Piezoelectric diaphragm and piezoelectric vibration device

Abstract

A quartz diaphragm 10 comprises a vibrating section 11, an outer frame section 12, and a retaining section 13. A cutout section 10a is provided between the vibrating section 11 and the outer frame section 12. An electrode formed on one principal surface is connected to an electrode formed on another principal surface via internal wiring 17 formed in an inner wall surface of the outer frame section 12. If a region of the cutout section 10a sandwiched between the inner wall surface of the outer frame section 12 and an outer wall surface of the vibrating section 11 is considered a first region A1, a region of the cutout section 10a, excluding the first region A1 from the space and sandwiched between the inner wall surface of the outer frame section 12 and the outer wall surface of the retaining section 13 is considered a second region A2, and a region sandwiched between the inner wall surfaces of the outer frame section 12 is considered a third region A3, the internal wiring 17 is formed at a position on the inner wall surface of the outer frame section 12 facing at least the second region A2 or the third region A3.

Description

Technical Field

[0001] The present invention relates to a piezoelectric diaphragm and a piezoelectric vibration device including the same.

Background Art

[0002] In recent years, higher operating frequencies of various electronic devices and miniaturization of packages (particularly reduction in package height) have been progressing. Accordingly, along with higher frequencies and package miniaturization, crystal vibration devices (e.g., crystal resonators, crystal oscillators, etc.) are also required to comply with demands for higher operating frequencies and smaller packages.

[0003] A so-called sandwich-structure crystal vibration device is known as a crystal vibration device suitable for size and height reduction. In the sandwich-structure crystal vibration device, the housing of the device is formed of a substantially rectangular parallelepiped package. The package includes a first sealing member and a second sealing member made of, for example, glass or crystal, and a crystal diaphragm having excitation electrodes formed on both main surfaces thereof. The first sealing member and the second sealing member are stacked and bonded together with the crystal diaphragm interposed therebetween. A vibrating portion of the crystal diaphragm disposed in the interior (internal space) of the package is hermetically sealed by the first sealing member and the second sealing member (see, for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] In piezoelectric diaphragms as described above, when electrodes formed on one main surface are connected to electrodes formed on the other main surface by providing, for example, through-holes in the outer frame, space is required for the through-holes, making it difficult to miniaturize. On the other hand, as miniaturization reduces the distance between the vibrating part and the outer frame, there is a possibility that the vibrating part may come into contact with the wiring formed in the outer frame, potentially causing disconnections or other problems.

[0006] This invention has been made in consideration of the circumstances described above, and aims to provide a piezoelectric diaphragm and a piezoelectric vibration device equipped therewith that can be miniaturized while maintaining stable electrical characteristics. [Means for solving the problem]

[0007] The present invention provides the following means for solving the above-mentioned problems. In other words, the present invention relates to a rectangular piezoelectric diaphragm in which a first excitation electrode is formed on one main surface of a substrate and a second excitation electrode, which is paired with the first excitation electrode, is formed on the other main surface of the substrate, comprising a rectangular vibrating portion, an outer frame portion surrounding the outer circumference of the vibrating portion, and a holding portion connecting a part of the vibrating portion and a part of the outer frame portion, wherein a cutout portion formed by cutting out the substrate is provided between the vibrating portion and the outer frame portion, the electrode formed on one main surface of the substrate is electrically connected to the electrode formed on the other main surface of the substrate via internal wiring formed on the inner wall surface of the outer frame portion, and if the space of the cutout portion is defined as the two areas on the side where the holding portion is provided, with respect to the two areas on the side where the holding portion is not provided, with respect to the internal wiring being formed on the inner wall surface of the outer frame portion at a position facing at least one of the second and third regions, and the internal wiring being formed at a position not facing the vibrating portion. The inner wall surface of the outer frame is formed in a rectangular and annular shape in plan view, and a notch is formed at the corner of the inner wall surface in plan view, which extends into the outer frame, and the internal wiring is formed on the inner wall surface of the notch.The present invention is characterized by the following: Here, electrodes formed on one main surface and the other main surface of the substrate include, for example, electrodes of an annular sealing portion (seal path) that hermetically seals the vibrating portion of the piezoelectric diaphragm, wiring electrodes connected to ground, lead electrodes drawn out from the first and second excitation electrodes, and wiring electrodes connected to the IC provided in the piezoelectric oscillator. Furthermore, the present invention relates to a rectangular piezoelectric diaphragm in which a first excitation electrode is formed on one main surface of a substrate and a second excitation electrode, which is paired with the first excitation electrode, is formed on the other main surface of the substrate, comprising a rectangular vibrating portion, an outer frame portion surrounding the outer circumference of the vibrating portion, and a holding portion connecting a part of the vibrating portion and a part of the outer frame portion, wherein a cutout portion formed by cutting out the substrate is provided between the vibrating portion and the outer frame portion, the electrode formed on one main surface of the substrate is electrically connected to the electrode formed on the other main surface of the substrate via internal wiring formed on the inner wall surface of the outer frame portion, the area of ​​the cutout portion space sandwiched between the inner wall surface of the outer frame portion and the outer wall surface of the vibrating portion is defined as the first region, and the remaining area after removing the first region from the cutout portion space is defined as The invention relates to a method where, of the four corner spaces of the cutout portion, the two areas on the side where the retaining portion is provided are designated as the second region, and the two areas on the side where the retaining portion is not provided are designated as the third region. The invention relates to a method where the internal wiring is formed on the inner wall surface of the outer frame portion at a position facing at least one of the second region and the third region, the inner wall surface of the outer frame portion is formed in a rectangular and annular shape in plan view, and a notch is formed at the corner of the inner wall surface in plan view that extends into the outer frame portion, the internal wiring is formed on the inner wall surface of the notch, and the notch in which the internal wiring is provided is formed to extend into the outer frame portion relative to a portion of the inner wall surface of the outer frame portion that is formed linearly in plan view.

