Formation/growth behaviour, phase stability, and mechanical properties of interfacial Cu6Sn5 intermetallics influenced by micro-alloying in Pb-free solder joints, are of ongoing interest as this phase is crucial to the service reliability of solder joints. Our recent work has demonstrated that, after reflow, the homogeneously located micro-alloying elements of both Ni and Zn in interfacial (Cu,Ni)6(Sn,Zn)5 act to increase phase stability and prevent the undesirable polymorphic phase transformation of Cu6Sn5. This paper further investigates the influence of ageing on the phase stability of interfacial intermetallics containing Ni, Zn and Au. Phase transformations of hexagonal to monoclinic Cu6Sn5 driven by ageing, was suppressed by alloying Ni/Zn/Au, resulting in improvements in phase stability. The findings help to further understand the reliability of interfacial structures in micro-alloyed Pb-free solder joints.
All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry