Crystal element and crystal device

Abstract

The crystal element comprises: a vibration portion having a first surface and a second surface; a flat plate portion having a first surface and a second surface, having a thickness greater than that of the vibration portion, and being located at an outer edge of the vibration portion when viewed from above; a fixed portion having a first surface and a second surface, having a thickness greater than that of the flat plate portion, and being located at an outer edge of the flat plate portion when viewed from above; an excitation electrode located at the first surface and the second surface of the vibration portion; a mounting electrode located at at least one of the first surface and the second surface of the fixed portion; and a wiring electrode electrically connecting the excitation electrode and the mounting electrode.

Description

Technical Field

[0001] The present disclosure relates to a crystal element in a thickness shear vibration mode and a crystal device having the crystal element. Examples of the crystal device include a crystal vibrator and a crystal oscillator. Background Art

[0002] The crystal element of the thickness shear vibration mode has excitation electrodes including metal film patterns formed on the two main surfaces of the AT-cut crystal plate (for example, refer to JP Patent Publication No. 2016-34061). The resonant frequency of the crystal element is inversely proportional to the thickness of the crystal plate. In other words, the higher the resonant frequency, the thinner the crystal plate.

[0003] Crystal devices use the piezoelectric effect and inverse piezoelectric effect of crystal elements to generate specific resonant frequencies. A typical crystal device is a structure in which a crystal element is housed in a package and hermetically sealed with a lid. Summary of the invention

[0004] The crystal element according to the present disclosure comprises: when the front side of two surfaces in a front-back relationship is set as the first surface, the back side is set as the second surface, and the dimension in a direction perpendicularly penetrating the first surface and the second surface is set as the thickness.

[0005] The vibration part has a first surface and a second surface,

[0006] A flat plate portion having a first surface and a second surface, having a thickness greater than that of the vibration portion, and being located at an outer edge of the vibration portion in a plan view;

[0007] A fixing portion having a first surface and a second surface, having a thickness greater than that of the flat plate portion, and being located at an outer edge of the flat plate portion in a plan view;

[0008] an excitation electrode, located on the first surface and the second surface of the vibration part;

[0009] A carrying electrode located on at least one of the first surface and the second surface of the fixing portion; and

[0010] A wiring electrode electrically connects the excitation electrode and the mounting electrode.

[0011] The crystal device according to the present disclosure comprises:

[0012] The crystal element involved in the present disclosure;

[0013] A substrate on which the crystal element is located; and

[0014] A cover body hermetically seals the crystal element together with the base body. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a plan view showing the crystal element of embodiment 1.

[0016] Figure 2 It's perspective Figure 1 Plan view of a crystal element as viewed from the back side.

[0017] Figure 3 yes Figure 1 Ic-Ic line cross-sectional view in.

[0018] Figure 4 This is a plan view showing the crystal plate in the first embodiment.

[0019] Figure 5 yes Figure 4 Sectional view along line IIb-IIb in FIG.

[0020] Figure 6 It is used to illustrate Figure 4 Plan view of an example of the dimensions of a crystal plate.

[0021] Figure 7 3 is a cross-sectional view showing the crystal plate of Example 1.

[0022] Figure 8 This is a cross-sectional view showing the crystal plate of Example 2.

[0023] Fig. 9 3 is a cross-sectional view showing a crystal plate of Example 3.

[0024] Fig.10 This is a cross-sectional view showing the crystal plate of Example 4.

[0025] Fig.11 It is a cross-sectional view showing the crystal plate of Example 5.

[0026] Fig.12 This is a perspective view showing a crystal device according to Embodiment 2.

[0027] Fig.13 yes Fig.12 Sectional view along line IVb-IVb in FIG. DETAILED DESCRIPTION

[0028] In recent years, as the resonant frequency of crystal elements has increased, the crystal plate has become thinner, and thus the mechanical strength of the crystal plate has decreased. For example, when the resonant frequency is 150MHz, the thickness of the crystal plate is about 11μm. In this case, since the crystal plate is too thin, it is easy for the crystal plate to deform due to stress. If deformation occurs in the crystal plate, the vibration balance of the vibrating part decreases, thereby reducing the electrical characteristics of the crystal element. The reduction in electrical characteristics includes, for example, an increase in the equivalent series resistance value, a decrease in the frequency-temperature characteristics (the generation of a dip, etc.). In particular, in crystal elements with a resonant frequency of more than 150MHz, this problem is significant because the crystal plate is very thin.

