1. Material inspection

 

Panels, substrates, silver paste, carbon ink, spacers, adhesives, adhesives, reinforcing plates, and insulation printing should comply with the drawings.

 

2. Shape comparison

 

The shape, conductor circuit, insulation treatment, liner combination, etc. should comply with the drawings. Or customers provide prototypes to us.

 

3. Check the dimensions

 

The allowable range of tolerances not noted in the drawings must comply with the standards, and the rest must comply with the drawings.

 

4. Check the appearance

 

There should be no obvious defects on the panel, such as missing strokes on characters, stains, light-transmitting spots, deinking, color spots, scratches, glue overflow and residual glue on transparent windows, etc. There is no misalignment in printing registration, combination of upper and lower key positions, combination of lines and key sheets, panel and keys, bubbles and substrate at the panel keys. The size of stamping burrs and extrusion bending should not be larger than 0.2mm. The position should be towards the side without conductors.

 

5. Check the color

 

Use visual inspection and compare with prototypes or color cards to see if there is any color difference. If the color requirements are particularly strict, use a colorimeter to compare.

 

6. Ink adhesion

 

The ink is attached with transparent tape and pressed by hand to ensure that there are no bubbles. Then peel it off quickly after 10 seconds. There must be no ink falling. After the insulating ink is dry, place the ink surfaces against each other and press hard for 24 hours to ensure that the insulating surfaces do not stick to each other. Use pressure-sensitive tape to attach it by hand without bubbles for 1 minute. Then peel it off quickly without any ink falling off.

 

7. Peel strength test

 

The peel strength of the glue should not be less than 8N/25mm.

 

8. Bubble detection

 

Make equal height and balanced strength. The flat type has a force of 57-284g, and the tactile force is 170-397g.

 

9. Folding strength test

 

After drying the silver paste and carbon ink circuits, the loop resistance should be measured first. Then the circuits should be folded 180 degrees and pressed with fingers for 2kg for 2 seconds, then return it to a flat surface. Repeat it 5 times, and then measure the resistance. The increased resistance after folding 5 times does not exceed 300% of the original resistance.

 

10. Hardness test

 

Use an H-level drawing pen tip to apply 1kg thrust to the line at 45 degrees. There should be no conductive ink peeling off or light transmission on the circuit.

 

11. Life test

 

For membrane switches without shrapnels, the contact and conduction times for each button should be more than 1 million times. For those with shrapnels, the tactile conduction times should be more than 500000 times.

 

12. Loop resistance measurement

 

The resistance should not be greater than 100Ω. For the total length of the loop greater than 150cm and special requirements, the loop resistance is separately specified on the drawing. No interruption or short circuit is allowed.

 

13. Insulation resistance measurement

 

In a normal temperature and humidity environment, the insulation resistance of the conductor circuit is greater than 500MΩ (500VDC for 1 minute). It should not be less than 20MΩ after high temperature and constant humidity tests and salt spray tests.

 

14. High temperature test

 

After the membrane switch is subjected to high temperature of 55±2℃ for 72 hours, the appearance quality shall be checked to comply with the drawings. After recovery for 2 hours under normal atmospheric conditions, the measured insulation resistance value should comply with regulations.

 

15. Low temperature test

 

After the membrane switch withstands a low temperature of -10±3°C for 16 hours, it is restored under normal atmospheric conditions for 2 hours. Wipe off the water droplets on the surface. The resistance should comply with the regulations.

 

16. 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°C (connector seal). After a 72-hour salt spray test, it is restored for 2 hours under normal atmospheric conditions. Insulation resistance should comply with regulations.

 

17. Constant humidity and heat test

 

After the membrane switch is subjected to a constant humidity and heat test of 40±2℃, a relative humidity of 93 (+2% –3%), which lasts for 96 hours, it is restored to normal atmospheric conditions for 2 hours, and the insulation resistance and circuit are measured. Resistance and key strength should comply with regulations.