A systems approach to reduce processing and materials induced warpage in large single ply PCB cores

The objective of this research endeavor was to gain a fundamental understanding of the warpage in printed circuit board (PCB) cores. The important materials and process related parameters that impact the problem were studied through designed experiments. Experimental and analytical studies based on Finite Element Analysis (FEA) were performed to investigate the residual deformation, dimensional stability and warpage in a variety of commonly used composite substrates. Experimental values of the substrate thermomechanical and thermoelastic properties were used as inputs to the analytical model to predict the warpage in single ply, thin but large PCB cores. In effect, a comprehensive insight into the effect of processing parameters and material properties was obtained by comparing the experimental data with the analytical predictions.; The research endeavor would facilitate the PCB fabrication industry's attempt one step further towards the reduction, if not elimination, of the curling/warpage phenomenon in thin cores. Reduced warpage will enhance yields and significantly reduce scrap caused due to a variety of reasons. Some of these reasons include interplanar off-registration, broken circuits and damage that results from poor handling, to name a few. Results from the study may be used as justification tools for altering materials, processes and if required, production equipment to reduce scrap.; Although warpage analysis and effect of processing parameters and materials have been reported for multilayered PCBs in the past, no studies have been conducted in regards to individual cores. This research is unique in the sense that it investigates thin, single ply, large individual cores. The overall warpage in the PCBs is an effect of the combination of warpage of the individual cores, among other factors, and hence it is necessary to understand the same. The dimensional stability results from this study will also help in enhancing the accuracy of the relatively inflexible compensation rules and models that are currently being used. (Abstract shortened by UMI.)...