Microspring Contact Technology

This SBIR Phase I project involves the development of a new MicroSpring Contract (MSC) technology for making compliant, low-cost silicon backplane interconnects for multi-chip hybrid assemblies and modules. The microsprings are compressible coils about 50 ¿m diameter with sufficient compliance to maintain ohmic contact throughout a continuous displacement of at least 10 ¿m. The use of a silicon wafer as backplane permits the addition of passive components, active IC devices, and transmission lines on the opposite surface for applications involving high-frequency and other critical device dies, connected to microsprings through "vias". MSC technology has additional applications to 2) probe cards for "known-good-die" testing, 3)high-density interconnects for complex chips, and 4) contact/interconnect interfaces in vertically-stacked modules. Essential advantages are 1) high compliance of spring elements to accommodate dies/modules which vary in height, 2) high compliance to maintain contact during motion due to thermal expansion differences, 3) non-permanent nature of contacts for easy replacement of defective modules. While fabrication of a MSC backplane card is the aim of this proposal, the feasibility of MSC technology demonstrated in Phase I is also viewed as a springboard for application of MSC technology to these other areas.