Piezoelectric transducer

Abstract

The present invention comprises: a piezoelectric oscillation element that comprises a piezoelectric piece, a first excitation electrode that is disposed on a first surface of the piezoelectric piece, and a second excitation electrode that is disposed on a second surface of the piezoelectric piece; a first quartz substrate that has an external terminal and is bonded to the first surface of the piezoelectric piece; and a second quartz substrate that is bonded to the second surface of the piezoelectric piece. The first quartz substrate comprises a principal surface that is defined by a first basic axis and a second basic axis that intersects the first basic axis. When a first axis, a second axis, and a third axis are the crystallographic axes of quartz and are mutually intersected, and a first inclined axis is determined by inclining the third axis by a first prescribed angle around the first axis, the first axis is made to correspond to the first basic axis, the first inclined axis is made to correspond to the second basic axis, and the first prescribed angle is either in the angular range −90° to −°60 or in the angular range 80° to 90°.

Description

[Technical field]

[0001] The present invention relates to a piezoelectric vibrator. [Background technology]

[0002] Conventionally, piezoelectric vibrators that use thickness-shear vibration as the main vibration have been widely used as a signal source of a reference signal used in an oscillator, a bandpass filter, etc. For example, Patent Document 1 discloses a configuration in which a quartz lid wafer (first quartz substrate) bonded to the first surface of an AT-cut quartz wafer (piezoelectric vibration element) and a quartz base wafer (second quartz substrate) bonded to the second surface of the AT-cut quartz wafer are each cut out in a range of 24°00 minutes to 32°28 minutes from the Z axis, which is the crystal axis of the quartz. In this configuration, the difference in the thermal expansion coefficient between the quartz lid wafer, the quartz base wafer, and the AT-cut quartz wafer is reduced, thereby reducing the stress transmitted from the quartz base wafer and the quartz lid wafer to the AT-cut quartz wafer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5492697 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional technology, for example, when a piezoelectric vibrator is mounted on a mounting board, external stress caused by the difference in thermal expansion coefficient between the mounting board and the piezoelectric piece of the piezoelectric vibration element may be transmitted to the piezoelectric vibrator.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a piezoelectric vibrator that can reduce the stress transmitted to a piezoelectric vibration element. [Means for solving the problem]

[0006] A piezoelectric vibrator according to one aspect of the present invention comprises a piezoelectric vibration element having a piezoelectric piece, a first excitation electrode provided on a first surface of the piezoelectric piece, and a second excitation electrode provided on a second surface of the piezoelectric piece; a first quartz substrate having external terminals and bonded to the first surface of the piezoelectric piece; and a second quartz substrate bonded to the second surface of the piezoelectric piece, wherein the first quartz substrate has a main surface defined by a first base axis and a second base axis intersecting the first base axis, and when the third axis, of the first, second, and third axes which intersect with each other and are crystal axes of the quartz, is inclined around the first axis by a first predetermined angle as the first inclination axis, the first axis corresponds to the first base axis and the first inclination axis corresponds to the second base axis, and the first predetermined angle is any angle included in the angle range of -90 degrees or more and -60 degrees or less, and the angle range of 80 degrees or more and 90 degrees or less. Effect of the Invention

[0007] According to the present invention, it is possible to reduce the stress transmitted to the piezoelectric vibration element. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of a crystal oscillator according to an embodiment. [Diagram 2] FIG. 1 is a plan view illustrating a schematic configuration of a device substrate according to an embodiment. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 13 is a diagram showing an example of the characteristics of a quartz crystal resonator for each combination of the cut angle of the CAP substrate and the cut angle of the handle substrate. [Diagram 5] 11 is a graph showing the characteristics of a quartz crystal resonator for each combination of the cut angle of the CAP substrate and the cut angle of the handle substrate. [Figure 6] 11 is a graph showing the characteristics of a quartz crystal resonator for each combination of the cut angle of the CAP substrate and the cut angle of the handle substrate. [Figure 7] 1 is a diagram for explaining characteristics of a quartz crystal resonator under various conditions; [Figure 8]1 is a diagram for explaining characteristics of a quartz crystal resonator under various conditions; [Figure 9] FIG. 11 is a cross-sectional view illustrating a schematic configuration of a quartz crystal resonator according to another embodiment. [Figure 10] FIG. 11 is a cross-sectional view illustrating a schematic configuration of a quartz crystal resonator according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment in which the piezoelectric vibrator of the present disclosure is embodied as a quartz crystal vibrator will be described.

