Moiré interferometry was used to analyze the thermal deformation of four flip-chip devices mounted on FR-4 substrate and a new multi-layer substrate, with and without underfill. Thermal loading was applied by cooling the devices from 100 °C to room temperature (25 °C). The effects of underfill and the low-CTE (coefficient of thermal expansion) substrate on thermal deformation were investigated. The experimental results showed that the underfill curved in a manner similar to the silicon chip. For the flip-chip devices mounted on the multi-layer substrate, the CTE mismatch between the silicon chip and substrate was reduced, and bending deformation decreased. Of the four flip-chip devices studied, the underfilled flip-chip device mounted on the multi-layer substrate had the least deformed solder balls.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Safety, Risk, Reliability and Quality
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Electrical and Electronic Engineering