Given previous reports on constrain

Given previous reports on constrained sintering limiting densification of ceramics on dense substrates including rigid plates and metal foils [46-49], tape cast Cu powder layers were also explored. The tape casting procedures for Cu resembles that of the PZT tape: 6.70 g Cu (Shoei Chemical, Inc., Tokyo, Japan) were mixed with 5.5 g binder containing 20 vol% QPAC-40 and 80 vol% propylene carbonate. 0.4 mL MEK was added to the slurries in order to adjust the viscosity before the slurries were homogenized in a mixer for 3 min. The mixtures were then tape cast on Mylar sheets, followed by baking in an oven at 80℃ for 5 h to remove the solvent. The thickness of the Cu tapes after drying was ~90 mm when the tapes were cast with a 13 mil (~330 mm) doctor blade height and a casting speed of 8 cm/s.