Method for applying solder bumps on contacting surface of e.g. wafer to produce wafer level package, involves spraying solder paste portions on pads by jet printing process, and melting portions to solder bumps in nitrogen atmosphere

摘要

The method involves spraying solder paste portions (3) on solder pads (4) by a jet printing process. The solder paste portions are melted to solder bumps in nitrogen atmosphere, where the solder bumps exhibits diameter of 0.3 mm. Movement of a wafer (1) or reconfigured wafer is produced on a circular path around a center of rotation via centrifuge. The wafer is warmed at temperature of about 25 degree, during movement of the wafer. Solder bumps are protruded from a contact surface (2) of the wafer in a perpendicular manner.