阅读说明：本技术 晶体元件以及晶体装置 (Crystal element and crystal device ) 是由 松井良司 于 2020-05-29 设计创作，主要内容包括：晶体元件具备：振动部,具有第一面以及第二面；平板部,具有第一面以及第二面,具有比振动部的厚度大的厚度,在俯视下位于振动部的外缘；固定部,具有第一面以及第二面,具有比平板部的厚度大的厚度,在俯视下位于平板部的外缘；激励电极,位于振动部的第一面以及第二面；搭载电极,位于固定部的第一面以及第二面的至少一方；和布线电极,将激励电极与搭载电极电连接。(The crystal element includes: a vibrating section having a first surface and a second surface; a flat plate portion having a first surface and a second surface, having a thickness larger than that of the vibration portion, and located at an outer edge of the vibration portion in a plan view; a fixed part having a first surface and a second surface, having a thickness larger than that of the flat plate part, and located at an outer edge of the flat plate part in a plan view; excitation electrodes located on the first and second surfaces of the vibrating portion; a mounting electrode located on at least one of the first surface and the second surface of the fixing portion; and a wiring electrode electrically connecting the excitation electrode and the mounting electrode.)

1. A crystal element, wherein, among two surfaces in a front-back relationship, when a front side is a first surface, a back side is a second surface, and a dimension in a direction perpendicularly penetrating through the first surface and the second surface is a thickness, the crystal element comprises:

a vibrating section having a first surface and a second surface;

a flat plate portion having a first surface and a second surface, having a thickness larger than that of the vibrating portion, and located at an outer edge of the vibrating portion in a plan view;

a fixed portion having a first surface and a second surface, having a thickness larger than that of the flat plate portion, and located at an outer edge of the flat plate portion in a plan view;

excitation electrodes on the first and second surfaces of the vibrating portion;

a mounting electrode located on at least one of the first surface and the second surface of the fixing portion;

and a wiring electrode electrically connecting the excitation electrode and the mounting electrode.

2. The crystal element of claim 1,

the first face of the flat plate portion and the first face of the fixed portion are on different planes, an

The second face of the flat plate portion and the second face of the fixed portion are on different planes.

3. The crystal element of claim 1,

the first surface of the flat plate portion and the first surface of the fixed portion are on the same plane, or

The second face of the flat plate portion and the second face of the fixed portion are on the same plane.

4. The crystal element of claim 2 or 3,

the first surface of the vibrating portion and the first surface of the flat plate portion are on different planes, an

The second face of the vibrating portion and the second face of the flat plate portion are on different planes.

5. The crystal element of claim 2 or 3,

the first surface of the vibrating portion and the first surface of the flat plate portion are on the same plane, or

The second surface of the vibrating portion and the second surface of the flat plate portion are on the same plane.

6. The crystal element of any of claims 1-5,

the vibrating portion, the flat plate portion, and the fixing portion are substantially rectangular in plan view,

the flat plate portion is disposed so as to surround all sides of the rectangle of the vibrating portion,

the fixed portion is located only on one side of the rectangle of the flat plate portion.

7. The crystal element of claim 6,

at least one of the first surface and the second surface of the flat plate portion has an inclined surface whose thickness becomes thinner as it is separated from the fixed portion.

8. The crystal element of claim 6 or 7,

the crystal element further includes: and a through hole penetrating in the thickness direction between the mounting electrode and the vibrating portion.

9. The crystal element of any of claims 6-8,

the distance from the center of the vibrating portion to the fixed portion is larger than the distance from the center of the flat plate portion to the fixed portion in a plan view.

10. The crystal element according to any one of claims 6 to 9,

when a direction perpendicular to the one side of the flat plate portion where the fixed portion is located is a longitudinal direction in a plan view,

the distance from the fixed portion to the vibrating portion in the flat plate portion is equal to or more than half and equal to or less than twice the dimension of the vibrating portion in the longitudinal direction.

11. The crystal element according to any one of claims 6 to 10,

when a direction parallel to the one side of the flat plate portion on which the fixed portion is located is a width direction in a plan view,

the distance from the outer edge of the flat plate portion to the vibrating portion in the width direction of the flat plate portion is larger than the dimension of the vibrating portion in the width direction.

12. A crystal device includes:

a crystal element according to any one of claims 1 to 11;

a substrate on which the crystal element is located; and

a lid body that hermetically seals the crystal element together with the base body.

