Patent ID: 8884448

Claim:
A microelectronic assembly, comprising: a substrate having a first surface, a plurality of first conductive pads exposed on the first surface and defining a face, and a plurality of first metal posts, each defining a base connected to a respective one of the first conductive pads and having an outer periphery, each of the first metal posts extending along a side wall from the base to an end remote from a respective one of the first conductive pads, wherein the side walls of the first metal posts taper continuously inward from the bases to the ends thereof, and wherein the first metal posts are frustoconical throughout the entirety of first heights thereof; a plurality of copper spacers surrounding the first metal posts on the outer periphery of the first surface of the substrate; a solder mask layer, having an inner surface, an outer surface, and a plurality of openings, the inner surface extending along the first surface of the substrate, the outer surface being remote from the substrate, and respective ones of the first metal posts projecting through the openings, the solder mask layer contacting at least the outside peripheries of the first metal posts; a plurality of fusible metal masses contacting the ends of at least some of first metal posts and extending along the continuously tapered side walls of the first metal posts towards the outer surface of the solder mask layer; and a microelectronic element carried on the substrate and electronically connected to at least some of the first conductive pads.