Dense and Highly Elastic Compressible MicroInterconnects (CMIs) for Electronic Microsystems

In this paper, dense, highly elastic compressible microinterconnects (CMIs) are presented as an enabling technology for next generation sockets, probe cards and heterogeneous integrated systems. Free-standing CMIs with 75 μm height are fabricated using a thick sacrificial photoresist layer with an upward curved sidewall profile. The CMIs show a 45 μm vertical elastic range of motion. The fabricated CMIs have an in-line pitch of 150 μm, mechanical compliance of 9.2 mm/N, and vertical elastic motion of up to 5,000 indentation cycles. The smallest in-line pitch of CMIs demonstrated is 40 μm. The average post-assembly resistance of the CMIs, including the contact resistance, was measured to be 176.3 mΩ.