A Comparison of Lock-in Thermography and Magnetic Current Imaging for Localizing Buried Short-Circuits

The relative effectiveness of lock-in thermography and magnetic current imaging for identifying defects in packaged ICs was studied by directly comparing results on the same three devices. One known (in-lab fabricated) and two unknown (field return) defects were studied in organic flip-chip and wirebond configurations. Both methods succeeded in identifying the defective area but significant differences were observed in the qualitative nature of the signals, XY localization resolution, and sensitivity. Depth estimates were obtained where possible which aided in localization.