[0029] According to the crystal element involved in the present disclosure, by including a vibration part, a plate part thicker than the vibration part and located at the outer edge of the vibration part, and a fixed part thicker than the plate part and located at the outer edge of the plate part, it is possible to realize a structure in which the thick plate part supports the outer edge of the thin vibration part, and the thicker fixed part supports the outer edge of the plate part. As a result, even if the resonance frequency becomes higher and the vibration part becomes thinner, the mechanical strength of the crystal element can be maintained, thereby ensuring stable electrical characteristics.

[0030] Hereinafter, with reference to the accompanying drawings, a method for implementing the present disclosure (hereinafter referred to as an "implementation method") is described. In addition, in this specification and the accompanying drawings, the same symbols are used for substantially the same structural elements, and the description is appropriately omitted. The shapes depicted in the drawings are depicted to be easily understood by those skilled in the art, and therefore may not necessarily be consistent with the actual dimensions and proportions.

[0031] <Implementation Method 1>

[0032] Figure 1 is a plan view showing the crystal element 10, Figure 2 is a plan view viewed through the back side of the crystal element 10. Figure 3 yes Figure 1 Ic-Ic line cross-sectional view in. Figure 4 is a plan view showing the crystal plate 21, Figure 5 yes Figure 4 The IIb-IIb line section view in the figure, Figure 6 It is a plan view for explaining the dimension example of the crystal plate 21. Hereinafter, description will be given based on these drawings.

[0033] The front side of the two surfaces in the front-back relationship is referred to as the "first surface", the back side is referred to as the "second surface", and the dimension in the direction perpendicular to the first surface and the second surface is referred to as the "thickness". The crystal element 10 of the first embodiment includes: a vibration portion 11 having a first surface 111 and a second surface 112; a plate portion 12 having a first surface 121 and a second surface 122, having a thickness greater than the thickness of the vibration portion 11, and being located at the outer edge of the vibration portion 11 in a plan view; a fixed portion 13 having a first surface 131 and a second surface 132, having a thickness greater than the thickness of the plate portion 12, and being located at the outer edge of the plate portion 12 in a plan view; excitation electrodes 141, 142, located at the first surface 111 and the second surface 112 of the vibration portion 11; mounting electrodes 151, 152, located at least one of the first surface 131 and the second surface 132 of the fixed portion 13; and wiring electrodes 161, 162, electrically connecting the excitation electrodes 141, 142 and the mounting electrodes 151, 152.

[0034] The first surfaces 111, 121, 131 and the second surfaces 112, 122, 132 may also 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 vibration portion 11 and the first surface 121 of the flat plate portion 12 are on different planes. The second surface 112 of the vibration portion 11 and the second surface 122 of the flat plate portion 12 are on different planes. That is, the first surfaces 111, 121, 131 of the vibration portion 11, the flat plate portion 12 and the fixed portion 13 are arranged in a stepped shape, and the second surfaces 112, 122, 132 of the vibration portion 11, the flat plate portion 12 and the fixed portion 13 are also arranged in a stepped shape.

[0035] In a plan view, the vibration part 11, the flat plate part 12 and the fixed part 13 may be in a roughly rectangular shape, the flat plate part 12 is arranged to surround all sides of the rectangle of the vibration part 11, and the fixed part 13 is located only on one side 120 of the rectangle of the flat plate part 12. If the flat plate part 12 is arranged to surround all sides of the vibration part 11, the vibration part 11 becomes a recessed part arranged in the center of the flat plate part 12. Here, "roughly rectangular" also includes a square, or a rectangle with rounded corners. In addition, the flat plate part 12 may not surround all sides of the vibration part 11, but surround three sides or two sides. In this case, the flat plate part 12 includes the vibration part 11 and becomes a roughly rectangular shape. The fixed part 13 may not be located on one side 120 of the flat plate part 12, but may be arranged to surround two sides, three sides or all sides. In this case, the fixed part 13 includes the flat plate part 12 and becomes a roughly rectangular shape.

[0036] The first surface 121 and the second surface 122 of the flat plate portion 12 may respectively have inclined surfaces 121a and 122a whose thickness decreases as they move away from the fixing portion 13. The inclined surfaces 121a and 122a may be set to either side. In addition, if the crystal axis of the crystal plate is set as shown in the figure, the inclined surfaces 121a and 122a are formed by wet etching.

[0037] 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 vibration portion 11. In the first embodiment, the through hole 17 is formed on the inclined surfaces 121a and 122a.

[0038] exist Figure 4 as well as Figure 6 In the plan view, a distance 114 from a center 113 of the vibration portion 11 to the fixed portion 13 may be set to be greater than a distance 124 from a center 123 of the flat portion 12 to the fixed portion 13 .

