Patent ID: 7053531

Claim:
A composite piezoelectric transducer, comprising: a piezoelectric ceramic having a first surface, a second surface opposite to the first surface, a side surface extended between the first and second surfaces, and a thickness, a groove formed on the second surface to extend in the direction perpendicular to the side surface, the groove having a depth; a non-diced area formed by forming the groove, the non-diced area having a width; an organic polymer filled in the groove, the organic polymer including bubbles; a first electrode formed on the first surface; and a second electrode formed on the second surface, which is extended to the first surface through the side surface, or which is extended to the side surface; a margin insulating the first electrode from the second electrode; wherein the first and the second electrodes are formed only on the piezoelectric ceramic, wherein the groove has a depth 50% to 90% of the thickness of the piezoelectric ceramic, and wherein a ratio w/d between the width and the depth is 0.2 to 0.7.