High-Accuracy Measurement on Thermal Displacement and Strain Distributions of Electronic Packaging

Abstract

The thermal deformation of electronic package, QFP (Quad Flat Package), was measured by phase-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 80 nm/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 result showed that the normal and shear strains concentrated in the packaging resins around the silicon chip, mount island, and lead frames.