Thermally-induced failure is a major reliability issue for electronic packaging. Due to the highly nonlinear behaviors and thermal mismatch of packaging materials, an electronic package exhibits uneven thermal deformation in the whole temperature range during thermal cycling. This behavior will affect the buildup of thermal strain/stress within the package, which may affect the reliability of the package. Therefore, a real-time method is needed to monitor the thermal deformation of packages during the thermal cycling. In this study, a real-time moire´ interferometry technique coupled with a thermal vacuum chamber is used to monitor the thermal deformation of a plastic package. A grating is transferred onto the cross section of the sample at room temperature. The fringe patterns are recorded by a CCD camera system and are compared with the displacement contours obtained by nonlinear finite element simulation. High temperature moire´ results up to 200°C are reported here. The comparison between the moire´ fringe patterns and finite element results shows a good agreement. The results also show that the real-time moire´ interferometry technique is an effective way to monitor the thermal deformation of electronic packaging and is a powerful validation method for finite element analysis.
Health Monitoring for Electronic Package Using a Simple Moiré Interferometry
