Patent ID: 7064012

Claim:
A method of making a semiconductor chip assembly, comprising: providing a metal base, a routing line and an etch mask, wherein the metal base includes a metal plate, a metal layer and first and second opposing surfaces, the metal layer provides the first surface of the metal base, the metal plate provides the second surface of the metal base, the routing line contacts the first surface of the metal base and the etch mask contacts the second surface of the metal base; then mechanically attaching a semiconductor chip to the routing line, wherein the chip includes a conductive pad; electrically connecting the routing line to the pad; and etching the metal base using a first wet chemical etch that is selective of the metal plate with respect to the metal layer and the etch mask and then a second wet chemical etch that is selective of the metal layer and the etch mask, wherein an unetched portion of the metal base defined by the etch mask forms a pillar that contacts the routing line.