Technical Field

The present disclosure relates to a crystal element of a thickness shear vibration mode, and a crystal device provided with the crystal element. Examples of the crystal device include a crystal oscillator and a crystal oscillator.

Background

In a thickness shear vibration mode crystal element, excitation electrodes including metal film patterns are formed on both main surfaces of an AT-cut crystal plate (see, for example, JP 2016-34061 a). The resonant frequency of the crystal element is inversely proportional to the thickness of the crystal plate. That is, the higher the resonant frequency, the thinner the crystal plate.

The crystal device utilizes the piezoelectric effect and the inverse piezoelectric effect of the crystal element to generate a specific resonant frequency. A general crystal device has a structure in which a crystal element is housed in a package and hermetically sealed by a lid.

Disclosure of Invention

A crystal device according to the present disclosure includes, when a front side of two surfaces in a front-back relationship is a first surface, a back side is a second surface, and a dimension in a direction perpendicularly penetrating the first surface and the second surface is a thickness:

a vibrating portion having a first surface and a second surface,

a flat plate portion having a first surface and a second surface, having a thickness larger than that of the vibrating portion, and located at an outer edge of the vibrating portion in a plan view;

a fixed portion having a first surface and a second surface, having a thickness larger than that of the flat plate portion, and located at an outer edge of the flat plate portion in a plan view;

excitation electrodes on the first and second surfaces of the vibrating portion;

a mounting electrode located on at least one of the first surface and the second surface of the fixing portion; and

and a wiring electrode electrically connecting the excitation electrode and the mounting electrode.

The crystal device according to the present disclosure includes:

a crystal element to which the present disclosure relates;

a substrate on which the crystal element is located; and

a lid body that hermetically seals the crystal element together with the base body.

Drawings

Fig. 1 is a plan view showing a crystal device according to embodiment 1.

Fig. 2 is a plan view seen from the back side in the crystal element of fig. 1.

FIG. 3 is a sectional view taken along line Ic-Ic of FIG. 1.

Fig. 4 is a plan view showing a crystal plate in embodiment 1.

FIG. 5 is a sectional view taken along line IIb-IIb in FIG. 4.

Fig. 6 is a plan view for explaining a size example of the crystal plate of fig. 4.

FIG. 7 is a sectional view showing a crystal plate of example 1.

FIG. 8 is a sectional view showing a crystal plate of example 2.

FIG. 9 is a sectional view showing a crystal plate of example 3.

FIG. 10 is a sectional view showing a crystal plate of example 4.

FIG. 11 is a sectional view showing a crystal plate of example 5.

Fig. 12 is a perspective view showing a crystal device according to embodiment 2.

Fig. 13 is a sectional view taken along line IVb-IVb of fig. 12.

Detailed Description

In recent years, as the resonance frequency of the crystal element becomes higher, the crystal plate becomes thinner, whereby the mechanical strength of the crystal plate is decreasing. For example, in the case where the resonance frequency is 150MHz, the thickness of the crystal plate is about 11 μm. In this case, since the crystal plate is too thin, the crystal plate is likely to be deformed by stress. When the crystal plate is deformed, the vibration balance of the vibrating portion is lowered, and thus the electrical characteristics of the crystal element are lowered. The decrease in the electrical characteristics includes, for example, an increase in the equivalent series resistance value, a decrease in the frequency-temperature characteristics (generation of a dip, etc.), and the like. Particularly in a crystal device having a resonance frequency of 150MHz or higher, this problem is significant because the crystal plate is very thin.

According to the crystal element of the present disclosure, the vibrating portion, the flat plate portion thicker than the vibrating portion and located at the outer edge of the vibrating portion, and the fixing portion thicker than the flat plate portion and located at the outer edge of the flat plate portion are provided, whereby a structure in which the thick flat plate portion supports the outer edge of the thin vibrating portion and the thick fixing portion supports the outer edge of the flat plate portion can be realized. As a result, even if the resonance frequency is increased and the vibrating portion is thinned, the mechanical strength of the crystal element can be maintained, and thus stable electrical characteristics can be ensured.

Hereinafter, a mode for carrying out the present disclosure (hereinafter, referred to as "embodiment") will be described with reference to the drawings. In the present specification and the drawings, the same reference numerals are used for substantially the same components, and the description thereof is appropriately omitted. The shapes depicted in the drawings are depicted as being readily understood by those skilled in the art, and thus are not necessarily consistent with actual dimensions and proportions.

