JP2542150B2 - Method of manufacturing thin film switch - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film switch (membrane switch) in which two films each having an electrode pattern are superposed with an insulating spacer interposed therebetween, and more particularly to a thin film switch. The present invention relates to improvement of an insulating spacer. 2. Description of the Related Art FIG. 3 is a sectional view showing an example of a conventional thin film switch. In FIG. 3, 1 is a lower electrode 2 on the upper surface.
A lower film printed with 3; an upper film having an upper electrode 4 printed on the lower surface; 5 a spacer film;
Is an adhesive. The lower film 1, the upper film 3 and the spacer film 5 are integrated with each other via the adhesive 6 applied on the upper and lower surfaces of the spacer film 5, and the upper electrode 4 and the lower electrode 2 are formed on the spacer film 5. They face each other in a separated state via the through hole 5a. And
When a pressing force is applied from above the upper film 3 with a finger or the like to push down the flexible upper film 3 for a predetermined stroke, the upper electrode 4 and the lower electrode 2 are brought into contact with each other to be switched on. Further, when this pressing force is removed, the state of FIG. 3 is restored due to the flexibility of the upper film 3, and the upper electrode 4 and the lower electrode 2 are separated from each other to be switched off. However, in the above-mentioned thin film switch using the spacer film 5, the spacer film 5 is previously formed.
It is necessary to attach the upper film 3 and the lower film 1 to the spacer film 5 with the release paper (not shown) attached to the upper and lower surfaces of the adhesive film 6 and both films at this time. It is very difficult to stack the films 1, 3 and 5 so that air bubbles do not enter between 1 and 3 and the positions of the upper electrode 4 and the lower electrode 2 are not misaligned.
It required considerable skill. Therefore, in order to simplify the attaching work, a thin film switch in which synthetic resin ink is printed on the upper or lower film instead of the spacer film is disclosed in Japanese Patent Laid-Open No. 138725/1982. ing. FIG. 4 is a cross-sectional view showing a conventional example of this type of thin film switch. In FIG. 4, 7 is an insulating spacer, and parts corresponding to those in FIG. In the figure, the insulating spacer 7 is made of a printing ink made of an insulating material, and is formed on a portion of the lower film 1 excluding the lower electrode 2 by a method such as a screen printing method. Then, the adhesive 6 is applied onto the insulating spacer 7, and the lower surface of the upper film 3 is attached to the adhesive 6, whereby the upper film 3, the insulating spacer 7 and the lower film 1 are integrated. . As described above, in the thin film switch in which the spacers are formed by printing, the bonding work between the lower film 1 and the insulating spacers 7 can be omitted.
Although the working efficiency can be improved as compared with the one using the spacer film, the complicated bonding work between the upper film 3 and the insulating spacer 7 is still necessary, and the adhesive 6 swells between the electrodes 2 and 4. There was a risk of malfunction of the switch. In addition, spacers are printed
When forming, an insulating spacer that can be formed by one printing
Since the thickness of the laser 7 is limited, it is necessary between the electrodes 2 and 4.
If the gap length is increased, the ink is printed many times.
There was also the problem of having to print. Therefore, an object of the present invention is to provide a thin film switch which has good assembling workability and does not have a defective switch operation at low cost, except for the above-mentioned drawbacks of the prior art. The object of the present invention described above is such that the lower electrode provided on the lower film and the upper electrode provided on the upper film face each other so as to be contactable and separable via an insulating spacer. In the method for manufacturing a thin film switch comprising the above, a plastisol type insulating paste in which a thermoplastic resin powder is dispersed in a liquid plasticizer is printed on one film on which the lower electrode and the upper electrode are formed, and the insulation After heating the paste to gel it, by bending the one film so that these insulating pastes overlap, the insulating paste is interposed between the lower film and the upper film, and then the insulating paste By heating and pressurizing to form the insulating spacer, the upper film, the insulating spacer, and the lower film are integrated with each other. It is achieved by According to the present invention, the upper film and the insulating spacer are heated and pressed by an insulating paste preprinted on a single film having the lower electrode and the upper electrode formed thereon.
And the lower film are integrated respectively.
Therefore, easy manufacturing of the membrane switch without using an adhesive
Can be built . Here, since the insulating spacer is a plastisol type in which a thermoplastic resin powder is dispersed in a liquid plasticizer, the film-forming solid content in the liquid is significantly higher than that of an organosol having an organic solvent as a dispersion medium, Not only can the film thickness be increased by printing once, but the film thickness can be easily controlled . Moreover, printed insulation paste
Bend one film after heating to gel
Therefore, the insulation paste does not flow when bent.
Is getting worse. Because of this, when bending
Flow through and the lower and upper electrodes face each other
The area where the print is not formed)
It is possible to prevent problems. It is also heated and pressurized
Since the insulating paste is made of the same material, the upper film
The adhesion between the insulating spacer and the lower film can be made extremely good. Further, the upper film and the lower film were formed by bending a single film.
