10b.
Are so close to each other that bleeding 11 and 12 occurs during screen printing, the electrode 10 in that portion
Insulation failure occurs due to a pseudo short circuit between a and 10b.
For this reason, it is difficult to ensure insulation, and there is a problem that the quality of the printed wiring board deteriorates.

Therefore, the present invention has been made in consideration of the above circumstances, and even if the key contact pattern 10 is screen-printed, a printed wiring having a key contact in which insulation failure due to bleeding does not occur between the electrodes 10a and 10b. For the purpose of providing boards.

[0009]

In order to achieve the above object, the present invention provides a key contact pattern made of a conductive paste by screen printing on at least a part of a printed wiring board for forming a conductive pattern on an insulating substrate. In the printed wiring board forming the above, a separation line made of an insulator is provided between the electrodes of the key contact pattern before screen printing the key contact pattern.

[0010]

According to the present invention, the occurrence of bleeding during screen printing can be prevented by providing an insulating layer between the electrodes of the key contact pattern before screen printing the key contact pattern.

[0011]

1 and 2 show key contact patterns of a printed wiring board according to the present invention. The key contact pattern 1 is made of a conductive paste and is composed of electrodes 1a and 1b.
The electrodes 1a and 1b have an intricate shape, face each other with a slight gap, and form a square shape as a whole.

In the key contact pattern 1, each of the connecting portion 3a of the electrode 1a and the connecting portion 3b of the electrode 1b is
By being connected to the conductive pattern 5, the structure serves as a key contact.

In the present invention, in the key contact pattern 1 having the above-mentioned structure, the separation line 2 is provided in a slight gap between the electrodes 1a and 1b.

The steps of forming the key contact pattern 1 of the present invention will be described below. First, the conductive pattern 5 is formed on the surface of the insulating substrate 4 by a conventional method. Next, the connection portions 5a and 5b of the conductive pattern 5 with the key contact pattern 1 are formed.
Solder resist 6 is applied to other required portions except for.

In the subsequent step of printing a symbol mark (not shown) made of an insulating material, at the same time as the printing of the symbol mark, a separation line 2 having a width corresponding to the gap is formed between the electrodes 1a and 1b. To print. The thickness of the printed separation line 2 is about 15 μm.

After the separation line 2 is printed, the key contact pattern 1 is printed. In this case, the electrodes 1a, 1b
The connecting portions 3a, 3b of the connecting portions 5a, 5b of the conductive pattern 5 are
The key contact pattern 1 and the conductive pattern 5 are connected by superposing and printing on b.

When the key contact pattern 1 is printed, as shown in FIG. 2, the separation line 2 has a thickness of about 15 μm, while the key contact pattern 1 has a thickness of about 20 μm. The step due to the thickness of the contact wire 2 is the key contact pattern 1
Of paint bleeding during printing. Therefore, electrode 1
Insulation failure will not occur between a and 1b.

[0018]

In the printed wiring board having the key contact of the present invention, the separating line is provided between the electrodes of the key contact pattern before the key contact pattern is printed, so that bleeding occurs when the key contact pattern is printed. Does not happen. Further, since the separation line between the key contact pattern electrodes is printed at the same time as the printing of the symbol mark, it can be installed without increasing the number of steps. This prevents insulation failure between electrodes,
The reliability of the printed wiring board can be improved.

[Brief description of drawings]

FIG. 1 is a plan view of a key contact of the present invention.

FIG. 2 is a sectional view of FIG.

FIG. 3 is an explanatory view of a conventional key contact.

FIG. 4 is a sectional view of FIG.

[Explanation of symbols]

 1 key contact pattern 1a, 1b electrode 2 separation line 3a, 3b connection part 4 insulating substrate 5a, 5b conductor pattern 6 solder resist

Claims (1)

[Claims] 1. A printed wiring board in which a key contact pattern made of a conductive paste is formed by screen printing on at least a part of a printed wiring board on which an electrically conductive pattern is formed on an insulating substrate. Before the above, a printed wiring board having a key contact, characterized in that a separation line made of an insulator is provided between the electrodes of the key contact pattern.