Interfacial Reactions in Sn-0.7wt.%Cu/Ni-V Couples at 250°C
Authors: Chen, Sinn-wen; Chen, Chih-chi
Source: Journal of Electronic Materials, Volume 36, Number 9, September 2007 , pp. 1121-1128(8)
Abstract:The Delco process is a major flip chip under-bump metallurgy process and its contact is soldered with the Ni-7wt.%V substrate; there are, however, only a few studies on the interfacial reactions between solders and Ni-V alloys. This study examines the interfacial reactions of the Sn-0.7wt.%Cu alloy with the Ni-7wt.%V, Ni-5wt.%V, and Ni-3wt.%V substrates at 250°C. It is found that the interfacial reactions between Sn-0.7wt.%Cu and Ni-V alloys are different from those between Sn-0.7wt.%Cu and pure Ni. In addition to the formation of the Cu6Sn5 phase, a new Sn-rich phase, denoted the Q phase, is found in the Ni-V substrate couples. Nucleation of the Ni3Sn4 phase is at a much earlier stage and the rates of consumption of Ni are much higher in Ni-V substrate couples than in Ni substrate couples. Knowledge of these different reactions is important for proper assessment of the flip chip products.
Document Type: Research Article
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Publication date: September 1, 2007