Apparatus and method for improving ball joints in semiconductor packages

Abstract

Provided is an apparatus and method for modifying the manufacture of chip carrier bond pads to increase the quality and reliability of semiconductor packages and ball joints in particular. This is accomplished by minimizing the corrosion of the barrier metal layer on the functional bond pads during gold deposition with the use of sacrificial pads electrically connected with the functional bond pads. According to one embodiment of the invention, a semiconductor package has copper conductive pads on a substrate that are exposed through a dielectric. Both functional and sacrificial (nonfunctional) copper conductive pads are provided. A barrier metal layer composed of nickel is electrolessly plated onto these conductive pads, and a bond metal layer of gold is deposited onto the nickel using electroless, generally immersion, gold plating. The surface area of the nickel on the sacrificial pads is less than that on the functional pads, and the nickel on the sacrificial pads corrodes first during electroless gold deposition. Without nickel corrosion on the functional bond pad, gold can more uniformly be deposited on the surface of the nickel layer. A eutectic solderable material placed on the gold can form a uniform bond with the nickel because the nickel on the functional bond pad is largely corrosion free.

Dependencies are inferred from the claim text.