Piezoelectric vibrator button and piezoelectric vibrator

Abstract

This piezoelectric vibration element comprises: a piezoelectric plate; a pair of mounted electrodes; and a conductor pattern. The piezoelectric plate has a vibration part, and a thick part that is positioned along at least a portion of the vibration part and is thicker than the vibration part. The pair of mounted electrodes are respectively positioned at the thick part on both surfaces of the piezoelectric plate. The conductor pattern spreads across both surfaces of the thick part and is not electrically connected to the mounted electrodes. The pair of mounted electrodes may be positioned at diagonal positions on the piezoelectric plate in planar perspective. The conductor pattern may be positioned at a corner of the thick part where the pair of mounted electrodes are not positioned.

Description

Technical Field

[0001] The present disclosure relates to a piezoelectric vibrating element and a piezoelectric vibrator.

Background Art

[0002] A piezoelectric vibrating element deforms and vibrates in accordance with a periodic voltage pattern applied between excitation electrodes located on both surfaces of a piezoelectric member. Further, it outputs an electric signal corresponding to the deformation of the piezoelectric member between the electrodes. In order to stably output a signal of an appropriate frequency with low loss, equivalent circuit parameters representing the characteristics of the piezoelectric vibrating element are adjusted.

[0003] Japanese Patent Application Laid-Open No. 2021-29013 describes a crystal element having an adjustment electrode connected to an excitation electrode on one surface and not facing an electrode on the other surface. Accordingly, the series capacitance can be easily adjusted by the adjustment electrode without changing the series resistance or the resonance frequency in the equivalent circuit.

Summary of Invention

[0004] One aspect of the present disclosure is (1) a piezoelectric plate including a vibrating portion, and a thick portion located along at least a part of the vibrating portion and being thicker than the vibrating portion; A pair of excitation electrodes located on both sides of the vibrating section, located at the thick portion on each of both surfaces of the piezoelectric plate Then, connect one to each of the pair of excitation electrodes. a pair of mounting electrodes, and a conductor pattern that extends across both surfaces of the thick portion and is not electrically connected to the mounting electrodes and any of the excitation electrodes too A piezoelectric vibrating element comprising: a conductor pattern that is not electrically connected to the mounting electrodes. (2) The piezoelectric vibrating element according to (1), wherein the pair of mounting electrodes are located at diagonal positions of the piezoelectric plate in plan perspective view. (3) The piezoelectric vibrating element according to (2), wherein the conductor pattern is located at a corner portion of the thick portion where the pair of mounting electrodes are not located. ​(4) A piezoelectric vibrator comprising a piezoelectric vibrating element as described in any one of (1) to (3), a package having a recess and an electrode surface located within the recess, wherein the piezoelectric vibrating element is located within the recess and the mounted electrode is joined to the electrode surface via a conductive bonding member. [Brief explanation of the drawing]

[0005] [Figure 1] This is an overall perspective view of a piezoelectric vibrator. [Figure 2A] This is a plan view of a piezoelectric vibrator. [Figure 2B] This is a cross-sectional view of a piezoelectric vibrator. [Figure 2C] This is a cross-sectional view of a piezoelectric vibrator. [Figure 3] This is a perspective view of a piezoelectric vibration element. [Modes for carrying out the invention]

[0006] The embodiments will be described below with reference to the drawings. Figure 1 is an overall perspective view of the piezoelectric vibrator 1 of this embodiment. Figure 1 shows the vibrator with the cover 30 removed. Note that in the drawings of this disclosure, the ratios of the dimensions in the X direction (vertical), Y direction (horizontal), and Z direction (height) do not necessarily reflect actual values ​​for illustrative purposes. One embodiment of the piezoelectric device, the piezoelectric vibrator 1, comprises a package 10, a piezoelectric vibrating element 20, and a cover 30.

[0007] Package 10 is a housing made of, for example, a ceramic material, a semiconductor material, or a glass material, or a combination thereof. The package 10 also has conductive signal lines on its interior and surface. These signal lines include those for power supply and grounding. Examples of signal lines include molybdenum, copper, silver, and tungsten. Some or all of the signal lines may have nickel plating and gold plating laminated on their surfaces. Package 10 has a recess 10a with an open end at the top, which is the positive end in the Z direction.

[0008] In this embodiment, the piezoelectric vibration element 20 is a quartz crystal vibration element. The piezoelectric vibration element 20 is located inside the recess 10a.