[0010] For the sake of clarity and understanding of the relationships between the drawings, each drawing may be accompanied by an orthogonal coordinate system consisting of an X-axis, a Y'-axis, and a Z'-axis. The X-axis, the Y'-axis, and the Z'-axis correspond to each other in each drawing. The X-axis, the Y'-axis, and the Z'-axis correspond to the crystallographic axes of quartz, respectively. The X-axis corresponds to the electrical axis (polarity axis), the Y-axis corresponds to the mechanical axis, and the Z-axis corresponds to the optical axis. The Y'-axis and the Z'-axis are respectively axes obtained by rotating the Y-axis and the Z-axis around the X-axis by 35 degrees 15 minutes ± 1 minute 30 seconds in the direction from the Y-axis to the Z-axis. The X-axis is an example of the first axis, the Y-axis is an example of the second axis, and the Z-axis is an example of the third axis.

[0011] As shown in FIG. 1, the crystal oscillator 100 includes, for example, a crystal unit 1, a mounting substrate 130, a cover member 140, and an electronic component 156.

[0012] The quartz crystal unit 1 and the electronic component 156 are housed in the space between the mounting substrate 130 and the lid member 140. The quartz crystal unit 1 is electrically connected to the wiring layer of the mounting substrate 130 by, for example, a bonding wire 166. The quartz crystal unit 1 is electrically connected to the wiring layer of the mounting substrate 130 by, for example, solder 153. The space between the mounting substrate 130 and the lid member 140 is hermetically sealed. The space between the mounting substrate 130 and the lid member 140 may be in a vacuum state, or may be filled with a gas such as an inert gas.

[0013] The mounting substrate 130 is a flat circuit board and includes, for example, a glass epoxy plate and a wiring layer patterned on the glass epoxy plate. The mounting substrate 130 may include, for example, an alumina substrate and a wiring layer patterned on the alumina substrate.

[0014] The lid member 140 is made of, for example, a metal material, and includes a top surface 140A, a side wall 140B, and a flange 140C. The side wall 140B extends from the outer edge of the top surface 140A toward the mounting substrate 130. The flange 140C protrudes outward from the tip of the side wall 140B, and is joined to the first surface 130A of the mounting substrate 130.

[0015] The electronic component 156 includes, for example, a capacitor, an IC chip, and the like, and is bonded to the first surface 130A of the mounting substrate 130. The electronic component 156 is bonded to a wiring layer of the mounting substrate 130 by, for example, solder 153. The electronic component 156 includes, for example, a part of an oscillation circuit that is a circuit for oscillating the crystal resonator 1, and a temperature compensation circuit that is a circuit for compensating for the temperature characteristics of the crystal resonator 1.

[0016] 2 and 3, the quartz crystal unit 1 includes, for example, a device substrate 10, a CAP substrate 20, a bonding portion 30, a handle substrate 40, and a bonding layer 50. The device substrate 10 is an example of a piezoelectric vibration element. The CAP substrate 20 is an example of a first quartz crystal substrate. The handle substrate 40 is an example of a second quartz crystal substrate.

[0017] The device substrate 10 includes a crystal blank 11, a first excitation electrode 14a provided on a first main surface 12a of the crystal blank 11, and a second excitation electrode 14b provided on a second main surface 12b of the crystal blank 11. The crystal blank 11 is formed by etching a crystal substrate (for example, a crystal wafer) obtained by cutting and polishing a synthetic quartz crystal. The first excitation electrode 14a and the second excitation electrode 14b are provided opposite each other with the crystal blank 11 in between. The first excitation electrode 14a and the second excitation electrode 14b are rectangular when the first main surface 12a of the crystal blank 11 is viewed from above, and are arranged so that the entire electrodes overlap. The planar shapes of the first excitation electrode 14a and the second excitation electrode 14b are not limited to rectangular, but may be polygonal, circular, elliptical, or a combination thereof.

[0018] The quartz crystal piece 11 is, for example, an AT-cut quartz crystal substrate, and includes a vibrating portion 11A, a groove portion 11B, a holding portion 11C, extraction electrodes 15a and 15b, connection electrodes 16a and 16b, and a via electrode 17.

[0019] The vibrating portion 11A has a rectangular shape when the first main surface 12a of the crystal piece 11 is viewed in plan, and vibrates at a predetermined oscillation frequency with thickness-shear vibration as the main vibration.

[0020] Groove portion 11B is formed so as to surround the periphery of vibrating portion 11A when first main surface 12a of crystal blank 11 is viewed in plan view, and penetrates crystal blank 11 in the thickness direction.

