Michel Rapeaux

Thermal Aging Study of Tin plating on Aluminum

This paper presents a thermal study of aluminum with tin plating deposited on Al using three different types of tin plating using various cyanide and non-cyanide processes. We determined the quality of plating before and after it was exposed to the temperature of 150degC in air for up to eight weeks using multiple testing techniques, such as adhesion test, thermal shock test, SEM techniques, EDS X-ray analysis, and thickness measurements. We determined that after aging test tin plating shows aging related cracks, voids and separation appearing at the plating interfaces although in different concentration and progression rates depending on plating technique. All types of plating demonstrated deteriorated plating adhesion. Accelerated thermal aging tests at 150degC discriminate plating types. Aged samples exhibit medium to poor adhesion characteristics, and these results are likely related to the plating process itself. At the origin of this behavior, we might suggest thermal- induced mechanisms including formation of intermetallics and diffusion, presence of impurities at the plating-bar interface, defect propagation and stress relaxation at the interface.