[0008] The above configuration allows for miniaturization of the piezoelectric diaphragm while maintaining stable electrical characteristics. Specifically, by connecting electrodes formed on one main surface to electrodes formed on the other main surface via internal wiring, it becomes unnecessary to form through-holes or the like in the outer frame, thus enabling miniaturization of the piezoelectric diaphragm while securing the effective area of ​​the vibrating part. Furthermore, the inner wall surface of the outer frame facing (contacting) the second and third regions has a larger cutout width than the inner wall surface of the outer frame facing (contacting) the adjacent first region, allowing for space between the opposing wall surfaces. This suppresses contact between the vibrating part and the internal wiring, reducing the risk of disconnection. Moreover, internal wiring can be easily and reliably formed on the inner wall surface of the outer frame. In this case, the photolithography process for forming internal wiring on the inner wall surface of the outer frame can reliably remove the resist from the inner wall surface of the outer frame and the outer wall surface of the vibrating part, ensuring reliable formation of internal wiring on the inner wall surface of the outer frame. Therefore, the electrodes formed on one main surface and the electrodes formed on the other main surface can be electrically connected stably and reliably, thereby suppressing a decrease in the electrical characteristics of the piezoelectric diaphragm and preventing the occurrence of defective products.

[0010] With the piezoelectric diaphragm configuration described above, the inner wall surface of the notch is made inclined, which makes it difficult for the internal wiring to break. Furthermore, since the notch is formed to fit into the outer frame, the effective area of ​​the vibrating part can be secured, enabling the realization of a piezoelectric diaphragm that is both compact and has stable electrical characteristics.

[0011] Furthermore, the present invention relates to a piezoelectric vibration device comprising a piezoelectric diaphragm as described above, wherein a first sealing member covering the first excitation electrode of the piezoelectric diaphragm and a second sealing member covering the second excitation electrode of the piezoelectric diaphragm are provided, and the first sealing member and the piezoelectric diaphragm are joined together, and the second sealing member and the piezoelectric diaphragm are joined together, thereby providing an internal space in which the vibrating portion of the piezoelectric diaphragm, including the first excitation electrode and the second excitation electrode, is hermetically sealed.

[0012] The piezoelectric vibration device with the above configuration provides the same effects as the piezoelectric diaphragm described above. Furthermore, since the internal wiring is not exposed on the outer surface of the piezoelectric vibration device package, the internal wiring will not be broken or worn down due to contact during assembly or transportation.

[0013] In the piezoelectric vibration device with the above configuration, it is preferable that the grounding electrode formed on one of the two main surfaces of the first sealing member is electrically connected via the internal wiring to an external electrode terminal formed on the main surface of the second sealing member that does not face the internal space. With this configuration, the internal wiring ensures a reliable connection between the grounding electrode and the external electrode terminal, thereby improving the shielding performance of the grounding electrode.

[0014] In the piezoelectric vibration device with the above configuration, it is preferable that annular sealing portions are provided between the first sealing member and the piezoelectric diaphragm, and between the second sealing member and the piezoelectric diaphragm, respectively, to hermetically seal the vibrating portion of the piezoelectric diaphragm, and that each of the sealing portions is electrically connected to the internal wiring. With this configuration, the sealing portions can be reliably connected to each other by the internal wiring.

[0015] In the piezoelectric vibration device with the above configuration, it is preferable that only one holding portion is provided, and that the holding portion extends from the corner of the vibrating portion toward the outer frame portion. With this configuration, multiple second and third regions of the cutout can be secured, thereby improving the stability of conductivity due to internal wiring, and making it possible to have a configuration that is less likely to suppress the main vibration of the piezoelectric diaphragm.

[0016] In the piezoelectric vibration device with the above configuration, it is preferable that the piezoelectric diaphragm is an AT-cut quartz diaphragm, and that the internal wiring is formed on the inner wall surface along the Z' axis direction of the AT cut of the outer frame. Here, on the inner wall surface along the X axis direction of the AT cut of the outer frame, an inclined surface is formed in the wet etching process to form the cutout, and sharp angles tend to appear, which could lead to wire breakage or other problems when forming internal wiring. However, on the inner wall surface along the Z' axis direction of the AT cut of the outer frame, such sharp angles are less likely to appear, so internal wiring can be easily formed, and the risk of wire breakage or other problems can be reduced. [Effects of the Invention]

[0017] The piezoelectric diaphragm and piezoelectric vibration device of the present invention can be miniaturized while maintaining stable electrical characteristics. [Brief explanation of the drawing]

[0018] [Figure 1] Figure 1 is a schematic diagram illustrating the crystal oscillator according to this embodiment. [Figure 2] Figure 2 is a schematic plan view of the first main surface side of the first sealing member of the quartz crystal oscillator. [Figure 3] Figure 3 is a schematic plan view of the second main surface side of the first sealing member of the quartz crystal oscillator. [Figure 4] Figure 4 is a schematic plan view of the first main surface side of the quartz diaphragm according to this embodiment. [Figure 5] Figure 5 is a schematic plan view of the second main surface side of the quartz diaphragm according to this embodiment. [Figure 6] Figure 6 is a schematic plan view of the first main surface side of the second sealing member of the quartz crystal oscillator. [Figure 7] Figure 7 is a schematic plan view of the second main surface side of the second sealing member of the quartz crystal oscillator. [Figure 8] Figure 8 is a diagram corresponding to Figure 4 of a crystal diaphragm according to another embodiment 1. [Figure 9] Figure 9 is a diagram corresponding to Figure 3 of the first sealing member according to another embodiment 2. [Figure 10] FIG. 10 is a view equivalent to FIG. 4 of a quartz crystal diaphragm according to another third embodiment. [Figure 11] FIG. 11 is a view equivalent to FIG. 5 of a quartz crystal diaphragm according to another third embodiment. MODE FOR CARRYING OUT THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a case where the piezoelectric vibration device to which the present invention is applied is a quartz crystal resonator will be described.

[0020] First, the basic structure of the quartz crystal resonator 100 according to the present embodiment will be described. As shown in FIG. 1, the quartz crystal resonator 100 is configured to include a quartz crystal diaphragm (piezoelectric diaphragm) 10, a first sealing member 20, and a second sealing member 30. In this quartz crystal resonator 100, the quartz crystal diaphragm 10 and the first sealing member 20 are bonded to each other, and the quartz crystal diaphragm 10 and the second sealing member 30 are bonded to each other, whereby a package having a substantially rectangular parallelepiped sandwich structure is formed. That is, in the quartz crystal resonator 100, the first sealing member 20 and the second sealing member 30 are bonded to both main surfaces of the quartz crystal diaphragm 10 respectively, thereby forming an internal space (cavity) of the package, and a vibrating portion 11 (see FIGS. 4 and 5) is hermetically sealed in this internal space.