[0009] The lid 30 is joined to the upper end of the package 10, i.e., to the upper surface of the side wall of the recess 10a, thereby sealing the recess 10a. The lid 30 is a flat plate of metal conductor, for example, a metal containing iron, copper, nickel, cobalt, molybdenum, or tungsten, or an alloy thereof, such as Kovar. The joining material used for sealing with the lid 30 is preferably joined by heating within a temperature range that does not adversely affect the properties of the piezoelectric vibration element 20 sealed inside. For example, the lid 30 is joined with a brazing material. A frame-shaped metallized layer may be located between the upper end of the package 10 and the lid 30. The metallized layer may be a plated layer or a coated and fired conductor layer.

[0010] Figure 2A is a plan view of the piezoelectric vibrator 1. Figures 2B and 2C are cross-sectional views of the piezoelectric vibrator 1. In Figure 2A, for illustrative purposes, some of the components that are not visible from above are shown as dashed lines in planar perspective. Figure 2B is a cross-sectional view along cross-sectional line AA in Figure 2A. Figure 2C is a cross-sectional view along cross-sectional line BB in Figure 2A.

[0011] As shown in Figure 2A, the piezoelectric vibrating element 20 is located near the center of the recess 10a. The piezoelectric vibrating element 20 includes a quartz crystal 21, a pair of excitation electrodes 22, a pair of mounting electrodes 23, a test electrode 24, a connecting conductor 25, and a metal pattern 26. In other words, the piezoelectric vibrating element 20 in this embodiment is a quartz crystal vibrating element.

[0012] The quartz crystal 21 is a piezoelectric plate in this embodiment, and is substantially rectangular in plan view with its normal direction aligned with the Z direction. As shown in Figures 2B and 2C, the quartz crystal 21 has a central vibrating portion 211 and a thickened portion 212 located at the periphery. The thickened portion 212 is thicker than the vibrating portion 211, i.e., it has a greater thickness in the Z direction. The thickened portion 212 is located along at least a part of the quartz crystal 21, in this case along two sides. The quartz crystal 21 may be an inverted mesa type in which the thickened portion 212 completely surrounds the vibrating portion 211. Also, the thickened portion 212 does not have to protrude and thicken in the ± directions in the Z direction relative to the vibrating portion 211, i.e., on both the upper and lower sides. In this case, the protrusion width may differ between the upper and lower sides. It may also protrude and thicken only above or below the vibrating portion 211. With such a shape, the thin vibrating portion 211 can be supported from the surroundings, so that the strain corresponding to stress can be reduced. Therefore, the adverse effect on the vibration of the vibrating portion 211 is reduced. The boundary between the vibrating portion 211 and the thickened portion 212 does not have to have a stepped thickness change. The boundary may have a slope with a gradually changing thickness. The excitation electrodes 22 are positioned opposite the upper and lower surfaces of the vibrating portion 211 of the quartz crystal piece 21.

[0013] The mounted electrode 23, the inspection electrode 24, and the metal pattern 26 are located in the thickened portion 212. The mounted electrode 23 and the excitation electrode 22 are connected by a connecting conductor 25, which spans the vibrating portion 211 and the thickened portion 212. In this embodiment, the upper connecting conductor 251 extends to the upper right mounted electrode 23 in the plan view of Figure 2A. The lower connecting conductor 252 extends to the lower left mounted electrode 23 in the plan view of Figure 2A. That is, the pair of mounted electrodes 23 may be located diagonally opposite each other on the crystal piece 21 in a plan view. The excitation electrode 22 is a laminate of a base layer containing chromium (Cr), titanium (Ti), or nickel (Ni), or an alloy containing two or more of these (NiCr), and a conductor layer containing gold (Au), silver (Ag), copper (Cu), or aluminum (Al), or an alloy containing two or more of these (AuPdCu). The mounted electrode 23, inspection electrode 24, connecting conductor 25, and metal pattern 26 may also be laminates of a base layer and a conductor layer, similar to the excitation electrode 22.

[0014] As shown in Figure 2B, the mounted electrode 23 connected to the upper connecting conductor 251 is connected to the lower surface via the side surface of the quartz crystal 21. The mounted electrode 23 is joined to the electrode pad 11 located at the bottom surface of the recess 10a by a conductive bonding member 15 on the lower surface of the quartz crystal 21. The electrode pad 11 is the electrode surface in this embodiment. Furthermore, the piezoelectric vibration element 20 may be joined and fixed to the bottom surface of the recess 10a in addition to the portion where the mounted electrode 23 and the electrode pad 11 are joined. The joining member at the portion joined to something other than the electrode pad 11 does not have to be a conductive joining member.

