piezoelectric oscillator

Abstract

The piezoelectric vibrator (1) of the present invention comprises: a piezoelectric vibrating element (10) having a piezoelectric sheet (11) and excitation electrodes (14a, 14b) configured to apply a voltage to the piezoelectric sheet (11); a base member (30) on which the piezoelectric vibrating element (10) is mounted; a cover member (40) having an internal space provided between the base member (30) and the cover member (40) for housing the piezoelectric vibrating element (10); and a joint (50) for joining the base member (30) and the cover member (40) to seal the internal space, the joint (50) comprising an organic adhesive, which, when applied along the base member... When the direction in which the main surface (31A) of the component (30) intersects with the circumferential direction of the joint (50) is set as the width direction, and the direction in which the main surface (31A) of the base component (30) intersects with the thickness direction is set as the thickness direction, when the volume of the internal space is set as the internal volume V, the dimension in the width direction of the joint (50) is set as the sealing width W, the dimension in the thickness direction of the joint (50) is set as the sealing thickness t, the dimension in the circumferential direction of the joint (50) is set as the circumference Lc, and the product of the sealing thickness t and the circumference Lc is set as the sealing cross-sectional area S, the relationship S / V / W≤6 holds true.

Description

Technical Field

[0001] This invention relates to piezoelectric vibrators. Background Technology

[0002] Piezoelectric vibration elements are used in various electronic devices such as mobile communication terminals, communication base stations, and home appliances, as well as in applications such as timing devices, sensors, or oscillators. A piezoelectric vibration element comprises: a piezoelectric sheet having a pair of main surfaces, and a pair of excitation electrodes disposed on the pair of main surfaces of the piezoelectric sheet.

[0003] For example, Patent Document 1 discloses a piezoelectric vibration member comprising: a substrate, a piezoelectric vibrator held on the substrate, and a cap fixed to the substrate by an adhesive.

[0004] Patent Document 1: Japanese Patent No. 4947213.

[0005] However, according to the piezoelectric vibration component described in Patent Document 1, atmospheric and water vapor can penetrate through the adhesive, resulting in frequency variations due to increased internal pressure and electrode oxidation. Summary of the Invention

[0006] The present invention was made in view of the following circumstances, and its object is to provide a piezoelectric oscillator capable of suppressing frequency variations.

[0007] One aspect of the piezoelectric vibrator of the present invention comprises: a piezoelectric vibrating element having a piezoelectric sheet and an excitation electrode configured to apply a voltage to the piezoelectric sheet; a base member on which the piezoelectric vibrating element is mounted; a cover member having an internal space disposed between the base member and the cover member accommodating the piezoelectric vibrating element; and a joint member joining the base member and the cover member to seal the internal space. The joint member comprises an organic adhesive. When the direction intersecting the main surface of the base member and the circumferential direction of the joint member is defined as the width direction, and the direction intersecting the main surface of the base member is defined as the thickness direction, when the volume of the internal space is defined as the internal volume V, the dimension of the joint member in the width direction is defined as the sealing width W, the dimension of the joint member in the thickness direction is defined as the sealing thickness t, the dimension of the joint member in the circumferential direction is defined as the circumference Lc, and the product of the sealing thickness t and the circumference Lc is defined as the sealing cross-sectional area S, the relationship S / V / W ≤ 6 is satisfied.

[0008] According to the present invention, a piezoelectric oscillator capable of suppressing frequency variations can be provided. Attached Figure Description

[0009] Figure 1 This is an exploded perspective view of the crystal oscillator according to the first embodiment.

[0010] Figure 2 This is a cross-sectional view of the crystal oscillator according to the first embodiment.

[0011] Figure 3 This is an enlarged cross-sectional view of the joint of the crystal oscillator in the first embodiment.

[0012] Figure 4 This is a top view of the crystal oscillator according to the first embodiment.

[0013] Figure 5 It is a graph showing the frequency variation based on the first embodiment.

[0014] Figure 6 This is a cross-sectional view of the crystal oscillator according to the second embodiment.

[0015] Figure 7 This is an enlarged cross-sectional view of the joint of the crystal oscillator in the second embodiment.

[0016] Figure 8 This is a cross-sectional view of the crystal oscillator according to the third embodiment.

[0017] Figure 9 This is an enlarged cross-sectional view of the joint of the crystal oscillator in the third embodiment.

[0018] Figure 10 This is a cross-sectional view of the crystal oscillator according to the fourth embodiment.

[0019] Figure 11 This is a graph showing the variation of the equivalent series resistance based on the embodiment of the first implementation. Detailed Implementation

[0020] The embodiments of the present invention will be described below. In the following drawings, the same or similar constituent elements are indicated by the same or similar reference numerals. The drawings are illustrative, and the dimensions and shapes of the parts are schematic structures; they should not be interpreted as limiting the scope of the present invention to these embodiments.

[0021] In the accompanying drawings, to clarify the relationships between the drawings and facilitate understanding of the positional relationships of the components, an orthogonal coordinate system consisting of the X-axis, Y'-axis, and Z'-axis is sometimes used. The X-axis, Y'-axis, and Z'-axis correspond to each other in the accompanying drawings. The X-axis, Y'-axis, and Z'-axis correspond to the crystal axes of the crystal wafer 11, which will be described later. The X-axis corresponds to the electrical axis (polar axis) of the crystal, the Y-axis corresponds to the mechanical axis of the crystal, and the Z-axis corresponds to the optical axis of the crystal. The Y'-axis and Z'-axis are obtained by rotating the Y-axis and Z-axis counterclockwise by θ degrees around the X-axis when viewed from the positive direction of the X-axis.

[0022] In the following description, the direction parallel to the X-axis is referred to as the "X-axis direction," the direction parallel to the Y'-axis is referred to as the "Y'-axis direction," and the direction parallel to the Z'-axis is referred to as the "Z'-axis direction." Furthermore, the direction of the arrowheads on the X, Y', and Z' axes is referred to as "positive" or "+ (positive)," and the direction opposite to the arrowhead is referred to as "negative" or "- (negative)." For convenience, the +Y'-axis direction will be described as the upward direction, and the -Y'-axis direction as the downward direction, but the upward and downward directions of the crystal oscillator 10 and the crystal oscillator 1 are not limited. Additionally, the plane defined by the X-axis and Z'-axis is referred to as the Z'X plane, and the same applies to the planes defined by other axes.