< embodiment 1>

Fig. 1 is a plan view showing a crystal element 10, fig. 2 is a plan view seen through a back side of the crystal element 10, and fig. 3 is a sectional view taken along line Ic-Ic in fig. 1. Fig. 4 is a plan view showing the crystal plate 21, fig. 5 is a sectional view taken along line IIb-IIb in fig. 4, and fig. 6 is a plan view for explaining a dimensional example of the crystal plate 21. Hereinafter, the description will be made based on these drawings.

The front side of the two surfaces in the front-back relationship is referred to as a "first surface", the back side is referred to as a "second surface", and the dimension in the direction perpendicular to the first surface and the second surface is referred to as a "thickness". The crystal element 10 of embodiment 1 includes: a vibrating section 11 having a first surface 111 and a second surface 112; a flat plate portion 12 having a first surface 121 and a second surface 122, having a thickness larger than that of the vibrating portion 11, and located at an outer edge of the vibrating portion 11 in a plan view; a fixed portion 13 having a first surface 131 and a second surface 132, having a thickness larger than that of the flat plate portion 12, and located at an outer edge of the flat plate portion 12 in a plan view; excitation electrodes 141 and 142 located on the first surface 111 and the second surface 112 of the vibrating portion 11; mounting electrodes 151 and 152 located on at least one of the first surface 131 and the second surface 132 of the fixing portion 13; and wiring electrodes 161 and 162 for electrically connecting the excitation electrodes 141 and 142 and the mounting electrodes 151 and 152.

The first surfaces 111, 121, and 131 and the second surfaces 112, 122, and 132 may be configured as follows. The first surface 121 of the flat plate portion 12 and the first surface 131 of the fixed portion 13 are on different planes. The second surface 122 of the flat plate portion 12 and the second surface 132 of the fixed portion 13 are on different planes. The first surface 111 of the vibrating portion 11 and the first surface 121 of the flat plate portion 12 are on different planes. Second surface 112 of vibrating portion 11 and second surface 122 of flat plate portion 12 are on different planes. That is, the first surfaces 111, 121, and 131 of the vibrating portion 11, the flat plate portion 12, and the fixed portion 13 are arranged in a step shape, and the second surfaces 112, 122, and 132 are also arranged in a step shape.

In a plan view, the vibrating portion 11, the flat plate portion 12, and the fixing portion 13 may be substantially rectangular, the flat plate portion 12 may be provided so as to surround all sides of the rectangle of the vibrating portion 11, and the fixing portion 13 may be located only on one side 120 of the rectangle of the flat plate portion 12. When the flat plate portion 12 is provided so as to surround all sides of the vibrating portion 11, the vibrating portion 11 becomes a recess provided at the center of the flat plate portion 12. Here, "substantially rectangular" also includes a square, a rectangle with rounded corners, or the like. The flat plate portion 12 may surround three or two sides, instead of all sides of the vibrating portion 11. In this case, the flat plate portion 12 includes the vibrating portion 11 and has a substantially rectangular shape. Instead of being located at one side 120 of flat plate portion 12, fixed portion 13 may be provided so as to surround two, three, or all sides. In this case, the fixed portion 13 includes the flat plate portion 12 and is substantially rectangular.

The first surface 121 and the second surface 122 of the flat plate portion 12 may have inclined surfaces 121a and 122a, respectively, which become thinner as they are separated from the fixed portion 13. Either one of the inclined surfaces 121a and 122a may be provided. In addition, if the crystal axis of the crystal plate is set as shown in the drawing, the inclined surfaces 121a and 122a are formed by wet etching.

The crystal element 10 may further include a through hole 17 penetrating in the thickness direction between the mounting electrodes 151 and 152 and the vibrating portion 11. In embodiment 1, the through-holes 17 are formed in the inclined surfaces 121a and 122 a.

In fig. 4 and 6, in a plan view, a distance 114 from a center 113 of vibrating portion 11 to fixed portion 13 may be set larger than a distance 124 from a center 123 of flat plate portion 12 to fixed portion 13.

In fig. 4 and 6, when a direction perpendicular to one side 120 of the flat plate portion 12 where the fixed portion 13 is located is a longitudinal direction in a plan view, a distance 125 from the fixed portion 13 to the vibrating portion 11 in the flat plate portion 12 may be equal to or more than half and equal to or less than twice a dimension (length 115) in the longitudinal direction of the vibrating portion 11.