[0021] The quartz crystal resonator 100 according to the present embodiment has, for example, a package size of 1.0×0.8 mm, and is designed to achieve miniaturization and low profile. Further, the quartz crystal resonator 100 is adapted to be electrically connected to an external circuit board (not shown) provided outside via solder.

[0022] Next, the crystal diaphragm 10, the first sealing member 20, and the second sealing member 30 of the crystal oscillator 100 described above will be explained with reference to Figures 1 to 7. Here, we will explain each component as a separate unit that is not joined together. Figures 2 to 7 merely show one example configuration of the crystal diaphragm 10, the first sealing member 20, and the second sealing member 30, and these do not limit the present invention.

[0023] As shown in Figures 4 and 5, the quartz diaphragm 10 is a piezoelectric substrate made of quartz, and both of its main surfaces (first main surface 101, second main surface 102) are formed as flat, smooth surfaces (mirror finish). In this embodiment, an AT-cut quartz plate that performs thickness-sliding vibration is used as the quartz diaphragm 10. In the quartz diaphragm 10 shown in Figures 4 and 5, both main surfaces 101 and 102 of the quartz diaphragm 10 are considered to be the XZ' plane. In this XZ' plane, the direction parallel to the short side of the quartz diaphragm 10 is considered to be the X-axis direction, and the direction parallel to the long side of the quartz diaphragm 10 is considered to be the Z' axis direction. Note that AT cutting is a processing method in which artificial quartz is cut at an angle of 35°15′ inclined around the X-axis with respect to the Z-axis, which is one of the three crystal axes of artificial quartz: the electrical axis (X-axis), the mechanical axis (Y-axis), and the optical axis (Z-axis). In an AT-cut quartz plate, the X-axis coincides with the crystal axis of the quartz. The Y' and Z' axes coincide with axes that are tilted approximately 35°15′ from the Y and Z axes of the quartz crystal axis, respectively (this cutting angle may be slightly modified to adjust the frequency-temperature characteristics of the AT-cut quartz diaphragm). The Y' and Z' axis directions correspond to the cutting direction when cutting the AT-cut quartz plate.

[0024] A pair of excitation electrodes (first excitation electrode 111, second excitation electrode 112) are formed on both main surfaces 101 and 102 of the quartz crystal diaphragm 10. The quartz crystal diaphragm 10 has a vibrating section 11 formed in a substantially rectangular shape, an outer frame section 12 surrounding the outer circumference of the vibrating section 11, and a holding section 13 that holds the vibrating section 11 by connecting the vibrating section 11 and the outer frame section 12. In other words, the quartz crystal diaphragm 10 has a configuration in which the vibrating section 11, the outer frame section 12, and the holding section 13 are integrally provided. The holding section 13 extends (projects) from only one corner of the vibrating section 11 located in the +X direction and the -Z' direction to the outer frame section 12 in the -Z' direction. A cutout section 10a formed by cutting out the quartz crystal diaphragm 10 is provided between the vibrating section 11 and the outer frame section 12. In this embodiment, the crystal diaphragm 10 is provided with only one holding portion 13 that connects the vibrating portion 11 and the outer frame portion 12, and the cutout portion 10a is continuously formed to surround the outer circumference of the vibrating portion 11. In this embodiment, the outer frame portion 12 of the crystal diaphragm 10 is not provided with through holes or castellations. The crystal diaphragm 10 is configured not to have any through-holes other than the cutout portion 10a.

[0025] The first excitation electrode 111 is provided on the first main surface 101 side of the vibrating section 11, and the second excitation electrode 112 is provided on the second main surface 102 side of the vibrating section 11. Lead-out wiring (lead-out electrodes) for connecting these excitation electrodes to external electrode terminals is connected to the first excitation electrode 111 and the second excitation electrode 112. The first lead-out wiring 113 is led out from the first excitation electrode 111 and connected via the holding section 13 to a connecting joint pattern 12a formed on the first main surface 101 side of the outer frame section 12. Furthermore, the connecting joint pattern 12a is connected via internal wiring 12g formed on the inner wall surface of the outer frame section 12 to a connecting joint pattern 12e formed on the second main surface 102 side of the outer frame section 12. The internal wiring 12g is provided on the inner wall surface of the outer frame section 12 that is aligned with the X-axis direction and on the -Z' side. In this case, the internal wiring 12g is formed in a V-shaped recess in plan view provided on the inner wall surface of the outer frame 12. By forming a V-shaped recess on the inner wall surface of the outer frame 12 in this way, the internal wiring 12g can be formed in a direction other than the X-axis direction of the AT cut. Therefore, even if an inclined surface is formed in the wet etching process, parts other than acute angles will also be present, thus reducing the risk of disconnection. The second lead-out wiring 114 is led out from the second excitation electrode 112 and connected via the holding part 13 to the connecting joint pattern 12d formed on the second main surface 102 side of the outer frame 12.

[0026] Both main surfaces (first main surface 101, second main surface 102) of the crystal diaphragm 10 are provided with diaphragm-side sealing portions for joining the crystal diaphragm 10 to the first sealing member 20 and the second sealing member 30. A diaphragm-side first bonding pattern 121 is formed as the diaphragm-side sealing portion of the first main surface 101, and a diaphragm-side second bonding pattern 122 is formed as the diaphragm-side sealing portion of the second main surface 102. The diaphragm-side first bonding pattern 121 and the diaphragm-side second bonding pattern 122 are provided on the outer frame portion 12 and are formed in an annular shape in plan view. The outer edge of the diaphragm-side first bonding pattern 121 is provided close to the outer edge of the first main surface 101 of the crystal diaphragm 10 (outer frame portion 12). The outer edge of the diaphragm-side second bonding pattern 122 is provided close to the outer edge of the second main surface 102 of the crystal diaphragm 10 (outer frame portion 12). In this embodiment, the diaphragm-side first bonding pattern 121 and the diaphragm-side second bonding pattern 122 are connected via internal wiring 17 formed on the inner wall surface of the outer frame portion 12. The internal wiring 17 is provided on the inner wall surface of the outer frame portion 12 that is aligned with the Z' axis direction and on the -X direction side, and is provided on the inner wall surface perpendicular to the inner wall surface on which the aforementioned internal wiring 12g is provided. Connecting bonding patterns 12b and 12c are formed on the first main surface 101 side of the outer frame portion 12, and connecting bonding pattern 12f is formed on the second main surface 102 side of the outer frame portion 12.

