GB/T 4937.20 - 2018 Focus semiconductor plastic seal surface mount devices. This standard specifies the method of testing the performance of such devices under the combined influence of humidity and welding heat. Specify the applicable device type, and specify the temperature and Humidity conditions of simulated humid environment, the application method of welding heat and equipment requirements. Through a standardized test process, evaluate the ability of the device to resist moisture erosion and withstand welding high temperature. This standard provides a key basis for semiconductor manufacturers to control the mass of products and electronic equipment manufacturers to select devices, ensure that the device maintains stable performance in complex environments and welding processes, and ensure the Reliability and service life of electronic equipment.