In fig. 4 and 6, when a direction parallel to one side 120 of the flat plate portion 12 where the fixed portion 13 is located is taken as a width direction in a plan view, a distance 126 from an outer edge of the flat plate portion 12 to the vibrating portion 11 in the width direction of the flat plate portion 12 may be set larger than a dimension (width 116) of the vibrating portion 11 in the width direction.

Next, the crystal element 10 will be described in more detail.

The crystal element 10 operates in a thickness shear vibration mode, and the resonance frequency (fundamental wave) is 150MHz or higher, for example. The vibrating portion 11, the flat plate portion 12, and the fixing portion 13 are constituted by one crystal plate 21. The excitation electrodes 141 and 142, the mounting electrodes 151 and 152, and the wiring electrodes 161 and 162 are formed of metal patterns of the same material.

The crystal plate 21 is an AT-cut crystal plate. That is, in the crystal, when an orthogonal coordinate system XY 'Z' is defined by rotating an orthogonal coordinate system XYZ composed of an X axis (electric axis), a Y axis (mechanical axis), and a Z axis (optical axis) by 30 ° or more and 50 ° or less (35 ° 15 'as an example) around the X axis, a wafer cut out in parallel with the XZ' plane is a raw material of the crystal plate 21. The crystal plate 21 has a longitudinal direction parallel to the X axis, a short-side direction parallel to the Z 'axis, and a thickness direction parallel to the Y' axis.

Fig. 6 shows an example of the dimensions as follows. The length 211 of the crystal plate 21 is 700-1000 μm and the width 212 is 400 μm. The length 115 and width 116 of the vibrating portion 11 are both 100 μm. The distance 126 from the outer edge of the flat plate portion 12 to the vibrating portion 11 was 150 μm. The length 133 of the fixing portion 13 is 50 to 200 μm.

The pair of excitation electrodes 141 and 142 are substantially elliptical in plan view, and are provided substantially at the center of each of the first surface 111 and the second surface 112 of the vibrating portion 11. Wiring electrodes 161 and 162 for connection, which do not contribute to excitation, extend from the excitation electrodes 141 and 142 to the mounting electrodes 151 and 152. In other words, the excitation electrode 141 is electrically connected to the mounting electrode 151 via the wiring electrode 161, and the excitation electrode 142 is electrically connected to the mounting electrode 152 via the wiring electrode 162. The excitation electrodes 141 and 142 are not limited to a substantially elliptical shape, and may be, for example, a substantially circular shape or a substantially rectangular shape.

Both of the mounting electrodes 151 and 152 are located on the second surface 132 of the fixing portion 13, but at least one may be located on the first surface 131 of the fixing portion 13. In this case, the mounting electrodes 151 and 152 may be electrically connected to the package or the like by wires.

The metal patterns constituting the excitation electrodes 141, 142, and the like form a laminate of, for example, a base layer including chromium (Cr) and a conductor layer including gold (Au). That is, a base layer is provided on the quartz-crystal plate 21, and a conductor layer is provided on the base layer. The base layer mainly plays a role of obtaining a close adhesion force with the crystal plate 21. The conductor layer mainly plays a role of obtaining electrical conduction.

In the metal pattern production step, the formation of the metal film is referred to as film formation, and examples thereof include a method in which a photoresist pattern is formed after the film formation of the crystal plate 21 and etching is performed, a method in which a film is formed after the photoresist pattern is formed on the crystal plate and peeling is performed, and a method in which a film is formed by covering the crystal plate with a metal mask. Sputtering, vapor deposition, or the like is used for film formation.

The crystal element 10 can be manufactured as follows using, for example, a photolithography technique and an etching technique.

First, a resist film is provided on the entire surface of an AT-cut crystal wafer, and a photoresist is provided thereon. Next, a mask in which the outer shape of the crystal plate 21 (including the through hole 17) and the pattern of the flat plate portion 12 are drawn is superimposed on the photoresist, and exposure and development are performed to expose a part of the resist film, and wet etching is performed on the resist film in this state. Thereafter, the crystal wafer is subjected to wet etching using the remaining resist as a mask to form the outer shape of the crystal plate 21 (halfway) and the flat plate portion 12 (flat plate portion processing step). Next, the outer shape of the crystal plate 21 (halfway) and the vibrating portion 11 are formed in the same manner (vibrating portion processing step). Next, the outer shape (through) of the crystal plate 21 is formed in the same manner (outer shape processing step). The simultaneous etching of the first surface and the second surface of the crystal plate 21 is referred to as "double-sided etching", and the etching of either the first surface or the second surface of the crystal plate 21 is referred to as "single-sided etching". Double-sided etching is used in each of the above steps.