[0027] As shown in Figures 2 and 3, the first sealing member 20 is a rectangular substrate formed from a single AT-cut quartz plate, and the second main surface 202 of the first sealing member 20 (the surface that joins to the quartz diaphragm 10) is formed as a flat, smooth surface (mirror finish). Although the first sealing member 20 does not have a vibrating part, by using an AT-cut quartz plate similar to the quartz diaphragm 10, the thermal expansion coefficients of the quartz diaphragm 10 and the first sealing member 20 can be made the same, thereby suppressing thermal deformation in the quartz oscillator 100. Furthermore, the orientation of the X, Y, and Z' axes of the first sealing member 20 is the same as that of the quartz diaphragm 10. In this embodiment, since the first sealing member 20 does not have through holes or castellations, the manufacturing process of the first sealing member 20 can be significantly shortened. In addition, by eliminating the path for moisture to enter the internal space of the package in the first sealing member 20, corrosion resistance can be improved.

[0028] A first sealing member side bonding pattern 24 is formed on the second main surface 202 of the first sealing member 20, serving as the first sealing portion on the sealing member side for bonding to the crystal diaphragm 10. The first sealing member side bonding pattern 24 is formed in an annular shape in plan view. The outer edge of the first sealing member side bonding pattern 24 is provided close to the outer edge of the second main surface 202 of the first sealing member 20. In addition, connecting bonding patterns 22a, 22b, and 22c are formed on the second main surface 202 of the first sealing member 20 for bonding to the connecting bonding patterns 12a, 12b, and 12c formed on the first main surface 101 of the outer frame portion 12 of the crystal diaphragm 10.

[0029] As shown in Figures 6 and 7, the second sealing member 30 is a rectangular substrate formed from a single AT-cut quartz plate, and the first main surface 301 of this second sealing member 30 (the surface that joins to the quartz diaphragm 10) is formed as a flat, smooth surface (mirror finish). It is desirable that the second sealing member 30 also uses an AT-cut quartz plate, similar to the quartz diaphragm 10, and that the orientation of the X, Y, and Z' axes is the same as that of the quartz diaphragm 10.

[0030] The first main surface 301 of the second sealing member 30 has a second sealing pattern 31 on the sealing member side, which serves as a second sealing portion on the sealing member side for joining to the crystal diaphragm 10. The second sealing pattern 31 on the sealing member side is formed in an annular shape in plan view. The outer edge of the second sealing pattern 31 on the sealing member side is provided close to the outer edge of the first main surface 301 of the second sealing member 30. In addition, the first main surface 301 of the second sealing member 30 has connecting patterns 34a, 34b, and 34c formed on the first main surface 301 of the second sealing member 30 for joining to connecting patterns 12d, 12e, and 12f formed on the second main surface 102 of the outer frame portion 12 of the crystal diaphragm 10. The connecting patterns 34a and 34c are connected by a wiring pattern 35 extending in the Z' axis direction.

[0031] The second main surface 302 of the second sealing member 30 (the outer main surface not facing the crystal diaphragm 10) is provided with four external electrode terminals 32 that are electrically connected to an external circuit board provided outside the crystal oscillator 100. The external electrode terminals 32 are formed in a substantially rectangular shape and are located at the four corners (corners) of the second main surface 302 of the second sealing member 30. In a plan view, the external electrode terminals 32 are provided in a position that overlaps with the outer frame portion 12 of the crystal diaphragm 10 described above.

[0032] As shown in Figures 6 and 7, the second sealing member 30 has three through-holes 33a, 33b, and 33c that penetrate between the first main surface 301 and the second main surface 302. The through-holes 33a, 33b, and 33c are provided in the four corner (corner) regions of the second sealing member 30. Through electrodes are formed along the inner wall surfaces of the through-holes 33a, 33b, and 33c to ensure electrical conductivity between the electrodes formed on the first main surface 301 and the second main surface 302. The through electrodes formed on the inner wall surfaces of the through-holes 33a, 33b, and 33c provide electrical conductivity between the electrode (connection pattern) formed on the first main surface 301 and the external electrode terminal 32 formed on the second main surface 302. Furthermore, the central portions of each through-hole 33a, 33b, and 33c are hollow through-holes that penetrate between the first main surface 301 and the second main surface 302.

[0033] In the crystal oscillator 100, which includes the crystal diaphragm 10, the first sealing member 20, and the second sealing member 30 as described above, the crystal diaphragm 10 and the first sealing member 20 are diffusion-bonded with the first bonding pattern 121 on the diaphragm side and the first bonding pattern 24 on the sealing member side superimposed, and the crystal diaphragm 10 and the second sealing member 30 are diffusion-bonded with the second bonding pattern 122 on the diaphragm side and the second bonding pattern 31 on the sealing member side superimposed, thereby manufacturing a sandwich-structure package as shown in Figure 1. As a result, the internal space of the package, that is, the space housing the vibrating part 11, is hermetically sealed.

[0034] In this process, the aforementioned connection patterns are also superimposed and diffusely bonded. Through the bonding of the connection patterns, electrical conductivity is achieved in the crystal oscillator 100 between the first excitation electrode 111, the second excitation electrode 112, and the external electrode terminals 32, 32. Specifically, the first excitation electrode 111 is connected to the external electrode terminal 32 via the first lead wiring 113, the internal wiring 12g, and the through-hole 33a in that order. The second excitation electrode 112 is connected to the external electrode terminal 32 via the second lead wiring 114, the wiring pattern 35, and the through-hole 33b in that order.

