Quartz crystal unit and its manufacturing method

A quartz crystal unit comprising a flexural mode, tuning fork, quartz crystal resonator, a case and a lid, wherein said flexural mode, tuning fork, quartz crystal resonator comprises:

• tuning fork tines;
• and
• a tuning fork base;
• said tuning fork tines and said tuning fork base that are formed integrally;
• a plurality of step difference portions constructed at said tuning fork tines along the direction of length thereof;
• the at least two step difference portions connected via at least one step portion;
• and
• electrodes disposed on said step difference portions and sides of said tuning fork tines.

A quartz crystal unit comprising a flexural mode, tuning fork, quartz crystal resonator, a case and a lid, wherein said flexural mode, tuning fork, quartz crystal resonator comprises:

• tuning fork tines;
• and
• a tuning fork base;
• said tuning fork tines and said tuning fork base that are formed integrally;
• a plurality of grooves constructed only within said tuning fork base;
• and
• electrodes provided in the plurality of grooves.

A quartz crystal unit comprising a plurality of individual quartz crystal resonators, a case, and a lid, wherein at least one of the plurality of quartz crystal resonators is a flexural mode, tuning fork, quartz crystal resonator comprising:

• tuning fork tines;
• and
• a tuning fork base;
• said tuning fork tines and said tuning fork base that are formed integrally;
• and
• at least one step difference portion constructed at said tuning fork tines along the direction of length thereof.

A method of manufacturing a quartz crystal unit comprising at least one flexural mode, tuning fork, quartz crystal resonator with tuning fork tines and a tuning fork base, a case and a lid, wherein the quartz crystal unit comprises the steps of:

• disposing a metal film on upper and lower faces of a quartz crystal wafer by an evaporation method or a spattering method;
• spreading resist on the metal film, and removing the resist and the metal film from the quartz crystal wafer except those of at least one tuning fork shape with tuning fork tines and a tuning fork base, using a photolithographic process and an etching process;
• forming integrally the at least one tuning fork shape with the tuning fork tines, each of which has sides and upper and lower faces and the tuning fork base, to which the plurality of tuning fork tines are attached, in the quartz crystal wafer by a chemical etching process;
• forming at least one step difference portion in the quartz crystal wafer, such that the at least one step difference portion is constructed at each tuning fork tine along the direction of length thereof;
• disposing electrodes of opposite electrical polarity on the step difference portion and sides of the tuning fork tines opposite to the step difference portion, and constructing the electrodes so that the tuning fork tines are capable of vibrating in inverse phase;
• fixing the tuning fork base on a mounting portion of the case;
• and
• connecting the case and the lid via connecting member, and wherein resonance frequency for tuning fork quartz crystal resonators formed by said steps is adjusted by a separate step of at least twice.