An Engineering Approach to Thermal‐stress Analysis in SMT Applications

Abstract

This paper introduces thermal‐stress analysis methods which follow electrical engineering procedures. The spring constant or c‐value is found to be related to the electrical impedance, combining dimensions and material characteristics in a performance parameter which simplifies calculations. Voltage is used to represent thermal deformation, and thermal forces are modelled as currents. Relationships equivalent to Ohm's Law are applied to calculate thermal stresses in leads or traces of surface‐mount assemblies. The thermal performance of laminates, e.g., thermal expansion coefficients of interconnect boards with a restraining core, and the thermal stresses in the bonded layers, are derived from the analysis of an electrical network which represents the composite structure. The method provides visual concepts which facilitate a first‐order solution of engineering problems related to thermal stress.

Citation

Riemer, D.E. (1989), "An Engineering Approach to Thermal‐stress Analysis in SMT Applications", Soldering & Surface Mount Technology, Vol. 1 No. 3, pp. 11-20. https://doi.org/10.1108/eb037686