Therefore, by simultaneously printing the same surface of one film to the insulating spacer, thereby improving the productivity by simplifying the printing process. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a thin film switch according to an embodiment of the present invention, in which 8 is an insulating spacer, and other lower film 1, lower electrode 2, upper film 3 and upper electrode 4 are the same as those of the conventional one described above. It is similar to that of No. 1, and description thereof will be omitted by giving the same number. In this embodiment, an insulating spacer 8 is formed between the upper surface of the lower film 1 and the lower surface of the upper film 3 except for the electrodes 2 and 4 by a printing technique. The lower film 1 and the lower film 1 are laminated and integrated to form a thin film switch. [0012] The insulating spacer 8, after the insulating paste mainly composed of thermoplastic resin formed by printing on both lower film 1 and the upper film 3, is formed by heating and pressing them. As this insulating paste, for example, a plastisol in which a thermoplastic resin powder such as vinyl chloride resin is dispersed in a liquid plasticizer such as DOP (dioctyl phthalate) and a stabilizer, a thickener, a pigment and the like are further added if necessary. The type is preferable. That is, since such a plastisol has a significantly higher film-forming solid content in the liquid than an organosol or the like using an organic solvent as a dispersion medium, the film thickness in one printing can be increased and the number of printing can be significantly reduced. Next, the manufacturing process of the thin film switch will be described with reference to FIGS. 2 (a) and 2 (b). First, as shown in FIG. 2 (a), a lower film 1 on which a lower electrode 2 is patterned and an upper film 3 on which an upper electrode 4 is patterned are integrated.
Prepare a film . Next, as shown in FIG. 2 (b), insulating pastes 8 ', 8 "are printed on the portions of the lower film 1 and the upper film 3 excluding the electrodes 2 and 4 by a screen printing method or the like. Next, the film is dried and further heated to be melted and gelled.Next, the above film is bent at its central portion, and a plurality of positioning holes 1a and 3a formed in the lower film 1 and the upper film 3 respectively form electrodes. 2,4
While accurately positioning the other insulating paste 8 ′ on the other insulating paste 8 ′, and then heating both insulating pastes 8 ′ and 8 ″ by a compression device with a heater (not shown). When pressed, both insulating pastes 8 ′ and 8 ″ are melted to become the insulating paste 8 and the thin film switch shown in FIG. 1 is obtained. In this one embodiment, the lower film 1
The insulating paste 8 ′ printed on the upper film 3 and the insulating paste 8 ″ printed on the upper film 3 are melted to form the insulating spacers 8.
The adhesiveness with can be made extremely good. Further, in the above-mentioned thin film switch, in order to avoid the undesired natural contact between the lower electrode 2 and the upper electrode 4, the insulating spacer 8 having a thickness of 30 μm or more is usually required. insulating paste 8 to about 100μm thick with print ', since it is possible to form the 8 ", not only it is possible to simplify the printing process, the film thickness control of the insulating spacer 8 is facilitated. Furthermore, the In the embodiment, the lower electrode 2 and the upper
Insulation paste on a piece of film on which the partial electrode 4 is formed
After printing 8 ', 8 ", these insulating pastes 8',
The single film was folded so that 8 "overlap.
Insulation paste 8 ', 8 "on the same side of the film
By printing simultaneously on the lower film 1 and upper film
It is possible to form an insulating spacer 8 on the
The productivity can be improved by simplifying the process. As described above, according to the present invention,
When the upper film, the insulating spacer, and the lower film are integrated, the upper film, the insulating spacer, and the lower film are formed by heating and pressing the insulating paste previously printed on the single film on which the lower electrode and the upper electrode are formed. Since the film and the film are integrated with each other, the thin film switch can be easily manufactured without using an adhesive. Further, since the insulating spacer is a plastisol type in which a thermoplastic resin powder is dispersed in a liquid plasticizer, the film-forming solid content in the liquid is significantly higher than that of an organosol having an organic solvent as a dispersion medium. Not only can the film thickness be increased by printing once, but also the film thickness can be easily controlled. Moreover, since the printed insulating paste is heated to gel and then one film is folded, the fluidity of the insulating paste is lost when the film is folded. For this reason, the insulating paste flows during bending,
It is possible to prevent the problem that the lower electrode and the upper electrode block the opposing through holes. Further, since the insulating paste to be heated and pressed is the same kind of material, the adhesion between the upper film, the insulating spacer and the lower film can be made extremely good. Furthermore, since the upper film and the lower film are formed by bending one film, the insulating spacers are printed on the same surface of one film at the same time, so that the printing process can be simplified and the productivity can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a thin film switch according to an embodiment of the present invention. FIG. 2 is an explanatory view showing a manufacturing process of the thin film switch of FIG. FIG. 3 is a cross-sectional view of a thin film switch according to a conventional example. FIG. 4 is a cross-sectional view of a thin film switch according to another conventional example. [Explanation of reference numerals] 1 lower film 2 lower electrode 3 upper film 4 upper electrode 8 insulating spacers 8 ', 8 "insulating paste

Claims (1)

(57) [Claims] 1. In a method for manufacturing a thin film switch in which a lower electrode provided on a lower film and an upper electrode provided on an upper film face each other so as to be contactable and separable with an insulating spacer interposed therebetween, On a sheet of film, a plastisol type insulating paste in which a thermoplastic resin powder is dispersed in a liquid plasticizer is printed, and after this insulating paste is heated to gel, the above-mentioned one is applied so that these insulating pastes overlap. By bending the sheet of film, the insulating paste is interposed between the lower film and the upper film, and then the insulating paste is heated and pressed to form the insulating spacer. A method of manufacturing a thin film switch, characterized by integrating a film and a film respectively.