| abstract |
Lead-free solders containing 85-96 wt.% Tin (Sn) and 4-15 wt.% Indium (In) by weight and exemplary use thereof are disclosed. Sn-In solders undergo martensitic phase changes when cooled from reflow temperature to room temperature. As a result, the residual stress typically caused by solder deformation caused by relative movement between the bonded components is actually reduced. Typically, relative movement is due to mismatches in the coefficient of thermal expansion (CTE) between the bonded components. Exemplary uses disclosed include flip-chip assemblies and IC packages mounted on circuit boards, such as BGA packages.n n n Lead Free Solder, Martensitic, Reflow, Phase Change, Superplastic |