Influence of electroless Sn/Bi on Sn/Pb soldered joint strength
(Nanjing Research Institute of Electronics Technology Nanjing 210013 China)
Abstract: The solder joint strength of Pb/Sn soldering aluminum with electroless layer Sn/Bi and Cu was studied. The results show that the joint shear strength of electroless Sn/Bi on aluminum surface is lower than that of Cu. A Pb-riched region with porosity is formed in region of soldering fillet with electroless Sn/Bi. Both the electroless Sn/Bi layer and Pb-riched layer become thicker, which are the reasons why the shear strength of the solder joint with electroless Sn/Bi on aluminum surface is lower than that of electroless Cu, and the higher the thickness of the electroless Sn/Bi layer is, the lower the shear strength of solder joint is.
Key words: electroless layer； soldered joint； Sn/Pb； Sn/Bi； shear strength