Study on Induction Spontaneous Heating Reflow

The focus of this study was on discussing the novel reflow method ISHR (Induction spontaneous heat reflow) used for high-density area array packaging and assembly. Multi-layer under bump metallization (UBM) and Sn3.5Ag lead-free solder ball were laid in the high frequency electromagnetic field. Because of the induction heating, solder balls melted and spread onto the UBM to form solder bumps. The solder bumps could be formed within 2 seconds through this method; meanwhile, the infrared temperature measurement results showed that the rosin substrate temperature was lower. The shear test indicated that the solder bumps made by ISHR can satisfy the mechanical requirement. Finally, the feasibility experiment was performed to demonstrate the application feasibility of this ISHR technology. Through all these experiments, conclusion can be made that the ISHR as a novel reflow method can be applied in microelectronics packaging.