JPH07105785A - Panel switch - Google Patents

Abstract

PURPOSE:To provide a panel switch for operational input of an electronic equipment of which a flexible circuit board can not be disconnected as far as the flexible circuit board is ruptured or the adhesive between a printed circuit board and the flexible circuit board is not peeled even in the case load is applied to the stuck edge face between the flexible circuit and a rigid substrate in the direction to part the flexible circuit from the printed circuit by freely bending the flexible circuit. CONSTITUTION:A rigid substrate 5 is stuck to a part of a circuit patterned face side of a flexible circuit board 4 with an adhesive 6 where in the flexible circuit board 4 is prepared by printing a prescribed circuit pattern 2 on a synthetic resin film 1 with a conductive paste and forming a covercoating 3 on the parts except at least the contact points with an insulating paste. Regarding this panel switch, to prevent circuit disconnection, a protective pattern 7 with the same width as or wider width than the circuit pattern 2 is formed on the covercoating 3 of the flexible circuit board 4 in the boundary part of the rigid substrate 5 with a paste which has the same or less adhesive strength as or than that of the conductive paste and the insulating paste to the synthetic resin film 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a panel switch used for operation input of various electronic devices.

[0002]

2. Description of the Related Art In recent years, various electronic devices have been reduced in size and weight in order to be portable or to have multiple functions concentrated, and at the same time, flexible wiring boards which are inexpensive, thin and lightweight and have a high degree of freedom in design have been used. The demand for panel switches is increasing.

Conventionally, a panel switch is based on a flexible wiring board in which a wiring pattern is formed by printing on a synthetic resin film with a conductive paste, and the pattern excluding the contact portion is covered with an insulating paste. To reinforce the parts, a rigid substrate was adhered to the whole surface or a part thereof with an adhesive double-sided tape or a hot melt adhesive.

When a paper phenol laminated board or a glass epoxy printed wiring board is used as a rigid substrate, the contacts and wiring pattern surface of the flexible wiring board are arranged and adhered so as to face the corresponding contact wiring pattern surface of the printed wiring board. It was

[0005]

However, in the above structure, when the flexible wiring board is bent freely and a load is applied in the direction of peeling the flexible wiring board from the printed wiring board, the flexible wiring board at the boundary portion of the rigid printed wiring board is There is a problem that the wiring pattern is easily broken.

This is because the adhesive for bonding the insulating paste or the flexible wiring board and the rigid substrate can be composed of almost 100% adhesive resin, so that the adhesive strength is strong, while the conductive paste for forming the wiring pattern has high conductivity. For this reason, generally, the adhesive force to the synthetic resin film is weak because the conductive powder such as silver powder of 75 to 90% by weight is contained and the resin component ratio as the adhesive is extremely small. When the flexible wiring board is bent and a load is applied in the direction of peeling it off from the printed wiring board. The weakest adhesive part, that is, the wiring pattern, is peeled off from the synthetic resin film on the end surface of the rigid board that is bonded, resulting in disconnection failure. Met.

The present invention solves the above-mentioned conventional problems. Even if a flexible wiring board is flexed freely and a load is applied to the end surface of the flexible wiring board that is bonded to the rigid board in the direction of peeling the flexible wiring board from the printed wiring board, the flexible wiring board is broken. It is an object of the present invention to provide a panel switch that does not break unless the adhesive between the printed wiring board and the flexible wiring board is peeled off.

[0008]

In order to solve this problem, the present invention provides a flexible wiring board in which a predetermined wiring pattern is printed and formed on a synthetic resin film with a conductive paste, and at least a portion excluding contacts is covered with an insulating paste. In a panel switch in which a rigid substrate is adhered to a part of the wiring pattern surface by an adhesive agent 6, it is not adhered by an adhesive agent on the cover coat of the flexible wiring board at the boundary portion of the rigid substrate, or a synthetic resin of a conductive paste and an insulating paste. A protective pattern having the same width as or a wider width than the wiring pattern is formed by a paste having an adhesive strength equal to or less than the adhesive strength to the film.