[0039] exist Figure 4 as well as Figure 6 In the figure, when the direction perpendicular to a side 120 of the flat plate portion 12 where the fixed portion 13 is located is set as the length direction, the distance 125 from the fixed portion 13 to the vibration portion 11 in the flat plate portion 12 can be set to be greater than half and less than twice the length direction dimension (length 115) of the vibration portion 11.

[0040] exist Figure 4 as well as Figure 6 In the figure, when a direction parallel to a side 120 of the flat plate portion 12 where the fixing portion 13 is located is set as a width direction, a distance 126 from the outer edge of the flat plate portion 12 to the vibration portion 11 in the width direction of the flat plate portion 12 can be set to be larger than a dimension (width 116) of the vibration portion 11 in the width direction.

[0041] Next, the crystal element 10 will be described in more detail.

[0042] The crystal element 10 operates in a thickness shear vibration mode, and the resonance frequency (fundamental wave) is, for example, 150 MHz or more. The vibration part 11, the plate part 12, and the fixed part 13 are composed of a crystal plate 21. The excitation electrodes 141, 142, the mounting electrodes 151, 152, and the wiring electrodes 161, 162 are composed of metal patterns of the same material.

[0043] The crystal plate 21 is an AT-cut crystal plate. That is, in the crystal, when the orthogonal coordinate system XYZ consisting of the X-axis (electrical axis), the Y-axis (mechanical axis), and the Z-axis (optical axis) is rotated about the X-axis by more than 30° and less than 50° (as an example, 35°15′) to define the orthogonal coordinate system XY'Z', the wafer cut out parallel to the XZ' plane is the raw material of the crystal plate 21. In addition, the long side direction of the crystal plate 21 is parallel to the X-axis, the short side direction is parallel to the Z' axis, and the thickness direction is parallel to the Y' axis.

[0044] Figure 6 An example of the dimensions is shown as follows. The length 211 of the crystal plate 21 is 700 to 1000 μm, and the width 212 is 400 μm. The length 115 and the width 116 of the vibration part 11 are both 100 μm. The distance 126 from the outer edge of the flat plate part 12 to the vibration part 11 is 150 μm. The length 133 of the fixed part 13 is 50 to 200 μm.

[0045] 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 vibration part 11. Wiring electrodes 161 and 162 for connection that do not contribute to excitation extend from the excitation electrodes 141 and 142 to the mounting electrodes 151 and 152. That is, 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. In addition, the excitation electrodes 141 and 142 are not limited to being substantially elliptical, and may be, for example, substantially circular or substantially rectangular.

[0046] Both mounting electrodes 151 and 152 are located on second surface 132 of fixing portion 13, but at least one of them may be located on first surface 131 of fixing portion 13. In this case, mounting electrodes 151 and 152 may be electrically connected to a package or the like through a wire.

[0047] The metal pattern constituting the excitation electrodes 141, 142, etc., for example, forms a laminate of a base layer containing chromium (Cr) and a conductor layer containing gold (Au). That is, the base layer is provided on the crystal plate 21, and the conductor layer is provided on the base layer. The base layer mainly plays a role in obtaining a close fit with the crystal plate 21. The conductor layer mainly plays a role in obtaining electrical conduction.

[0048] As a manufacturing process of the metal pattern, if providing a metal film is called film formation, there are listed a method of forming a photoresist pattern and etching after film formation on the crystal plate 21, a method of forming a film and peeling after forming a photoresist pattern on the crystal plate, or a method of covering the crystal plate with a metal mask and forming a film, etc. Sputtering or evaporation is used for film formation.

[0049] The crystal element 10 can be manufactured as follows using, for example, photolithography technology and etching technology.

[0050] First, a corrosion-resistant film is provided on the entire surface of the AT-cut crystal wafer, and a photoresist is provided thereon. Next, a mask depicting the outer shape of the crystal plate 21 (including the through hole 17) and the pattern of the flat plate portion 12 is overlapped on the photoresist, and a portion of the corrosion-resistant film is exposed by exposure and development, and wet etching is performed on the corrosion-resistant film in this state. Thereafter, the remaining corrosion-resistant film is used as a mask, and wet etching is performed on the crystal wafer to form the outer shape of the crystal plate 21 (to the middle) and the flat plate portion 12 (flat plate portion processing step). Next, in the same manner, the outer shape of the crystal plate 21 (to the middle) and the vibration portion 11 are formed (vibration portion processing step). Next, in the same manner, the outer shape of the crystal plate 21 (to the through-hole) is formed (outer shape processing step). In addition, etching the first and second surfaces of the crystal plate 21 at the same time is referred to as "double-sided etching", and etching either the first or second surface of the crystal plate 21 is referred to as "single-sided etching". Double-sided etching is used in each of the above-mentioned steps.

