Flexible micro-spring interconnects for high performance probing

Abstract

Advances in integrated circuit fabrication have given rise to a need for an innovative, inexpensive, yet reliable probing technology with ultra-fine pitch capability. Research teams at Georgia Tech, Xerox PARC, and Nanonexus, Inc. are developing flexible micro-spring structures that can far exceed the packaging and probing needs of the next-generation microelectronic devices. Highly compliant cantilevered springs have been fabricated at pitches as small as 6 /spl mu/m. These micro-springs are designed to accommodate topological variation in probing surfaces while flexing within the elastic regime. The micro-springs have demonstrated reliable electrical contact and mechanical ruggedness. Non-linear finite element models have been developed to understand the deformation of a micro-spring under mechanical loading. Through the models, the probing force versus displacement relation for a spring as well as the internal stress distribution have been determined. Design guidelines have been established to maximize probing force.