JPS6219010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a switch board and a method for manufacturing the same, and aims to have good wear resistance,
Another object of the present invention is to provide a switch board that is easy to manufacture and inexpensive.

Generally, rotary switches used for detecting the position of a type wheel in a printer, detecting the number of rotations in a counter, etc. are required to have extremely good wear resistance. Figures 1 and 2 show this kind of switch, that is, a disk-shaped substrate 52 is attached to a rotating shaft 51 that drives a type wheel 50, and the contact pattern on the substrate 52 rotates at high speed together with the rotating shaft 51. On top of 53, there is a contact 54 made of a springy metal piece with good conductivity.
A general example of a high-speed rotary switch is shown in which the rotational position of the type wheel 50 is detected by making elastic contact with the type wheel 50.

In the conventional circuit board structure used in this type of switch, the surface of the circuit board 52 and the contact pattern 53 are located on the same plane in order to eliminate unevenness on the contact surface of the contactor 54, and as described above, a wear-resistant structure is used. I'm trying to improve. However, since this contact pattern 52 is formed using a transfer method, it requires a large number of printing processes, transfer processes, and peeling processes, making the manufacturing process complicated, and also due to the thin thickness of the contact pattern 52. (Because the contact pattern is formed by printing or plating, the thickness is thinner than that of a metal plate.) Therefore, it is difficult to guarantee a long life.

On the other hand, in order to solve this problem, it is possible to embed a thin metal plate punched into a predetermined shape into the substrate, but if fine strips are punched and formed to form a micro pattern, it will be difficult to do so during the insert molding process. It is extremely difficult to prevent deformation and position the strips, and if the fine strips are buried with their surfaces flush with the substrate surface, the adhesion between the strips and the substrate will be poor. Become. On the other hand, it is also possible to bond a thin metal plate to the board using the die stamping method, but since the substrate material requires a certain degree of hardness, the surface of the contact pattern made of the thin metal plate is stamped to the same height as the board surface. This was difficult and resulted in unevenness on the substrate surface.

Therefore, in order to eliminate the above-mentioned drawbacks, as shown in FIG. 3, protrusions 61 corresponding to the contact pattern are formed on a thin metal plate 60 by embossing, and this thin metal plate 60 is made of insulating synthetic resin. A switch board which is embedded in a board 63 by integral molding and whose contact point is a protruding part 61 which is exposed so as to be located substantially on the same plane as the surface of the board 63 was proposed by the applicant of this application in U.S. Pat. proposed as a number.
Although the switch board disclosed in this prior application is easy to manufacture and has excellent wear resistance, it has the disadvantage that the yield of precious metal plating applied to the surface of the thin metal plate 60 is poor.

After all, if the surface of the protrusion 61 is plated with the thin metal plate 60 buried in the substrate 63,
The resin (substrate 63) is easily attacked by the plating liquid, making it difficult to select a resin with appropriate hardness and corrosion resistance, and the acidic liquid that penetrated between the substrate 63 and the thin metal plate 60 during the plating process. (This is due to the poor tightness between the substrate 63 and the thin metal plate 60, so there are holes in the thin metal plate 60 for connecting the upper and lower resins.)
2...... is provided. ) cannot be completely removed in the cleaning process and remains, which over time causes the thin metal plate 60 to
This causes corrosion and reduces the reliability of the switch board. Therefore, a method is adopted in which precious metal plating is applied to the thin metal plate 60 before embedding it in the substrate 63. However, the partial plating method in which only the surface of the protrusion 61 is selectively plated is difficult because the thin metal plate 60 has irregularities. It is extremely difficult and impractical to manufacture a mask for resist application, align the mask, etc. Therefore, plating an extremely expensive precious metal such as gold is applied to the entire surface of the thin metal plate 60, and this is applied to the substrate 63. Currently, they are buried, and the yield of precious metal plating is extremely poor.

The present invention has been made in view of the above points, and details thereof will be explained below with reference to an embodiment shown in FIGS. 5 to 11.

5 to 10 are explanatory diagrams showing the manufacturing process of the switch board, each diagram a is a plan view, each diagram b is a sectional view of the main part corresponding to a, and FIG. 11 is an explanatory diagram of the entire process. It is.

