combined thermodynamic-kinetic analysis of the interfacial reactions between ni metallization and various lead-free solders结合thermodynamic-kinetic分析之间的界面反应镍金属化和各种无铅焊料.pdf

Materials 2009, 2, 1796-1834; doi:10.3390/ma2041796 OPEN ACCESS materials ISSN 1996-1944 /journal/materials Review Combined Thermodynamic-Kinetic Analysis of the Interfacial Reactions between Ni Metallization and Various Lead-Free Solders Tomi Laurila * and Vesa Vuorinen Electronics Integration and Reliability, Helsinki University of Technology, P.O.Box 3340, FIN-02015 TKK Espoo, Finland; E-Mail: vesa.vuorinen@tkk.fi (V.V.) * Author to whom correspondence should be addressed; E-Mail: tomi.laurila@tkk.fi; Tel.: +358-9-451578. Received: 19 October 2009; in revised form: 6 November 2009 / Accepted: 11 November 2009 / Published: 11 November 2009 Abstract In this paper we will demonstrate how a thermodynamic-kinetic method can be utilized to rationalize a wide range of interfacial phenomena between Sn-based lead-free solders and Ni metallizations. First, the effect of P on the interfacial reactions, and thus on the reliability, between Sn-based solders and electroless Ni/immersion Au (ENIG) metallizations, will be discussed. Next, the effect of small amounts of Cu in Sn-based solders on the intermetallic compound (IMC), which forms first on top of Ni metallization, will be covered. With the help of thermodynamic arguments a so called critical Cu concentration for the formation of (Cu,Ni)6Sn5 can be determined as a function of temperature. Then the important phenomenon of redeposition of (Au,Ni)Sn layer on top of