[0023] <First Implementation>

[0024] First, refer to Figure 1 as well as Figure 2 The structure of the crystal oscillator according to the first embodiment will be described. Figure 1 This is an exploded perspective view of the crystal oscillator according to the first embodiment. Figure 2 This is a cross-sectional view of the crystal oscillator according to the first embodiment.

[0025] The crystal oscillator 1 includes a crystal resonating element 10, a base component 30, a cover component 40, and a joint 50. Hereinafter, the Y' axis direction will be defined as the "thickness direction" of the crystal resonating element 10.

[0026] The crystal oscillator 1 is used, for example, as a component of a temperature-compensated crystal oscillator (TCXO), a voltage-controlled crystal oscillator (VCXO), or an oven-controlled crystal oscillator (OCXO).

[0027] The crystal vibration element 10 is an electromechanical energy conversion element that converts electrical energy and mechanical energy into each other through the piezoelectric effect.

[0028] The crystal resonator 10 is excited at a predetermined frequency based on the applied alternating voltage. The crystal resonator 10 is maintained in the vibration space disposed between the base member 30 and the cover member 40 to be capable of vibration. The main vibration of the crystal resonator 10 is the thickness shear vibration mode.

[0029] Furthermore, the main vibration of the crystal resonator is not limited to the thickness shear vibration mode; for example, it can also be the thickness longitudinal vibration mode, the extension vibration mode, the length vibration mode, or the bending vibration mode.

[0030] like Figure 1 As shown, the crystal oscillating element 10 includes: a thin-film crystal element 11; a first excitation electrode 14a and a second excitation electrode 14b forming a pair of excitation electrodes; a first lead-out electrode 15a and a second lead-out electrode 15b forming a pair of lead-out electrodes; and a first connecting electrode 16a and a second connecting electrode 16b forming a pair of connecting electrodes.

[0031] The wafer 11 has an upper surface 11A and a lower surface 11B that are opposite to each other. The upper surface 11A is located on the side opposite to the top wall portion 41 of the cover member 40 (described later). The lower surface 11B is located on the side opposite to the base member 30. The upper surface 11A and the lower surface 11B correspond to a pair of main surfaces of the wafer 11.

[0032] The crystal sheet 11 is, for example, an AT-cut type crystal. The AT-cut type crystal is formed with the XZ' plane as the main plane and the direction parallel to the Y' axis as the thickness. As an example, when the upper surface 11A is viewed from above in the thickness direction (hereinafter referred to as "top view"), the shape of the crystal sheet 11 (hereinafter referred to as "planar shape") is a rectangle having a pair of short sides extending along the Z' axis and a pair of long sides extending along the X axis. As an example, the shape of the crystal sheet 11 is a flat plate with uniform thickness.

[0033] Furthermore, the planar shape of the crystal sheet is not limited to the above-mentioned aspects. For example, the planar shape of the crystal sheet can also be a rectangle with a long side extending along the Z' axis and a short side extending along the X axis, or a square with a side extending along the Z' axis and a side extending along the X axis. The planar shape of the crystal sheet can also be a rectangle with sides extending along directions intersecting the Z-axis and Z' axis. The planar shape of the crystal sheet can also be polygonal, circular, elliptical, or a combination thereof. In addition, the crystal sheet is not limited to a flat plate shape. The crystal sheet can also have a mesa-like structure or an inverted mesa-like structure with concave and convex surfaces on at least one of its upper and lower surfaces. The crystal sheet can also be a convex structure with a continuously varying thickness, or a sloping structure with a discontinuously varying thickness.

[0034] The AT-cut crystal sheet 11 is a crystal sheet cut by rotating the Y-axis and Z-axis, which are the crystal axes of the Synthetic Quartz Crystal, around the X-axis in the direction from the Y-axis to the Z-axis by 35 degrees 15 minutes ± 1 minute 30 seconds, respectively, as the Y' axis and Z' axis, and using the XZ' plane as the main plane.

[0035] The crystal resonator 10 using the AT-cut crystal wafer 11 exhibits high frequency stability over a wide temperature range. Furthermore, the AT-cut crystal resonator also demonstrates excellent time-varying characteristics and can be manufactured at low cost. Moreover, the AT-cut crystal resonator utilizes a thickness shear vibration mode as its primary vibration.

[0036] Furthermore, the cutting angle of the crystal wafer is not limited to the above. The rotation angles of the Y' and Z' axes in the AT-cut crystal wafer 11 can also be tilted within a range of -5 degrees or more, or +15 degrees, starting from 35 degrees 15 minutes. Additionally, the cutting angle of the crystal wafer can also utilize different cuts besides AT cutting, such as BT cutting, GT cutting, and SC cutting. Furthermore, the main vibration mode of the crystal resonator is not limited to the thickness shear vibration mode; for example, it can also be thickness longitudinal vibration, spreading vibration, length vibration, or bending vibration.

[0037] The first excitation electrode 14a and the second excitation electrode 14b apply an alternating voltage to the water crystal 11, causing the water crystal 11 to vibrate. The first excitation electrode 14a and the second excitation electrode 14b are disposed in the center of the water crystal 11 when viewed from above. The first excitation electrode 14a is disposed on the upper surface 11A, and the second excitation electrode 14b is disposed on the lower surface 11B. The first excitation electrode 14a and the second excitation electrode 14b are positioned opposite each other in the Y' axis direction, separated by the water crystal 11.

[0038] The first excitation electrode 14a has a planar shape that is rectangular, having a short side extending along the Z' axis and a long side extending along the X axis. Additionally, the first excitation electrode 14a has a thickness in the Y' axis direction. The second excitation electrode 14b has the same shape.

[0039] Furthermore, the planar shapes of the first and second excitation electrodes are not limited to those described above. The planar shapes of the first and second excitation electrodes can also be rectangles with a short side extending along the X-axis, or squares with a side extending along the X-axis and a side extending along the Z'-axis. The planar shapes of the first and second excitation electrodes can also be rectangles with sides extending along directions intersecting the Z-axis and Z'-axis. The planar shapes of the first and second excitation electrodes can also be polygonal, circular, elliptical, or combinations thereof.

[0040] The first lead-out electrode 15a electrically connects the first excitation electrode 14a and the first connecting electrode 16a, and the second lead-out electrode 15b electrically connects the second excitation electrode 14b and the second connecting electrode 16b. The first lead-out electrode 15a extends from the upper surface 11A of the water-filled wafer 11 to the lower surface 11B, and the second lead-out electrode 15b is disposed on the lower surface 11B of the water-filled wafer 11.

