Relay welding process and cleaning process
1、 Coating flux
PCB type non plastic relay is easy to be polluted by flux. It is suggested to use anti flux or plastic relay to prevent flux gas from invading from the gap between the lead end and the base and the shell. If the anti flux relay is preheated and dried (100 ℃ for 1 minute), it can further prevent flux from invading.
2、 Welding process
When using flux coating or automatic welding, care should be taken not to damage the relay performance. Flux resistant relay or plastic encapsulated relay can be used for immersion welding or wave soldering process, but the maximum welding temperature and time should be controlled according to the selected relay.
a. Wave soldering: the recommended soldering temperature is 240 ℃～ 260 ℃, the time is about 5 seconds, and the best soldering temperature is 250 ℃. For other welding temperature and welding time (for example, higher solder temperature will shorten the tin dipping time), please contact our technical service support or confirm the welding quality.
b. Manual welding: the recommended welding temperature is 300 ℃ - 350 ℃, and the welding time is controlled within 2 seconds.
c. Cooling: the heating of relay caused by soldering process can be alleviated by cooling in process, so do not change the temperature suddenly, especially avoid cold shock to thermal relay.
Clean free flux shall be used for welding as far as possible, and integral cleaning of relay shall be avoided. Prevent the detergent from entering the relay and causing failure. It is forbidden to use ultrasonic cleaning to avoid contact cold welding, enameled wire breakage and other structural damage caused by ultrasonic energy. After cleaning and drying, ventilation should be carried out immediately to reduce the relay to room temperature.
Sometimes, in order to ensure the moisture resistance and high insulation of the circuit board, it is necessary to coat the circuit board with preservative. The soft adhesive without silicon should be selected. The coating process should avoid the negative pressure generated by the relay and the inhalation of preservative.