Deformation induced by thermal loading in a severe automotive environment, between an electronic ceramic substrate — bonded to an aluminum heatsink — and an adjacent nylon material, was investigated by numerical and experimental methods. The goal of this paper is to quantify the relative displacement of certain points of interest, where an aluminum wire bond exists. This displacement is caused by 1) coefficient of thermal expansion (CTE) mismatches of various parts of the assembly when temperature distribution is uniform, and 2) when temperature gradients exist in either steady-state or transient conditions due to thermal cycling (between +150°C and −40°C) as well as power cycling. ANSYS Workbench™ finite element analysis (FEA) software was used to model the system level deformation under various conditions. A unique, quick, and repeatable method of experimentally measuring displacement using a Differential Variable Reluctance Transducer (DVRT®) was utilized. The DVRT® and its signal conditioner provide an analog DC voltage output, which is proportional to linear displacement (resolution as fine as 1.5 micrometer). Error inherent to the DVRT® was adjusted by further testing using a modified sample of Invar. The numerical and experimental results showed good overall correlation.
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Analysis of Thermal Displacements Due to CTE Mismatches Using FEA Simulation and Experimental Validation With a Differential Variable Reluctance Transducer
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Asghari, TA, & Janas, J. "Analysis of Thermal Displacements Due to CTE Mismatches Using FEA Simulation and Experimental Validation With a Differential Variable Reluctance Transducer." Proceedings of the ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASME 2007 InterPACK Conference, Volume 2. Vancouver, British Columbia, Canada. July 8–12, 2007. pp. 843-848. ASME. https://doi.org/10.1115/IPACK2007-33217
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