[0035] In the quartz oscillator 100, it is preferable that the various bonding patterns consist of multiple layers stacked on a quartz plate, with the Ti (titanium) layer and Au (gold) layer formed from the bottom layer side by vapor deposition or sputtering. Furthermore, if the other wiring and electrodes formed on the quartz oscillator 100 have the same configuration as the bonding patterns, the bonding patterns, wiring, and electrodes can be patterned simultaneously, which is preferable.

[0036] In the crystal oscillator 100 configured as described above, the sealing portions (seal paths) 15 and 16 that hermetically seal the vibrating portion 11 of the crystal diaphragm 10 are formed in annular shape in plan view. The seal path 15 is formed by diffusion bonding (Au-Au bonding) of the diaphragm-side first bonding pattern 121 and the sealing member-side first bonding pattern 24 described above. The outer edge shape of the seal path 15 is formed to be approximately rectangular, and the outer edge of the seal path 15 is positioned close to the outer edge of the package. Similarly, the seal path 16 is formed by diffusion bonding (Au-Au bonding) of the diaphragm-side second bonding pattern 122 and the sealing member-side second bonding pattern 31 described above. The outer edge shape of the seal path 16 is formed to be approximately rectangular, and the outer edge of the seal path 16 is positioned close to the outer edge of the package. The seal paths 15 and 16 are not electrically connected to the electrical conduction path between the first and second excitation electrodes 111 and 112 and the external electrode terminals 32 and 32. Specifically, the seal path 15 is connected to the seal path 16 via internal wiring 17, and the seal path 16 is further connected to earth (using a portion of the external electrode terminal 32) via a through-hole electrode 33c.

[0037] In the quartz crystal oscillator 100 in which seal paths 15 and 16 are formed by diffusion bonding as described above, the gap between the first sealing member 20 and the quartz crystal diaphragm 10 is 1.00 μm or less, and the gap between the second sealing member 30 and the quartz crystal diaphragm 10 is 1.00 μm or less. In other words, the thickness of the seal path 15 between the first sealing member 20 and the quartz crystal diaphragm 10 is 1.00 μm or less, and the thickness of the seal path 16 between the second sealing member 30 and the quartz crystal diaphragm 10 is 1.00 μm or less (specifically, 0.15 μm to 1.00 μm in the Au-Au bonding of this embodiment). For comparison, in conventional metal paste sealing materials using Sn, the gap is 5 μm to 20 μm.

[0038] In this embodiment, in the crystal diaphragm 10 with the above configuration, a cutout portion 10a formed by cutting out a substrate is provided between the vibrating portion 11 and the outer frame portion 12, and an electrode (seal path 15) formed on the first main surface 101 of the substrate is electrically connected to an electrode (seal path 16) formed on the second main surface 102 of the substrate via internal wiring 17 formed on the inner wall surface of the outer frame portion 12. If, within the space of the cutout portion 10a, the area sandwiched between the inner wall surface of the outer frame portion 12 and the outer wall surface of the vibrating portion 11 is defined as the first region A1, and of the remaining area after removing the first region A1 from the space of the cutout portion 10a, the area sandwiched between the inner wall surface of the outer frame portion 12 and the outer wall surface of the holding portion 13 is defined as the second region A2, and the area sandwiched between the inner wall surfaces of the outer frame portion 12 is defined as the third region A3, then the internal wiring 17 is formed at a position on the inner wall surface of the outer frame portion 12 that faces at least one of the second region A2 and the third region A3. This point will be explained with reference to Figure 4.

[0039] As shown in Figure 4, the space of the cutout portion 10a is divided into multiple regions (eight regions in Figure 4) by four straight lines L1 to L4 along the outer edge (outer wall surface) of the rectangular vibrating portion 11 in a plan view. Straight lines L1 and L2 are parallel to the Z' axis direction, and straight lines L3 and L4 are parallel to the X axis direction. The region sandwiched between the inner wall surface of the outer frame portion 12 and the outer wall surface of the vibrating portion 11 is defined as the first region A1. The first region A1 is provided at four locations that are in contact with the outer wall surface of the vibrating portion 11. The first region A1 is a region that faces the vibrating portion 11 in the X axis direction and the Z' axis direction, respectively. The first region A1 is provided at locations other than the spaces at the four corners of the cutout portion 10a.

[0040] Furthermore, the area remaining after removing the first area A1 from the space of the cutout portion 10a, sandwiched between the inner wall surface of the outer frame portion 12 and the outer wall surface of the holding portion 13, is defined as the second area A2. The second area A2 is provided at two locations on the -Z' side of the space at the four corners of the cutout portion 10a. The area remaining after removing the first area A1 from the space of the cutout portion 10a, sandwiched between the inner wall surfaces of the outer frame portion 12, is defined as the third area A3. The third area A3 is provided at two locations on the +Z' side of the space at the four corners of the cutout portion 10a.

[0041] In this embodiment, the internal wiring 17 is formed at a position facing one of the third regions A3 on the inner wall surface of the outer frame portion 12. More specifically, the internal wiring 17 is formed at a position facing the third region A3 at the corner on the -X direction side and the +Z' direction side of the cutout portion 10a. The internal wiring 17 is formed on the inner wall surface of the outer frame portion 12 along the Z' axis direction. The holding portion 13 and the internal wiring 17 are arranged at diagonal positions in the space of the cutout portion 10a.

[0042] According to this embodiment, the crystal diaphragm 10 can be miniaturized while maintaining stable electrical characteristics. Specifically, by connecting the electrode (seal path 15) formed on the first main surface 101 of the outer frame 12 to the electrode (seal path 16) formed on the second main surface 102 via the internal wiring 17, it becomes unnecessary to form through holes or the like in the outer frame 12, and the crystal diaphragm 10 can be miniaturized while securing the effective area of ​​the vibrating part 11. In addition, the inner wall surface of the outer frame 12 facing (contacting) the third region A3 has a larger cutout width than the inner wall surface of the outer frame 12 facing (contacting) the adjacent first region A1, and space can be secured between it and the opposing wall surface. As a result, the internal wiring 17 can be formed in a position that does not face the vibrating part 11, so that the vibrating part 11 does not come into contact with the internal wiring 17, and the risk of wire breakage can be reduced.

