| 摘要 |
PROBLEM TO BE SOLVED: To prevent disconnection by leading lead electrodes led out of respective exciting electrodes form a vibrating part rear face without going through a step part located on a rear face side where a recessed part is formed. SOLUTION: This balanced type dual mode piezoelectric filter consists of an AT cut crystal element plate 22 having a recessed part 23 on the principal plane of a rear side, exciting electrodes 25a, 25b, 26a and 26b which are respectively formed by two each on the both surface and rear face of a very thin plate vibrating part 24 located at the bottom face of the recessed part and thin lead electrodes pulled out respectively to element plate edges from the respective exciting electrodes. In such a case, the lead electrodes 26a' and 26b' pulled out toward corner parts from the exciting electrodes on the rear face side provided on the bottom face in the recessed part are led out to a flat surface side through through-holes 30 on the way to the vibrating part.
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