[0009]

According to the panel switch of the present invention, even if the flexible wiring board is flexed freely and a load is applied to the end surface of the flexible wiring board that is bonded to the rigid substrate in the direction of peeling the flexible wiring board from the printed wiring board, the flexible wiring board is broken or the printed wiring board is printed. It will not break unless the adhesive between the board and the flexible wiring board is peeled off.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A panel switch according to the present invention will be described with reference to one embodiment of FIGS. As shown in the figure, 4 is a flexible wiring board in which a predetermined wiring pattern 2 is formed by printing on a synthetic resin film 1 with a conductive paste, and a cover coat 3 is formed with an insulating paste on at least a portion excluding contacts, and 5 is a wiring pattern. It is a rigid substrate that is adhered to the two sides with an adhesive 6. 7 is a flexible wiring board 4 at the boundary of the rigid substrate 5.
Is a protective pattern provided on the cover coat 3 with a paste having an adhesive strength equal to or less than the adhesive strength of the conductive paste and the insulating paste to the synthetic resin film 1 and having the same width as or a wider width than the wiring pattern 2.

The paste material used for the protective pattern 7 may be any material as long as it has adhesion or cohesive failure strength equal to or lower than that of the conductive paste used for the wiring pattern. For example, non-adhesive materials such as silicone paste, conductive paste, insulating paste for cover coat,
Even a resin of the same type as an adhesive or the like, if the paste has a high content of talc, such as a conductive paste, silica, a filler such as titanium oxide is substantially filled in the paste to reduce the adhesive strength and cohesive failure strength. Good. Even if the adhesive strength and the cohesive failure strength are the same as those of the conductive paste used for the wiring pattern, the protective pattern is not peeled off and the wiring pattern is not broken when the tensile load is applied substantially. Therefore, when the multilayer wiring is printed with the conductive paste, the protection pattern 7 can be printed at the same time as a discard pattern when the conductive paste is printed.

Next, a more specific embodiment of the above embodiment will be described.

(Specific Example 1-) As the synthetic resin film 1, a biaxially stretched polyethylene terephthalate sheet material having a thickness of 100 μm was screen printed to form a wiring pattern 2 with a conductive paste (Fujikura Chemical Co., Ltd. XA-256M). Then, the cover coat 3 was formed with an insulating resist (XB-803A, Fujikura Kasei Kogyo KK) except for the push contact portion and the tail portion 13. Next, a protective pattern 7 was formed on the portion of the tail portion 13 of the printed circuit board 5 corresponding to the substrate end portion with a silicone paste (KE4805, Shin-Etsu Chemical Co., Ltd.). The drying and curing conditions for each paste were specified or recommended by each manufacturer. The push switch portion C of the flexible wiring board was formed into a hemispherical shape so that a good reversing operation feeling can be obtained. On the other hand, a printed board on which a predetermined copper foil pattern 10 is formed and coated with a resist 11 is used as a rigid board 5, and an adhesive 6 (bisphenol A) is applied to the surface of the printed board except the flexible wiring board and the push switch portion C of the printed board. Type epoxy was coated with 4E4MZ (4% by weight of Shikoku Kasei Kogyo Co., Ltd.), and the contacts were attached facing each other, and cured at 50 ° C. for 24 hours to prepare a panel switch according to the present invention.

The width of the tail portion 13 of this panel switch is 15 mm. (Comparative Example 1-) A panel switch without the protective pattern 7 was prepared in the above-described specific example 1-.

The above specific examples 1- and comparative examples-
The tail portion 13 of the flexible wiring board 4 of the 1-panel switch was pulled in the direction perpendicular to the rigid substrate 15 to test whether or not the wiring pattern 2 was broken, n = 10 each. As a result, the panel switch of Comparative Example 1 is 0.58-
Although the wire breakage occurred in the range of 2.3 kg, the panel switch of Example 1 did not break until the film was broken at 4 to 4.6 kg.

