Real-time warpage measurement of electronic components with variable sensitivity

Far infra-red Fizeau interferometry and shadow moire with enhanced sensitivity are described as tools for warpage measurement of electronics devices. The methods are implemented by developing a compact apparatus that combines the two methods to provide a capability of thermally-induced warpage measurement with a variable sensitivity ranging from 2.5 /spl mu/m to 100 /spl mu/m. The apparatus is based on a computer controlled environmental chamber, which allows real-time measurement during thermal cycling. Selected applications of PBGA packages are presented to demonstrate its capability. The technique offers a unique capability of accurate documentation of warpage, which leads to precise assessment of package performance and thus helps optimize package reliability and manufacturing process at the early stage of product development.