[0051] After that, the remaining anti-corrosion film is removed from the crystal wafer, and a metal film serving as the excitation electrodes 141, 142, etc. is provided on the entire surface of the crystal wafer. Next, a photoresist mask including a pattern of the excitation electrodes 141, 142, etc. is formed on the metal film, and the unnecessary metal film is removed by etching to form the excitation electrodes 141, 142, etc. After that, the unnecessary photoresist is removed, and a plurality of crystal elements 10 are formed on the crystal wafer. Finally, the crystal wafer is singulated into individual crystal elements 10, thereby obtaining a single crystal element 10.

[0052] 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. As a result, the crystal plate 21 undergoes thickness shear vibration so that the first surface 111 and the second surface 112 are offset from each other, generating a specific resonant frequency. In this way, the crystal element 10 operates by utilizing the piezoelectric effect and the inverse piezoelectric effect of the crystal plate 21 so as to output a signal of a certain resonant frequency. At this time, the thinner the thickness of the crystal plate 21 (i.e., the vibration portion 11) between the excitation electrodes 141, 141, the higher the resonant frequency.

[0053] Next, the operation and effects of the crystal element 10 will be described.

[0054] (1) The crystal element 10 of the first embodiment includes, as described above, a vibration portion 11 having a first surface 111 and a second surface 112; a plate portion 12 having a first surface 121 and a second surface 122, having a thickness greater than that of the vibration portion 11, and being located at an outer edge of the vibration portion 11 in a plan view; a fixed portion 13 having a first surface 131 and a second surface 132, having a thickness greater than that of the plate portion 12, and being located at an outer edge of the plate portion 12 in a plan view; excitation electrodes 141, 142, located at the first surface 111 and the second surface 112; mounting electrodes 151, 152, located at least on one of the first surface 131 and the second surface 132; and wiring electrodes 161, 162, which electrically connect the excitation electrodes 141, 142 to the mounting electrodes 151, 152.

[0055] According to the crystal element 10 of the first embodiment, by including the vibration part 11, the plate part 12 which is thicker than the vibration part 11 and located at the outer edge of the vibration part 11, and the fixing part 13 which is thicker than the plate part 12 and located at the outer edge of the plate part 12, it is possible to realize a structure in which the thick plate part 12 supports the outer edge of the thin vibration part 11, and the thicker fixing part 13 supports the outer edge of the thick plate part 12. As a result, even if the resonance frequency becomes higher and the vibration part 11 becomes thinner, the mechanical strength of the crystal element 10 can be maintained, thereby ensuring stable electrical characteristics.

[0056] Here, an example of the effect of the crystal element 10 is specifically described. A crystal element without a flat plate portion and including a vibration portion and a fixed portion is used as a comparative example. In this comparative example, stress is concentrated on the boundary between the thinner vibration portion and the thicker fixed portion, and deformation is easily caused in the thinner vibration portion. Therefore, as the vibration portion becomes thinner with higher frequencies, the vibration portion is more likely to deform. In contrast, in the crystal element 10, since the stress generated between the vibration portion 11 and the fixed portion 13 is dispersed or absorbed by the flat plate portion 12, the vibration portion 11 is difficult to deform even if the vibration portion 11 becomes thinner. In addition, as stress sources, there are gravity or tension of a metal pattern, etc.

[0057] In particular, in the crystal element 10 having a resonance frequency of 150 MHz or higher, the vibration portion 11 is quite thin, so it is necessary to be careful about damage during mounting. According to the crystal element 10, the fixing portion 13 thicker than the plate portion 12 is mounted on the package, so that the handling can be improved.

[0058] (2) The first surfaces 111, 121, and 131 are arranged in a step-like shape, and the second surfaces 112, 122, and 132 are also arranged in a step-like shape. In this case, the front side and the back side of the crystal plate 21 have the same structure. As a result, for example, the tension of the metal pattern on the front side and the tension of the metal pattern on the back side are offset, and the deformation of the vibration part 11 can be further suppressed. In addition, since the flat plate part 12 and the vibration part 11 can be formed by double-sided etching, the etching time of each process can be shortened to about half of that of single-sided etching.

[0059] Furthermore, these effects become more significant if the front and back sides of the crystal plate 21 are configured to be vertically symmetrical. In addition, by being vertically symmetrical relative to the center of gravity of the crystal plate 21, the vibration state of the upper and lower halves of the crystal plate 21 is the same, thereby improving the vibration balance and reducing the CI (crystal impedance) value.

