Materials challenges in interconnection: Trade-offs for rapid deployment

This article addresses the subtle changes necessary to achieve a margin aga inst an intrinsic failure mechanism in a highly time-constrained developmen t would. The problem of a coefficient of thermal expansion mismatch between a liquid crystal polymer connector and a FR4 substrate was exacerbated by the size, dimensions, and ball-grid array attachment for such a connector. By carefully controlling the solder-mask wall profile, opening, and overhan g, if was possible to avoid the time- and resource-consuming option of chan ging the connector materials.