Receptor pad structure for chip carriers

Abstract

Receptor pad structures for chip carriers, and in particular, non-floating BLM C-4 receptor pads for organic chip carriers preferably utilizing eutectic solder. On the receptor pads of chip carriers, particularly in providing equal distributions of the solder so that all pad areas are equalized irrespective as the type and size of receptor pad configuration, there is a utilization of a solder mask constituted of an insulating material, and which incorporates specifically sized and shaped solder openings or windows wherein, in a particular instance, the C4 receptor pad is essentially at the intersection of a copper trace and the solder mask window. Pursuant to a particular aspect, the solder mask opening is of a polygonal configuration, whereas in other instances, as described hereinbelow, the C4 receptor pad design may be essentially of a socalled “band aid” or circular configuration in which a circular pad is located below and within a round solder mask opening or window. The circular pad extends within and beyond the solder mask window or opening through the intermediary of the copper trace, thereby enabling the formation of equal solder areas on all pads and eliminating the previously encountered BLM floating problem leading to potentially unreliable connections and resulting chip failures.