Variable size capture pads for multilayer ceramic substrates and

Abstract

Capture pads of variable size are provided on the face of a multilayer ceramic substrate, to accommodate the actual shrinkage tolerance of the substrate at each capture pad position. For example, assuming a minimum shrinkage reference point is at the center of the substrate face, the capture pad size is relatively large adjacent the edges of the substrate face and relatively small adjacent the center of the substrate face. By sizing each capture pad based on the maximum positional variation at the particular capture pad position, higher contact density is obtainable than with known uniform size capture pads. The variable size capture pads may also be used at one or more rows of capture pads located along one or more edges of the substrate, for electrical connection to an edge connector. For example, assuming a minimum shrinkage reference point at the center of the row, the capture pads are relatively large adjacent the ends of the row of capture pads and are relatively small adjacent the center of the row. Edge connectors with variable spacing of edge connector contacts are also provided. Capacitive ground plane coupling to the variable size capture pads is made uniform by providing a uniform size ground plane region adjacent each capture pad, with the uniform size being smaller than the smallest capture pad. A high density microelectronic substrate is thereby obtained without degrading the performance of the substrate.