A process in which discrete semiconductor chips are flip-attached by thermocompression bonding to 30-microndiameter gold bumps on fine-featured passive integrated circuits was employed in the fabrication of diode subharmonic mixers for use over the 71-76 GHz and 81-86 GHz ranges. Incorporated in the substrate were high-precision grounded heat sinks, semi-lumped filters, and matching networks in low-loss microstrip format. Measurements show conversion loss minima of 12 dB, but the frequency response was impaired by inaccuracies in the filter design. Parasitics characteristic of flipchip technology were not an impediment, and a mixer technology with high performance and low materials cost appears feasible.