Shadow moiré interferometry with a phase-stepping technique applied to thermal warpage measurement of modern electronic packages

Thermally induced warpage of electronic substrates is a big concern in the manufacturing process. Electronic package miniaturization has led to wide usage of BGAs (ball grid arrays) and other surface mounted technologies that require a greater flatness for the chip carrier than the older through-hole connection techniques. The ability to evaluate the substrate behaviour as a function of temperature is particularly important to the manufacturing engineers.