[0041] The first connecting electrode 16a and the second connecting electrode 16b electrically connect the crystal oscillating element 10 to the base component 30. The first connecting electrode 16a and the second connecting electrode 16b are disposed on the lower surface 11B of the crystal wafer 11.

[0042] The first excitation electrode 14a, the first lead-out electrode 15a, and the first connecting electrode 16a are integrally disposed. The second excitation electrode 14b, the second lead-out electrode 15b, and the second connecting electrode 16b are disposed similarly. A set of electrodes consisting of the first excitation electrode 14a, the first lead-out electrode 15a, and the first connecting electrode 16a is designated as the first electrode, and a set of electrodes consisting of the second excitation electrode 14b, the second lead-out electrode 15b, and the second connecting electrode 16b is designated as the second electrode.

[0043] The first and second electrodes are, for example, multilayer structures formed by stacking a base layer and a surface layer in this order. For instance, the base layer is a chromium (Cr) layer with good adhesion to the wafer 11, and the surface layer is a chemically stable gold (Au) layer. The first and second electrodes may also contain titanium (Ti), aluminum (Al), molybdenum (Mo), or an aluminum-copper alloy (AlCu) with aluminum (Al) as the main component. The first and second electrodes may also be single-layer structures.

[0044] The base component 30 holds the crystal vibrating element 10 in a position to vibrate. The base component 30 includes a base 31, connecting electrodes 33a and 33b, lead-out electrodes 34a and 34b, and external electrodes 35a, 35b, 35c, and 35d.

[0045] The substrate 31 is a plate-shaped insulator having an upper surface 31A and a lower surface 31B that are opposed to each other in the thickness direction. The upper surface 31A and the lower surface 31B correspond to a pair of main surfaces of the substrate 31. The upper surface 31A is located on the side opposite to the crystal resonator 10 and the cover member 40, and corresponds to the mounting surface for mounting the crystal resonator 10. From the viewpoint of suppressing the thermal stress acting on the crystal resonator 10 from the substrate 31 due to thermal history such as reflow, it is preferable that the substrate 31 is made of a heat-resistant material. According to the same viewpoint, the substrate 31 may also be made of a material having a thermal expansion coefficient close to that of the crystal wafer 11. The substrate 31 may be made of, for example, a ceramic substrate, a glass substrate, or a crystal substrate.

[0046] The corner portion of the substrate 31 has a cut-out side surface that is partially formed in a cylindrical curved surface (also known as a crenellated shape). However, the shape of the corner portion of the substrate 31 is not limited to this. The corner portion of the substrate may also have a cut-out side surface formed in a prism shape, or it may be a roughly right-angled corner portion without a cut.

[0047] Connecting electrodes 33a and 33b are electrically connected to the crystal resonator 10. Connecting electrode 33a is electrically connected to the first connecting electrode 16a of the crystal resonator 10, and connecting electrode 33b is connected to the second connecting electrode 16b of the crystal resonator 10.

[0048] Lead-out electrode 34a electrically connects connecting electrode 33a and external electrode 35a, and lead-out electrode 34b electrically connects connecting electrode 33b and external electrode 35b. Lead-out electrodes 34a and 34b are disposed on the upper surface 31A of substrate 31.

[0049] External electrodes 35a and 35b are external terminals used to electrically connect the crystal resonator 10 to an external substrate (not shown). External electrode 35a electrically connects the first excitation electrode 14a of the crystal resonator 10 to the external substrate, and external electrode 35b electrically connects the second excitation electrode 14b of the crystal resonator 10 to the external substrate. One of the external electrodes 35c and 35d is a grounding electrode that grounds the cover member 40, and the other is a virtual electrode that is not electrically connected to the crystal resonator 10 or the cover member 40. External electrodes 35a, 35b, 35c, and 35d are continuously provided from the cut sides of the four corners of the base 31, extending across to the lower surface 31B. Figure 1 In the example shown, external electrodes 35a and 35b are located at opposite corners of the upper surface 31A of the substrate 31, and external electrodes 35c and 35d are located at the other opposite corner of the upper surface 31A of the substrate 31.

[0050] Furthermore, the functions and positions of external electrodes 35a, 35b, 35c, and 35d are not limited to those described above. Both external electrodes 35c and 35d can be grounded electrodes, or both can be virtual electrodes. External electrodes 35c and 35d can also be omitted. External electrode 35c can be electrically connected to one of external electrodes 35a and 35b, and external electrode 35d can be electrically connected to the other of external electrodes 35a and 35b. In a top view, external electrodes 35a and 35b can be located on the same short side or the same long side of the upper surface 31A of the substrate 31.

[0051] Conductive retaining members 36a and 36b are provided on the side of the crystal vibrating element 10 of the base component 30. The conductive retaining members 36a and 36b electrically connect the base component 30 and the crystal vibrating element 10 and mechanically retain the crystal vibrating element 10. The conductive retaining member 36a electrically connects the first connecting electrode 16a of the crystal vibrating element 10 to the connecting electrode 33a of the base component 30. The conductive retaining member 36b electrically connects the second connecting electrode 16b of the crystal vibrating element 10 to the connecting electrode 33b of the base component 30. The conductive retaining members 36a and 36b are cured products of conductive adhesives containing thermosetting resins, photocurable resins, etc. The main component of the conductive retaining members 36a and 36b is, for example, silicone resin. The conductive retaining members 36a and 36b contain conductive particles, and for example, metal particles containing silver (Ag) are used as these conductive particles.

[0052] The main components of the conductive retaining components 36a and 36b are not limited to silicone resin; for example, they can also be epoxy resin, acrylic resin, etc. Furthermore, the conductive particles contained in the conductive retaining components 36a and 36b are not limited to silver particles; they can also be formed from other metals, conductive ceramics, conductive organic materials, etc. The conductive retaining components 36a and 36b may also contain conductive polymers.

[0053] The cover member 40 forms an internal space 39 between itself and the base member 30, housing the crystal resonator 10. The cover member 40 has a top wall portion 41 and side wall portions 42 extending and protruding from the outer periphery of the top wall portion 41 toward the base member 30. The top wall portion 41 faces the base member 30 across the crystal resonator 10 in the Y' axis direction. The side wall portions 42 surround the crystal resonator 10 at intervals in the XZ' plane direction. The cover member 40 is preferably made of a conductive material, and more preferably a metal material with high airtightness. The cover member 40 being made of a conductive material provides electromagnetic shielding by reducing the entry and exit of electromagnetic waves into the internal space 39. From the viewpoint of suppressing thermal stress, the cover member 40 is preferably made of a material with a thermal expansion coefficient close to that of the base member 30, such as an Fe-Ni-Co alloy whose thermal expansion coefficient near room temperature is consistent with that of glass and ceramics over a wide temperature range. The cover component 40 is electrically connected to at least one of the external electrodes 35c, 35d via a grounding component (not shown).

