CHARACTERIZING THE TEMPERATURE-DEPENDENCE OF ELECTRONIC PACKAGING-MATERIAL PROPERTIES

A computer-controlled, temperature-dependent material characterization system has been developed for thermal deformation analysis in electro nic packaging applications, especially for printed wiring assembly war page study. For fiberglass-reinforced epoxy (FR-4 type) material, the Young's moduli decrease to as low as 20-30% of the room-temperature va lues, while the shear moduli decrease to as low as 60-70% of the room- temperature values. The electrical resistance strain gage technique wa s used in this research. The test results produced overestimated value s in property measurements, and this was shown in a case study. A nonc ontact strain measurement technique (laser extensometer) is now being used to measure these properties. Discrepancies of finite-element warp age predictions using different property values increase as the temper ature increases from the stress-free temperature.