[0043] Furthermore, internal wiring 17 can be easily and reliably formed on the inner wall surface of the outer frame portion 12. In the photolithography process for forming internal wiring 17 on the inner wall surface of the outer frame portion 12, when forming internal wiring 17 on the inner wall surface of a region where the distance between the vibrating portion 11 and the outer frame portion 12 is small (for example, the first region A1), there is a possibility that resist will remain in that region, making it difficult to form the internal wiring 17. However, according to this embodiment, in the photolithography process for forming internal wiring 17 on the inner wall surface of the outer frame portion 12, the resist on the inner wall surface of the outer frame portion 12 and the outer wall surface of the vibrating portion 11 can be reliably removed, and internal wiring 17 can be reliably formed on the inner wall surface of the outer frame portion 12. Therefore, the electrode (seal path 15) formed on the first main surface 101 of the outer frame portion 12 and the electrode (seal path 16) formed on the second main surface 102 can be electrically connected stably and reliably, and a decrease in the electrical characteristics of the crystal diaphragm 10 and the occurrence of defective products can be suppressed.

[0044] In a quartz oscillator 100 equipped with the quartz diaphragm 10 described above, the same effects and benefits as those of the quartz diaphragm 10 described above can be obtained. Furthermore, since the internal wiring 17 is not exposed on the outer surface of the package of the quartz oscillator 100, the internal wiring 17 will not be broken or worn down due to contact during assembly or transportation.

[0045] In this embodiment, the internal wiring 17 connects the annular seal path 15 formed on the first main surface 101 side of the outer frame portion 12 of the crystal diaphragm 10 and the annular seal path 16 formed on the second main surface 102 side of the outer frame portion 12. With this configuration, the internal wiring 17 can reliably connect the seal paths 15 and 16 to each other, reliably connect the seal paths 15 and 16 to the ground, and enhance the shielding performance of the seal paths 15 and 16.

[0046] In this embodiment, only one holding portion 13 is provided, and the holding portion 13 extends from the corner of the vibrating portion 11 toward the outer frame portion 12. With this configuration, multiple second and third regions A2 and A3 of the cutout portion 10a can be secured, thereby improving the stability of conductivity by the internal wiring 17 and making it difficult to suppress the main vibration of the crystal diaphragm 10.

[0047] Furthermore, the internal wiring 17 is formed on the inner wall surface of the outer frame portion 12 along the Z' axis direction of the AT cut. Here, on the inner wall surface of the outer frame portion 12 along the X axis direction of the AT cut, an inclined surface is formed during the wet etching process to form the cutout portion 10a, and sharp angles are likely to appear, which could lead to disconnection of the internal wiring. However, on the inner wall surface of the outer frame portion 12 along the Z' axis direction of the AT cut, such sharp angles are less likely to appear, so the internal wiring 17 can be easily formed, reducing the risk of disconnection of the internal wiring. It is preferable that the internal wiring 17 be formed at a slight distance from the edge of the inner wall surface of the outer frame portion 12 along the Z' axis direction of the AT cut.

[0048] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of the present invention is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the equivalents of the claims.

[0049] In the above embodiment, the internal wiring 17 is provided at a position facing the third region A3 at the corner of the cutout portion 10a on the -X direction and the +Z' direction. However, the internal wiring 17 may also be provided at a position facing the third region A3 at the corner of the cutout portion 10a on the +X direction and the +Z' direction, or at a position facing the second region A2 at the corner of the cutout portion 10a on the -X direction and the -Z' direction.

[0050] Furthermore, although only one internal wiring 17 is provided in the above embodiment, the configuration is not limited to this, and multiple internal wirings 17 may be provided. For example, internal wiring 17 may be provided at positions on the inner wall surface of the outer frame 12 that face the two third regions A3, or internal wiring 17 may be provided at a position on the inner wall surface of the outer frame 12 that faces the second region A2 and also at a position that faces the third region A3. In this case, internal wiring 17 may be provided on the inner wall surface of the outer frame 12 that is aligned with the Z' axis, or on the inner wall surface that is aligned with the X axis, or on both the inner wall surface that is aligned with the X axis and the inner wall surface that is aligned with the Z' axis. When internal wiring 17 is provided on the inner wall surface that is aligned with the X axis, it is preferable to form the internal wiring 17 in a V-shaped recess provided on the inner wall surface of the outer frame 12, similar to the case of internal wiring 12g described above.

[0051] In the example shown in Figure 8, three internal wirings 17 are provided on the inner wall surface of the outer frame 12. Specifically, the first internal wiring 17 is provided on the inner wall surface of the outer frame 12 along the Z' axis direction, on the -X side, and is positioned to face the second region A2 of the corner of the cutout 10a on the -X and -Z' sides. The second internal wiring 17 is provided on the inner wall surface of the outer frame 12 along the Z' axis direction, on the +X side, and is positioned to face the third region A3 of the corner of the cutout 10a on the +X and +Z' sides. Furthermore, the third internal wiring 17 is provided on the inner wall surface of the outer frame 12 along the X axis direction, on the +Z' side, and is positioned to face the third region A3 of the corner of the cutout 10a on the -X and +Z' sides. The third internal wiring 17 is provided in a V-shaped recess on the inner wall surface of the outer frame portion 12 on the +Z' side.

[0052] In the above embodiment, the internal wiring 17 connects the electrodes of the annular seal paths 15 and 16 formed on the first main surface 101 and the second main surface 102 sides of the outer frame portion 12 of the crystal diaphragm 10. However, the embodiment is not limited to this, and other electrodes may also be connected by the internal wiring 17. For example, the internal wiring 17 may be connected to the first lead wire 113 drawn out from the first excitation electrode 111, or to the second lead wire 114 drawn out from the second excitation electrode 112. Alternatively, as shown in Figure 9, for example, the internal wiring 17 may be connected to a wiring electrode connected to ground.