[0021] The holding portion 11C is connected to the end portion of the vibrating portion 11A in the X-axis direction, and holds the vibrating portion 11A.

[0022] The extraction electrode 15a is provided on the first main surface 12a of the crystal piece 11, and electrically connects the first excitation electrode 14a and the connection electrode 16a. bis provided on the second main surface 12b of the crystal blank 11 and electrically connects the second excitation electrode 14b and the connection electrode 16b. The via electrode 17 penetrates the crystal blank 11 in the thickness direction. The via electrode 17 electrically connects the extraction electrode 15b and the connection electrode 16b.

[0023] Then, by applying an alternating electric field to the first excitation electrode 14a and the second excitation electrode 14b via the extraction electrodes 15a, 15b, the connection electrodes 16a, 16b, and the via electrode 17, the quartz crystal blank 11 vibrates the vibrating part 11A in a predetermined vibration mode.

[0024] The CAP substrate 20 is, for example, a quartz substrate. The CAP substrate 20 has an external terminal, and when the CAP substrate 20 is mounted on the mounting substrate 130, the external terminal of the CAP substrate 20 is electrically connected to the wiring layer of the mounting substrate 130. The CAP substrate 20 has, for example, a recess 21 formed in a portion corresponding to the vibration portion 11A of the device substrate 10. The space formed by the device substrate 10 and the recess 21 of the CAP substrate 20 forms a part of the vibration space of the vibration portion 11A. The lower end of the CAP substrate 20 is bonded to the first main surface 12a of the quartz blank 11. The lower end of the CAP substrate 20 is, for example, bonded to the first main surface 12a of the quartz blank 11 via a bonding portion 30. The lower end of the CAP substrate 20 may be, for example, directly bonded to the first main surface 12a of the quartz blank 11 without the bonding portion 30.

[0025] When the Z'-axis (third tilted axis) is defined as an axis obtained by tilting the Z-axis by a first predetermined angle around the X-axis among the X-axis, Y-axis, and Z-axis that intersect with each other as crystal axes of quartz, the CAP substrate 20 has the X-axis correspond to the first base axis and the Z'-axis correspond to the second base axis. In this case, the CAP substrate 20 has a main surface that is parallel to a plane specified by the X-axis and the Z'-axis that is obtained by tilting the Z-axis by the first predetermined angle around the X-axis. The first predetermined angle corresponds to the cut angle of the CAP substrate 20.

[0026] The bonding portion 30 is provided between the CAP substrate 20 and the first main surface 12a of the crystal blank 11, over the entire circumference of each of the CAP substrate 20 and the device substrate 10. The bonding portion 30 has electrical insulation (non-conductivity). The bonding portion 30 contains, for example, Au as a main component. The main component of the bonding portion 30 may be SiO2 or a resin material. The bonding portion 30 may be omitted, and the CAP substrate 20 may be directly bonded to the device substrate 10. When the main component of the bonding portion 30 is Au, for example, the Au thin film formed on the CAP substrate 20 and the device substrate 10 is activated by plasma or the like, and the surfaces of both are brought together and a load is applied to bond them. When the main component of the bonding portion 30 is SiO2, for example, a silicon oxide film is formed on the CAP substrate 20 and the device substrate 10 by deposition or sputtering, and the surfaces of both are cleaned and bonded together in a vacuum. When the main component of the bonding portion 30 is a resin material, the resin material may include a thermosetting resin or a photosetting resin, and for example, an epoxy resin can be used. When directly bonding the CAP substrate 20 and the device substrate 10, for example, the main surfaces of the CAP substrate 20 and the device substrate 10 are mirror-polished to be hydrophilic, and the two main surfaces are brought into contact with each other and subjected to a heat treatment to remove H2O from the main surfaces, thereby bonding the CAP substrate 20 and the device substrate 10 by siloxane bonding.

[0027] The handle substrate 40 is made of, for example, a quartz substrate. The handle substrate 40 has, for example, a flat plate shape, and supports the device substrate 10 so that the device substrate 10 can vibrate.

[0028] When the Z'-axis (third tilted axis) is an axis obtained by tilting the Z-axis by a second predetermined angle around the X-axis among the X-axis, Y-axis, and Z-axis that intersect with each other as crystal axes of quartz, the X-axis corresponds to the third base axis and the Z'-axis corresponds to the fourth base axis. For example, the main surface of the handle substrate 40 is a plane parallel to a plane specified by the Z'-axis, which is obtained by tilting the Z-axis by the second predetermined angle around the X-axis, and the X-axis. The second predetermined angle corresponds to the cut angle of the handle substrate 40.