Thereafter, the remaining resist film is removed from the crystal wafer, and a metal film as the excitation electrodes 141 and 142 is provided over the entire crystal wafer. Next, a photoresist mask including a pattern of the excitation electrodes 141, 142, and the like is formed on the metal film, and unnecessary metal film is removed by etching to form the excitation electrodes 141, 142, and the like. Thereafter, the unnecessary photoresist is removed, and a plurality of crystal elements 10 are formed on the crystal wafer. Finally, the crystal elements 10 are singulated from the crystal wafer, thereby obtaining individual crystal elements 10.

The operation of the crystal element 10 is as follows. An alternating voltage is applied to the crystal plate 21 via the excitation electrodes 141, 142. Then, the crystal plate 21 generates thickness shear vibration so that the first surface 111 and the second surface 112 are displaced from each other, and a specific resonance frequency is generated. In this way, the crystal element 10 operates by the piezoelectric effect and the inverse piezoelectric effect of the crystal plate 21 so as to output a signal of a constant resonance frequency. At this time, the resonance frequency is higher as the thickness of the crystal plate 21 (i.e., the vibrating portion 11) between the excitation electrodes 141, 141 is thinner.

Next, the operation and effect of the crystal element 10 will be described.

(1) As described above, the crystal element 10 of embodiment 1 includes: a vibrating section 11 having a first surface 111 and a second surface 112; a flat plate portion 12 having a first surface 121 and a second surface 122, having a thickness larger than that of the vibrating portion 11, and located at an outer edge of the vibrating portion 11 in a plan view; a fixed portion 13 having a first surface 131 and a second surface 132, having a thickness larger than that of the flat plate portion 12, and located at an outer edge of the flat plate portion 12 in a plan view; excitation electrodes 141 and 142 located on the first surface 111 and the second surface 112; mounting electrodes 151 and 152 located on at least one of the first surface 131 and the second surface 132; and wiring electrodes 161 and 162 for electrically connecting the excitation electrodes 141 and 142 and the mounting electrodes 151 and 152.

According to crystal element 10 of embodiment 1, by providing vibrating portion 11, flat plate portion 12 thicker than vibrating portion 11 and located at the outer edge of vibrating portion 11, and fixing portion 13 thicker than flat plate portion 12 and located at the outer edge of flat plate portion 12, it is possible to realize a structure in which thick flat plate portion 12 supports the outer edge of thin vibrating portion 11, and thicker fixing portion 13 supports the outer edge of thick flat plate portion 12. As a result, even if the resonance frequency becomes high and the vibrating portion 11 becomes thin, the mechanical strength of the crystal element 10 can be maintained, and thus stable electrical characteristics can be ensured.

Here, an example of the effect of the crystal element 10 will be specifically described. The crystal element without the flat plate portion and including the vibrating portion and the fixed portion was used as a comparative example. In this comparative example, stress is concentrated on the boundary between the thin vibrating portion and the thick fixing portion, and deformation tends to occur in the thin vibrating portion. Therefore, the vibrating portion becomes thinner with an increase in frequency, and the vibrating portion is more easily deformed. In contrast, in the crystal element 10, since the stress generated between the vibrating portion 11 and the fixed portion 13 is dispersed or absorbed by the flat plate portion 12, the vibrating portion 11 is less likely to be deformed even if the vibrating portion 11 is thinned. In addition, as a stress source, there is gravity, tension of the metal pattern, or the like.

In particular, in the crystal element 10 having a resonance frequency of 150MHz or higher, since the vibrating portion 11 is relatively thin, it is necessary to pay attention to breakage or the like at the time of mounting. According to the crystal element 10, the fixed portion 13 thicker than the flat plate portion 12 is attached to the package, and the workability can be improved.

(2) The first surfaces 111, 121, 131 are arranged in a step shape, and the second surfaces 112, 122, 132 are also arranged in a step shape. In this case, the front side and the back side of the crystal plate 21 have the same structure. This makes it possible to further suppress deformation of the vibrating portion 11 by, for example, canceling the tension of the metal pattern on the front side and the tension of the metal pattern on the back side. Further, since the flat plate portion 12 and the vibrating portion 11 can be formed by double-sided etching, the etching time per one step can be shortened to about half of that of single-sided etching.

