Label：Membrane Switch, Production Process
Nov 22, 20232180
Membrane switches are indispensable components. You can see them in daily life. The top layer of membrane switch is graphic overlay. There are other parts. Now, let's talk about production process of membrane switch assembly.
1. Put the silk-screened circuit into the oven, and bake for 40 minutes at a temperature of 115 ℃. (Note that silk-printed circuits should be allowed to dry naturally.) After the baking, simply assemble it and test whether there are short circuits, broken circuits, excessive resistance, etc..
2. Attach the tail cable
After testing the single-wire resistance of the baked circuit, use the laminating machine to press a layer of insulating tape on the tail cable from the outlet hole to the point where the carbon slurry overlaps 1 mm. Do not stick it to the button.
3. Punch out the tail cable
Punch out the tail cable with die. Both sides of the tail cable should be even (pay attention to the tail cable with small spacing). When making prototypes, use a ruler with glue to align it with the inside of the outlet hole from top to bottom, and draw to the edge of the tail. The ruler should be glued to the opposite side of the circuit to avoid sticking the silver paste off.
4. Assemble the circuit
Firstly, attach the lower circuit with the punched tail cable to the spacer. When attaching, the silver paste point should be placed in the middle of the spacer hole without any bubbles. Then attach the circuit. Pay attention to the positioning of the upper and lower circuits to be aligned. The points cannot be misplaced.
5. Apply back adhesive
Apply the prepared back adhesive to the lower circuit. When pasting, the tail cable should be taken out. The adhesive position should cover the 4 corners. There should be no air bubbles during the pasting.
6. Apply upper adhesive
Stick the upper adhesive on the upper circuit. The adhesive holes should be aligned with the keys and cover the 4 corners.
Get a scrap panel, and stick it on the assembled circuit. Align the four corners. Expand the transparent hole by 1 mm on all four sides, and fix it on the assembled circuit. Knock it off with a suitable die.
8. Apply graphic overlay
Paste the graphic overlay on the upper circuit. Pay attention to aligning the four corners when pasting. If there are any bubbles on the upper circuit, get rid of them. Paste it to a transparent window to see if the window is stuck, and then paste it properly. Protect the transparent window while pasting.
9. Tail cable treatment
Cut the tail cable flat. If there are no terminals, stick a layer of PET with 0.125 single-sided tape on the back of the carbon paste for reinforcement. If terminals need to be punched, put riveting pin in the conductive side of the tail cable toward the terminal. The double-layer tail cable should be cut with a rounded corner outlet about 1-1.5 cm high at the bottom.
10. Make spacer
Find a piece of waste circuit and lay it flat on a spacer of suitable size, and stick it. Use awl to dig down the center point of the line key, and then use compass to draw circles on the center points. Cut the circle, then cut a ventilation groove with a width of 2 mm between the circles. There should be at least three circles connected. Do not pass at intersections between upper and lower circuit. The spacer where the pot slices are placed should be shaped into a square the size of the pot). The mold is formed in one go during mass production.
Stamping is an indispensable process for membrane switches. The dimensions require precision, and the design of the mold is the guarantee. The dimensions should be varied based on the customer need, as well as the thickness, size, shape, etc. of the substrate. Precise structural dimensions are necessary. The quality of the mold is the key to the molding quality. During the embossing, the mold must reflect all the patterns on the original version. High-quality embossing requires hot pressing.
First visually inspect to see if there is any deviation in appearance or poor silkscreen printing. Then inspect buttons one by one with a detector according to the circuit principle to see if there are broken circuits, short circuits, excessive resistance, etc. At the same time, pay attention to the sensitivity of the buttons, whether the detection light with LED is on or always on, and whether the brightness is uneven, etc. Pay attention to check with the prototype. Each product must be continuously prototyped for service life testing (500000 times pressing can be confirmed as qualified).