[0054] Furthermore, the material of the cover component is not limited to a conductive material. The cover component can also be made of an insulating material such as ceramic. Accordingly, the electrode traversing the joint portion provided on the main surface of the base component will not experience an electrical short circuit through the cover component, thus reducing the thickness of the joint portion. When the cover component is made of ceramic, from the viewpoint of suppressing the generation of thermal stress, it is preferable to make the base body of the base component and the cover component the same material.

[0055] The joint 50 joins the base member 30 and the cover member 40, sealing the internal space 39. The joint 50 is configured to surround the crystal vibrating element 10 in a frame shape along the end of the side wall portion 42 of the cover member 40 on the side of the base member 30 (hereinafter referred to as the "front end portion"). The joint 50 is held by the front end portion of the side wall portion 42 of the cover member 40 and the upper surface 31A of the base member 30.

[0056] The joint 50 has an insulating film 52 and an organic adhesive 51.

[0057] An insulating film 52 covers the front end of the sidewall portion 42 of the cover member 40. An organic adhesive 51 bonds the insulating film 52 to the base member 30. The insulating film 52 is provided, for example, by an organic insulating material containing epoxy, vinyl, acrylic, polyurethane, or silicone resins. The organic adhesive 51 is, for example, an adhesive containing epoxy, vinyl, acrylic, polyurethane, or silicone resins. The insulating film 52 increases the contact area with the sidewall portion 42, thereby improving the bonding strength. In addition, the insulating film 52 reduces the variation in the thickness of the organic adhesive 51 caused by the positional variation of the front end of the sidewall portion 42 due to the undulations of the cover member 40. That is, the flatness of the front end of the insulating film 52 is higher than the flatness of the front end of the sidewall portion 42, thus suppressing the reduction in bonding strength and sealing performance caused by the variation in the thickness of the organic adhesive 51.

[0058] The elastic modulus of the organic adhesive 51 is, for example, 3 GPa or more and 7 GPa or less. The organic adhesive 51 may also include an insulating filler. The insulating filler functions as a spacer held between the base member 30 and the cover member 40, ensuring a certain distance between them. The material of the insulating filler is not particularly limited as long as it is an insulating material, such as resin, limestone, or clay. Resin-based insulating fillers may be, for example, spherical particles with a particle size of 3 μm or more and 100 μm or less.

[0059] Next, refer to Figure 3 as well as Figure 4 The dimensions of the joint 50 in the first embodiment will be described. Figure 3 This is an enlarged cross-sectional view of the joint of the crystal oscillator in the first embodiment. Figure 4 This is a top view of the crystal oscillator according to the first embodiment.

[0060] Regarding the joint 50, the direction in which the upper surface 31A of the base body 31 of the base member 30 intersects with the circumferential direction of the joint 50 is defined as the width direction, and the direction in which it intersects with the upper surface 31A of the base body 31 of the base member 30 is defined as the thickness direction. Furthermore, the upper surface 31A of the base body 31 is an example of the main surface of the base member 30.

[0061] The volume of the internal space 39 of the crystal oscillator 1 is defined as the internal volume V. The internal volume V is the volume of the space surrounded by the base 31 of the base member 30 and the cover member 40, and includes the volume of the crystal oscillating element 10, the conductivity holding members 36a, 36b, etc. In order to reduce the influence of gas intruding into the internal space 39 on the crystal oscillating element 10, it is preferable to increase the internal volume V.

[0062] The dimension in the width direction of the joint 50 is defined as the sealing width W. The sealing width W is the distance in the width direction between the inner side of the joint 50 on the side of the inner space 39 and the outer side of the joint 50 opposite to the inner space 39. The sealing width W is, for example, determined as the average value of the sealing width in each of a plurality of cross-sections of the joint 50, but it can also be determined as the sealing width in a cross-section at a specific location. The sealing width of the joint 50 in a certain cross-section is, for example, determined as the minimum or average value of the dimension in the width direction of the joint 50. The sealing width of the joint 50 in a certain cross-section can also be determined as the dimension in the width direction of the portion where the base member 30 contacts the joint 50. The sealing width of the joint 50 in a certain cross-section can also be determined as the dimension in the width direction of the portion where the cover member 40 contacts the joint 50. In this case, for example, the sealing width W is determined as the thickness of the cover member 40. In order to improve the difficulty of gas intrusion from the outside of the joint 50 into the inner space 39 (hereinafter referred to as "gas barrier property of the joint 50"), a larger sealing width W is preferred.

[0063] The thickness dimension of the joint 50 is defined as the sealing thickness t. The sealing thickness t is the distance in the thickness direction between the mating surfaces of the base member 30 and the joint 50, and between the mating surfaces of the cover member 40 and the joint 50. The sealing thickness t is, for example, determined as the average sealing thickness in each of a plurality of cross-sections of the joint 50, but it can also be determined as the sealing thickness in a cross-section at a specific location. The sealing thickness of the joint 50 in a certain cross-section is, for example, determined as the maximum or average value of the thickness dimension of the portion of the joint 50 sandwiched between the base member 30 and the cover member 40. To improve the gas barrier properties of the joint 50, a smaller sealing thickness t is preferred. To reduce the sealing thickness t, the flatness of the mating surface where the base member 30 contacts the joint 50 is preferably 3 μm or less, and the flatness of the mating surface at the front end of the sidewall portion 42 of the cover member 40 that faces the base member 30 and contacts the joint 50 is preferably 3 μm or less.

[0064] The circumferential dimension of the joint 50 is defined as the perimeter Lc. The perimeter Lc is the length of the outermost circumference of the outer surface of the joint 50 when viewed from above. For example, the perimeter Lc is defined as the length of the outermost circumference of the cover member 40 when viewed from above. The product of the sealing thickness t and the perimeter Lc is defined as the sealing cross-sectional area S (S = t × Lc). To improve the gas barrier properties of the joint 50, it is preferable that the perimeter Lc is small and the sealing cross-sectional area S is small.

