Void-effect modeling of flip-chip encapsulation on ceramic substrate

A detailed numerical and experimental study of the thermal-mechanical stress and strain in the C4 solder bumps of a flip chip ceramic chip carrier has been completed. The numerical model used was based upon the finite element method. The model simulated accelerated thermal cycling (ATC) from 0/spl deg/C to 100/spl deg/C. Several parametric studies were conducted, including the effects of chip size, micro-encapsulation, and the effect of the presence of voids in the micro-encapsulant. It was notably found that the presence of voids in the encapsulant does not significantly increase the stress/strain in the C4s, with the exception of very large voids and voids at or near the edge of the chip.