Direct digital manufacturing of mm-wave vertical interconnects

Additive manufacturing (AM) is increasingly being shown as a viable technology for the fabrication of complex 3D structures. For microwave components, the combination of laser processing and AM techniques has been reported to enhance the performance and frequency limits of the devices. In this paper, a process to fabricate a 200 μm × 200 μm × 200 μm vertical interconnect that combines fused deposition modeling (FDM), micro-dispensing, and picosecond laser machining is studied. A test structure that includes two vertical transitions is designed, fabricated, and tested, as a performance benchmark. The 4 mm long structure shows a low dissipative loss (2.5 dB at 45 GHz) and excellent frequency response up to mm-wave frequencies. The described structure will help to enable the fabrication of high-performance structural RF electronics.