[0060] (3) The vibration part 11, the plate part 12, and the fixed part 13 are substantially rectangular in shape, the plate part 12 is provided so as to surround all sides of the rectangle of the vibration part 11, and the fixed part 13 is located only on one side 120 of the rectangle of the plate part 12. When the vibration part 11 is substantially rectangular in shape, it is easier to manage etching residues when the vibration part 11 is formed by wet etching than when the vibration part 11 is substantially circular or elliptical. This is because: if the vibration part 11 is substantially rectangular in shape, the crystal plane exposed to the outer edge of the vibration part 11 is simple, and thus 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 vibration part 11 can be reduced. In addition, when the plate part 12 is provided so as to surround all sides of the vibration part 11, since all sides of the thin vibration part 11 are supported by the thick plate part 12, deformation generated in the vibration part 11 can be further reduced.

[0061] (4) The first surface 121 of the flat plate portion 12 has an inclined surface 121a whose thickness decreases as it moves away from the fixed portion 13, or the second surface 122 of the flat plate portion 12 has an inclined surface 122a whose thickness decreases as it moves away 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 fixed portion 13 side to the vibration portion 11 side is absorbed or dispersed by the inclined surfaces 121a, 122a (gentle step difference), so that the deformation of the vibration portion 11 can be further suppressed. In addition, since the vibration generated in the vibration portion 11 gradually decays as it moves toward the fixed portion 13, the influence of the vibration reflected by the fixed portion 13 on the vibration portion 11 is reduced. Therefore, the cross-sectional shape of the flat plate portion 12 near the fixed portion 13 suppresses the influence of the fixed portion 13 on the vibration of the vibration portion 11, so that the CI value can be reduced. The inclined surfaces 121 a and 122 a may be provided at either one, but the effect can be further increased by providing both.

[0062] (5) A through hole 17 penetrating in the thickness direction is further provided between the mounting electrodes 151 and 152 and the vibration part 11. In this case, since the stress transmitted from the fixing part 13 side to the vibration part 11 side is absorbed or dispersed by the through hole 17, the deformation of the vibration part 11 can be further suppressed. In other words, when the fixing part 13 is fixed to the package, the deformation generated in the flat plate part 12 can be reduced, and the deformation generated in the vibration part 11 can also be reduced. In addition, the through hole 17 can reduce the CI value by sealing the vibration energy of the vibration part 11. Furthermore, by forming the through hole 17 on the inclined surfaces 121a and 122a, these effects become more significant in combination with the effects of the inclined surfaces 121a and 122a.

[0063] (6) Distance 114 from center 113 of vibrating portion 11 to fixed portion 13 is greater than distance 124 from center 123 of plate portion 12 to fixed portion 13. In this case, since vibrating portion 11 and fixed portion 13 are separated, the influence of stress when fixing fixed portion 13 to the package can be reduced.

[0064] (7) The distance 125 from the fixed portion 13 to the vibrating portion 11 in the flat plate portion 12 is not less than half and not more 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 plate portion 12 is easily affected by the stress from the fixed portion 13. If the distance 125 is more than twice the length 115 of the vibrating portion 11, the plate portion 12 is easily deformed, and thus the vibrating portion 11 is also easily deformed.

[0065] (8) In the width direction of the flat plate portion 12, the distance 126 from the outer edge of the flat plate portion 12 to the vibrating portion 11 is greater than the width 116 of the vibrating portion 11. In this case, the vibrating portion 11 can be supported in the width direction by a sufficient portion of the flat plate portion 12, so that deformation of the vibrating portion 11 can be further reduced.

[0066] <Other embodiments>

[0067] Figure 7 to Figure 11 These are cross-sectional views respectively showing crystal plates 21 to 25 of Examples 1 to 5. Hereinafter, description will be given based on these drawings.

[0068] By forming the flat plate portion and the vibration portion in Embodiment 1 by double-sided etching or single-sided etching, a crystal plate having various cross-sectional shapes can be obtained. These crystal plates will be described as Examples 1 to 5 of Embodiment 1.

[0069] Figure 7 The crystal plate 21 of the embodiment 1 shown in FIG. Figure 3 as well as Figure 5 Hereinafter, in the crystal plates 22 to 25 , the components corresponding to the components of the crystal plate 21 are denoted by the same reference numerals as those of the crystal plate 21 .

[0070] When the flat plate portion 12 is formed by double-side 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.

[0071] 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 in 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 in different planes. Alternatively, the second surface 122 of the flat plate portion 12 and the second surface 132 of the fixed portion 13 are in 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 in different planes.