[0015] As shown in Figure 2C, the mounted electrode 23 connected to the lower connecting conductor 25 may be connected to the upper portion 231 via the side surface of the quartz crystal 21. Also, as shown in Figures 2A and 2B, a connecting conductor 253 may extend from the upper excitation electrode 22 to a corner of the quartz crystal 21 different from the corner where the pair of mounted electrodes 23 are located. This connecting conductor 253 connects the inspection electrode 24 to the excitation electrode 22. The upper portion 231 extending from the lower mounted electrode 23 and the inspection electrode 24 are connected to inspection wiring and electrodes on the wafer before being separated from the wafer during manufacturing. These are used to inspect the electrical characteristics of the piezoelectric vibration element 20 using a prober.

[0016] As shown in Figure 2C, external connection pads 12 are located on the bottom surface of the package 10. The external connection pads 12 are located at at least two of the four corners of the bottom surface of the package 10. One of the external connection pads 12 is connected to one of the two electrode pads 11 via wiring inside and on the surface of the package 10. One or more of the other external connection pads 12 may be ground electrodes and are connected to the side opposite to any of the electrode pads 11. If the external connection pads 12 include two or more ground electrodes, these may be commonly connected to one of the external connection pads 12 via wiring inside the package 10. When the external connection pads 12 are connected to a circuit board of an electronic device, an electrical signal is supplied, and this electrical signal is supplied to the piezoelectric vibration element 20. In addition, an electrical signal corresponding to the vibration of the piezoelectric vibration element 20 is output to the circuit board.

[0017] As shown in Figure 2A, the metal pattern 26, which is the conductive pattern in this embodiment, is located at the corners of the quartz crystal 21 in a plan view, where none of the electrodes are located. Here, the corners do not necessarily have to be in contact with the corners, but they are located closer to the corners than to the center of the sides along the longitudinal direction of the quartz crystal 21. The metal pattern 26 is not electrically connected to any of the electrodes, and does not face any of the electrodes or connecting conductors 25 across the quartz crystal 21. The metal pattern 26 is located across both the top and bottom surfaces via the side surfaces. The width of the metal pattern 26 in the X direction does not have to be uniform. For example, the width of the metal pattern 26 on the side surfaces may be narrower than the width of the metal pattern 26 on the top and bottom surfaces.

[0018] Figure 3 is a perspective view of the piezoelectric vibration element 20. In the metal pattern 26, an upper surface portion 261, a side surface portion 262, and a lower surface portion 263 are connected as one body. Therefore, the entire metal pattern 26 has the same potential. In addition, the metal pattern 26 forms a capacitance between itself and each mounting electrode 23 or the like. This capacitance is parallel to the capacitance between the excitation electrodes 22. That is, the metal pattern 26 forms a part of the parallel capacitance C0 in the equivalent circuit of the piezoelectric vibrating element 20. The sizes and shapes of the upper surface portion 261 and the lower surface portion 263 do not need to be identical. The size of the metal pattern 26 in plan view is approximately the same as or smaller than that of the mounting electrode 23, but is not limited thereto.

[0019] With such a structure, the parallel capacitance C0 of the piezoelectric vibrating element 20 can be adjusted by the position, size, shape, or a combination thereof of the metal pattern 26. In particular, since the metal pattern 26 is connected as one body across the upper and lower surfaces, a single capacitance is generated as a whole with respect to the mounting electrode 23. Therefore, adjustment of the parallel capacitance C0 by this metal pattern 26 is simplified. Furthermore, since the metal pattern 26 is located near a corner of the crystal blank 21 different from the mounting electrode 23, the distance between the metal pattern 26 and the mounting electrode 23 is increased. Accordingly, adjustment of the size, shape, and the like of the metal pattern 26 does not become excessively fine, making it easy to adjust the parallel capacitance C0.

[0020] As described above, the piezoelectric vibrating element 20 of the present embodiment includes the crystal blank 21, a pair of the mounting electrodes 23, and the metal pattern 26. The crystal blank 21 has a vibrating portion 211, and a thick portion 212 that is located along at least a part of the vibrating portion 211 and is thicker than the vibrating portion 211. The pair of mounting electrodes 23 are respectively located on the thick portions 212 on both surfaces of the crystal blank 21. The metal pattern 26 extends across both surfaces of the thick portion 212, and is not electrically connected to the mounting electrode 23. As described above, the parallel capacitance C0 is obtained by the metal pattern 26 that is electrically separated from the mounting electrode 23. Since such an integral metal pattern 26 is located across both surfaces of the crystal blank 21, the metal pattern 26 has the same potential on both surfaces. This facilitates adjustment of the parallel capacitance C0. In particular, it is not directly connected to the wiring to the excitation electrode, and the thick portion212 The upper surface portion 261 and lower surface portion 263 of the metal pattern 26 located at [the aforementioned position] enable easy adjustment of the parallel capacitance C0. Therefore, the piezoelectric vibrating element 20 does not require modifications to conventional circuit designs, and tends to reduce the labor and cost associated with adjustment. Accordingly, the piezoelectric vibrating element 20 that oscillates at a desired frequency in a stable manner can be obtained more easily.

