Gold Ball Bumping: An Effective Wafer-Bumping Method

Gold-ball bumping is a popular method for wafer bumping to improve electrical performance and reduce package size using 1-mil gold wire.

Wafer bumping involves putting a conductive material on each die pad on a wafer to attach it to a package or circuit board forming the first-level interconnect. Bumping has gained popularity due to demand for reduced package size, the need for improved electrical performance, and thermal transfer.

Gold-ball bumping - or stud bumping - can be accomplished with commercially available gold wire bonders using a 1-mil gold wire. In fact, gold ball bumping is an evolution of the 50-year-old wire bonding process. In wire bonding, a gold ball is forced down and thermosonically bonded to a die-bond pad forming the first connection of an integrated circuit (IC) and substrate. With the ball connected, the wire is fed out and attached to a second surface, and then torn off to complete the connection.