A flip-chip LIGA assembly technique via electroplating

Abstract

A novel flip-chip assembly technique by means of electroplating at a low processing temperature has been developed. Mesoscopic gears, made of nickel with 1500 μm in diameter and 250 μm in height, have been bonded to glass substrate. The bonding process is conducted by nickel electroplating at 50 °C with a current density at 53.3 A/m 2 . The nickel electrolyte is found to penetrate about 100 μm from the perimeter to the center of the gear and form a good bond. This process can be applied to the integration of high-aspect-ratio microstructures with substrates that have pre-fabricated microelectronics massively and in parallel. As such, it provides a powerful way to achieve the integration of meso- and microscopic electromechanical systems.