Piezoelectric vibrator, piezoelectric oscillator, and piezoelectric vibrator manufacturing method having electrodes with different thicknesses

Abstract

A quartz crystal resonator unit that includes: a piezoelectric blank; a first excitation electrode on a first principal surface and within at least a part of a vibration portion of the piezoelectric blank; a second excitation electrode on a second principal surface and within at least a part of the vibration portion of the piezoelectric blank; a first extended electrode on the first principal surface and electrically connected to the first excitation electrode; and a second extended electrode on the second principal surface and electrically connected to the second excitation electrode; and an insulation layer including a hollow portion which defines a space with the second excitation electrode. A thickness of the first extended electrode is larger than a thickness of the second extended electrode. An end portion of the first extended electrode extends over the hollow portion in a plan view of the piezoelectric vibrator.