[0053] In the example shown in Figure 9, a grounding electrode 25 is formed on the second main surface 202 of the first sealing member 20. The grounding electrode 25 is connected to a seal path 15 on the first main surface 101 side of the outer frame portion 12 of the crystal diaphragm 10, and further connected to a seal path 16 on the second main surface 102 side of the outer frame portion 12 of the crystal diaphragm 10 via internal wiring 17. The seal path 16 is then connected to an external electrode terminal 32 formed on the second main surface 302 of the second sealing member 30 via a through-hole 33c electrode. With this configuration, the internal wiring 17 ensures a reliable connection between the grounding electrode 25 and the external electrode terminal 32, thereby improving the shielding performance of the grounding electrode 25. In this case, the second main surface 202 of the first sealing member 20 can be effectively utilized as space for the grounding electrode 25, allowing for a larger size for the grounding electrode 25 and improving its shielding performance. Furthermore, an earthing electrode may be provided on the first main surface 201 of the first sealing member 20, or an earthing electrode may be provided on both the first and second main surfaces 201 and 202 of the first sealing member 20.

[0054] In the above embodiment, the crystal diaphragm 10 was provided with only one holding portion 13 connecting the vibrating portion 11 and the outer frame portion 12, and the cutout portion 10a was formed continuously to surround the outer circumference of the vibrating portion 11. However, any configuration in which the cutout portion 10a is provided between the vibrating portion 11 and the outer frame portion 12 is acceptable, and the configuration of the crystal diaphragm 10 can be changed in various ways. For example, the crystal diaphragm 10 may be configured to have two or more holding portions 13 connecting the vibrating portion 11 and the outer frame portion 12. Also, the holding portion 13 may be configured to extend toward the outer frame portion 12 from a location other than the corner of the vibrating portion 11.

[0055] The internal wiring 17 for grounding described above can also be provided in a region along the short side of the outer frame portion 12 of the crystal diaphragm 10. For example, as shown in Figures 10 and 11, a notch 17a is formed at the +Z' end of the Z' end face (end face parallel to the Z' axis direction) of the inner wall surface 12h of the outer frame portion 12, and the internal wiring 17 for grounding is formed on the inner wall surface of the notch 17a. Specifically, as shown in Figures 10 and 11, the inner wall surface 12h of the outer frame portion 12 of the crystal diaphragm 10 is formed in a rectangular and annular shape in plan view, and a notch 17a is formed at the corner of the inner wall surface 12h in plan view, extending into the outer frame portion 12. The notch 17a is formed in a substantially rectangular shape in plan view and is provided on the inner wall surface 12h of the outer frame portion 12, which is aligned with the X axis direction and on the +Z' side. The notch 17a is formed to extend into the outer frame 12, or in other words, the space of the notch 17a is formed to protrude outward toward the outer frame 12. The notch 17a is provided in continuity with the cutout 10a of the crystal diaphragm 10 described above. Thus, the internal wiring 17 is formed at a position facing one of the third region A3 (see Figure 4, etc.) of the inner wall surface of the outer frame 12.

[0056] Here, the second inner wall portion 17c of the notch portion 17a (the wall portion on the +Z' direction side and the wall portion on the +X direction side) is not formed linearly with the inner wall surface 12h of the outer frame portion 12 (the inner wall surface on the +Z' direction side). The second inner wall portion 17c is not formed along the X end face (the end face parallel to the X axis direction) of the inner wall surface 12h of the outer frame portion 12. As a result, on the second main surface 102 side (the surface side in the -Y' direction) of the inner wall surface 12h of the outer frame portion 12, there are no corners protruding in the -Z' direction and the +X direction, and etching-induced gouges caused by these corners are not formed.

[0057] Internal wiring 17 is formed on the second inner wall portion 17c, extending from the diaphragm-side first joining pattern 121 formed on the first main surface 101 side of the outer frame portion 12 to the second main surface 102 side. The internal wiring 17 connects the diaphragm-side first joining pattern 121 formed on the first main surface 101 side of the outer frame portion 12 to the diaphragm-side second joining pattern 122 formed on the second main surface 102 side of the outer frame portion 12. Although not shown, the second inner wall portion 17c also has an inclined surface that makes an obtuse angle with the second main surface 102 of the outer frame portion 12, similar to the embodiment described above, and the internal wiring 17 is formed on this inclined surface.

[0058] In the examples shown in Figures 10 and 11, in addition to the internal wiring 17 for grounding described above, a notch 18 is formed at the -Z' end of the Z' end face of the inner wall surface 12h of the outer frame 12, and internal wiring 19 is formed on the inner wall surface of the notch 18. The notch 18 has substantially the same configuration as the notch 17a described above, is formed in a substantially rectangular shape in plan view, and is provided on the inner wall surface 12h of the outer frame 12, along the X axis direction, on the -Z' side. The internal wiring 19 is formed at a position facing the second region A2 (see Figure 4, etc.) of the inner wall surface of the outer frame 12. The notch 18 is formed to extend into the outer frame 12 side and is provided continuously with the cutout 10a of the crystal diaphragm 10. Then, the connecting joint pattern 12a is connected to the connecting joint pattern 12e formed on the second main surface 102 side of the outer frame 12 via internal wiring 19 provided in the notch 18 formed in the inner wall surface 12h of the outer frame 12.

[0059] In the examples shown in Figures 10 and 11, the inner wall surfaces of the notches 17a and 18 are made inclined, which makes it difficult for the internal wiring 17 and 19 to break. Furthermore, since the notches 17a and 18 are formed to fit into the outer frame 12, the effective area of ​​the vibrating part 11 can be secured, enabling the realization of a compact crystal diaphragm 10 with stable electrical characteristics. In this example, the notches 17a and 18 are roughly rectangular in shape when viewed from above, but the shape of the notches 17a and 18 may be V-shaped, trapezoidal, arc-shaped, elliptical arc-shaped, etc.

[0060] In the above embodiment, an AT-cut quartz crystal diaphragm was used as the quartz crystal diaphragm 10, but other types of quartz crystal diaphragms (for example, an SC-cut quartz crystal diaphragm, a quartz Z-plate, etc.) may also be used.

