Flip chip assembly and process with sintering material on metal bumps

A method is disclosed of fabricating a microelectronic package comprising a substrate overlying the front face of a microelectronic element. A plurality of metal bumps project from conductive elements of the substrate towards the microelectronic element, the metal bumps having first ends extending from the conductive elements, second ends remote from the conductive elements, and lateral surfaces extending between the first and second ends. The metal bumps can be wire bonds having first and second ends attached to a same conductive pad of the substrate. A conductive matrix material contacts at least portions of the lateral surfaces of respective ones of the metal bumps and joins the metal bumps with contacts of the microelectronic element.