Resolving displacement field of solder ball in flip-chip package by both phase shifting moire interferometry and FEM modeling

In this paper, phase shifting moire interferometry was used to resolve the deformation field of solder balls in a flip-chip package under thermal loading condition. A nanoscale deformation field of the outmost solder ball was obtained by using the proposed phase shifting technique associated with the corresponding image processing software. In addition, a nonlinear finite element technique, in which the viscoelastic material properties of underfill and the viscoplastic material properties of solder balls were considered was also adapted to simulate the global displacement field - the whole cross-section of the flip-chip package and the local displacement field - the whole cross-section of one solder ball in the flip-chip package. By comparing the predicted deformation values of the flip-chip package obtained from the finite element analysis with the test data obtained from the laser moire interferometry technique, good agreement is obtained. In particular, the nanoscale displacement contours of the solder ball both in x and y directions obtained from the phase shifting technique show much more similar distribution patterns compared with those modeled by the finite element method