[0061] In the above embodiment, the number of external electrode terminals 32 on the second main surface 302 of the second sealing member 30 is set to four, but it is not limited to this, and the number of external electrode terminals 32 may be, for example, two, six, or eight. Furthermore, although the present invention has been described in the case where it is applied to a quartz crystal oscillator 100, it is not limited to this, and the present invention may also be applied to piezoelectric oscillators such as crystal oscillators. In the case of a crystal oscillator, it is possible to connect the internal wiring 17 to the wiring electrodes connected to the IC mounted on the quartz crystal oscillator.

[0062] In the above embodiment, the first sealing member 20 and the second sealing member 30 were formed from a quartz plate, but the invention is not limited to this, and the first sealing member 20 and the second sealing member 30 may be formed from, for example, glass or resin.

[0063] Furthermore, although the above embodiment describes an example in which the present invention is applied to a piezoelectric vibration device with a three-layer structure in which a quartz diaphragm is sandwiched between a first sealing member and a second sealing member, the present invention is not limited to this and may also be applied to piezoelectric vibration devices with a structure in which a quartz diaphragm is mounted inside a base made of ceramic or the like.

[0064] This application claims priority under Japanese Patent Application No. 2023-032554, filed in Japan on March 3, 2023. By reference thereto, all its contents are incorporated into this application. [Explanation of Symbols]

[0065] 10 Crystal diaphragm 10a Cut-out section 11 Vibration section 12 Outer frame 13 Holding part 17 Internal wiring 100 crystal oscillator 111 1st excitation electrode 112 2nd excitation electrode A1 1st area A2 2nd area A3 3rd area

Claims

1. A rectangular piezoelectric diaphragm having a first excitation electrode formed on one main surface of the substrate and a second excitation electrode, which is paired with the first excitation electrode, formed on the other main surface of the substrate, The device comprises a rectangular vibrating part, an outer frame surrounding the outer circumference of the vibrating part, and a holding part connecting a part of the vibrating part and a part of the outer frame, with a cutout formed by cutting out the substrate between the vibrating part and the outer frame. An electrode formed on one main surface of the substrate is electrically connected to an electrode formed on the other main surface of the substrate via internal wiring formed on the inner wall surface of the outer frame. If, within the space of the cutout portion, the area sandwiched between the inner wall surface of the outer frame portion and the outer wall surface of the vibrating portion is defined as the first region, and the remaining area after removing the first region from the space of the cutout portion, the two areas on the side where the holding portion is provided among the four corner spaces of the cutout portion are defined as the second region, and the two areas on the side where the holding portion is not provided among the four corner spaces of the cutout portion are defined as the third region, The internal wiring is formed at a position on the inner wall surface of the outer frame portion that faces at least one of the second region and the third region. The internal wiring is formed in a position that does not face the vibrating part. The piezoelectric diaphragm is characterized in that the inner wall surface of the outer frame is formed in a rectangular and annular shape in plan view, a notch is formed at the corner of the inner wall surface in plan view that extends into the outer frame, and the internal wiring is formed on the inner wall surface of the notch.

2. A rectangular piezoelectric diaphragm having a first excitation electrode formed on one main surface of the substrate and a second excitation electrode, which is paired with the first excitation electrode, formed on the other main surface of the substrate, The device comprises a rectangular vibrating part, an outer frame surrounding the outer circumference of the vibrating part, and a holding part connecting a part of the vibrating part and a part of the outer frame, with a cutout formed by cutting out the substrate between the vibrating part and the outer frame. An electrode formed on one main surface of the substrate is electrically connected to an electrode formed on the other main surface of the substrate via internal wiring formed on the inner wall surface of the outer frame. If, within the space of the cutout portion, the area sandwiched between the inner wall surface of the outer frame portion and the outer wall surface of the vibrating portion is defined as the first region, and the remaining area after removing the first region from the space of the cutout portion, the two areas on the side where the holding portion is provided among the four corner spaces of the cutout portion are defined as the second region, and the two areas on the side where the holding portion is not provided among the four corner spaces of the cutout portion are defined as the third region, The internal wiring is formed at a position on the inner wall surface of the outer frame portion that faces at least one of the second region and the third region. The inner wall surface of the outer frame is formed in a rectangular and annular shape in plan view, and a notch is formed at the corner of the inner wall surface in plan view, extending inward towards the outer frame, and the internal wiring is formed on the inner wall surface of the notch. A piezoelectric diaphragm characterized in that the notch portion, which is provided with the internal wiring, is formed to extend into the outer frame portion of the inner wall surface of the outer frame portion, in a portion that is formed linearly in a plan view.

3. A piezoelectric vibration device comprising a piezoelectric diaphragm according to claim 1 or 2, A piezoelectric vibration device is provided, comprising: a first sealing member covering the first excitation electrode of the piezoelectric diaphragm; and a second sealing member covering the second excitation electrode of the piezoelectric diaphragm; wherein the first sealing member and the piezoelectric diaphragm are joined together, and the second sealing member and the piezoelectric diaphragm are joined together, thereby providing an internal space in which the vibrating portion of the piezoelectric diaphragm, including the first and second excitation electrodes, is hermetically sealed.

4. In the piezoelectric vibration device according to claim 3, A piezoelectric vibration device characterized in that an earth electrode formed on one of the two main surfaces of the first sealing member is electrically connected via the internal wiring to an external electrode terminal formed on the main surface of the second sealing member that does not face the internal space.

5. In the piezoelectric vibration device according to claim 3, A piezoelectric vibration device characterized in that annular sealing portions are provided between the first sealing member and the piezoelectric diaphragm, and between the second sealing member and the piezoelectric diaphragm, respectively, to hermetically seal the vibrating portion of the piezoelectric diaphragm, and each of the sealing portions is electrically connected to the internal wiring.

6. In the piezoelectric vibration device according to claim 3, A piezoelectric vibration device characterized in that only one holding portion is provided, and the holding portion extends from the corner of the vibrating portion toward the outer frame portion.

7. In the piezoelectric vibration device according to claim 3, The piezoelectric vibrating device is characterized in that the piezoelectric diaphragm is an AT-cut quartz diaphragm, and the internal wiring is formed on the inner wall surface along the Z' axis direction of the AT cut of the outer frame.

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