Further, these effects become more remarkable if the front and back sides of the crystal plate 21 are set to be vertically symmetrical. In addition, since the crystal plate 21 is vertically symmetrical with respect to the center of gravity of the crystal plate 21 and the state of vibration is the same in the upper half and the lower half of the crystal plate 21, the vibration balance can be improved and the CI (crystal impedance) value can be reduced.

(3) The vibrating portion 11, the flat plate portion 12, and the fixing portion 13 are substantially rectangular, the flat plate portion 12 is provided so as to surround all sides of the rectangle of the vibrating portion 11, and the fixing portion 13 is located only on one side 120 of the rectangle of the flat plate portion 12. When the vibrating portion 11 has a substantially rectangular shape, the etching residue in forming the vibrating portion 11 by wet etching can be easily managed as compared with a case where the vibrating portion 11 has a substantially circular or elliptical shape. This is because: if the vibrating portion 11 has a substantially rectangular shape, the crystal plane exposed to the outer edge of the vibrating portion 11 is simple, and therefore the shape of the etching residue is also simple. As a result, disconnection of the wiring electrodes 161 and 162 at the outer edge of the vibrating portion 11 can be reduced. In addition, when the flat plate portion 12 is provided so as to surround all sides of the vibrating portion 11, the thick flat plate portion 12 supports all sides of the thin vibrating portion 11, and therefore, deformation of the vibrating portion 11 can be further reduced.

(4) The first surface 121 of the flat plate portion 12 has an inclined surface 121a whose thickness becomes thinner as it is separated from the fixed portion 13, or the second surface 122 of the flat plate portion 12 has an inclined surface 122a whose thickness becomes thinner as it is separated from the fixed portion 13. In this case, the following effects are achieved. The thickness of the flat plate portion 12 (inclined surfaces 121a, 122a) near the fixed portion 13 gradually increases toward the fixed portion 13. Therefore, the stress transmitted from the fixing portion 13 side to the vibrating portion 11 side is absorbed or dispersed by the inclined surfaces 121a and 122a (gentle step), and thus the deformation of the vibrating portion 11 can be further suppressed. Further, since the vibration generated in the vibrating portion 11 is gradually attenuated toward the fixed portion 13, the influence of the vibration reflected by the fixed portion 13 on the vibrating portion 11 is reduced. Accordingly, the influence of the fixed portion 13 on the vibration of the vibrating portion 11 is suppressed by the sectional shape of the flat plate portion 12 near the fixed portion 13, and thus the CI value can be reduced. The inclined surfaces 121a and 122a may be provided in either one of them, but the effect can be further increased by providing both of them.

(5) A through hole 17 penetrating in the thickness direction is further provided between the mounting electrodes 151 and 152 and the vibrating portion 11. In this case, since the stress transmitted from the fixed portion 13 side to the vibrating portion 11 side is absorbed or dispersed by the through hole 17, the deformation of the vibrating portion 11 can be further suppressed. In other words, when the fixing portion 13 is fixed to the package, the deformation of the flat plate portion 12 and further the deformation of the vibrating portion 11 can be reduced. The through-hole 17 can reduce the CI value by blocking the vibration energy of the vibration portion 11. Further, by forming the through holes 17 in the inclined surfaces 121a and 122a, these effects become more remarkable in combination with the action of the inclined surfaces 121a and 122 a.

(6) The distance 114 from the center 113 of the vibrating portion 11 to the fixed portion 13 is larger than the distance 124 from the center 123 of the flat plate portion 12 to the fixed portion 13. In this case, since the vibrating portion 11 is separated from the fixing portion 13, the influence of stress when the fixing portion 13 is fixed to the package can be reduced.

(7) The distance 125 from the fixed portion 13 to the vibrating portion 11 in the flat plate portion 12 is equal to or more than half and equal to or less than twice the length 115 of the vibrating portion 11. If the distance 125 is less than half the length 115 of the vibrating portion 11, the fixed portion 13 is susceptible to stress. If the distance 125 exceeds twice the length 115 of the vibrating portion 11, the flat plate portion 12 is easily deformed, and thus the vibrating portion 11 is also easily deformed.

(8) In the width direction of the flat plate portion 12, a distance 126 from the outer edge of the flat plate portion 12 to the vibrating portion 11 is larger than the width 116 of the vibrating portion 11. In this case, the width direction of the vibrating portion 11 can be supported by the sufficient flat plate portion 12, and thus deformation of the vibrating portion 11 can be further reduced.

