Patent ID: 7412764

Claim:
A method for manufacturing a quartz crystal unit, comprising the steps of: forming a quartz crystal tuning fork resonator capable of vibrating in a flexural mode of an inverse phase by etching a quartz crystal wafer to form a quartz crystal tuning fork base, and first and second quartz crystal tuning fork tines connected to the quartz crystal tuning fork base, each of the first and second quartz crystal tuning fork tines having side surfaces, the quartz crystal tuning fork resonator having a piezoelectric constant e′ 12 to drive the quartz crystal tuning fork resonator; disposing an electrode on each of two of the side surfaces of each of the first and second quartz crystal tuning fork tines so that the electrodes disposed on the side surfaces of the first quartz crystal tuning fork tine have an electrical polarity opposite to an electrical polarity of the electrodes disposed on the side surfaces of the second quartz crystal tuning fork tine; providing a case having a mounting portion; providing a lid for covering an open end of the case; mounting the quartz crystal tuning fork resonator on the mounting portion of the case; and connecting the lid to the case to cover the open end thereof; and wherein the quartz crystal unit comprises the quartz crystal tuning fork resonator with the piezoelectric constant e′ 12 within a range of 0.12 C/m 2 to 0.19 C/m 2 in the absolute value.