Self Excite Reflowing and Interfacial Reaction of SnPb Eutectic Solder on BGA Pad Under Alternate Electromagnetic Radiation
交变电磁辐射下SnPb共晶钎料在BGA焊盘上的自发热重熔及界面反应

SnPb eutectic solder reflow on BGA pad metallized with Au/Ni to form solder bump with induction self excite heat under alternate electromagnetic radiation is performed, and impacts of induction self excite heat and solid state aging on interfacial reaction between SnPb eutectic solder and Au/Ni metallization are investigated. Experimental results show that Au layer disappeared completely from metallization layer under first reflow by alternate electromagnetic radiation and formed needle shape AuSn4 scattered in SnPb eutectic solder, it is the same as that re-flowed by infrared heat. Under second reflow by alternate electromagnetic radiation the AuSn4 is concentrated at interface between the solder and the pad due to effect of solid metal granule conglomeration in liquid metal under electromagnetic field. The needle shape AuSn4 is evolved into layer shape (AuxNi1-x)Sn4 during solid state aging, it restrains growth of Ni3Sn4 at the interface.