Solder process optimization: Influence of heating and cooling rate on the thermo-mechanical stress generated in components

Optimisation of the reflow solder cycle is a critical task, in the sense that the consequences of poor process definition may affect the reliability of the assembly on the one side, as well as the industrial profitability on the other side. The present paper analysis the thermo-mechanical stress behavior of a typical electronic component under thermal profiles with heating and cooling rates varying from 0.15 to 3.0degC/s. The thermo-mechanical stress in the components is assessed by real-time measurements of the components surface topography (warpage) and deformation during temperature increase and decrease cycles typical for JEDEC type reflow profiles. The consequences for the solder process are discussed.