[0065] If we summarize the internal volume V, sealing width W, and sealing cross-sectional area S, then to improve the gas barrier properties of the joint 50 and reduce the influence of gas intruding into the internal space 39, it is preferable that the parameter S / V / W is small. For example, in the crystal oscillator 1, the relationship S / V / W ≤ 6 holds true, and it is preferable that S / V / W ≤ 4 holds true. In addition, from the viewpoint of manufacturing accuracy, it is preferable that the relationship 1.5 ≤ S / V / W holds true. Furthermore, the so-called "S / V / W" is a parameter obtained by dividing S by V and then further dividing the value obtained by W, and can also be expressed as S / (V×W).

[0066] Next, refer to Figure 5 The relationship between S / V / W and frequency variation is explained. Figure 5 This is a graph showing the frequency variations based on the embodiments of the first implementation and the comparative examples. Figure 5 In the chart shown, the horizontal axis represents S / V / W. Figure 5In the chart shown, the vertical axis represents the average frequency variation Δfavg of multiple crystal resonators in the damp heat durability test based on the various embodiments of the first embodiment and the comparative examples. The conditions for this durability test were a test temperature of 60°C, a test humidity of 93%RH, and a test time of 1000 hours. The frequency variation Δf is the difference in frequency before and after the durability test. Furthermore, in a damp heat environment, the gas invading the internal space 39 of the crystal oscillator 1 increases the internal pressure of the crystal oscillator 1, which acts as resistance to the vibration of the crystal resonator 10, thus reducing the frequency. In addition, in a damp heat environment, water vapor and oxygen invading the internal space 39 of the crystal oscillator 1 oxidize the electrodes of the crystal resonator 10, increasing the mass of the crystal resonator 10, thus reducing the frequency.

[0067] (Comparative example)

[0068] The top-view dimensions of the base 31 of the base component 30 are: 1.65mm × 1.25mm.

[0069] The base 31 of the base component 30 is made of aluminum oxide.

[0070] The top-view dimensions of the cover component 40 are: 1.53mm × 1.13mm.

[0071] Material of cover component 40: Fe-Ni-Co alloy

[0072] Organic adhesive 51 is made of epoxy resin.

[0073] Elastic modulus of organic adhesive 51: 3 GPa

[0074] Internal volume V of the 39mm² interior space: 0.17mm² 3

[0075] The sealing cross-sectional area S of the joint 50 is 0.12 mm. 2

[0076] The sealing width W of the joint 50 is 0.10 mm.

[0077] S / V / W = 7.1

[0078] Δfavg = -9.0ppm

[0079] (First embodiment)

[0080] The top-view dimensions of the base 31 of the base component 30 are: 1.65mm × 1.25mm.

[0081] The base 31 of the base component 30 is made of aluminum oxide.

[0082] The top-view dimensions of the cover component 40 are: 1.53mm × 1.13mm.

[0083] Material of cover component 40: Fe-Ni-Co alloy

[0084] Organic adhesive 51 is made of epoxy resin.

[0085] The elastic modulus of organic adhesive 51 is 3 GPa to 7 GPa.

[0086] Internal volume V of the 39mm² interior space: 0.21mm² 3

[0087] The sealing cross-sectional area S of the joint 50 is 0.07 mm. 2

[0088] The sealing width W of the joint 50 is 0.07 mm.

[0089] S / V / W = 4.8

[0090] Δfavg = -5.0ppm

[0091] In the organic adhesive 51 of the first embodiment, spherical resin particles with a particle size of 10 μm are added, and the insulating film 52 is omitted.

[0092] (Second Embodiment)

[0093] The top-view dimensions of the base 31 of the base component 30 are: 1.25mm × 1.05mm.

[0094] The base 31 of the base component 30 is made of aluminum oxide.

[0095] The top-view dimensions of the cover component 40 are: 1.24mm × 1.04mm.

[0096] Material of cover component 40: ceramic

[0097] Organic adhesive 51 is made of epoxy resin.

[0098] Elastic modulus of organic adhesive 51: 7 GPa

[0099] Internal volume V of 39 mm: 0.45 mm 3

[0100] The sealing cross-sectional area S of the joint 50 is 0.18 mm. 2

[0101] The sealing width W of the joint 50 is 0.11 mm.

[0102] S / V / W = 3.6

[0103] Δfavg = -4.0ppm

[0104] (Third embodiment)

[0105] The top view dimensions of the base 31 of the base component 30 are: 2.05mm × 1.65mm.

[0106] The base 31 of the base component 30 is made of aluminum oxide.

[0107] The top-view dimensions of the cover component 40 are: 1.82mm × 1.62mm.

[0108] Material of cover component 40: Fe-Ni-Co alloy

[0109] Organic adhesive 51 is made of epoxy resin.

[0110] Elastic modulus of organic adhesive 51: 7 GPa

[0111] The internal volume V of the 39mm² interior space is 0.2mm². 3

[0112] The sealing cross-sectional area S of the joint 50 is 0.04 mm. 2

[0113] The sealing width W of the joint 50 is 0.14 mm.

[0114] S / V / W = 1.4

[0115] Δfavg = -3.0ppm

[0116] In the third embodiment, the electrical connection between the connecting electrodes 33a and 33b of the base component 30 and the external electrodes 35a and 35b is achieved by a through electrode penetrating the base 31 in the thickness direction, without forming a lead-out electrode overlapping with the joint 50. As a result, the flatness of the joint surface of the base component 30 joined by the joint 50 is improved. Due to the improved flatness of the joint surface, the sealing thickness t, which is the average thickness of the joint 50, decreases, and the sealing cross-sectional area S, which is proportional to the sealing thickness t, decreases.

[0117] The inventors discovered a relationship between the parameter S / V / W and the average value Δfavg of the frequency variation. Figure 5 The correlation is as shown. The smaller the S / V / W ratio, the closer Δfavg is to 0; the larger the S / V / W ratio, the smaller Δfavg is. Here, "Δfavg decreasing" means that the absolute value of Δfavg, which is a negative value, increases. As S / V / W increases, the change in Δfavg relative to the change in S / V / W increases. The lower the gas barrier properties of the joint 50, the smaller Δfavg is. A small Δfavg indicates a large frequency variation under humid and hot conditions. From... Figure 5As shown in the charts, the smaller the S / V / W ratio, the smaller the frequency variation under humid and hot conditions, and the higher the humid and hot durability. For example, by ensuring that S / V / W ≤ 6.0, it is possible to set -7.0ppm ≤ Δfavg. That is, the frequency variation at 60℃, 93%RH, and after 1000 hours can be suppressed to below 7.0ppm. Furthermore, by ensuring that S / V / W ≤ 4.0, it is possible to set -4.1ppm ≤ Δfavg. That is, the frequency variation at 60℃, 93%RH, and after 1000 hours can be suppressed to below 4.1ppm.

