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What are the steps for inspecting thin film switches?

Release time:

2023-06-06 08:46

What are the steps for inspecting thin film switches?
1. Material inspection: The panel, substrate, silver paste, carbon ink, spacer, adhesive, adhesive, reinforcing plate, and insulation printing should comply with the requirements of the drawing.
2. Shape comparison: The appearance, conductor circuit, insulation treatment, lining plate combination, etc. should comply with the drawings or provide physical samples.
3. Check size: The allowable range of tolerance not indicated on the drawing should comply with the standard, and the rest should comply with the drawing regulations.
4. Appearance inspection: The panel should not have obvious defects, such as missing strokes in characters; Stains and transparent spots; Deinking, stains, scratches; Transparent window overflow, residue, etc. There is no deviation phenomenon, such as printing overprint, combination of upper and lower line key positions, combination of line and key piece, panel and key combination, and bubbling and substrate at panel key positions. The size of stamping burrs and bending should not exceed 0.2mm, and the position should be towards the side without conductors.
5. Check the color: Use visual inspection to compare with the sample or color card to see if there is any color difference. If the color requirements are particularly strict, use a color difference meter to compare.
6. Adhesion inspection of ink: The ink should be manually pressed with transparent tape to ensure no bubbles for 10 seconds, and then quickly peeled off without any ink falling. After the insulation ink is dry, the ink surfaces should be pressed against each other for 24 hours to ensure that the insulation surfaces do not stick to each other. Apply pressure-sensitive tape and press for 1 minute without bubbles, then peel off quickly without any ink peeling off.
7. Peel strength test: The peel strength of the adhesive should not be less than 8N/25mm.
8. Bubble detection: Equal height and balanced force. Flat type: 57-284g force, tactile sensation: 170-397g force.
9. Bending strength test: the circuit resistance of silver paste and carbon ink lines that have been dried shall be measured first, and then 180 degree folding shall be made on the lines, and 2kg/2s of pressure shall be applied with fingers, then they shall be restored to the plane, and the resistance shall be measured after 5 times of back and forth. The increased resistance after folding 5 times does not exceed 300% of the original resistance.
10. Hardness testing: Use an H-level drawing pen to apply 1kg of thrust to the circuit at 45 degrees, and the circuit must not have conductive ink peeling off or produce light transmission.
11. Life test: The number of times each button contacts and conducts without shrapnel should be over 1 million times. The number of times there are shrapnel and tactile conduction should be within 500000.
12. Circuit resistance detection: The resistance value should not exceed 100 Ω. For circuits with a total length greater than 150cm and special requirements, the circuit resistance should be specified separately on the drawing. No interruptions or short circuits are allowed.
13. Insulation resistance detection: In a normal temperature and humidity environment, the insulation resistance of the conductor line is greater than 500M Ω (500VDC1 minutes). After high temperature and constant humidity tests and salt spray tests, it should not be less than 20M Ω.
14. High temperature test: After withstanding a high temperature of 55 ± 2 ℃ for 72 hours, the appearance quality of the thin film switch should comply with the requirements of the drawing. After recovering under normal atmospheric conditions for 2 hours, the measured insulation resistance value should comply with regulations.
15. Low temperature test: After enduring a low temperature action of -10 ± 3 ℃ for 16 hours, the thin film switch is restored for 2 hours under normal atmospheric conditions, and the surface water droplets are removed. The resistance value should comply with