[0072] When the vibration part 11 is formed by double-side etching, the first surface 111 of the vibration part 11 and the first surface 121 of the plate part 12 are different planes, and the second surface 112 of the vibration part 11 and the second surface 122 of the plate part 12 are different planes.

[0073] When the vibration part 11 is formed by single-side etching, the first surface 111 of the vibration part 11 and the first surface 121 of the plate part 12 are the same plane, and the second surface 112 of the vibration part 11 and the second surface 122 of the plate part 12 are different planes. Alternatively, the second surface 112 of the vibration part 11 and the second surface 122 of the plate part 12 are the same plane, and the first surface 111 of the vibration part 11 and the first surface 121 of the plate part 12 are different planes.

[0074] Figure 7 The plate portion 12 and the vibration portion 11 of the crystal plate 21 of the embodiment 1 shown are both formed by double-sided etching. As described in the embodiment 1, three etching steps are required: (double-sided etching of the plate portion 12 + double-sided etching of the outer shape) → (double-sided etching of the vibration portion 11 + double-sided etching of the outer shape) → double-sided etching of the outer shape.

[0075] Figure 8 The crystal plate 22 of the second embodiment shown forms the flat plate portion 12 by double-sided etching, and forms the vibration portion 11 by single-sided etching. In this case, the etching may be two times (double-sided etching of the flat plate portion 12 + double-sided etching of the outer shape) → (single-sided etching of the vibration portion 11 + double-sided etching of the outer shape). In the second embodiment, the vibration portion 11 is formed on the first surface 121 of the flat plate portion 12, but the vibration portion 11 may also be formed on the second surface 122 of the flat plate portion 12. Even in this case, if the crystal plate is reversed, the cross-sectional shape is the same as that of the second embodiment.

[0076] Fig. 9 The crystal plate 23 of the third embodiment shown forms the flat plate portion 12 by single-sided etching and forms the vibration portion 11 by double-sided etching. In this case, the etching may be performed twice: (single-sided etching of the flat plate portion 12 + double-sided etching of the outer shape) → (double-sided etching of the vibration portion 11 + double-sided etching of the outer shape). In the third embodiment, 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 also be formed on the first surface 131 side of the fixed portion 13. Even in this case, if the crystal plate is reversed, the cross-sectional shape is the same as that of the third embodiment (the same applies to the fourth and fifth embodiments).

[0077] Fig.10 The plate portion 12 and the vibration portion 11 of the crystal plate 24 of the fourth embodiment shown are both formed by single-sided etching. In this case, the etching may be two times (single-sided etching of the plate portion 12 + single-sided etching of the outer shape) → (single-sided etching of the vibration portion 11 + double-sided etching of the outer shape).

[0078] Fig.11The crystal plate 25 of the fifth embodiment shown is similar to the crystal plate 24 of the fourth embodiment, in that both the flat plate portion 12 and the vibration portion 11 are formed by single-sided etching. However, in the fourth embodiment, the vibration portion 11 is formed on the first surface 121 of the flat plate portion 12, whereas in the fifth embodiment, the vibration portion 11 is formed on the second surface 122 of the flat plate portion 12. In this case, the etching may be two times (single-sided etching of the flat plate portion 12 + single-sided etching of the outer shape) → (single-sided etching of the vibration portion 11 + double-sided etching of the outer shape).

[0079] The structure, function, and effect of the crystal element including the crystal plates 21 to 25 of each example are the same as those of the crystal element of the first embodiment.

[0080] <Implementation Method 2>

[0081] Fig.12 is a perspective view showing the crystal device 60, Fig.13 yes 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.

[0082] like Fig.12 as well as Fig.13 As shown, the crystal device 60 of the second embodiment includes: the crystal element 10 of the first embodiment, the base 61 on which the crystal element 10 is provided, and the cover 62 which hermetically seals the crystal element 10 together with the base 61. The base 61 is also called a package, and includes a substrate 61a and a frame 61b. The space surrounded by the upper surface of the substrate 61a, the inner side surface of the frame 61b, and the lower surface of the cover 62 becomes a housing portion 63 of the crystal element 10. The crystal element 10 outputs a reference signal used in, for example, an electronic device.

[0083] In other words, the crystal device 60 comprises: a substrate 61a having a pair of electrode pads 61d on the upper surface and four external terminals 61c on the lower surface, a frame 61b arranged along the outer peripheral edge of the upper surface of the substrate 61a, a crystal element 10 mounted on the pair of electrode pads 61d via a conductive adhesive 61e, and a cover 62 that hermetically seals the crystal element 10 together with the frame 61b.

