Printed wiring board with coaxial wirings for high speed signal transmission

The clock frequency in digital electronic systems is exceeding the GHz range. A high-speed signal transmission ability of over Gbps is required for a signal transmission line of even a printed wiring board (PWB). We developed a new coaxial PWB technology. The coaxial PWB with coaxial wiring lines was designed for a test system of low-temperature electronic devices. It was fabricated by buildup PWB technology, using a drill to make a vertical shielding wall electrode. The electrical results of the fabricated coaxial PWB were carried out by the time domain reflectometry (TDR) measurement and the vector impedance measurement. The characteristic impedances of the coaxial wiring lines were evaluated using a TDR waveform analyzer. The average characteristic impedance was controlled within 50 Ω ± 10 %. The vector impedance measurements were evaluated using a vector network analyzer. The insertion loss was measured to be less than 0.39 dB/cm at 5 GHz.