Piezoelectric filter of the ladder type

Abstract

A piezoelectric filter is one not changing in the holding position of resonator in spite of impulse, small in the number of parts, easy to assemble from one direction, small, thin, and stable in characteristic. For example, as shown in FIG. 7, on electrode patterns on a package 10 forming wiring electrode patterns 11, holding protrusions 13 for holding resonators, and partition boards 14 for positioning resonators, a rectangular plate type piezoelectric resonators 12 are adhered with conductive adhesive. The rectangular plate type piezoelectric resonators 12 and the package 10 are adhered and reinforced from above with a vibration absorbing member 15, and wiring is formed from above the resonators by a wire bonding 16, thereby wiring resonators in a ladder form. Or, as shown in FIG. 11, after forming electrode patterns 102 on a piezoelectric substrate 101, a rectangular plate resonator 104 is cut out from a piezoelectric substrate 101 by laser in a shape consecutive to the piezoelectric substrate 101 by the node of length expander mode, and the piezoelectric substrate 101 is enclosed by a spacer 106 and a sheet 107 from above and beneath.