[0084] The substrate 61a and the frame 61b include ceramic materials such as alumina ceramics or glass ceramics, and are integrally formed to form the base 61. The base 61 and the cover 62 are roughly rectangular in a plan view. The external terminal 61c is electrically connected to the electrode pad 61d and the cover 62 via a conductor formed inside or on the side of the base 61. In detail, the external terminals 61c are respectively provided at the four corners of the lower surface of the substrate 61a. Two of the external terminals 61c are electrically connected to the crystal element 10, and the remaining two external terminals 61c are electrically connected to the cover 62. The external terminals 61c are used for printed wiring boards mounted on electronic devices, etc.

[0085] As described above, the crystal element 10 includes: the crystal plate 21, the excitation electrode 141 formed on the upper surface of the crystal plate 21, and the excitation electrode 142 formed on the lower surface of the crystal plate 21. Furthermore, the crystal element 10 is bonded to the electrode pad 61d via the conductive adhesive 61e, and achieves the function of oscillating a reference signal of an electronic device or the like through stable mechanical vibration and piezoelectric effect.

[0086] The electrode pads 61d are pads for mounting the crystal element 10 on the base 61, and a pair of them are provided adjacent to each other so as to be along one side of the substrate 61a. Furthermore, the pair of electrode pads 61d connect the mounting electrodes 151 and 152 respectively, and one end of the crystal element 10 is used as a fixed end, and the other end of the crystal element 10 is used as a free end separated from the upper surface of the substrate 61a, thereby fixing the crystal element 10 on the substrate 61a through the cantilever support structure.

[0087] The conductive adhesive 61e is, for example, a silicone resin adhesive containing conductive powder as a conductive filler. The cover 62 is, for example, an alloy containing at least one of iron, nickel or cobalt, and is joined to the frame 61b by seam welding, etc., to hermetically seal the receiving portion 63 which is in a vacuum state or filled with nitrogen, etc.

[0088] According to the crystal device 60, by including the crystal element 10, stable electrical characteristics can be exhibited. In addition, the crystal device 60 is mounted on the surface of the printed circuit board constituting the electronic device by fixing the bottom surface of the external terminal 61c to the printed circuit board by soldering, a gold (Au) block, or a conductive adhesive. In addition, the crystal device 60 is used as an oscillation source in various electronic devices such as smart phones, personal computers, watches, game consoles, communication equipment, or in-vehicle devices such as car navigation systems.

[0089] <Others>

[0090] The present disclosure has been described above with reference to the above-mentioned embodiments, but the present disclosure is not limited thereto. Various changes that can be understood by those skilled in the art can be applied to the structure and details of the present disclosure. For example, the shape of the vibration part is described as being roughly rectangular, but it can also be other patterns (circular, elliptical, polygonal, etc.).

[0091] This application claims the benefit of priority based on Japanese patent application No. 2019-101757, filed on May 30, 2019, the entire disclosure of which is incorporated herein by reference.

Claims

1. A crystal element, wherein, when the front side of two surfaces in a front-back relationship is set as a first surface, the back side is set as a second surface, and the dimension in a direction perpendicularly penetrating the first surface and the second surface is set as a thickness, the crystal element comprises: A vibration part having a first surface and a second surface; A flat plate portion having a first surface and a second surface, having a thickness greater than that of the vibration portion, and being located at an outer edge of the vibration portion in a plan view; A fixing portion having a first surface and a second surface, having a thickness greater than that of the flat plate portion, and being located at an outer edge of the flat plate portion in a plan view; an excitation electrode, located on the first surface and the second surface of the vibration part; A carrying electrode located on at least one of the first surface and the second surface of the fixing portion; wiring electrodes to electrically connect the excitation electrodes to the mounting electrodes, In a plan view, the vibration part, the flat plate part and the fixing part are rectangular in shape. The flat plate portion is arranged to surround all sides of the rectangle of the vibration portion, The fixing portion is located only on one side of the rectangle of the flat plate portion, At least one of the first surface and the second surface of the flat plate portion has an inclined surface whose thickness decreases as it moves away from the fixing portion. The crystal element further includes, on the inclined surface, a through hole penetrating between the mounting electrode and the vibration portion in the thickness direction.

2. The crystal element according to claim 1, wherein The first surface of the flat plate portion and the first surface of the fixing portion are on different planes, and The second surface of the flat plate portion and the second surface of the fixing portion are on different planes.

3. The crystal element according to claim 1, wherein The first surface of the flat plate portion and the first surface of the fixing portion are on the same plane, or The second surface of the flat plate portion and the second surface of the fixing portion are located on the same plane.