[0118] Next, refer to Figure 11 The relationship between S / V / W and Equivalent Series Resistance (ESR) is explained. Figure 11 This is a graph showing the ESR variation based on the equivalent series resistance of the first embodiment. Figure 11 In the chart shown, the horizontal axis represents S / V / W, and the vertical axis represents the change rate of the equivalent series resistance ΔESR [%] during the moisture resistance test. The conditions for this moisture resistance test are a test temperature of 25°C, a test humidity of 60%RH, and a test time of 2000 hours. When the equivalent series resistance before the test is set to ESR_0, and the equivalent series resistance after the test is set to ESR_2000, ΔESR is calculated using the following formula: ΔESR = {(ESR_2000 - ESR_0) / ESR_0} × 100. That is, a positive ΔESR indicates that the ESR increases through the moisture resistance test. If the moisture resistance of the crystal oscillator 1 is low, the water vapor and oxygen that penetrate the internal space 39 of the crystal oscillator 1 will oxidize the electrodes of the crystal oscillating element 10, thus increasing ΔESR. The smaller the ESR, the more beneficial it is for oscillation; therefore, a small ΔESR is preferred.

[0119] The inventors discovered a relationship between the parameters S / V / W and the rate of change of the equivalent series resistance ΔESR. Figure 11 The relationship shown is as depicted. Figure 11As shown, the ΔESR is approximately 3.7% when S / V / W is around 6.0, approximately 1.6% when S / V / W is around 2.9, and approximately -0.3 when S / V / W is around 1.3. These data reveal a linear correlation between ΔESR and S / V / W; for example, ΔESR is approximately 0 when S / V / W is around 1.5. The smaller the S / V / W, the smaller the ΔESR. A small ΔESR indicates high moisture resistance for crystal oscillator 1; therefore, a smaller S / V / W indicates higher moisture resistance for crystal oscillator 1. For example, by making the relationship S / V / W ≤ 6.0 true, ΔESR can be set to below 4%; by making the relationship S / V / W ≤ 5.0 true, ΔESR can be set to below 3%; by making the relationship S / V / W ≤ 4.0 true, ΔESR can be set to below 2%; and by making the relationship S / V / W ≤ 2.4 true, ΔESR can be set to below 1%.

[0120] As described above, according to this embodiment, the crystal oscillator 1 includes: a crystal resonating element 10, a base member 30 on which the crystal resonating element 10 is mounted, a cover member 40 forming an internal space 39 for accommodating the crystal resonating element 10 between the cover member 30 and the base member 30, and a joint portion 50 that joins the base member 30 and the cover member 40 and seals the internal space 39. The joint portion 50 includes an organic adhesive 51, and the internal volume V of the internal space 39, the sealing width W of the joint portion 50, and the sealing cross-sectional area S of the joint portion 50 satisfy the relationship S / V / W ≤ 6.

[0121] Accordingly, the frequency variation of the crystal oscillator 1 caused by gas intruding into the internal space 39 through the joint 50 can be suppressed, for example, the frequency variation can be set to 7.0 ppm or less.

[0122] As one embodiment of this method, the relationship S / V / W ≤ 4 holds true.

[0123] Accordingly, the frequency variation of the crystal oscillator 1 can be further suppressed, for example, the frequency variation can be set to below 4.1 ppm.

[0124] As one embodiment of this method, the relationship 1.5 ≤ S / V / W holds true.

[0125] Accordingly, it is possible to suppress the increase in manufacturing difficulty of crystal oscillator 1 due to the need for minute processing, and to suppress the decrease in the yield of crystal oscillator 1.

[0126] As one embodiment of this invention, the elastic modulus of the organic adhesive 51 is 3 GPa or more and 7 GPa or less.

[0127] Accordingly, by setting the elastic modulus of the organic adhesive 51 to 3 GPa or higher, the gas barrier properties of the organic adhesive 51 can be improved. By setting the elastic modulus of the organic adhesive 51 to 7 GPa or lower, processability can be improved, and the generation of defects such as peeling of the joint 50 can be suppressed.

[0128] As one embodiment of this invention, the organic adhesive 51 includes an insulating filler that is held between the base component 30 and the cover component 40.

[0129] Accordingly, since the insulating filler ensures the gap between the base component 30 and the cover component 40, short circuits on the electrodes of the base component 30 via the cover component 40 are suppressed. Therefore, when the cover component 40 is joined to the base component 30, the cover component 40 can be brought close to the base component 30 without worrying about short circuits, thus reducing the sealing thickness t.

[0130] Furthermore, in this embodiment, the crystal vibrating element 10 side of the base component 30 is planar, and the crystal vibrating element 10 side of the cover component 40 is concave; however, the embodiments of the present invention are not limited to this. For example, the crystal vibrating element side of the base component may be concave, and the crystal vibrating element side of the cover component may be planar. Alternatively, both the crystal vibrating element side of the base component and the crystal vibrating element side of the cover component may be concave.

[0131] The following describes other embodiments. Furthermore, for structures that are the same as or similar to those shown in the first embodiment, their descriptions will be appropriately omitted. Also, the same effects produced by the same structures will not be mentioned sequentially.

[0132] <Second Implementation>

[0133] Next, refer to Figure 6 as well as Figure 7 The structure of the crystal oscillator 2 in the second embodiment will be described. Figure 6 This is a cross-sectional view of the crystal oscillator according to the second embodiment. Figure 7 This is an enlarged cross-sectional view of the joint of the crystal oscillator in the second embodiment.

[0134] The cover component 240 of the crystal oscillator 2 also has a flange 43. The flange 43 extends and protrudes from the front end of the sidewall portion 42 on the side of the base component 30, towards the side opposite to the internal space 39. The flange 43 is frame-shaped when viewed from above and is located in the cover component 240 closest to the base component 30. The joint portion 250 is held between the flange 43 and the base component 30. The width of the flange 43 is greater than the width of the front end of the sidewall portion 42, thus increasing the sealing width W. Furthermore, by providing the flange 43, the contact area between the cover component 240 and the joint portion 250 can be increased, thereby improving the tightness of the seal between the cover component 240 and the joint portion 250. Therefore, as... Figure 6 as well as Figure 7 As shown, the insulating film 52 may also be omitted in the joint 250.

[0135] <Third Implementation Method>

[0136] Next, refer to Figure 8 as well as Figure 9 The structure of the crystal oscillator 3 in the third embodiment will be described. Figure 8 This is a cross-sectional view of the crystal oscillator according to the third embodiment. Figure 9 This is an enlarged cross-sectional view of the joint of the crystal oscillator in the third embodiment.

