A MODELING TOOL FOR THE THERMAL OPTIMIZATION OF THE REFLOW SOLDERING OF PRINTED-CIRCUIT ASSEMBLIES

Thermal history variation within printed circuit assemblies (PCAs) dur ing reflow soldering is considered one of the main drivers for manufac turing defects. It is recognised that predictive tools could be used t o identify the temperature variations that arise during the reflow pro cess and, in conjunction with experimentally derived data, determine t heir impact on manufacturing quality. A predictive model would also be useful to a designer for rearranging component placement for thermal mass distribution, hence enabling the optimisation of the design for m anufacture prior to final design commitment. Likewise, such a predicti ve tool could be utilised for off-line optimisation of reflow oven pro files and in the design of more thermally efficient production equipme nt. This paper describes the development of representative process mod els of the reflow soldering of PCAs and outlines some of the more impo rtant parameters to consider for accurate simulation of the reflow pro cess. Furthermore, the utilisation of the predictive model is presente d as a tool for a number of end uses applicable to different applicati on domains, namely: process configuration for any given PCA; selection of the most appropriate process and as a product design or verificati on tool to improve thermal mass distribution and hence temperature his tory during processing. (C) 1998 Elsevier Science B.V. All rights rese rved.