4. The crystal element according to claim 2 or 3, wherein: The first surface of the vibration portion and the first surface of the flat plate portion are on different planes, and The second surface of the vibration portion and the second surface of the flat plate portion are on different planes.

5. The crystal element according to claim 2 or 3, wherein: The first surface of the vibration portion and the first surface of the flat plate portion are on the same plane, or The second surface of the vibration portion and the second surface of the flat plate portion are on the same plane.

6. The crystal element according to claim 1, wherein In a plan view, a distance from a center of the vibrating portion to the fixed portion is greater than a distance from a center of the flat plate portion to the fixed portion.

7. The crystal element according to claim 1, 2, 3 or 6, wherein: In a plan view, when a direction perpendicular to the side of the flat plate portion where the fixing portion is located is set as a length direction, A distance from the fixed portion to the vibrating portion in the flat plate portion is not less than half and not more than twice a dimension in a longitudinal direction of the vibrating portion.

8. The crystal element according to claim 1, 2, 3 or 6, wherein: In a plan view, when a direction parallel to the side of the flat plate portion where the fixing portion is located is defined as a width direction, In the width direction of the flat plate portion, a distance from an outer edge of the flat plate portion to the vibrating portion is greater than a dimension of the vibrating portion in the width direction.

9. A crystal device comprising: The crystal element according to claim 1, 2, 3 or 6; A substrate on which the crystal element is located; and A cover body hermetically seals the crystal element together with the base body.

10. A crystal element, wherein, when the front side of two surfaces in a front-back relationship is set as a first surface, the back side is set as a second surface, and the dimension in a direction perpendicularly penetrating the first surface and the second surface is set as a thickness, the crystal element comprises: A vibration part having a first surface and a second surface; A flat plate portion having a first surface and a second surface, having a thickness greater than that of the vibration portion, and being located at an outer edge of the vibration portion in a plan view; A fixing portion having a first surface and a second surface, having a thickness greater than that of the flat plate portion, and being located at an outer edge of the flat plate portion in a plan view; an excitation electrode, located on the first surface and the second surface of the vibration part; A carrying electrode located on at least one of the first surface and the second surface of the fixing portion; wiring electrodes to electrically connect the excitation electrodes to the mounting electrodes, In a plan view, the vibration part, the flat plate part and the fixing part are rectangular in shape. The flat plate portion is arranged to surround all sides of the rectangle of the vibration portion, The fixing portion is located only on one side of the rectangle of the flat plate portion, In a plan view, a distance from a center of the vibrating portion to the fixed portion is greater than a distance from a center of the flat plate portion to the fixed portion.

11. The crystal element according to claim 10, wherein: The first surface of the flat plate portion and the first surface of the fixing portion are on different planes, and The second surface of the flat plate portion and the second surface of the fixing portion are on different planes.

12. The crystal element according to claim 10, wherein: The first surface of the flat plate portion and the first surface of the fixing portion are on the same plane, or The second surface of the flat plate portion and the second surface of the fixing portion are located on the same plane.

13. The crystal element according to claim 11 or 12, wherein: The first surface of the vibration portion and the first surface of the flat plate portion are on different planes, and The second surface of the vibration portion and the second surface of the flat plate portion are on different planes.

14. The crystal element according to claim 11 or 12, wherein: The first surface of the vibration portion and the first surface of the flat plate portion are on the same plane, or The second surface of the vibration portion and the second surface of the flat plate portion are on the same plane.

15. The crystal element according to claim 10, wherein At least one of the first surface and the second surface of the flat plate portion has an inclined surface whose thickness decreases as it moves away from the fixing portion.

16. The crystal element according to claim 10 or 15, wherein: The crystal element further includes a through hole penetrating between the mounting electrode and the vibration portion in a thickness direction.

17. The crystal element according to any one of claims 10 to 12 and 15, wherein: In a plan view, when a direction perpendicular to the side of the flat plate portion where the fixing portion is located is set as a length direction, A distance from the fixed portion to the vibrating portion in the flat plate portion is not less than half and not more than twice a dimension in a longitudinal direction of the vibrating portion.

18. The crystal element according to any one of claims 10 to 12 and 15, wherein: In a plan view, when a direction parallel to the side of the flat plate portion where the fixing portion is located is defined as a width direction, In the width direction of the flat plate portion, a distance from an outer edge of the flat plate portion to the vibrating portion is greater than a dimension of the vibrating portion in the width direction.

19. A crystal device comprising: The crystal element according to any one of claims 10 to 12 and 15; A substrate on which the crystal element is located; and A cover body hermetically seals the crystal element together with the base body.

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