NANUFACTURE OF THICKNESS-SHEAR VIBRATION COMPOSITE TYPE CERAMIC FILTER

摘要

PURPOSE:To contrive to reduce the size of a product by a simple manufacturing process by forming a recessed part in the center of one end surface side and forming no electrode for polarization in the recessed part when a rectangular plate type piezoelectric substrate is polarized. CONSTITUTION:The recessed part 2 is formed in the center of one end surface side of the rectangular plate type piezoelectric substrate 1 and electrodes 3 and 4 for polarization which are made of silver, etc., are provided to a side end surface part other than the recessed part 2 and the other side end surface opposite the side end surface part where the recessed part is not formed. A voltage is applied between the electrodes 3 and 4 for polarization to polarize the piezoelectric substrate 1, and the electrodes 3 and 4 are washed away to obtain the piezoelectric substrate 1 which is polarized in a surface direction. The periphery of the bottom surface of the recessed part 2 in the center of the piezoelectric substrate 1 is left as a completely unpolarized part 5, so thickness shear vibration coupled type 3-terminal filters F1 and F2 in plural energy confined type multiple mode and a capacitor C which couples them are formed on the same piezoelectric substrate 1.