[0137] The joint 350 of the crystal oscillator 3 has an organic adhesive 51 and a protrusion 53. The protrusion 53 is provided on the surface of the base member 30 that engages with the cover member 240. The protrusion 53 is provided, for example, by an organic insulating material containing resins such as epoxy, vinyl, acrylic, polyurethane, or silicone. Accordingly, the protrusion 53 functions as an insulating barrier, thus preventing short circuits of electrodes provided on the surface of the base member 30 via the cover member 240, even when it is desired to bring the cover member 240 closer to the base member 30 to reduce the sealing thickness t.

[0138] The flatness of the surface on the cover member 240 side of the protrusion 53 is higher than the flatness of the upper surface 31A of the base 31 of the base member 30. Accordingly, variations in the thickness of the organic adhesive 51 in the circumferential direction of the joint 350 can be suppressed. For example, by limiting the proximity of the flange 43 and the base member 30 in the closest region where the gap between the flange 43 and the base member 30 is smallest, it is possible to suppress the increase of the gap between the flange 43 and the base member 30 in regions other than the closest region. Therefore, it is possible to suppress the increase of the average thickness of the joint 350, i.e., the sealing thickness t.

[0139] The inner end portion of the protrusion 53 on the crystal vibrating element 10 side in the width direction is located closer to the crystal vibrating element 10 than the inner end portion of the flange 43 on the crystal vibrating element 10 side in the width direction. Furthermore, the center portion of the protrusion 53 in the width direction is located closer to the inner space 39 than the center portion of the joint 350 in the width direction, and closer to the inner space 39 than the center portion of the flange 43 in the width direction. Figure 8 As shown, the distance Lti between the inner ends of the crystal vibrating element 10 side of the protrusion 53 in the width direction is smaller than the distance Lci between the inner ends of the crystal vibrating element 10 side of the flange 43 in the width direction. Figure 9 As shown, in the cross-section along the width direction, the distance Hct from the outermost end of the crystal oscillator 1 to the center of the protrusion 53 is greater than the distance Hcc from the outermost end of the crystal oscillator 1 to the center of the flange 43. Accordingly, the protrusion 53 can restrict the wetting and diffusion of the organic adhesive 51 into the internal space 39, reducing the surface area of ​​the organic adhesive 51 on the internal space 39 side. Therefore, frequency variations caused by organic matter from the organic adhesive 51 adhering to the crystal oscillating element 10 can be suppressed.

[0140] Furthermore, in this embodiment, the protrusion is provided on the base member side, but it is not limited to this. The protrusion may also be provided on the cover member side, or it may be provided on both the base member side and the cover member side.

[0141] <Fourth Implementation>

[0142] Next, refer to Figure 10 The structure of the crystal oscillator 4 in the fourth embodiment will be described. Figure 10 This is a cross-sectional view of the crystal oscillator according to the fourth embodiment.

[0143] A through electrode 37a is provided in the base component 430 of the crystal oscillator 4 to electrically connect the connecting electrode 33a and the external electrode 35a. The through electrode 37a penetrates the substrate 31 in the thickness direction. In the base component 430, the lead electrode 34a is omitted and replaced by the through electrode 37a. Although not shown in the figure, the base component 430 also has a through electrode 37b to electrically connect the connecting electrode 33b and the external electrode 35b. Accordingly, the lead electrode that crosses the joint 250 can be omitted, thus improving the flatness of the joint surface of the base component 430.

[0144] The following are some or all of the embodiments of the present invention. However, the present invention is not limited to the following descriptions.

[0145] <1>

[0146] A piezoelectric oscillator having:

[0147] A piezoelectric vibration element has a piezoelectric sheet and an excitation electrode configured to apply a voltage to the piezoelectric sheet;

[0148] The base component is equipped with a piezoelectric vibration element;

[0149] The cover component, with an internal space between it and the base component housing a piezoelectric vibrating element; and

[0150] The joint connects the base component and the cover component, sealing the internal space.

[0151] The joint contains an organic adhesive.

[0152] When the direction intersecting the circumferential direction of the main surface of the base component and the joint is defined as the width direction, and the direction intersecting the main surface of the base component is defined as the thickness direction...

[0153] When the volume of the internal space is defined as the internal volume V, the width dimension of the joint is defined as the sealing width W, the thickness dimension of the joint is defined as the sealing thickness t, the circumferential dimension of the joint is defined as the circumference Lc, and the product of the sealing thickness t and the circumference Lc is defined as the sealing cross-sectional area S,

[0154] The relationship S / V / W≤6 holds true.

[0155] <2>

[0156] According to the piezoelectric oscillator described in <1>, among which,

[0157] The relationship S / V / W ≤ 4 holds true.

[0158] <3>

[0159] According to the piezoelectric oscillator described in <1> or <2>, among which,

[0160] The relationship 1.5 ≤ S / V / W holds true.

[0161] <4>

[0162] According to any one of <1> to <3>, the piezoelectric oscillator described therein,

[0163] Organic adhesives have an elastic modulus of 3 GPa or higher and 7 GPa or lower.

[0164] <5>

[0165] According to any one of <1> to <4>, the piezoelectric oscillator described therein,

[0166] Organic adhesives are adhesives that contain epoxy resins.

[0167] <6>

[0168] According to any one of <1> to <5>, the piezoelectric oscillator described therein,

[0169] Organic adhesives contain insulating fillers.

[0170] The insulating filler is held between the base component and the cover component.

[0171] <7>

[0172] According to any one of <1> to <6>, the piezoelectric oscillator described therein,

[0173] At least one of the mating surfaces of the base component and the cover component is provided with a protrusion.

[0174] <8>

[0175] According to the piezoelectric oscillator described in <7>, among which,

[0176] The center portion of the protrusion in the width direction is located closer to the inner space side than the center portion of the joint in the width direction.

[0177] <9>

[0178] According to the piezoelectric oscillator described in <7> or <8>, among which,

[0179] The protrusion is made of an insulator.

[0180] <10>

[0181] According to any one of <1> to <9>, the piezoelectric oscillator described therein,

[0182] At least one of the piezoelectric vibrating element side of the cover component and the piezoelectric vibrating element side of the base component is configured to be concave.

[0183] <11>

[0184] According to the piezoelectric oscillator described in <10>, among which,

[0185] The cover component has:

[0186] The top wall is positioned opposite the base component, separated by a piezoelectric vibration element;

[0187] The side wall portion extends and protrudes from the outer edge of the top wall portion toward the cover component; and

[0188] The flange extends and protrudes from the end of the base component side of the sidewall portion toward the side opposite to the internal space.