[0029] The bonding layer 50 bonds the device substrate 10 and the handle substrate 40. The bonding layer 50 is provided, for example, on the upper surface of the handle substrate 40, and bonds the upper surface of the handle substrate 40 and the second main surface 12b of the crystal piece 11. By bonding the device substrate 10 and the handle substrate 40 with the bonding layer 50, it becomes possible to seal the device substrate 10 between the CAP substrate 20 and the handle substrate 40, for example. The bonding layer 50 has a recess 51 formed in a portion corresponding to the vibration portion 11A of the device substrate 10. The device substrate 10 and the recess 51 of the bonding layer 50 are bonded to each other. Yo The space thus formed forms a part of the vibration space of the vibration part 11A.

[0030] The bonding layer 50 is made of, for example, a silicon oxide film, and bonds the upper surface of the handle substrate 40 and the second main surface 12b of the crystal blank 11. The bonding layer 50 contains, for example, Au as a main component. The main component of the bonding layer 50 may be SiO2 or a resin material. The resin material may include a thermosetting resin or a photocurable resin, for example, an epoxy resin. The bonding layer 50 may be omitted, and the handle substrate 40 may be directly bonded to the device substrate 10. When the main component of the bonding layer 50 is Au, for example, the Au thin film formed on the handle substrate 40 and the device substrate 10 is activated by plasma or the like, and the surfaces of both are brought together and a load is applied to bond them. When the main component of the bonding layer 50 is SiO2, for example, a silicon oxide film is formed on the handle substrate 40 and the device substrate 10 by deposition or sputtering, and the surfaces of both are cleaned and bonded together in a vacuum. Bonding layer 50 When the main component is a resin material, the resin material may contain a thermosetting resin or a photosetting resin, for example, an epoxy resin can be used. When directly bonding the handle substrate 40 and the device substrate 10, for example, the main surfaces of the handle substrate 40 and the device substrate 10 are mirror-polished to make them hydrophilic, and the two main surfaces are brought into contact with each other and heat-treated to remove H2O from the main surfaces, thereby bonding the handle substrate 40 and the device substrate 10 by siloxane bonding.

[0031] Next, the configuration of the crystal unit 1 according to the present embodiment will be described with reference to FIGS. 4 to 8. FIGS. 4 to 6 show the characteristics of the crystal unit 1 predicted using a simulation model of the crystal unit 1 according to the present embodiment. In the simulation model, the thickness of the CAP substrate 20 is 150 μm, the thickness of the bonding portion 30 is 100 nm, the thickness of the device substrate 10 is 1 μm, the thickness of the bonding layer 50 is 1 μm, and the thickness of the handle substrate 40 is 150 μm. FIGS. 4 to 6 are diagrams showing the magnitude of stress applied to the device substrate 10 when the crystal unit 1 vibrates for each combination of the cut angle of the CAP substrate 20 and the cut angle of the handle substrate 40. In the example shown in FIGS. 4 to 6, the magnitude of the stress applied to the device substrate 10 is shown as a standardized value, and the smaller this value, the better the characteristics of the crystal unit 1. In this example, as shown by the wavy lines in Figures 5 and 6, the angle range of -90 degrees or more and -60 degrees or less, and the angle range of 80 degrees or more and 90 degrees or less correspond to the first angle range, and when the cut angle of the CAP substrate 20 is any angle included in the first angle range, the stress applied to the device substrate 10 becomes relatively small. That is, it is preferable that the cut angle of the CAP substrate 20 is any angle of the angle range of -90 degrees or more and -60 degrees or less, and the angle range of 80 degrees or more and 90 degrees or less. Also, in this example, the angle range of -90 degrees or more and -30 degrees or less, and the angle range of 30 degrees or more and 90 degrees or less correspond to the second angle range, and when the cut angle of the CAP substrate 20 is any angle included in the first angle range and the cut angle of the handle substrate 40 is any angle included in the second angle range, the stress applied to the device substrate 10 becomes smaller. In other words, when the cut angle of the CAP substrate 20 is any angle in the angle range of -90 degrees or more and -60 degrees or less, and the angle range of 80 degrees or more and 90 degrees or less, it is more preferable that the cut angle of the handle substrate 40 is any angle in the angle range of -90 degrees or more and -30 degrees or less, and the angle range of 30 degrees or more and 90 degrees or less.

