An interconnect for out-of-plane assembled biomedical probe arrays

An out-of-plane interconnect system has been developed for biomedical microprobes. With this type of interconnect, different microelectromechanical system (MEMS) structures can be electrically and mechanically connected perpendicular to a backbone. The probes and backbone are processed separately which enables a modular approach. The MEMS structures are inserted into cavities (which act as sockets) and the electrical contact is established by means of overhanging gold clips which are bent and squeezed between the cavity wall and the MEMS upon insertion. The assembly is done using a flip-chip bonder. Prior to the deposition of the overhanging contact blades, an extreme planarization technique is employed for the fabrication of the gold clips. Topographies of 200 µm have been planarized using benzocyclobutene as a sacrificial material. Test structures have been made and assembled perpendicular to the substrate to perform a contact resistance measurement.