Nanoindentation of Lead Free Solders for Harsh Environments

Abstract

ABSTRACTTo better understand the factors governing the reliability of lead free solders during severe excursions in temperature, the hardness and elastic modulus of the micro-phases formed in a Sn-Ag-Cu/Cu solder joint were characterized using nanoindentation at temperatures from 25 to 175°C. The creep behaviour of the different micro-phases was also studied as function of temperature. The hardness and elastic modulus of Cu6Sn5, Cu3Sn had a weak dependence on temperature, while primary Sn, eutectic regions and electroplated Cu hardness and modulus were sensitive to temperature. Creep studies indicated that intermetallic were more creep resistant than softer phases that readily underwent creep, the type and rate of which was shown to be strongly temperature dependent.