[0032] FIG. 7 is a diagram for explaining the characteristics of the crystal unit 1 according to the present embodiment under each condition. In the example shown in the figure, the characteristics of the crystal unit 1 under each condition when the material of the bonding portion 30 and the material of the bonding layer 50 are changed for each case where the recess 21 is formed in the CAP substrate 20 and the recess 21 is not formed in the CAP substrate 20 are shown. Specifically, the characteristics of the crystal unit 1 under each condition are shown when the main components of the materials of the bonding portion 30 and the bonding layer 50 are Au, SiO2, and resin, or when the bonding portion 30 and the bonding layer 50 are omitted and the CAP substrate 20 and the handle substrate 40 are directly bonded to the device substrate 10. In this example, similar to the cases shown in FIGS. 4 to 6, the characteristics of the crystal unit 1 predicted using the simulation model for each condition of the crystal unit 1 showed that there was no difference in the optimal conditions for the cut angle of the CAP substrate 20 and the cut angle of the handle substrate 40 under each condition.

[0033] FIG. 8 is a diagram for explaining the characteristics of the crystal unit 1 according to the present embodiment under each condition. In the example shown in the figure, the magnitude of the stress applied to the device substrate 10 is shown as an absolute value before normalization under each condition set in the same manner as in the case shown in FIG. 7. In the example shown in the figure, the magnitude of the stress applied to the device substrate 10 is, in ascending order, when the recess 21 is formed in the CAP substrate 20, when the bonding portion 30 is omitted, when the main component of the material of the bonding portion 30 is Au, when the main component of the material of the bonding portion 30 is resin, and when the main component of the material of the bonding portion 30 is SiO2. On the other hand, in the example shown in the figure, when the recess 21 is not formed in the CAP substrate 20, the magnitude of the stress applied to the device substrate 10 is, in ascending order, when the main component of the material of the bonding portion 30 is Au, when the bonding portion 30 is omitted, when the main component of the material of the bonding portion 30 is resin, and when the main component of the material of the bonding portion 30 is SiO2. That is, in the crystal unit 1 according to the present embodiment, when the recess 21 is formed in the CAP substrate 20, the main component of the material of the bonding portion 30 is preferably SiO2, more preferably the main component of the material of the bonding portion 30 is resin, more preferably the main component of the material of the bonding portion 30 is Au, and more preferably the bonding portion 30 is omitted and the CAP substrate 20 and the device substrate 10 are directly bonded. On the other hand, in the crystal unit 1 according to the present embodiment, when the recess 21 is not formed in the CAP substrate 20, the main component of the material of the bonding portion 30 is preferably SiO2, more preferably the main component of the material of the bonding portion 30 is resin, more preferably the bonding portion 30 is omitted and the CAP substrate 20 and the device substrate 10 are directly bonded, and more preferably the main component of the material of the bonding portion 30 is Au. Similarly, in the example shown in the same figure, when a recess 21 is formed in the CAP substrate 20, the stress applied to the device substrate 10 is, in order of increasing magnitude, when the bonding layer 50 is omitted, when the main component of the material of the bonding layer 50 is Au, when the main component of the material of the bonding layer 50 is resin, and when the main component of the material of the bonding layer 50 is SiO2.On the other hand, in the example shown in the figure, when the recess 21 is not formed in the CAP substrate 20, the stress applied to the device substrate 10 is, in ascending order, when the main component of the material of the bonding layer 50 is Au, when the bonding layer 50 is omitted, when the main component of the material of the bonding layer 50 is resin, and when the main component of the material of the bonding layer 50 is SiO2. That is, in the crystal unit 1 according to this embodiment, when the recess 21 is formed in the CAP substrate 20, it is preferable that the main component of the material of the bonding layer 50 is SiO2, it is more preferable that the main component of the material of the bonding layer 50 is resin, it is more preferable that the main component of the material of the bonding layer 50 is Au, and it is more preferable that the bonding layer 50 is omitted and the handle substrate 40 and the device substrate 10 are directly bonded. On the other hand, in the quartz crystal resonator 1 according to this embodiment, when the recess 21 is not formed in the CAP substrate 20, it is preferable that the main component of the material of the bonding layer 50 is SiO2, it is preferable that the main component of the material of the bonding layer 50 is resin, it is more preferable to omit the bonding layer 50 and directly bond the handle substrate 40 and the device substrate 10, and it is more preferable that the main component of the material of the bonding layer 50 is Au.

