The Interfacial Reaction between Liquid Sn-Ag Solder and Electroless Nickel-Phosphorous Deposit

• Main Authors: Pei-ShanHsieh, 謝佩珊
• Other Authors: Kwang-Lung Lin
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/92987538844660830797

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 98 === This research investigated the interfacial reaction between liquid Sn-3Ag solder and electroless nickel with 7 wt.% phosphorous. The wettability between Sn-Ag solder and electroless nickel was investigated with wetting balance. After the wettability test, the interfacial reaction and the growth kinetics of the IMCs were investigated and discussed. The result of wettability test revealed that the wetting behavior occurred between the liquid Sn-Ag solder and electroless nickel deposit at 250 oC. The wetting time at 270 oC was smaller than 1 second and demonstrated a better wettability. After the wettability test, the IMCs, Ni3Sn4 and Ni3P formed at the interface between the Sn-Ag solder and electroless nickel. When the test was processed at 250 oC, there were Ni-Sn-P layer formed between Ni3Sn4 and Ni3P after reaction for 30 seconds. The result of TEM analysis on the 5 second reaction specimen indicates that Sn atoms diffused into the interface between Ni3Sn4 and Ni3P to form a Ni-Sn-P ternary layer. It formed Ni3SnP phase in the region near Ni3P layer. When the test was processed at 270 oC, the diffusion rate of Ni, Sn atoms increased so that the P-rich layer might include Ni3P and other Ni-P compounds. Because of the compositions of IMCs were so close that the IMC layers could not be clearly distinguished. With the increasing reaction time, the Kirkendall voids appeared in the P-rich layer gradually. In the interfacial reaction between the liquid Sn-Ag solder and electroless nickel, the thickness of Ni3Sn4 did not significantly change with the reaction time. The reaction at 250 oC was diffusion controlled, while it becomes a mixed mode at 270 oC.