[0189] <12>

[0190] According to any one of <1> to <11>, the piezoelectric oscillator described therein,

[0191] The cover is made of ceramic.

[0192] <13>

[0193] According to any one of <1> to <12>, the piezoelectric oscillator described therein,

[0194] The base component has:

[0195] An insulating, plate-like substrate;

[0196] The connecting electrode is disposed on the piezoelectric vibration element side of the substrate and is electrically connected to the piezoelectric vibration element.

[0197] External electrodes are disposed on the side of the substrate opposite to the piezoelectric vibrating element; and

[0198] The through electrode is designed to penetrate the substrate and electrically connect the connecting electrode and the external electrode.

[0199] <14>

[0200] According to any one of <1> to <12>, the piezoelectric oscillator described therein,

[0201] Piezoelectric resonators are crystal resonators.

[0202] Furthermore, while this specification describes a crystal resonator with a quarter crystal element as the piezoelectric element, the piezoelectric resonator is not limited to this. Examples of preferred piezoelectric elements for this embodiment include lead zirconate titanate (PZT), aluminum nitride, lithium niobate, and lithium tantalate, but the piezoelectric element is not limited to these and can be appropriately selected.

[0203] The embodiments of the present invention are not particularly limited as long as they are devices that perform electromechanical energy conversion through the piezoelectric effect, such as timing devices, sound generators, oscillators, and load sensors, and can be appropriately applied.

[0204] As described above, according to one aspect of the present invention, a piezoelectric oscillator capable of suppressing frequency variations can be provided.

[0205] Furthermore, the embodiments described above are for the purpose of facilitating understanding of the present invention and are not intended to limit or interpret the scope of the present invention. The present invention can be modified / improved without departing from its spirit, and its equivalents are also included within the present invention. That is, structures obtained by appropriately applying design changes to the embodiments and / or modifications by those skilled in the art, as long as they possess the features of the present invention, are also included within the scope of the present invention. For example, the elements, their configurations, materials, conditions, shapes, dimensions, etc., of the embodiments and / or modifications are not limited to the illustrated content and can be appropriately modified. In addition, the embodiments and modifications are illustrative, and of course, partial substitutions or combinations of the structures shown in different embodiments and / or modifications can be made; these structures, as long as they contain the features of the present invention, are included within the scope of the present invention.

[0206] Explanation of reference numerals in the attached figures

[0207] 1… Crystal oscillator; 10… Crystal vibrating element; 30… Base component; 31… Base; 31A… Upper surface; 31B… Lower surface; 39… Internal space; 40… Cover component; 41… Top wall; 42… Side wall; 43… Flange; 50… Joint; 51… Organic adhesive; 52… Insulating film; 11… Crystal wafer; 11A… Upper surface; 11B… Lower surface; 14a… First excitation electrode; 14b… Second excitation electrode; 15a… First lead-out electrode; 15b… Second lead-out electrode; 16a… First connecting electrode; 16b… Second connecting electrode; V… Internal volume; W… Sealing width; t… Sealing thickness; Lc… Perimeter; S… Sealing cross-sectional area.

Claims

1. A piezoelectric oscillator, comprising: A piezoelectric vibration element has a piezoelectric sheet and an excitation electrode configured to apply a voltage to the piezoelectric sheet; The base component is equipped with the piezoelectric vibration element; A cover component, wherein an internal space is provided between the cover component and the base component to house the piezoelectric vibrating element; and The joint connects the base component and the cover component, sealing the internal space. The joint comprises an organic adhesive. When the direction intersecting the circumferential direction of the main surface of the base component and the joint is defined as the width direction, and the direction intersecting the main surface of the base component is defined as the thickness direction, When the volume of the internal space is defined as the internal volume V, the width dimension of the joint is defined as the sealing width W, the thickness dimension of the joint is defined as the sealing thickness t, the circumferential dimension of the joint is defined as the circumference Lc, and the product of the sealing thickness t and the circumference Lc is defined as the sealing cross-sectional area S, The relationship S / V / W≤6 holds true.

2. The piezoelectric oscillator according to claim 1, wherein, The relationship S / V / W ≤ 4 holds true.

3. The piezoelectric vibrator according to claim 1 or 2, in, The relationship 1.5 ≤ S / V / W holds true.

4. The piezoelectric oscillator according to any one of claims 1 to 3, wherein, The elastic modulus of the organic adhesive is above 3 GPa and below 7 GPa.

5. The piezoelectric oscillator according to any one of claims 1 to 4, wherein, The organic adhesive is an adhesive containing epoxy resin.

6. The piezoelectric oscillator according to any one of claims 1 to 5, wherein, The organic adhesive contains insulating fillers. The insulating filler is held between the base component and the cover component.

7. The piezoelectric oscillator according to any one of claims 1 to 6, wherein, At least one of the mating surfaces of the base component and the cover component that engage with the base component is provided with a protrusion.

8. The piezoelectric vibrator according to claim 7, wherein, The center portion of the protrusion in the width direction is located closer to the inner space side than the center portion of the joint in the width direction.

9. The piezoelectric vibrator according to claim 7 or 8, wherein, The protrusion is made of an insulating material.

10. The piezoelectric oscillator according to any one of claims 1 to 9, wherein, At least one of the piezoelectric vibrating element side of the cover component and the piezoelectric vibrating element side of the base component is configured to be concave.

11. The piezoelectric oscillator according to claim 10, wherein, The cover component has: The top wall portion is positioned opposite the base component, separated by the piezoelectric vibration element; The sidewall portion extends and protrudes from the outer edge of the top wall portion toward the cover component; as well as The flange extends from the end of the sidewall portion on the base component side and protrudes toward the side opposite to the internal space.

12. The piezoelectric oscillator according to any one of claims 1 to 11, wherein, The cover component is made of ceramic.

13. The piezoelectric oscillator according to any one of claims 1 to 12, wherein, The base component has: An insulating, plate-like substrate; A connecting electrode is disposed on the piezoelectric vibration element side of the substrate and electrically connected to the piezoelectric vibration element; External electrodes are disposed on the side of the substrate opposite to the piezoelectric vibrating element; and A through electrode is provided, penetrating the substrate, to electrically connect the connecting electrode and the external electrode.

14. The piezoelectric oscillator according to any one of claims 1 to 13, wherein, The piezoelectric vibrating element is a crystal vibrating element.

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