[0034] The quartz crystal resonator 1 according to this embodiment includes a quartz crystal blank 11, a device substrate 10 including a first excitation electrode 14a provided on a first main surface 12a of the quartz crystal blank 11, and a second excitation electrode 14b provided on a second main surface 12b of the quartz crystal blank 11, a CAP substrate 20 having external terminals and bonded to the first main surface 12a of the quartz crystal blank 11, and a handle substrate 40 bonded to the second main surface 12b of the quartz crystal blank 11. The device substrate 10 has a main surface defined by a first base axis and a second base axis intersecting the first base axis. When the third axis is inclined around the first axis by a first predetermined angle among the first, second, and third axes that are intersecting each other and are the crystal axes of the quartz crystal, the first axis corresponds to the first base axis and the first tilt axis corresponds to the second base axis. The first predetermined angle is any angle included in the angle range of -90 degrees or more and -60 degrees or less, and the angle range of 80 degrees or more and 90 degrees or less. This makes it possible to reduce the stress applied to the device substrate 10 from the mounting substrate 130 when the crystal unit 1 is mounted on the mounting substrate 130.

[0035] The above embodiment may be modified as follows. In the above embodiment, as shown in FIG. 9, the quartz crystal unit 1 has the device substrate 10 and the handle substrate 40 directly bonded to each other without a bonding layer 50, and the handle substrate 40 may have a recess 41 that forms a space in which the quartz crystal blank 11 vibrates.

[0036] In the above embodiment, as shown in FIG. 10 , in the quartz crystal unit 1, the first main surface 12a of the quartz crystal blank 11 is joined to the CAP substrate 20 via a first bonding portion 30A, and the second main surface 12b of the quartz crystal blank 11 is joined to the handle substrate 40 via a second bonding portion 50A, and the first bonding portion 30A and the second bonding portion 50A may form a space in which the quartz crystal blank 11 vibrates.

[0037] The following describes some or all of the embodiments of the present invention and their effects. Note that the present invention is not limited to the following descriptions.

[0038] FIG. 8 is a diagram for explaining the characteristics of the crystal unit 1 according to the present embodiment under each condition. In the example shown in the figure, the magnitude of the stress applied to the device substrate 10 is shown as an absolute value before normalization under each condition set in the same manner as in the case shown in FIG. 7. In the example shown in the figure, the magnitude of the stress applied to the device substrate 10 is, in ascending order, when the recess 21 is formed in the CAP substrate 20, when the bonding portion 30 is omitted, when the main component of the material of the bonding portion 30 is Au, when the main component of the material of the bonding portion 30 is resin, and when the main component of the material of the bonding portion 30 is SiO2. On the other hand, in the example shown in the figure, when the recess 21 is not formed in the CAP substrate 20, the magnitude of the stress applied to the device substrate 10 is, in ascending order, when the main component of the material of the bonding portion 30 is Au, when the bonding portion 30 is omitted, when the main component of the material of the bonding portion 30 is resin, and when the main component of the material of the bonding portion 30 is SiO2. That is, in the crystal unit 1 according to the present embodiment, when the recess 21 is formed in the CAP substrate 20, the main component of the material of the bonding portion 30 is preferably SiO2, more preferably the main component of the material of the bonding portion 30 is resin, more preferably the main component of the material of the bonding portion 30 is Au, and more preferably the bonding portion 30 is omitted and the CAP substrate 20 and the device substrate 10 are directly bonded. On the other hand, in the crystal unit 1 according to the present embodiment, when the recess 21 is not formed in the CAP substrate 20, the main component of the material of the bonding portion 30 is preferably SiO2, more preferably the main component of the material of the bonding portion 30 is resin, more preferably the bonding portion 30 is omitted and the CAP substrate 20 and the device substrate 10 are directly bonded, and more preferably the main component of the material of the bonding portion 30 is Au. Similarly, in the example shown in the same figure, when a recess 21 is formed in the CAP substrate 20, the stress applied to the device substrate 10 is, in order of increasing magnitude, when the bonding layer 50 is omitted, when the main component of the material of the bonding layer 50 is Au, when the main component of the material of the bonding layer 50 is resin, and when the main component of the material of the bonding layer 50 is SiO2.On the other hand, in the example shown in the figure, when the recess 21 is not formed in the CAP substrate 20, the stress applied to the device substrate 10 is, in ascending order, when the main component of the material of the bonding layer 50 is Au, when the bonding layer 50 is omitted, when the main component of the material of the bonding layer 50 is resin, and when the main component of the material of the bonding layer 50 is SiO2. That is, in the crystal unit 1 according to this embodiment, when the recess 21 is formed in the CAP substrate 20, the main component of the material of the bonding layer 50 is preferably SiO2, more preferably the main component of the material of the bonding layer 50 is resin, more preferably the main component of the material of the bonding layer 50 is Au, and it is more preferable to omit the bonding layer 50 and directly bond the handle substrate 40 and the device substrate 10. On the other hand, in the crystal unit 1 according to this embodiment, when the recess 21 is not formed in the CAP substrate 20, the main component of the material of the bonding layer 50 is preferably SiO2, and the main component of the material of the bonding layer 50 is resin. twist It is preferable to omit the bonding layer 50 and directly bond the handle substrate 40 and the device substrate 10, and it is more preferable that the main component of the material of the bonding layer 50 is Au.

