JPS6298513A - Keyboard switch - 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 [Technical Field of the Invention] The present invention relates to a keyboard switch called a so-called flat keyboard or membrane switch, and particularly relates to an improvement of a keyboard switch equipped with a jumper circuit.

[Behind the scenes of invention]

In response to the miniaturization and multi-functionality of various electrical and electronic devices, the wiring circuits of printed wiring boards and keyboard switches used there are also becoming denser and more complex.

Under such circumstances, a so-called jumper circuit is generally formed in the wiring circuit within the keyboard.

A jumper circuit is a wiring circuit formed to cross or jump one or more wiring circuits and conductively connect the circuits located at both ends thereof.

FIG. 3 is a partial cross-sectional view of a keyboard switch having a jumper circuit formed in a conventional manner. That is, when one of the mutually opposing plastic sheets of a conventional keyboard switch is shown, contacts 2 and a wiring circuit 3a are provided at predetermined portions on a plastic sheet 1 which is a wiring board.
, 3b, 3c are formed, and furthermore, a wiring circuit 3a
and 3C are connected by a jumper circuit 5 via an insulating layer 4.

In forming the jumper circuit 5, the insulating layer 4 is generally formed by applying a synthetic resin paste by screen printing or the like and then curing the paste.

However, the conventional method described above has the following problems.

(b) During the curing process of the synthetic resin paste during the formation of the insulating layer, the solvent components contained in the paste evaporate, and the evaporation traces form fine pores in the insulating layer, which can cause short circuits. Cause.

(b) Screen printing used for applying synthetic resin paste involves repeating the application of the paste while a squeegee moves back and forth on the screen printing plate, so air bubbles are likely to be drawn into the paste when applying the paste, resulting in poor insulation. Bubbles are likely to form in the layer, which also causes poor insulation.

Conventionally, in order to avoid the problem of poor insulation, a method has been used to ensure good insulation by repeatedly applying a paste and curing the edges several times to form a multilayer insulating layer. However, with this method,
There is a problem in that at least six steps are required for laminating the insulating layer (that is, the steps of applying and curing the insulating paste usually need to be repeated three or more times), which makes the process of forming the jumper circuit extremely complicated.

[Summary of the invention]

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a keyboard switch for controlling a jumper circuit, which can further simplify the manufacturing process.

In order to achieve the above object, the keyboard switch of the present invention includes a first plastic sheet on which contacts and necessary contact circuits are formed, contacts opposite to the contacts of this first plus deck sheet, and necessary contacts. a second plus deck sheet on which a circuit is formed; a through hole for bringing the opposing contacts into contact with each other; 2 plastic seams 1~
A keyboard switch comprising a spacer layer interposed between a contact terminal for forming a jumper circuit provided on the first plastic sheet and a connecting terminal for forming a jumper circuit provided on the second plastic sheet. The jumper circuit is formed by conductively connecting the jumper circuit and the wiring circuit through the through hole provided in the spacer layer.

(Embodiments of 5Q Light) The present invention will be described in more detail below with reference to embodiments shown in the accompanying drawings.

FIG. 1 is a cross-sectional view showing the structure of the keyboard before the first plastic sheet 1-1a, the second plastic sheet 1b, and the spacer layer 6 are laminated together, and FIG. FIG.

As shown in FIG. 1, a contact 2a, connection terminals 7a and 7b for forming a peripheral circuit, and a contact circuit 3 are formed on the first plus deck sheet 1a. In addition,
The connection terminals 7a, 7b themselves generally form part of a contact circuit, and in the present invention, such cases are referred to as connection terminals for convenience.

On the other hand, on the second plus deck sheet 1b, contacts 2b are provided at positions opposite to the contacts 2a, and furthermore, a wiring circuit 8 for forming a jumper circuit is formed.

Further, the spacer layer 6 to be inserted includes contacts 2a, 2b and a connection for forming a jumper circuit 7a.

A through hole 6a is formed at a position corresponding to 7b.

