Characterization of Alumina Ribbon Ceramic Substrates for 5G and mm-Wave Applications

A recently developed material technology at Corning Inc., namely, Alumina Ribbon Ceramic (ARC), is investigated as a potential substrate candidate for fifth generation (5G) and millimeter-wave (mm-wave) applications. In this article, we characterize an 80- $\mu \text{m}$ -thick ARC substrate material in the frequency range of 3–50 GHz using microstrip ring resonator (MRR) method and extract the loss of various planar transmission lines, such as microstrip and coplanar waveguide (CPW) lines on ARC substrate up to 50 GHz as well. Moreover, different test structures designed on an 80- $\mu \text{m}$ -thick ARC substrate are utilized to extract the electrical parasitics associated with a single-grounded through-alumina via (TAV) and transmission properties of ground–signal–ground (GSG) TAV of 40 $\mu \text{m}$ diameter over the frequency range of 0.1–50 GHz. The semiadditive patterning (SAP) process is employed to metallize the top and bottom layers of ARC substrate to form the copper traces for the designed structures. Combined with the previous characterization results of a 40- $\mu \text{m}$ -thick ARC substrate in 30–170 GHz, the dielectric constant of ARC was extracted to be ~10.12 over 3–170 GHz, while its loss tangent varies in the range of $6.6\times 10^-5-1.3\times 10^-3$ over the same frequency band. The average measured insertion loss of CPW lines varied from 0.026 to 0.24 dB/mm over 3–170 GHz. For the microstrip lines, the average measured insertion loss over the same frequency range was extracted to be between 0.019 and 0.293 dB/mm. Furthermore, the parasitic inductance and resistance of a single-grounded TAV are extracted to be 24.41 pH and $0.987~\Omega $ , respectively, at 50 GHz, and the insertion loss per a GSG-TAV extracted from CPW-TAV daisy chain measurements is found to be 0.056 dB at 50 GHz as well. In addition to an excellent performance of ARC-based interconnects, the TAV in ARC is shown to have lower transmission loss up to 50 GHz, while exhibiting low parasitics.