Fabrication and Preparation of Micro-Coaxial Wires: Electrodeposition of Conductive Gold Shields

Abstract

Draper is developing a new paradigm in microelectronics packaging, in which the interconnects among components are made, not through the substrate, but rather through micro-coaxial wires. In this paper, we describe the design and fabrication of micro-coaxial wire segments of diameters between 30 m and 250 m. The micro-coax comprised a center metal wire, a polymer dielectric layer, and electroplated gold shield. To facilitate integration of the micro-coax on the package, the micro-coax were prepared in ~20 mm segments that are stripped back at the ends to expose < 1 mm of the core wire. To achieve the necessary stripping of the micro-coax shield layer, we have utilized two different seeding and electroplating processes and fixtures. We describe both processes and the fixture design that allowed the scale up in fabrication volume from 0.1 m of micro-coax to 1.2 m of micro-coax per batch.