Next, another embodiment of the panel switch of the present invention will be described with reference to FIG. 1 to 3, the same parts as those of the embodiment of the present invention are designated by the same reference numerals, and the description thereof will be omitted. 8 indicates a first wiring pattern on the cover coat 3 of the flexible wiring board 4. This is a second wiring pattern formed of a conductive paste that is partially or wholly connected. In the case of this embodiment, since the second wiring pattern 8 and the protection pattern 7 can be simultaneously formed with the same conductive paste, the protection pattern The number of man-hours for forming 7 is unnecessary.

A specific embodiment of the above embodiment will be described below. (Specific Example-2-) A wiring pattern 2 is formed on the rigid resin film 1 using the same material and method as those of the specific example-1-.
The cover coat 3 is formed, and the second wiring pattern 8 is further formed.
Was connected to the wiring pattern 2 and the second cover coat 12 was formed on the second wiring pattern 8. At the same time when the second wiring pattern 8 was formed by printing, the protection pattern 7 was formed with the same conductive paste. The push switch portion C of the flexible wiring board was formed into a hemispherical shape so that a good reversing operation feeling can be obtained. On the other hand, a printed board on which a predetermined copper foil pattern 10 has been formed in advance and coated with a resist 11 is used as a rigid board 5, and an adhesive 6 (TOYOBO UM-8300 100 parts by weight, 15 parts by weight of KE1001 made by Kyoto Elex, R972 made by Nippon Aerosil
10 parts by weight, 35 parts by weight of isophorone manufactured by Kanto Kagaku Kneading paste) are screen-printed and dried (150 ° C., 30 minutes).
Then, the flexible wiring board 1 and the rigid substrate 5 were pressed against each other and pressed against each other to form a panel switch by pressurizing and heating at 120 ° C. for 5 seconds at 15 kg / cm ² .

The tail portion of the flexible wiring board of the panel switch of the above-mentioned comparative example-1-and the concrete example-2-is pulled in a direction perpendicular to the side opposite to the rigid substrate 5 to check whether or not the wiring pattern 2 is broken. N = 10 each was tested. As a result, the panel switch of Comparative Example-1-is 0.58.
A wire breakage occurred in the range of up to 2.3 kg, but a specific example-
Each of the panel switches No. 2 was 4 to 4.6 kg and did not break until the film broke.

[0019]

As described above, according to the panel switch of the present invention, even if the flexible wiring board is freely bent and a load is applied to the end face bonded to the rigid substrate in the direction of peeling the flexible wiring board from the printed wiring board, the flexible wiring board is flexible. It is possible to easily construct a high-quality panel switch that is not broken or is not broken unless the flexible wiring boards are separated from each other.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a panel switch of the present invention.

FIG. 2 is a perspective view of the same.

FIG. 3 is a schematic diagram of a wiring pattern and a protection pattern at the boundary portion of the rigid board.

FIG. 4 is a sectional view of the other embodiment.

[Explanation of symbols] 1 synthetic resin film 2 wiring pattern 3 cover coat 4 flexible wiring board 5 rigid substrate 6 adhesive 7 protection pattern 8 wiring pattern

Claims (3)

[Claims] 1. A rigid substrate is formed on a part of a wiring pattern surface of a flexible wiring board formed by printing a predetermined wiring pattern on a synthetic resin film with a conductive paste and cover-coating with an insulating paste on at least a portion except a contact. In a panel switch adhered with an adhesive, the paste has the same or less adhesive strength as the adhesive strength of the conductive paste and the wiring paste on the synthetic resin film on the cover coat of the flexible wiring board at the boundary of the rigid substrate. Panel switch with a protective pattern of wide or wider width. 2. The second wiring pattern is formed on the cover coat of the flexible wiring board with a conductive paste so as to be partially or wholly connected to the first wiring pattern, or the contact portion and the connection portion are further removed. The panel switch according to claim 1, wherein the protective pattern is formed after cover-coating to form a third or more wiring pattern. 3. The panel switch according to claim 2, wherein the protective pattern is formed of a conductive paste simultaneously with the second and subsequent wiring patterns.