GB/T 4937.201-2018 is for surface-mounted semiconductor devices that are sensitive to the combined effects of moisture and welding heat. The standard specifies its operation in detail to avoid damage caused by improper touch; clarifies the requirements of Encasement, and uses suitable protective materials to block moisture, etc.; stipulates clear signs to facilitate the identification of device characteristics and precautions; also explains the transportation link to ensure that the transportation conditions are suitable. Following this standard can reduce the influence of moisture and welding heat on such devices during operation, Encasement, marking and transportation, ensure the mass and performance of the device, and lay the foundation for subsequent applications.