OBSERVING REAL-TIME THERMAL DEFORMATIONS IN ELECTRONIC PACKAGING

In recent years, the method has been used extensively in the electronics industry to determine thermal strains—strains caused by temperature changes—in microelectronics devices [1-17]. In the early papers on real-time observation [35], convection heating was used but the applications were limited to specimens with a simple geometry. The applicability of the method was extended to specimens with complex geometry by Guo et al. [6,7]. In the technique used in Refs. 6 and 7, called bithermal loading [2], only one elevated temperature condition could be investigated per test. Numerous applications of bithermal loading can be found in literature. The bithermal loading approach was extended later to document inelastic deformations accumulated during thermal cycles [14]. The real-time observation was also extended for specimens with more complex geometry [16], but the heating rate and the range of temperature were limited.