[0039] According to one aspect of the present invention, a piezoelectric vibrator is provided in which a second quartz substrate has a main surface defined by a third basis axis and a fourth basis axis that intersects with the third basis axis, and when the third axis is tilted around the first axis by a second predetermined angle as a second tilt axis, of the first axis, second axis, and third axis that are intersecting crystal axes of quartz, the first axis corresponds to the third basis axis and the second tilt axis corresponds to the fourth basis axis, and the second predetermined angle is any angle within the angle range of -90 degrees or more and -30 degrees or less, and 30 degrees or more and 90 degrees or less.

[0040] According to one aspect of the present invention, there is provided a piezoelectric vibrator, in which a first quartz crystal substrate has a recess on a surface opposite to a first surface of the piezoelectric piece.

[0041] According to one aspect of the present invention, there is provided a piezoelectric vibrator in which a first surface of a piezoelectric piece and a first quartz crystal substrate are directly bonded to each other.

[0042] According to one aspect of the present invention, there is provided a piezoelectric vibrator in which a first surface of a piezoelectric piece and a first quartz crystal substrate are bonded via a first bonding material, the first bonding material containing Au as a main component.

[0043] According to one aspect of the present invention, there is provided a piezoelectric vibrator in which a first surface of a piezoelectric piece and a first quartz crystal substrate are bonded via a first bonding material, the first bonding material containing SiO2 as a main component.

[0044] According to one aspect of the present invention, there is provided a piezoelectric vibrator in which a first surface of a piezoelectric piece and a first quartz crystal substrate are bonded via a first bonding material, the first bonding material containing a resin as a main component.

[0045] According to one aspect of the present invention, there is provided a piezoelectric vibrator in which a second surface of the piezoelectric piece and a second quartz crystal substrate are directly bonded to each other.

[0046] According to one aspect of the present invention, there is provided a piezoelectric vibrator in which a second surface of the piezoelectric piece and a second quartz crystal substrate are bonded via a second bonding material, the second bonding material containing Au as a main component.

[0047] According to one aspect of the present invention, there is provided a piezoelectric vibrator in which a second surface of the piezoelectric piece and a second quartz crystal substrate are bonded via a second bonding material, the second bonding material containing SiO2 as a main component.

[0048] According to one aspect of the present invention, there is provided a piezoelectric vibrator in which a second surface of the piezoelectric piece and a second quartz crystal substrate are bonded via a second bonding material, the second bonding material containing a resin as a main component.

[0049] According to one aspect of the present invention, a piezoelectric vibrator is provided in which a second surface of a piezoelectric piece and a second quartz crystal substrate are bonded via a second bonding material, and the second bonding material has a recess that forms a space in which the piezoelectric piece vibrates.

[0050] According to one aspect of the present invention, a piezoelectric vibrator is provided, in which the second quartz crystal substrate has a recess that defines a space in which the piezoelectric piece vibrates.

[0051] According to one aspect of the present invention, a piezoelectric vibrator is provided in which a first surface of a piezoelectric piece and a first quartz crystal substrate are bonded via a first bonding material, and a second surface of the piezoelectric piece and a second quartz crystal substrate are bonded via a second bonding material, the first bonding material and the second bonding material forming a space in which the piezoelectric piece vibrates.

[0052] According to one aspect of the present invention, there is provided a piezoelectric vibrator, wherein the piezoelectric piece is an AT-cut quartz crystal substrate.

[0053] As described above, according to one aspect of the present invention, it is possible to reduce the stress transmitted to the piezoelectric vibration element.