Hereinafter, an example will be described in the order of the manufacturing process. First, the metal thin plate 1 is guided from the raw material (hoop material 1A) around which the band-shaped metal thin plate 1 is wound to the press machine 31 via the leveler 30. Therefore, protrusions 2 corresponding to the contact pattern are formed on the flat metal thin plate 1 by embossing, and the metal thin plate 1 is processed as shown in FIG. 5. At this time, the metal thin plate 1 is are holes 3 for connecting the upper and lower resins of the thin metal plate 1 in the molding process described later;
In addition, positioning holes 4 for positioning the continuous thin metal plate 1 are simultaneously drilled in each step. As the thin metal plate 1, a material with good conductivity, corrosion resistance, plateability, and workability is selected. In this example, a phosphor bronze plate with a thickness of 0.4 mm is used, and the protruding portion 2 The height of the protrusion 2 is set to 0.2 mm, and the minimum width of the protrusion 2 is set to 0.2 mm. (Materials such as brass, nickel silver, and stainless steel can be substituted.
The shape of the protrusion 2 is arbitrarily selected depending on the material and the purpose. ) Next, the thin metal sheet 1 passes through a degreasing machine 32, and then is led to a known electrostatic powder coating machine 33, where the insulating paint 5 is coated on the entire surface, and then fired and dried in a high-temperature furnace 34 to remove the paint. 5 is completely adhered and fixed to the thin metal plate 1. FIG. 6 shows this state, and by employing the electrostatic powder coating method, the paint 5 is evenly adhered not only to the entire front and back surfaces of the thin metal plate 1 but also to its end surfaces. In this example, an epoxy paint (Powdax E manufactured by Nippon Paint Co., Ltd.) was used as the paint 5, and the thickness was approximately 50 μm, and the baking conditions were 200°C.
15 minutes, but the material of the paint 5 is selected appropriately taking into consideration the smoothness (adhesion) with the material of the substrate 8, which will be described later, and the thickness of the paint 5 and baking conditions are set to optimal values taking these factors into consideration. It is sufficient to select each of them.

Next, the thin metal plate 1 is guided to a polishing machine 35, and the surface of the protrusion 2 is polished to remove only the insulating paint 5 on the surface of the protrusion 2. In this polishing process,
With the thin metal plate 1 pressed against the base, only the surface of the protrusion 2 is polished with a rotary grindstone, etc., and in some cases, puff polishing is also performed to make the surface of the protrusion 2 where the metal is exposed as smooth as possible. Make it flat. Furthermore, since the thin metal plate 1 is polished while being held down, its warpage and the like are corrected, and the overall plane is also leveled. FIG. 7 shows the state after this polishing process.

Next, the thin metal plate 1 is removed by a cleaning machine 36 to remove wear particles, and then guided to a plating device 37, where the protruding portion 2 is pretreated (degreasing, pickling, etc.).
The surface is electroplated with Ni plating and then gold plating, followed by washing and drying. 8th
The figure shows the state after this plating, and the thickness is exaggerated in the illustration, but in this example, the thickness of the underlying Ni plating layer 6 and the thickness of the Au plating layer 7 were each set to 1μ. There is. The thickness of this plating layer, particularly the thickness of the Au plating layer (noble metal plating layer), can be made even thinner by mirror-finishing the surface of the protrusion during the polishing step.

Next, the metal thin plate 1 is guided to a molding machine 38, where the metal thin plate 1 is buried in a sandwich-like state with its flat plate part sandwiched in a substrate 8 made of insulating synthetic resin, and the protruding part It is integrally molded with only two surfaces exposed on the same plane as the substrate 8 surface. During this molding process, by pressing the surface of the protrusion 2 against a smooth mold, the surface of the protrusion 2 and the surface of the substrate 8 are positioned on the same plane, and the smoothness of the surface of the protrusion 2 is also maintained. Ru. In addition,
As for the material of the substrate 8, an appropriate material is selected in consideration of moldability, hardness, resistance to the paint 5, etc., but in this example, outsert molding was performed using acetal resin. The thickness of the metal thin plate 1 in the buried state is set to 1.0 mm. FIG. 9 shows this state.

