Gold Stud Bumping
Gold stud bumping is a process of the flip chip application method. The gold stud bump flip chip assembly process creates conductive gold bumps on the die bond pads, and connects the die to the substrate with adhesive or ultrasonic assembly. Since stud bumping can be done on a wire bonder, it does not require wafers or under-bump metallization. Stud bumping with flip chip is fast, efficient, and flexible for product development.
Microcircuits today also consist of one or more microchips/ICs (also called die) for its control. These die need to be connected to all other components of the circuit in order to make the device work as a whole. One commonly used interconnection method is ball bonding process technology. Automatic ball bonders today can use Au wires from .7 – 2 Mil (18 - 50µm).
However, in order to be able to precisely hit the small bond pads of a die (≤100µm), device packaging requires a highly controlled, highly accurate wire bonding process. One basic requirement is the generation of a repeatable size of a “Free-Air Ball” (FAB): the start of any ball bonding sequence.
Mobile electronic products continually require finer geometries for packaged integrated circuits. Wireless phones, PDA and digital cameras continue to merge into a common device that will benefit from finer pitch and lower profile wire bonding or ball bumping for flip chip, stacked chip and other advanced packaging technologies. Inherent variations in materials, tools and process can cause variations in ball shape and size, stitch shape, bond quality, and thus, yield.