The invention discloses an IGBT (Insulated Gate Bipolar Translator) 
welding process method, which comprises the following steps of high-temperature 
solder paste printing, IGBT and FRD (
Fast Recovery Diode) 
surface mounting, primary high-temperature 
welding, 
copper substrate printing, low-temperature 
solder paste printing, 
DBC (
Direct Bonding Copper) and bottom plate assembling and secondary low-temperature 
welding. According to the method, SnPbAg low-temperature 
solder paste is adopted for secondary welding, after the 
melting point of the solder paste is reached, secondary melting of 
soldering tin on a first 
backflow face is avoided, the phenomenon of deterioration of cavities is avoided, the yield of IGBT products is improved, SnAgCu is adopted as high-temperature solder paste, the 
melting point of the high-temperature solder paste is 217 DEG C, SnPbAg is adopted as low-temperature solder paste, the 
melting point of the low-temperature solder paste is 179 DEG C, the melting point is higher than the bearable limit temperature of a 
chip, the reliability of the products can be guaranteed, and the reliability of the products is improved. The low-temperature solder paste is used for secondary welding, so that 
tin beads and 
tin bridges can be reduced, the mold is easy to disassemble, product appearance failure caused by process problems is reduced, the low-temperature solder paste has excellent printability, the phenomena of missing, sinking and 
caking in the printing process can be eliminated, and the service life of the steel mesh is prolonged.