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Dongguan Chun Yip Electronic Technology Co.,Ltd.

  • Contact:Ivan
  • Tel:+86-769-85382422
  • Mobile phone:+86-13631669420
  • Add:No.19 5th Xingye Rd Xiabian Dist. Changan Town Dongguan City Guangdong Prov. China

New Information

Membrane switch inspection method and steps

From:admin Date: 2020-07-13
Membrane switch inspection method and steps
1. Shape: shape, conductor line, insulation treatment, lining board combination, etc. should conform to the drawings or provide physical samples.
2. Material: panel, substrate, silver paste, carbon ink, septum, adhesive, adhesive, reinforcement board, and insulation printing should comply with the drawings.
3. Check the appearance quality: the scope of this inspection is wide.
Panel: There must be no obvious defects (such as lack of strokes that affect readability; stains, light-transmitting points; deinking, stains, scratches; transparent window overflow glue, residual glue, etc.); no deviation phenomenon (print sleeve Offset of plate ≤0.2mm; Offset of key combination of upper and lower lines ≤0.5mm; Offset of combination of circuit and key sheet, panel and face key ≤0.3mm; Offset of blank area around the back of panel and circuit combination ≤0.2mm; Panel (The key bump and substrate offset ≤0.5mm).
Lines: There should be no residual material chips, foreign objects, stains, irregularities and grease attached to the surface and inside, fingerprints on the line, burrs on the edges of the finished shape; all lines and contacts must not have cut marks that penetrate through the surface (that is, the cut marks are caused by The substrate is cut to the substrate), and slight scratches are based on the principle of not affecting its impedance. The scratches on the surface of the carbon ink are based on the principle of not affecting the conduction of the circuit. The circuit must not have any foreign objects attached to it.
Conductive silver: The thickness of the silver paste is generally controlled at 7-12 μm, and should be uniform and smooth, without obvious defects and pinholes. No break or short circuit is allowed. Carbon ink: The carbon ink covered on the silver paste line should ensure that the silver paste is completely covered. Its thickness is 8-10 μm, and there must be no obvious silver paste protruding.
Insulation printing: All membrane switch contact points must not have any insulation ink attached. The surface of the insulating ink should be flat to avoid any bubbles or pinholes and other defects that affect the insulating effect.
Jumper: All jumper parts are in accordance with the requirements of the line conductor, and all jumper products must pass 100% open, short circuit test and insulation resistance test. Make sure that there is no open, short circuit and insulation resistance should be greater than 500MΩ (500VDC for 1 minute).
Punching burr and die squeeze size: The punching burr and squeeze size should not be greater than 0.2mm, and the position should be toward the side without conductor.
4. Check the color: use the visual method to compare with the sealed sample to see if there is any color difference. The color requirements are particularly strict.
5. Check the adhesion of ink: the ink is attached by hand with transparent tape to ensure that there is no air bubbles and it will peel off quickly after 10 seconds, and there should be no ink drop. After the insulating ink dries, press the ink surfaces against each other and press for 24 hours to ensure that the insulation does not stick to each other. After applying pressure sensitive tape for 1 minute without air bubbles, it peeled off quickly, and no ink fell off.
6. Bubbling quality: the height is equal and the strength is balanced. Flat type: 57~284g force, touch feeling: 170~397g force.
7. Peel strength: The peel strength of the glue should not be less than 8N/25mm.
8. Folding strength: after drying the silver paste, carbon ink circuit or silver circuit covered carbon ink, the loop resistance should be measured first, then the circuit should be folded 180 degrees, and the finger should be pressed 2kg/2 seconds, Then make it back to the plane, so back and forth 5 times, and then measure its resistance. The increased resistance after folding 5 times does not exceed 300% of the original resistance.
9. Hardness: Use a class H drawing pen to apply a 1kg thrust to the circuit at 45 degrees. The circuit must not peel off conductive ink or produce light.
10. Dimensions: The allowable tolerances of the drawings without tolerances are shown in Table 1, and the rest comply with the drawings.
General size (mm) Allowable tolerance (mm)
18 or less ±0.2
18-50 ±0.3
51-125 ±0.4
126-250 ±0.5
251 or more ±0.6
11. Loop resistance: The return line resistance value should not be greater than 100Ω. For the total length of the return line greater than 150cm and special requirements, the return line resistance is additionally specified on the drawing.
12. Insulation resistance: In normal temperature and humidity environment, the insulation resistance of the conductor line is greater than 500MΩ (500VDC for 1 minute). After high temperature and constant humidity test and salt spray test, it should be no less than 20MΩ.
13. Lifetime: The number of contact conduction for each button without reed should be 1 million times. The number of reeds and tactile conduction should be 500,000 times.
14. High temperature: After the membrane switch is subjected to a high temperature of 55±2℃ for 72 hours, the appearance quality should be in accordance with the drawings. After recovering for 2 hours under normal atmospheric conditions, the measured insulation resistance value should meet the regulations.
15. Low temperature: After the film is subjected to a low temperature of -10±3℃ for 16 hours, it will recover for 2 hours under normal atmospheric conditions, wipe off the water droplets on the surface, and measure the resistance value of the return line in accordance with the regulations.
16. Constant damp heat: Membrane switch withstands 40±2℃, relative humidity is 93 (+2% –3%), after 96 hours of constant damp heat test, recover under normal atmospheric conditions for 2 hours, measure insulation resistance, loop resistance 3. The button force should meet the regulations.
17. Salt spray test: The membrane switch is subjected to a salt solution of 5% sodium chloride, the temperature in the test space is 35±2℃, (connector seal) After 72 hours of salt spray test, it is restored for 2 hours under normal atmospheric conditions, Insulation resistance should meet the regulations.
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