JPS6237289Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a key circuit board suitable for forming a key switch on the board.

Conventionally, in this type of key circuit board, as shown in FIG. Lead conductive parts (lead circuit parts) 3 and 3' connected to the conductive parts 2 and 2' were wired at the same time. Note that a key switch is constructed by layering a flexible conductive member such as conductive rubber on the key circuit board formed as described above with an insulating spacer interposed therebetween. The two contact conductive parts 2 and 2' are short-circuited by pressing from the contact point. It was necessary to wire sections 3 and 3' avoiding this short circuit zone.

For this reason, in conventional key circuit boards, the contact conductive parts 2, 2' occupy a large proportion of the board area, and the wiring space for the lead conductive parts 3, 3' is limited, making circuit design difficult. In some cases, a double-sided through-hole board must be used for the wiring, which is a factor in increasing costs.

Furthermore, in the conventional key circuit board of this kind, if the lead conductive parts 3, 3' are wired close to the tangential conductive parts 2, 2', ignoring the short circuit zone, the lead conductive parts 3, 3' become the contact points. Because of the risk of short-circuiting, it is necessary to wire the conductive parts 3, 3' for leads at a certain distance from the conductive parts 2, 2' for contacts, which inevitably results in a large key circuit board. It was hot.

The present invention has been devised in view of these points, and it is an object of the present invention to provide a key circuit board in which space on the board can be effectively utilized without the risk of short-circuiting of the conductive parts for leads with the conductive parts for contacts.

The following will explain the embodiments shown in the drawings. Second
The figure shows a plan view of one embodiment of the present invention, and also shows a third embodiment of the present invention.
The figure shows a sectional view taken along the line -' of the same embodiment.

Here, for example, Japanese Patent Application No. 55-137172, JP-A-57-60888, ``Method for Manufacturing Wiring Board'', and JP-A-55-137173, JP-A-57-60889, which were previously proposed by the same inventors, will be discussed.
No. ``Wiring board manufacturing method'' or patent application No. 1983-39961
First, conductive parts 3 and 3' for leads made of metal foil are wired in a desired pattern on an insulating substrate 1 using the method disclosed in JP-A No. 57-153495 "Method for Manufacturing Printed Wiring Boards". At the same time, other lead conductive parts 3'' are also formed at the same time. In this case, a part of the lead conductive parts 3, 3', especially the connection points with the contact conductive parts 2, 2' to be formed later, The area is made higher with a difference in level from other parts.

Next, the substrate 1 is filled with an insulating resin, and an insulating resin layer 4 is formed so as to be flush with the surface of the connection points, and the conductive parts 3 for other leads are formed leaving the connection points. , 3', 3'' are buried.

After that, conductive parts 2 for contacts are printed thereon with conductive paint, chemical plating, electroplating, etc.
2' is formed into a desired pattern. At this time, the conductive parts 2, 2' for contacts and the conductive parts 3, 3' for leads are electrically connected to each other at the respective connection points.

If the key circuit board formed by the above method is used for a key switch, the conductive parts 2, 2'
The conductive parts 3, 3' for leads near the insulating resin layer 4
Even if the two conductive parts 2, 2' and 3, 3' are arranged close to each other or overlapping each other, there is no risk of short-circuiting when the key is pressed. ′ will be shorted.

By using the key circuit board of the present invention, the wiring space of the conductive part for leads can be widely utilized, making circuit design easier and making it possible to downsize the board.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a conventional key circuit board, FIG. 2 is a plan view of an embodiment of the present invention, and FIG. 3 is a sectional view taken along the line -' of the same embodiment. DESCRIPTION OF SYMBOLS 1... Insulating substrate, 2, 2'... Conductive part for contacts, 3, 3'... Conductive part for leads, 4... Insulating resin layer.

Claims (1)

[Scope of utility model registration request] On an insulating substrate, a conductive part for a lead is formed with a step so that only the connection point with the conductive part for a contact is one step higher, and the conductive part for a lead is buried in an insulating resin layer, leaving the above connection point. , a key circuit board on which conductive parts for contacts are wired.