Low temperature interconnect technology, especially RF signal transmission in the 40 K-4.2 K temperature range, is currently a key focus of development. The transmission line needs to have as little insertion loss and heat leakage as possible in this temperature range. We introduce a process method for preparing coplanar waveguide flexible transmission lines by mechanically cold exfoliating superconducting tape thin films. Especially YBCO thin films deposited through MOD are more easily exfoliate directly at room temperature.The superconducting transition width of YBCO thin film after exfoliating processing is 0.79 K. Although it has increased by 0.3 K compared to the transition width of the strip, the critical current density at 77 K and 0 T is 7.7×105 A/cm2, which is more than 75% of the critical current density of the strip.The exfoliated YBCO thin film is fabricated into a 12 cm long and 1 cm wide PI-YBCO-PI three-layer structure transmission line, and the heat leak value is measured to be 0.238 mW in the temperature range of 40 K to 4.2 K. Five signal channels are prepared on a 1 cm wide YBCO thin film, and the simulation shows that the crosstalk between adjacent signal channels is <-40 dB, the insertion loss at 9 GHz is <-2 dB, and the heat leak value of each signal channel is 47.6 μW. Compared to the metal transmission lines currently used in this temperature range, the heat leakage has been reduced by at least 5 times.
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