These constituent members are stacked on top of each other as shown in FIG. 2 to complete the keyboard switch. In the keyboard switch of the present invention, the connection terminals 7a and 7
b and the wiring circuit 8 are electrically connected through the through hole 6a of the spacer layer 6, thereby forming a jumper circuit. Therefore, in the present invention, in order to form a jumper circuit, the step of forming an insulating layer to insulate the contact circuit 3b on the first plastic sheet 1a is completely unnecessary. Moreover, since the jumper circuit forming connection terminals 7a and 7b as well as the jumper circuit forming wiring circuit 8 can be formed in the same process as the process of forming the contacts 2a and 2b, special This has the advantage that additional steps are not required. Furthermore, since insulation in the jumper circuit section is ensured by the spacer layer, the problem of poor insulation is resolved, thereby improving the reliability of the keyboard switch.

The plastic sheets 1a and 1b may be made of thermoplastic or thermosetting resin, but at least one of the sheets is made of a flexible and elastic plastic such as polyester resin, and has a thickness of about 50 to 300 t1m. can be used.

Contacts 2a, 2b, connection terminals 7a, 7b, wiring circuit 3a,
3b and 8 can be formed by applying a conductive paint according to a conventional method and then curing it into a desired pattern using an appropriate method such as heat curing or ultraviolet curing, and the thickness thereof is usually 5.
It is about ~30 μm.

The spacer layer 6 has a thickness of 50 mm with through-holes formed at positions that will serve as conductive connections for forming contacts and jumper circuits.
It can be made of a plastic sheet with a thickness of about 500 μm, or it can be formed by directly applying an insulating synthetic resin paste to the first or second plastic sheet surface.

As shown in FIG. 2, the jumper circuit is formed by overlapping the first and second plastic sheets with the base layer 6 in between, and connecting the jumper circuit forming wiring circuit 8 and the jumper circuit forming connecting terminals 7a and 7b. This jumper circuit is preferably formed by the following method.

(a) A method of forming the wiring circuit 8 and the connecting terminals 7a and 7b using a conductive paste having heat-sealing properties, and bonding them by thermocompression at the conductive connection portions.

In this case, the conductive paste includes conductive fine particles in a binder such as polyamide resin, polyamide resin, polyester resin, butyral resin, polyvinyl acetate resin, or polyurethane resin, which is conventionally known for use in hot melt adhesives. A dispersed version can be used.

(b) The conductive connection portions between the wiring circuit 8 and the connection terminals 7a and 7b are formed with a thick film that is equal to or thicker than the spacer layer, and is coated with a conductive adhesive, heat fusion, etc. A method of conductive connection using chemical fixing means or mechanical fixing means such as screws.

As the conductive adhesive used in this method, a conventionally known conductive adhesive can be used.

〔Effect of the invention〕

The keyboard switch according to the present invention has a wiring circuit formed on the first plastic sheet, a connection terminal formed on the second plastic sheet, and a spacer inserted between them. Since a jumper circuit is formed by combining the two, the step of forming an insulating layer for forming a jumper circuit, which was previously necessary, can be omitted, simplifying the manufacturing process and improving reliability all at once. be able to.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a keyboard switch according to an embodiment of the present invention, and FIG. 3 is a partial cross-sectional view of a conventional gilboard switch. 1...Plus deck sheet, 2...Contact, 3...
Contact circuit, 4... Insulating layer, 5... Jumper circuit,
6... Space layer, 7a, 7b... Connection terminal for forming jumper circuit, 8... Wiring circuit for forming jumper circuit.

Claims (1)

[Scope of Claims] A first plastic sheet on which contacts and a necessary contact circuit are formed, and a second plastic sheet on which contacts and a necessary contact circuit are formed, which are opposite to the contacts of the first plastic sheet. , having a through hole for bringing the opposing contacts into contact with each other, and inserted between the first and second plastic sheets so that the opposing contacts maintain a non-contact state in a non-press operation state. In the keyboard switch, the connection terminal for forming a jumper circuit provided on the first plastic sheet and the wiring circuit for forming a jumper circuit provided on the second plastic sheet are connected to the spacer layer. A keyboard switch characterized in that a jumper circuit is formed by conductive connection through a through hole provided in the keyboard switch.