The gold stud bump bonding technique eliminates the need for photolithography on a single die (individual prototype IC chips), which is typically required in order to provide suitable under-bump metallization. The gold-studs break through the oxide layer on the die pads, most commonly made of aluminum, and make good ohmic connections. The studs may be mated to opposing aluminum pads using thermo-sonic bonding or thermo-compression. We utilize the latter. However, thermo-compression still requires that the pads on the mating part have a top layer of gold in order to achieve a good attachment. The preparation of this gold surface, either via electro-less processes or sputtering, still requires photolithography steps.
- Gold Studs