Aerosol deposition for ceramic thick film formation at room temperature

Fabrication of ceramic thick films on Cu or other metal substrates is a key issue to realize the integration and the embedding of passive components in print wiring boards (PWB). The aerosol deposition (AD) process developed in AIST, Japan is the only technique to fabricate ceramics thick films at room temperature. Barium titanate films were successfully deposited on Cu substrate at room temperature for embedded capacitors. Dielectric permittivity of the film was less than 200 because particles of barium titanate were broken into small peaces in the deposition process. A heat treatment at 300degC improved the permittivity up to 240, giving rise to the capacitance density above 3 nF/mm². Microwave dielectric films of Ba_4.2Sm_9.2Til₈O₅₄ were deposited on Cu substrate. A transparent film shows almost the same permittivity and TC_f with bulk ceramics. Al₂O₃ films were deposited on Al for the application to high-power module substrates. This AI₂O₃/AI substrates showed better durability in a heat-cycle test than conventional AIN/Al substrates used in high-power electronic circuits of hybrid-cars.