[0054] The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention may be modified / improved without departing from the spirit thereof, and equivalents are also included in the present invention. That is, those in which a person skilled in the art appropriately adds design changes to each embodiment are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements and their arrangements, materials, conditions, shapes, sizes, etc. of each embodiment are not limited to those exemplified, and can be appropriately changed. In addition, the elements of each embodiment can be combined to the extent technically possible, and those combinations of these are also included in the scope of the present invention as long as they include the characteristics of the present invention. [Explanation of symbols]

[0055] 1...quartz crystal unit, 10...device substrate, 11...quartz crystal blank, 11A...vibration portion, 11B...groove portion, 11C...holding portion, 12a...first main surface, 12b...second main surface, 14a...first excitation electrode, 14b...second excitation electrode, 15a, 15b...drawing electrodes, 16a, 16b...connection electrodes, 17...via electrodes, 20...CAP substrate, 30...joint portion, 30A...first joint portion, 40...handle substrate, 41...recess, 50...joint layer, 50A...second joint portion, 51...recess, 100...quartz crystal oscillator, 130...mounting substrate, 140...cover member, 153...solder, 156...electronic component, 166...bonding wire.

Claims

1. a piezoelectric vibration element including a piezoelectric piece, a first excitation electrode provided on a first surface of the piezoelectric piece, and a second excitation electrode provided on a second surface of the piezoelectric piece; a first quartz crystal substrate having an external terminal and bonded to the first surface of the piezoelectric piece; a second quartz crystal substrate bonded to the second surface of the piezoelectric piece; Equipped with the first quartz substrate has a main surface defined by a first base axis and a second base axis intersecting with the first base axis, and when an axis obtained by inclining the third axis by a first predetermined angle around the first axis among the first axis, second axis, and third axis which are crystal axes of quartz, is defined as a first tilt axis, the first axis corresponds to the first base axis and the first tilt axis corresponds to the second base axis; The first predetermined angle is any angle included in an angle range of −80 degrees or more and −60 degrees or less. Piezoelectric vibrator.

2. the second quartz substrate has a main surface defined by a third basis axis and a fourth basis axis intersecting with the third basis axis, and when an axis obtained by inclining the third axis by a second predetermined angle around the first axis among the first axis, the second axis, and the third axis which are intersecting with each other and which are crystal axes of quartz is defined as a second tilt axis, the first axis corresponds to the third basis axis and the second tilt axis corresponds to the fourth basis axis; The second predetermined angle is any angle included in an angle range of -90 degrees or more and -30 degrees or less, and an angle range of 30 degrees or more and 90 degrees or less. The piezoelectric vibrator according to claim 1 .

3. the first quartz crystal substrate has a recess on a surface opposite to the first surface of the piezoelectric piece; 3. The piezoelectric vibrator according to claim 1 or 2.

4. The first surface of the piezoelectric piece and the first quartz crystal substrate are directly bonded to each other. The piezoelectric vibrator according to claim 1 .

5. the first surface of the piezoelectric piece and the first quartz crystal substrate are bonded via a first bonding material; The first bonding material contains Au as a main component. The piezoelectric vibrator according to claim 1 .

6. the first surface of the piezoelectric piece and the first quartz crystal substrate are bonded via a first bonding material; The first bonding material is SiO 2 Contains as the main component The piezoelectric vibrator according to claim 1 .

7. the first surface of the piezoelectric piece and the first quartz crystal substrate are bonded via a first bonding material; The first bonding material contains a resin as a main component. The piezoelectric vibrator according to claim 1 .

8. The second surface of the piezoelectric piece and the second quartz crystal substrate are directly bonded to each other. The piezoelectric vibrator according to claim 1 .

9. the second surface of the piezoelectric piece and the second quartz crystal substrate are bonded via a second bonding material; The second bonding material contains Au as a main component. The piezoelectric vibrator according to claim 1 .

10. the second surface of the piezoelectric piece and the second quartz crystal substrate are bonded via a second bonding material; The second bonding material is SiO 2 Contains as the main component The piezoelectric vibrator according to claim 1 .

11. the second surface of the piezoelectric piece and the second quartz crystal substrate are bonded via a second bonding material; The second bonding material contains a resin as a main component. The piezoelectric vibrator according to claim 1 .

12. the second surface of the piezoelectric piece and the second quartz crystal substrate are bonded via a second bonding material; The second bonding material has a recess that forms a space in which the piezoelectric piece vibrates. The piezoelectric vibrator according to claim 1 .

13. The second quartz crystal substrate has a recess that defines a space in which the piezoelectric piece vibrates. The piezoelectric vibrator according to claim 1 .

14. the first surface of the piezoelectric piece and the first quartz crystal substrate are bonded via a first bonding material; the second surface of the piezoelectric piece and the second quartz crystal substrate are bonded via a second bonding material; The first bonding material and the second bonding material form a space in which the piezoelectric piece vibrates. The piezoelectric vibrator according to claim 1 .

15. The piezoelectric piece is an AT-cut quartz crystal substrate. The piezoelectric vibrator according to claim 1 .

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