< other examples >

FIGS. 7 to 11 are cross-sectional views of crystal plates 21 to 25 according to examples 1 to 5, respectively. Hereinafter, the description will be made based on these drawings.

The flat plate portion and the vibrating portion in embodiment 1 are formed by double-sided etching or single-sided etching, and thereby crystal plates having various cross-sectional shapes can be obtained. These crystal plates are described as examples 1 to 5 of embodiment 1.

The crystal plate 21 of example 1 shown in fig. 7 is the same as that shown in fig. 3 and 5. Hereinafter, in the crystal plates 22 to 25, the same reference numerals as those of the crystal plate 21 are used for the portions corresponding to the structural elements of the crystal plate 21.

When the flat plate portion 12 is formed by double-sided etching, the first surface 121 of the flat plate portion 12 and the first surface 131 of the fixed portion 13 are different planes, and the second surface 122 of the flat plate portion 12 and the second surface 132 of the fixed portion 13 are different planes.

When the flat plate portion 12 is formed by single-sided etching, the first surface 121 of the flat plate portion 12 and the first surface 131 of the fixed portion 13 are the same plane, and the second surface 122 of the flat plate portion 12 and the second surface 132 of the fixed portion 13 are different planes. Alternatively, the second surface 122 of the flat plate portion 12 and the second surface 132 of the fixed portion 13 are the same plane, and the first surface 121 of the flat plate portion 12 and the first surface 131 of the fixed portion 13 are different planes.

When the vibrating portion 11 is formed by double-sided etching, the first surface 111 of the vibrating portion 11 and the first surface 121 of the flat plate portion 12 are different planes, and the second surface 112 of the vibrating portion 11 and the second surface 122 of the flat plate portion 12 are different planes.

When the vibrating portion 11 is formed by single-sided etching, the first surface 111 of the vibrating portion 11 and the first surface 121 of the flat plate portion 12 are the same plane, and the second surface 112 of the vibrating portion 11 and the second surface 122 of the flat plate portion 12 are different planes. Alternatively, the second surface 112 of the vibrating portion 11 and the second surface 122 of the flat plate portion 12 are the same plane, and the first surface 111 of the vibrating portion 11 and the first surface 121 of the flat plate portion 12 are different planes.

Both the flat plate portion 12 and the vibrating portion 11 of the crystal plate 21 of example 1 shown in fig. 7 were formed by double-sided etching. As described in embodiment 1, three times of etching are required, namely (double-sided etching of flat plate portion 12 + double-sided etching of outline) → (double-sided etching of vibrating portion 11 + double-sided etching of outline) → double-sided etching of outline.

The crystal plate 22 of example 2 shown in fig. 8 is subjected to double-sided etching to form the flat plate portion 12, and is subjected to single-sided etching to form the vibrating portion 11. In this case, the etching may be twice (double-sided etching of the flat plate portion 12 + double-sided etching of the outline) → (single-sided etching of the vibrating portion 11 + double-sided etching of the outline). In embodiment 2, the vibrating portion 11 is formed on the first surface 121 of the flat plate portion 12, but the vibrating portion 11 may be formed on the second surface 122 of the flat plate portion 12. Even in this case, if the crystal plate is inverted, the sectional shape is the same as that of embodiment 2.

The crystal plate 23 of example 3 shown in fig. 9 is etched on one side to form the flat plate portion 12, and is etched on both sides to form the vibrating portion 11. In this case, the etching may be twice (single-sided etching of the flat plate portion 12 + double-sided etching of the outline) → (double-sided etching of the vibrating portion 11 + double-sided etching of the outline). In embodiment 3, the flat plate portion 12 is formed on the second surface 132 side of the fixed portion 13, but the flat plate portion 12 may be formed on the first surface 131 side of the fixed portion 13. Even in this case, if the crystal plate is inverted, the cross-sectional shape is the same as that of example 3 (the same applies to examples 4 and 5).

Both the flat plate portion 12 and the vibrating portion 11 of the crystal plate 24 of example 4 shown in fig. 10 were formed by single-sided etching. In this case, the etching may be twice (one-sided etching of the flat plate portion 12 + one-sided etching of the outline) → (one-sided etching of the vibrating portion 11 + double-sided etching of the outline).

In the crystal plate 25 of example 5 shown in fig. 11, both the flat plate portion 12 and the vibrating portion 11 are formed by single-sided etching, similarly to the crystal plate 24 of example 4. However, while the vibrating portion 11 is formed on the first surface 121 of the flat plate portion 12 in embodiment 4, the vibrating portion 11 is formed on the second surface 122 of the flat plate portion 12 in embodiment 5. In this case, the etching may be performed twice (one-sided etching of flat plate portion 12 + one-sided etching of outline) → (one-sided etching of vibrating portion 11 + two-sided etching of outline).

