Familiarity with the methods for detecting various indicators of patch touch switches can help us select better quality patch touch switches. So, how to test the various indicators of SMD touch switches? Let's learn about the testing methods for SMD touch switches, including force, voltage resistance, stroke, solderability, insulation resistance, welding heat resistance, pin strength, appearance size, functional action, and contact resistance.

1、 Detect the pressing force of the patch touch switch

Apply the static load evenly in the direction of the light touch switch action at the center of the top end face of the SMT light touch switch handle, and measure twice, taking the average value. The measurement error should not exceed 15%. The press force of the light touch switch should be within the range specified in the component specification

2、 Test the voltage resistance of the patch touch switch

Apply a test voltage of AC250V (50Hz effective value) to adjacent but not connected contacts of the switch, as well as between contacts and other metal parts, and maintain it for 1 minute. During the test, there should be no breakdown, flashover, damage, flashing, and other phenomena, and the leakage current should not exceed 0.5mA

3、 Detect the travel of the patch touch switch

In the center of the top end face of the SMD touch switch handle, evenly apply the maximum allowable press force according to the action direction of the touch switch, measure the travel with Vernier scale, and the measurement error is not more than 15%. The travel of the touch switch shall be within the range specified in the component specification.

4、 Test the solderability of the patch touch switch

After immersing the welding area in flux, immerse it along the axis in a molten solder bath of Sn96.5 Ag 3Cu0.5 (RoHS material) at 240~245 ℃ and Sn63pb37 (non RoHS material) at 235 ± 5 ℃ for 2-3 seconds. The body should be 1.5mm away from the molten solder, and then observe with a 3-10 times magnifying glass. The immersed part should be bright and smooth with tin, and only a small amount of dispersed defects such as non wetting or weak wetting of pinholes are allowed, and these defects do not appear in the same position

5、 Detect the insulation resistance of the patch touch switch

Apply a voltage of DC250 ± 15V between adjacent but not connected contacts of the switch and between the contacts and other metal parts, and the measurement error should not exceed 10%. The insulation resistance should be greater than 100M Ω

6、 Testing the welding heat resistance of patch touch switches

After immersing the sample pins in flux, immerse them along the axis direction in a molten solder bath of Sn96.5 Ag 3Cu0.5 (RoHS material) at 265 ± 5 ℃ and Sn63pb37 (non RoHS material) at 260 ± 5 ℃ for 5 ± 0.5s, with the body located 1.5mm away from the molten solder. The switch should be able to withstand the welding heat resistance test. After the test, the switch should be able to operate under normal conditions for 30 minutes, the circuit conversion should be normal, the pins should be free of mechanical damage, and the appearance should not show any significant changes

7、 Detect the strength of the patch touch switch pins

Take one pin of the switch and place the sample in the normal installation position. Apply a tensile force of 9.8N along the axial direction of the pin for 10 ± 1 S. After the test, the pin should not fall off or be damaged, and the switch should be able to operate.

8、 Check the appearance size of the patch touch switch

The components of the SMD touch switch are well processed, and the surface is free of rust, oil stains, and other visible damage; The pins are well electroplated, without rust, oxidation, breakage, or bending; The button part should be smooth, free of burrs, protrusions, and firmly connected to the body without looseness; The number or letter identification on the surface of the switch is clear and complete. The structure, installation dimensions, and overall dimensions of the switch should comply with the requirements of the component specifications, with a tolerance of ± 0.2mm for the switch size.

9、 Detect the action of the patch touch switch function

By using the rated voltage and rated current in accordance with the specifications, the circuit can be checked for continuity through indicator lights, or by using contact resistance testing methods. The on-off of the switch should be accurate and clear, the operation cycle of the switch should be smooth, without jamming, and the circuit conversion should be normal.

10、 Check the contact resistance of the patch touch switch

Measure the resistance value of the switch contact when it is connected using a milliohmmeter; When there is a dispute, add 20mV DC (open circuit electromotive force of the test circuit) and 100mA according to the national standard, measure the voltage drop at the lead out end, and calculate the contact resistance. The requirement for a light touch switch is ≤ 0.03 Ω