TEM Observation of Interfacial Reaction Layers Formed Between Pb(Lead)-Free Sn-3.5Ag Solder and ENIG Plated Cu Substrate
The interfacial reaction between eutectic Sn-3.5Ag solder and ENIG substrate during reflow was investigated. During the reflow, the topmost Au layer dissolved into the molten solder, and the reaction layers of Ni3Sn4/Ni-Sn-P/Ni3P formed between Sn-Ag solder and Ni-P plating layer. After the reflow at 255 for 3 min, most of Ni3Sn4 intermetallic compound (IMC) spalled off the substrate. The formation of thick Ni3P and Ni-Sn-P layers was related to the direct reaction between solder and Ni-Sn-P layer by the IMC spalling.
Hyung Sun Kim, Yu Bao Li and Soo Wohn Lee
J. W. Yoon and S. B. Jung, "TEM Observation of Interfacial Reaction Layers Formed Between Pb(Lead)-Free Sn-3.5Ag Solder and ENIG Plated Cu Substrate", Materials Science Forum, Vols. 510-511, pp. 554-557, 2006