An apparatus comprising an insulating substrate having first and second surfaces and a plurality of metal-filled vias extending from the first to the second surface. The first and second surfaces have contact pads, each one comprising a connector stack to at least one of the vias. The stack comprises a seed metal layer in contact with the via metal capable of providing an adhesive and conductive layer for electroplating on its surface, a first electroplated support layer secured to the seed metal layer, a second electroplated support layer, and at least one reflow metal bonding layer on the second support layer. The electrolytic plating process produces support layers substantially pure (at least 99.0%), free of unwanted additives such as phosphorus or boron, and exhibiting closely controlled grain sizes. Reflow metal connectors provide attachment to chip contact pads and external parts.