Deposition and Single-Step Processing of YBCO Thick Films for Multilayered Electronics

The goal of this project was to successfully cofire a screen-printed yttrium bar ium copper oxide (YBCO) superconductor onto a low-temperature cofired ceramic (LTCC) substrate. The purpose was to investigate the compatibility of thick-film, high-temperature superconductors with multilayered ceramic (MLC) packages for cryogenic applications. Paste consisting of standard organics and YBCO powder of -325 mesh particle size was screen-printed onto Dupont 951 Green Tape. The system was cofired at temperatures ranging from 925°C to 975°C. The quality of the cofired system was characterized in several ways: Meissner diamagnetism, scanning electron microscopy, x-ray diffraction, and AC susceptibility tests were performed to determine the superconducting capability of the system. Samples cofired at 950°C retained some superconductivity after firing and showed the best compromise be­tween sintering and degradation.