2-DIMENSIONAL THERMAL-STRESS ANALYSIS OF SURFACE-MOUNT JOINTS UNDER UNIFORM TEMPERATURE-CHANGE

This study deals with the thermal stress in a surface mount joint unde r uniform temperature change, where an upper element is mounted on a s ubstrate and is adhesively bonded/soldered near both ends. The analyti cal approach is developed mainly in the case of a plane strain state a nd general solutions for the thermal stress and the strain distributio ns in the joint are derived using a two-dimensional theory of elastici ty. It is shown by numerical calculations that the thermal stress is s ingular at both edges of the interfaces between the upper element and the adhesive, and between the substrate material and the adhesive. Max imum principal thermal stresses are examined in order to predict the f racture initiation point in different types of surface mount joints. I n the experiments, the thermal stress distribution in an adhesive laye r is measured using photoelasticity. In comparisons between the analyt ical results and the experimental ones, fairly good agreement is shown .