Finally, the thin metal plate 1 (and substrate 8) in the state shown in FIG. 9 is led to a press machine 39, where it is separated and cut into disc-shaped independent switch substrates as shown in FIG. complete. Note that FIG. 10b is a sectional view taken along the line A-A in FIG. 10a, and in the figure, 9 is a center hole for shaft insertion.

The switch board shown in FIG. 10 is fixed to a rotating shaft 51 in the same way as in the conventional case, and is designed to output a predetermined signal by means of a contact 14 that comes into contact with and separates from the protrusion 2 (contact).

As detailed above, the advantages of the present invention are as follows: (a) Since the protrusions formed by embossing are used as contacts, it is easy to form protrusions (contacts) including fine patterns, and it is possible to easily form protrusions (contacts) during and before molding. There is no risk of deformation of the contact part during the process, and compared to a configuration in which a variety of fine metal strips are buried, positioning and prevention of deformation during molding is much easier, and the contact part is not connected to the protruding part (contact). Since the other thin metal plate parts are buried in the board, the adhesion between the contacts and the board is very good. Overall, this is a smooth, wear-resistant, long-life switch board that uses thin metal plates as contacts. However, it has an extremely simple structure, is easy to manufacture, and can be provided at low cost.

(b) After applying insulating paint to the entire surface of the thin metal plate, the paint on the surface of the protrusion is removed by polishing, and precious metal plating is applied only to the surface of the protrusion where this metal is exposed. There is no wastage of precious metal materials, and the yield is very high.

(c) Also, since the areas to be plated (protrusions) are polished, the surface of the protrusions becomes smooth, and therefore the precious metal plating layer can be made thinner, which also improves the yield in the plating process. Additionally, the polishing process can flatten the entire thin metal plate (correct warpage).

(d) The insulating paint that is in close contact with the metal thin plate can be selected to have good adhesion to the substrate, and therefore it can be expected that the adhesion between the metal thin plate and the substrate will be extremely good.

(e) The thin metal plate is molded and embedded in a substrate made of insulating synthetic resin, and is integrally molded with only the protruding surface exposed on the same plane as the substrate surface, improving reliability at the contact point. It is also highly suitable for mass production.

Overall, it is possible to provide a switch board that has good wear resistance, is easy to manufacture, and is inexpensive, and has the remarkable effect of being of great industrial value.

In the above-mentioned embodiments, a rotary switch used for detecting printed characters in a printer was explained as an example, but the switch board of the present invention is not limited to this, and can be used for various encoder switches or slide switches. Of course, it can also be applied to

[Brief explanation of the drawing]

Figures 1 and 2 relate to the first conventional example;
The figure is an explanatory view of the main parts of a switch used in a printer, Figure 2 is a plan view of the switch board, Figures 3 and 4 relate to the second conventional example, and Figure 3 is a plane view of a thin metal plate. 4 are sectional views of the main parts of the switch board, FIGS. 5 to 11 relate to an embodiment of the present invention, and FIGS. 5 to 10 are explanatory diagrams showing the manufacturing process. a is a plan view, each figure b is a sectional view of the main part,
FIG. 11 is an explanatory diagram of the entire process. 1... Metal thin plate, 2... Protrusion, 3... Hole, 5
...Insulating paint, 6...Ni plating layer, 7...Au
Plating layer (precious metal plating layer), 8...Substrate.

Claims (1)

[Scope of Claims] 1. A substrate made of an insulating synthetic resin, in which a protrusion is formed by embossing, an insulating paint is applied to the entire surface except for the protrusion, and the protrusion is coated with a noble metal plating. 1. A switch board, characterized in that the protruding part and the substrate surface are located on substantially the same plane, and the protruding part is used as a contact point. 2. A first step of forming a protrusion on a flat metal thin plate by embossing, a second step of applying insulating paint to the entire surface of the metal thin plate, and removing the insulating paint on the surface of the protrusion by polishing. a fourth step of applying noble metal plating to the surface of the protrusion where the metal was exposed in the third step; and outsert molding of the thin metal sheet that has gone through the fourth step to make it made of insulating synthetic resin. A method for manufacturing a switch board, comprising a fifth step of embedding the protrusion in the substrate and positioning the protrusion surface and the substrate surface substantially on the same plane.