The crystal devices including the crystal plates 21 to 25 of the respective examples have the same structure, operation, and effect as those of the crystal device of embodiment 1.

< embodiment 2>

Fig. 12 is a perspective view showing the crystal unit 60, and fig. 13 is a sectional view taken along line IVb-IVb in fig. 12. Hereinafter, a crystal device including the crystal element of embodiment 1 will be described as a crystal device 60 of embodiment 2 based on these drawings.

As shown in fig. 12 and 13, the crystal device 60 according to embodiment 2 includes: a crystal element 10 according to embodiment 1, a base 61 on which the crystal element 10 is provided, and a lid 62 that hermetically seals the crystal element 10 together with the base 61. The base 61 is also referred to as a package, and includes a substrate 61a and a frame 61 b. A space surrounded by the upper surface of the substrate 61a, the inner surface of the frame 61b, and the lower surface of the lid 62 serves as a housing portion 63 for the crystal element 10. The crystal element 10 outputs a reference signal used in an electronic device or the like, for example.

In other words, the crystal device 60 includes: a substrate 61a having a pair of electrode pads 61d on an upper surface and four external terminals 61c on a lower surface, a frame 61b provided along an outer peripheral edge of the upper surface of the substrate 61a, a crystal element 10 attached to the pair of electrode pads 61d via a conductive adhesive 61e, and a lid 62 hermetically sealing the crystal element 10 together with the frame 61 b.

The substrate 61a and the frame 61b are made of a ceramic material such as alumina ceramic or glass ceramic, and are integrally formed to form the base 61. The base 61 and the lid 62 are substantially rectangular in plan view. The external terminal 61c is electrically connected to the electrode pad 61d and the lid 62 via a conductor formed inside or on a side surface of the base 61. Specifically, the external terminals 61c are provided at four corners of the lower surface of the substrate 61 a. Of these, two external terminals 61c are electrically connected to the crystal element 10, and the remaining two external terminals 61c are electrically connected to the lid 62. The external terminal 61c is used for a printed wiring board or the like mounted on an electronic device or the like.

As described above, the crystal element 10 includes: a crystal plate 21, an excitation electrode 141 formed on the upper surface of the crystal plate 21, and an excitation electrode 142 formed on the lower surface of the crystal plate 21. The crystal element 10 is bonded to the electrode pad 61d via the conductive adhesive 61e, and functions to oscillate a reference signal of an electronic device or the like by stable mechanical vibration and piezoelectric effect.

The electrode pads 61d are pads for mounting the crystal element 10 on the base 61, and a pair of the electrode pads are provided adjacent to each other so as to be along one side of the substrate 61 a. The pair of electrode pads 61d connect the mounting electrodes 151 and 152, respectively, and fix the crystal element 10 to the substrate 61a by a cantilever support structure with one end of the crystal element 10 as a fixed end and the other end of the crystal element 10 as a free end separated from the upper surface of the substrate 61 a.

The conductive adhesive 61e contains conductive powder as a conductive filler in a binder such as a silicone resin, for example. The lid 62 is made of an alloy containing at least one of iron, nickel, and cobalt, and is joined to the frame 61b by seam welding or the like to hermetically seal the housing portion 63 in a vacuum state or filled with nitrogen gas or the like.

According to the crystal device 60, by providing the crystal element 10, stable electrical characteristics can be exhibited. The crystal device 60 is mounted on the surface of a printed board constituting an electronic device by fixing the bottom surface of the external terminal 61c to the printed board by soldering, a gold (Au) block, a conductive adhesive, or the like. The crystal device 60 is used as an oscillation source in various electronic devices such as a smart phone, a personal computer, a watch, a game machine, a communication device, and an in-vehicle device such as a car navigation system.

< others >

The present disclosure has been described above with reference to the above embodiments, but the present disclosure is not limited to these embodiments. Various modifications that can be understood by those skilled in the art can be made to the structure and details of the present disclosure. For example, although the vibration portion has been described as being substantially rectangular in shape, other patterns (circular, elliptical, polygonal, etc.) may be used.

The present application claims priority based on japanese application laid-open at 30/5/2019, application No. 2019-101757, the entire disclosure of which is hereby incorporated by reference.