A crystal oscillator includes a piezoelectric substrate, a first electrode, a second electrode, and a support frame. The first electrode includes a first electrode portion disposed on a first surface of the piezoelectric substrate. The second electrode is disposed on a second surface of the piezoelectric substrate opposite to the first surface of the piezoelectric substrate. The support frame is made of a photoresist material, and is disposed on the second surface. The support frame surrounds the second electrode portion. At least a portion of the second extending electrode portion is located outside the support frame. A method for making the crystal oscillator is also provided herein.

A crystal oscillator includes an oscillating substrate, a hollow frame, a first electrode, and a second electrode. The oscillating substrate includes a main oscillating region and a thinned region that has a thickness smaller than that of the main oscillating region. The first and second electrodes are disposed on a first surface of the oscillating substrate and a second surface opposite to the first surface, respectively. The hollow frame is disposed on the second surface. The second electrode includes a second electrode portion that has at least one opening in positional correspondence with the thinned region. A method for making the crystal oscillator is also provided herein.

A bulk acoustic wave (BAW) structure includes a single crystal piezoelectric material layer, a first electrode, a second electrode and an acoustic reflector. The first and second electrodes are respectively located on a first surface and a second surface of the single crystal piezoelectric material layer. The area of the second electrode is greater than or equal to that of the second surface of the single crystal piezoelectric material layer, and the contact area of the single crystal piezoelectric material layer with the second electrode is equal to the area of the second surface of the single crystal piezoelectric material layer. The acoustic reflector is disposed on a surface of the first electrode.

An electronic device that includes a base substrate having a mounting surface; an electronic component having a mechanical vibration portion mounted on the mounting surface of the base substrate; an intermediate layer mounted on the base substrate and forming an internal space with the base substrate so as to accommodate the electronic component therein, the intermediate layer having at least one through-hole that opens the internal space to an outside; and a sealing layer on the intermediate layer and sealing the internal space by closing the at least one through-hole.

Thin-film bulk acoustic resonator, forming method and filter are provided. The thin-film bulk acoustic resonator includes: a first substrate, an upper surface of the first substrate being provided with a first cavity; a piezoelectric stack structure, disposed on the upper surface of the first substrate and covering the first cavity, the piezoelectric stack structure including a second electrode, a piezoelectric layer and a first electrode which are sequentially stack from bottom to top; a groove, including a first groove and/or a second groove, the first groove penetrating through the first electrode and extending into or penetrating through the piezoelectric layer, the second groove penetrating the second electrode and extending into or penetrating through the piezoelectric layer; and a reinforcement layer, disposed on at least one side of the first electrode or the second electrode at a bottom of the groove.

A vibrating element includes a piezoelectric substrate having an excitation section adapted to excite a thickness-shear vibration, and provided with a step section in each of side surfaces on both ends, and a peripheral section having a thickness smaller than a thickness of the excitation section, and the peripheral section has at least one projection section disposed on both principal surfaces in an area where a vibratory displacement when the excitation section excites a vibration is sufficiently attenuated.

A vibration element includes: a quartz crystal substrate having a first vibration part and a second vibration part; a pair of first excitation electrodes formed at two main surfaces of the quartz crystal substrate, at the first vibration part; and a pair of second excitation electrodes formed in such a way as to sandwich the second vibration part in a direction of thickness of the quartz crystal substrate, at the second vibration part. At least one second excitation electrode of the pair of second excitation electrodes is formed at an inclined surface inclined to at least one of the two main surfaces.

The acoustic wave device includes a crystal substrate cut from a quartz crystal boule cut by a rotational angle specified by a right-handed Euler angle (ϕ, θ, Ψ), and at least one comb-shape excitation electrode to excite the crystal substrate to make a plate waves. The rotational angle specified by the right-handed Euler angle (ϕ, θ, Ψ) is within ranges of ϕ=0±2°, θ=16.0° to 20.0°, and Ψ=0±2°. A plate wave, among the plate waves, having a phase velocity in a range of from 3500−4000 m/s, is selected as a vibration mode of the crystal substrate. When H represents a substrate-thickness of the crystal substrate and λ represents a wavelength of the plate wave, a normalized plate thickness H/λ is in a range of 1.5<H/λ<2.0.

A vibration element includes a substrate having first and second principal surfaces, a first excitation electrode on the first principal surface, a second excitation electrode on the second principal surface, and a first extraction electrode on the first principal surface, and connected to the first excitation electrode. The first extraction electrode includes a first electrode section, and a second electrode section extending from the first electrode section in a first direction and connected to the first excitation electrode. The second electrode section is narrower in a second direction than the first electrode section. When an area of the first excitation electrode is S1, and an area of an overlapping part where the second electrode section overlaps the second excitation electrode is S2, (S2/S1)≦0.1.

In an acoustic wave device, in a rotated Y-cut crystal substrate to which a rotational angle based on a particular Euler angle is added, a vibration mode located farther in a low phase velocity area than the principal vibration has an electromechanical coupling coefficient K.sup.2 lower than that of the principal vibration, and the primary and secondary temperature coefficients of the principal vibration are approximately zero. The acoustic wave device includes a crystal substrate cut from a quartz crystal boule cut by a rotational angle specified by a right-handed Euler angle (ϕ, θ, Ψ), and at least one comb-shape excitation electrode to excite the crystal substrate to make a plate waves. The crystal substrate is made by cutting the quartz crystal boule such that the rotational angle is within ranges of ϕ=0±2°, θ=17.5° to 19.5°, and Ψ=0±2°.