If NTC thermistor is poor high-temperature resistance and poor moisture-proof performance, may lead to product performance aging, short circuit, open circuit and other faults. If used in a short-circuit state, a strong current is generated when the voltage is applied, which may cause the NTC thermistor to heat up and cause the circuit board to burn out. The performances of high-temperature-resistance and moisture-proof NTC thermistor is much better than existing NTC thermistor, which can work for long periods of time in up to 250 ℃ and humid environments, and its mechanical strength is better than glass-encapsulated NTC thermistor.
High-temperature-resistance, moisture-proof NTC thermistor, is soldered welding lead on both sides of the NTC thermistor chip through high-temperature soldering tin, from inside to outside of the periphery of NTC thermistor chip and lead welding point are successively encapsulated the first sealing layer, the second sealing layer, the third sealing layer. The first sealing layer is high-temperature-resistance silicone layer, the second sealing layer is silicon resin layer, the third sealing layer is high-temperature-resistance silicone layer. In this manufacturing method, the high-temperature-resistance range of high-temperature soldering tin is 350~400℃; the high-temperature-resistance range of the first sealing layer is 260℃~320℃; the high-temperature-resistance range of the second sealing layer is 280℃~300℃, and the high-temperature-resistance range of the third sealing layer is 260℃~320℃.
The production process of high-temperature-resistance, moisture-proof NTC thermistor:
(1) First, the NTC thermistor chip is welded to two leads through high-temperature soldering tin;
(2) Sealing the first sealing layer on the periphery of the NTC thermistor chip and the lead welding point, that is, using high-temperature-resistance silicone for encapsulation;
(3) Encapsulating the second sealing layer in turn, that is, use silicone resin for encapsulation;
(4) The third sealing layer is encapsulated on the surface of the head of the second sealing layer, that is, use high-temperature-resistance silicone for encapsulation;
(5) Doing the resistivity test of the finished NTC thermistor.
The manufacture of high-temperature-resistance and moisture-proof NTC thermistor can effectively improve the pass rate of finished products, save production costs and prolong their operating life.