Micro-coaxial cables (MCCs), with an outer diameter of 100 microm or less, enable a new microelectronics packaging platform that will reduce the time required to design and fabricate complex multi-chip microelectronic assemblies. Low-inductance MCCs for power distribution and 30-75 Ω MCCs for signal distribution, eliminate the need for lengthy simulations and fabrication processes, as in board design of photo-lithographically patterned microchips, because each individually shielded MCC provides sufficient isolation to prevent electro-magnetic interference (EMI) and crosstalk. The in-situ fabrication method presented here utilizes only conventional wire bonding and microfabrication techniques, providing a high-feasibility path toward a new interconnect paradigm based on MCCs.

Each cable measured consists of a 25.4 microm gold bond wire coated first with a dielectric and then a 5.0 microm thick gold shield. For power distribution, the dielectrics evaluated are 1.0 microm thick Parylene C dielectric and 100 nm thick HfO2. Their characteristic impedances are measured to be 3.2-5.9 Ω and 0.11-0.18 Ω, respectively. A third MCC, appropriate for signals, has a 38 microm thick Parylene C dielectric and a characteristic impedance of 39-68 Ω. For a wire pitch of 0.51 mm cross-talk is -62 dB at 1 GHz for micro-coax. Cross-talk increases to -30 dB at 26.5 GHz.