Thermal Strain Analysis of SOJ Electronic Package by Phase-Shifting Moiré Interferometry

Abstract

The thermal deformations of electronic package, SOJ (Small Outline J-Leaded Package), were measured by phasc-shifting moiré interferometry. This method was developed using a wedge-glass-plate as a phase shifter to obtain the displacement fields with the sensitivity of 100nm/line. Digital image processing was also introduced to determine the strain distributions quantitatively. Thermal loading was applied by heating the package from room temperature 25°C to an elevated temperature 100°C. The thermal strains were then investigated with the two packages before and after mounted on PWB (Printed Wiring Board). The results showed that the strains increased about 50% after mounted on the PWB.