Abstract: Effects of different soldering-ball process（ including paste soldering and flux soldering） on the quality of converting lead-free BGA to tin-lead device were studied. The X-ray inspection results show that the soldered balls made of paste soldering and flux soldering have a regular and homogeneous shape. The microstructure analyses results show that the thickness of intermetallic compounds layer between Cu-pad and soldered ball using flux soldering is 1. 81 μm,which is 49% higher than that of paste soldering. The mechanical properties test results indicate that the shear force of the soldered joint by paste soldering and flux soldering are 11. 86 N and 11. 40 N,respectively. Paste soldering is recommended for the soldering-ball process of avionics product.