Design and development of a high precision lens focusing mechanism using flexure bearings

The emergence of multi-tier stacked die architecture in semiconductor devices has given rise to the need for multi-level interconnection between dies (bare IC chips) and the substrate. In the context of interconnection by wire bonding, this necessitates the use of a vision system, which has real time focussing capability. This paper presents the design and development of such a high precision programmable focussing mechanism (PFM), which is used to move a lens relative to another fixed lens, thus altering the focus of the optical system. The device employs flexure bearings and is actuated by a voice coil motor (VCM).