Wetting Behavior Between Electroless Nickel and Sn-Zn-Al Solder

• Main Authors: Wang, Yu-Chien, 王育謙
• Other Authors: Kwang-Lung Lin
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/38467090652350630105

碩士 === 國立成功大學 === 材料科學(工程)學系 === 85 === This study is to investigate the wetting behavior between the copper substrate which was deposited with electroless nickel as a diffusion barrier for the ternary eutectic Sn-Zn-Al solder. The copper plating was deposited on the electroless nickel to improve the wetting behavior. The wetting experiment was conducted with the wetting balance for the two systems of Cu/Ni- P and Cu/Ni-P/Cu Plating at various temperature and fluxes. The interfacial reactions between the solder and these two systems after heat treatment were examined with Scanning Electron Microscope and with X-ray diffraction. The contact angle investigation was applied for estimating the temperature needed for the occurrence of solder wetting without flux. The experimental results for the Ni-P/solder system showed that good wetting was achieved only at high temperature (above 350℃) and with high concentration of active fluxes (above 5g/l DMAHCl). The solder layer contains pores. The crystallization of electroless nickel layer and less active fluxes could not improve wetting. The experiment results of the Ni-P/Cu system showed that the surface coverage of solder on Ni-P/Cu was more than that on Ni-P at low concentration of fluxes (above 2.5g/l DMAHCl), although it also showed partial wetting. The results of the interfacial elemental line - scanning showed that the Zn atom diffused to the interface between the solder and copper. The X-ray showed that the interaction between solder and Ni-P/Cu resulted in the formation of g-Cu5Zn8 compound which further avoids the tin diffusing into the layer of copper plating.