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Jasper Electronics Co.,Ltd

Add:2th Floor, No.3, Xinyuan North #2 Road, 
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How to check if the membrane switch is qualified

- Aug 25, 2018 -

How to check if the membrane switch is qualified

1. Material inspection of membrane switch: membrane switch panel, substrate, silver paste, carbon ink, separator, adhesive, adhesive, reinforcing plate, and insulation printing shall comply with the drawings.

2, film switch sub-shape comparison: shape, conductor circuit, insulation treatment, liner combination, etc. should comply with the drawings or provide physical samples.

3, the check size of the membrane switch: the allowable range of drawings without tolerances should meet the standards, and the rest meet the requirements of the drawings.

4, the appearance of the membrane switch inspection: membrane switch panel can not have obvious defects, such as characters lack of strokes; stains, light spots; deinking, stains, scratches; transparent window overflow, residual glue. Non-biased phenomenon, such as printing set, combination of upper and lower line keys, line and key sheet, panel and button combination, panel button bubbling and substrate. The stamping burr and the extrusion size should not be larger than 0.2mm, and the position should be toward the side without conductor.

5, check the color: using the visual method, compare with the sample or color card to see if there is color difference, the color requirements are particularly strict with the color difference meter comparison.

6, the adhesion of the ink inspection: the ink is attached to the hand with a transparent tape to ensure that no bubbles after 10 seconds, quickly peel off, no ink drop phenomenon. After the insulating ink is dried, the ink surfaces are placed against each other and then pressed for 24 hours, so that the insulating surfaces are not mutually adhered. After pressing the pressure-sensitive adhesive tape for 1 minute without air bubbles, it was quickly peeled off, and no ink was peeled off.

7. Peel strength test: The peel strength of the glue should not be lower than 8N/25mm.

8, bubbling detection: the height is equal, the strength is balanced. Plane type: 57 ~ 284g force, touch feeling: 170 ~ 397g force.

9. Folding strength test: After drying the silver paste and carbon ink line, the loop resistance should be measured first, then the line should be folded 180 degrees, and pressed with fingers for 2kg/2 seconds, then restored to the plane. So do it back and forth 5 times and measure its resistance. It increases the resistance after folding 5 times, and does not exceed 300% of the original resistance.

10, hardness test: with a H-class drawing pen, 45 degrees to the line to apply 1kg thrust, the line must not have conductive ink peeling or produce light.

11, life test: no elastic film each button contact conduction times, should be 1 million times. There are shrapnel and tactile conduction times, which should be 500,000 times.

12, loop resistance test: the resistance value should be no more than 100Ω, for the total length of the circuit is greater than 150cm and the special requirements of the loop resistance on the drawings. No breaks or short circuits are allowed.

13. Insulation resistance detection: In normal temperature and normal humidity environment, the insulation resistance of the conductor line is greater than 500MΩ (500VDC 1 minute). It should be no less than 20MΩ after high temperature and constant humidity test and salt spray test.

14. High temperature test: The membrane switch is subjected to 55±2°C. After 72 hours of high temperature, the appearance quality should be in accordance with the drawings. After recovering under normal atmospheric conditions for 2 hours, the measured insulation resistance value should meet the requirements.

15. Low temperature test: The membrane switch is subjected to -10±3 °C, and after 16 hours of low temperature action, it is restored under normal atmospheric conditions for 2 hours, and the water droplets on the surface are erased. The resistance value should meet the requirements.

16. Salt spray test: The membrane switch is subjected to a sodium chloride solution of 5% salt solution, and the temperature in the test space is 35±2°C, (the connector is sealed). After 72 hours of salt spray test, it recovers under normal atmospheric conditions for 2 hours. The insulation resistance should be in accordance with the regulations.

17. Constant damp heat test: The membrane switch is subjected to 40±2°C and the relative humidity is 93 (+2% –3%). After a constant wet heat test for 96 hours, it is restored under normal atmospheric conditions for 2 hours to measure the insulation resistance and circuit. The resistance and key strength should meet the requirements.

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