Mass produced copper-on-polymer-membrane boards for micromachined millimeter-wave circuits

Membrane-supported circuits (also known as dielectric-less circuits) have been well known for their negligible dielectric losses and for their allowance of relaxed dimensional tolerances in high-frequency circuit design. However, thus far, most of the commonly known silicon-based membrane-processing technologies require intensive and time-consuming thermal processing. This paper reports a simple but economical processing technique for production of self-supporting polymer-membrane-based printed circuits. Based on a pre-processed copper-on-polymer-membrane board, a planar millimeter/submillimeter wave component can be rapidly prototyped on a 5 μm thick polymer membrane with conventional photolithographical processing equipment. The simplicity of the process makes this technology particularly suitable for mass production of millimeter wave or sub-millimeter wave components. Vector-network-analyzer measurement reveals that the transmission losses of general E-plane components are typically less than 0.5 dB/cm across W-band