A method of manufacturing a piezoelectric resonator unit that includes preparing a piezoelectric resonator having a piezoelectric element, a pair of excitation electrodes respectively disposed on a first main surface and a second main surface of the piezoelectric element so as to face each other with the piezoelectric element therebetween, and a pair of connection electrodes that are respectively electrically connected to the pair of excitation electrodes; electrically connecting the pair of connection electrodes to a pair of electrode pads on a third main surface of a base member using an electroconductive holding member so as to excitably hold the piezoelectric resonator on the third main surface of the base member; and attaching an electroconductive material, which is scattered from an electroconductive member, to a surface of the electroconductive holding member.

In a quartz crystal unit, the unit comprising a quartz crystal resonator having a base portion, and first and second tuning fork arms connected to the base portion, the base portion having a length less than 0.5 mm and greater than a spaced-apart distance between the first and second tuning fork arms, each of the first and second tuning fork arms having a width less than 0.1 mm and a length less than 1.56 mm, and a plurality of different widths including a first width and a second width greater than the first width, at least one groove being formed in at least one of opposite main surfaces of each of the first and second tuning fork arms so that a length of the at least one groove is within a range of 0.3 mm to 0.79 mm, the quartz crystal resonator being housed in a case, and a lid being connected to the case.

In a quartz crystal unit, the unit comprising a quartz crystal resonator having a base portion, and first and second tuning fork arms connected to the base portion, the base portion having a length less than 0.5 mm and greater than a spaced-apart distance between the first and second tuning fork arms, each of the first and second tuning fork arms having a width less than 0.1 mm and a length less than 1.56 mm, and a plurality of different widths including a first width and a second width greater than the first width, at least one groove being formed in at least one of opposite main surfaces of each of the first and second tuning fork arms so that a length of the at least one groove is within a range of 0.3 mm to 0.79 mm, the quartz crystal resonator being housed in a case, and a lid being connected to the case.

An electronic device includes a base material, a first metal film disposed on the base material and containing nitrogen and chromium, and a second metal film disposed on the first metal film and containing gold. In the first metal film, the number of nitrogen atoms may be between 20% to 100% of the number of chromium atoms. Further, the distribution of nitrogen atoms in the first metal film is larger in a third region sandwiched between a first region on the base material side of the first metal film and a second region on the second metal film side than in the first region and in the second region.

An electronic device includes a base material, a first metal film disposed on the base material and containing nitrogen and chromium, and a second metal film disposed on the first metal film and containing gold. In the first metal film, the number of nitrogen atoms may be between 20% to 100% of the number of chromium atoms. Further, the distribution of nitrogen atoms in the first metal film is larger in a third region sandwiched between a first region on the base material side of the first metal film and a second region on the second metal film side than in the first region and in the second region.

A frequency adjustment method is provided in which a residual substance is unlikely to be generated, the frequency can be adjusted with high precision, and a decrease in strength is made small. A frequency adjustment method for a piezoelectric vibrator includes preparing the piezoelectric vibrator having a base portion, a vibration arm that includes a connection portion connected to the base portion as well as vibration arm main bodies extending from the connection portion and that is made of a single crystal, a lower electrode formed on the vibration arm, a piezoelectric thin film formed on the lower electrode, and an upper electrode formed on the piezoelectric thin film; and forming an alteration portion by irradiating the connection portion with a laser beam.

A frequency adjustment method is provided in which a residual substance is unlikely to be generated, the frequency can be adjusted with high precision, and a decrease in strength is made small. A frequency adjustment method for a piezoelectric vibrator includes preparing the piezoelectric vibrator having a base portion, a vibration arm that includes a connection portion connected to the base portion as well as vibration arm main bodies extending from the connection portion and that is made of a single crystal, a lower electrode formed on the vibration arm, a piezoelectric thin film formed on the lower electrode, and an upper electrode formed on the piezoelectric thin film; and forming an alteration portion by irradiating the connection portion with a laser beam.

A resonator includes: a resonator element that includes a base portion and a resonating arm; and a base. When n is one natural number of 2 or greater and j is 1 or greater and a natural number which is less than or equal to n, the resonator element performs resonations with n inherent resonation modes. In a relationship between arbitrary integers k.sub.j and resonance frequencies f.sub.j corresponding to the n inherent resonation modes, respectively, when f.sub.1 represents the resonance frequency of the main resonation of the resonator element and a normalized frequency difference f is defined by $f\left(\frac{\underset{j=2}{\overset{n}{.Math.}}{k}_j{f}_j}{-k_1}-f_1\right)/f_1,$
a relationship of |f|0.03 is satisfied. The arbitrary integers k.sub.j satisfy relationships of 3.sub.j=1.sup.n|k.sub.j|10 and n.sub.j=1.sup.n|k.sub.j|. A ratio of an amount of a change in the resonance frequency of the main resonation, to excitation power that electrically excites the main resonation, is 20 [ppm/W] or higher.

A resonator includes: a resonator element that includes a base portion and a resonating arm; and a base. When n is one natural number of 2 or greater and j is 1 or greater and a natural number which is less than or equal to n, the resonator element performs resonations with n inherent resonation modes. In a relationship between arbitrary integers k.sub.j and resonance frequencies f.sub.j corresponding to the n inherent resonation modes, respectively, when f.sub.1 represents the resonance frequency of the main resonation of the resonator element and a normalized frequency difference f is defined by $f\left(\frac{\underset{j=2}{\overset{n}{.Math.}}{k}_j{f}_j}{-k_1}-f_1\right)/f_1,$
a relationship of |f|0.03 is satisfied. The arbitrary integers k.sub.j satisfy relationships of 3.sub.j=1.sup.n|k.sub.j|10 and n.sub.j=1.sup.n|k.sub.j|. A ratio of an amount of a change in the resonance frequency of the main resonation, to excitation power that electrically excites the main resonation, is 20 [ppm/W] or higher.

A resonator includes a prong of which the width between edges is close to /2. The pressure variation at one edge is then in phase opposition with that at the other edge. Acoustic coupling with an incident wave having the wavelength is thus improved. The ratio between the width between edges and the height of the prong is chosen so that only the fundamental mode with bending oscillation of the prong is present. It to prongs of a tuning fork embedded in a solid shared base optimized to contain the energy in the tuning fork while avoiding energy losses in the support. Finally, the tuning fork is advantageously combined with a unit for containing acoustic energy including a rigid reflecting screen.