A thermomechanical analysis of MCM-D substrate of polymer and metal multilayer

Abstract

A multichip module (MCM) substrate is an example of multilayer structure under thermal loading. In MCM-D substrate, various thin film technologies are used and the number of layers increases to meet the demands of electronic industry. This multilayer substrate has the properties which are not well taken care of in the usual thermal stress analysis: that is, (i) each layer experiences the different thermal history because the multilayers are made by the sequential buildup of the alternating layers of polymer dielectric and metal conductor films, (ii) a single film thickness cannot be assumed to be infinitesimal any more compared to the others, (iii) the polymer films seem to undergo the relaxation of stress In this study, the thermomechanical bowing was experimentally measured layer-by-layer during the sequential build-up of the alternating layers, and it is compared with the result of the thermomechanical stress analysis of the multilayer MCM-D substrate based on a model which takes into account the different thermal history of each layer and the effect of the film thickness.