Effects of Ni thickness and reflow times on interfacial reactions between Ni/Cu under-bump metallization and eutectic Sn-Pb solder in flip-chip technology
Authors: Huang, Chien-Sheng; Duh, Jenq-Gong; Chen, Yen-Ming; Wang, Jyh-Hwa
Source: Journal of Electronic Materials, Volume 32, Number 2, February 2003 , pp. 89-94(6)
Abstract:Flip-chip interconnection technology plays a key role in today’s electronics packaging. Understanding the interfacial reactions between the solder and under-bump metallization (UBM) is, thus, essential. In this study, different thicknesses of electroplated Ni were used to evaluate the phase transformation between Ni/Cu under-bump metallurgy and eutectic Sn-Pb solder in the 63Sn-37Pb/Ni/Cu/Ti/Si3N4/Si multilayer structure for the flip-chip technology. Interfacial reaction products varied with reflow times. After the first reflow, layered (Ni1−x,Cux)3Sn4 was found between solder and Ni. However, there were two interfacial reaction products formed between solders and the UBM after three or more times reflow. The layered (Ni1−x,Cux)3Sn4 was next to the Ni/Cu UBM. The islandlike (Cu1−y,Niy)6Sn5 intermetallic compound (IMC) could be related to the Ni thickness and reflow times. In addition, the influence of Cu contents on phase transformation during reflow was also studied.
Document Type: Research Article
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Publication date: February 1, 2003