Thermal Deformation Analysis of Flip-Chip Devices by Moire Interferometry

Moire interferometry technique was adopted to analyze thermal deformations of four kinds of flip-chip devices mounted on FR-4 substrate and multi-layer substrate, with and without underfill. A thermal loading was applied by heating the devices from room temperature 25°C to an elevated temperature 100°C. The experimental results showed that the underfill gave similar curvatures of silicon chip and the substrate. In the flip-chip devices mounted on the multi-layer substrate, thermal expansion coefficient mismatch between the chip and substrate was reduced, and bending deformations were decreased. The deformation of solder balls in the underfilled flip-chip device mounted on the multi-layer substrate was the least in the four kinds of flip-chip devices.