[0021] Further, the pair of mounting electrodes 23 may be located at diagonal positions of the crystal blank 21 in planar perspective view. When the oscillation frequency of the piezoelectric vibrating element 20 is high, particularly in a frequency band of 50 to 75 MHz or higher, the vibrating portion 211 becomes thin. With the shape of the present embodiment, the piezoelectric vibrating element 20 in which the thin vibrating portion 211 is appropriately supported can be efficiently obtained. In particular, even when the vibrating portion 211 is vibrating, the piezoelectric vibrating element 20 is fixed in a reliably held state, so this piezoelectric vibrating element 20 can output appropriate vibration or a voltage signal corresponding to vibration. Further, since the mounting electrodes 23 are located at diagonal positions, when the piezoelectric vibrating element 20 is mounted with a conductive adhesive, the piezoelectric vibrating element 20 can be easily fixed in an appropriate positional relationship with respect to the bottom surface of the recess 10a. The appropriate positional relationship may be parallel to the bottom surface of the recess 10a.

[0022] Further, the metal pattern 26 may be located at a corner portion of the thick portion 212 where the mounting electrode 23 is not located. This makes it easy for the piezoelectric vibrating element 20 to adjust the parallel capacitance C0 with the mounting electrodes 23. Further, the possibility of short-circuiting with each electrode and the connection conductor 25 is further reduced.

[0023] Further, the piezoelectric vibrator 1 of the present embodiment includes the above-described piezoelectric vibrating element 20, and a package 10 having a recess 10a and electrode pads 11 located in the recess 10a. The piezoelectric vibrating element 20 is located in the recess 10a, and the mounting electrodes 23 are bonded to the electrode pads 11 via conductive bonding members 15. According to this piezoelectric vibrator 1, operation by the piezoelectric vibrating element 20 that oscillates at an appropriate oscillation frequency in a more stable manner can be achieved.

[0024] The above embodiments are illustrative examples, and various modifications are possible. For example, the piezoelectric vibration element 20 does not necessarily have to have an inspection electrode 24.

[0025] Furthermore, the metal pattern 26 does not have to be located near the corner of the crystal piece 21 in a plan view. That is, the metal pattern 26 may be located near the center of an edge along the longitudinal direction. Alternatively, the metal pattern 26 may be located in contact with the short side of the crystal piece 21 in a plan view.

[0026] Furthermore, the pair of mounted electrodes 23 do not necessarily have to be located diagonally opposite the quartz crystal 21 in a plan view. For example, the pair of mounted electrodes 23 may be located at both ends of the short side in a plan view. In this case, the side of the quartz crystal 21 opposite to the mounted electrodes 23 in the X direction does not necessarily have to be joined to the bottom surface of the recess 10a. That is, the piezoelectric vibration element 20 may be fixed in a handheld position.

[0027] Furthermore, the thickened portion 212 may be located along two or three of the four sides of the quartz crystal piece 21. That is, the vibrating portion 211 may be in contact with one or two of the four sides of the quartz crystal piece 21. If the thickened portion 212 is located along two sides, these two sides may be in contact with each other across a corner, or they may be two sides that are not in contact with each other.

[0028] Furthermore, the vibrating portion 211 does not necessarily have to be rectangular in plan view. For example, the planar shape of the vibrating portion 211 may be circular, elliptical, or a rectangle with rounded corners. In this case, the thickened portion 212 only needs to be located along at least half of the circumference of the vibrating portion 211.

[0029] Furthermore, the plan view shape of the excitation electrode 22 does not have to be circular. For example, the excitation electrode 22 may be elliptical or a rectangle with rounded corners in plan view.

[0030] Alternatively, the piezoelectric vibrating element may have other piezoelectric vibrating elements instead of the quartz crystal 21. Any material that can convert between electrical force and mechanical deformation is acceptable.

[0031] Furthermore, the piezoelectric vibrator 1 may have a package 10 of a different shape. For example, there may be steps within the recess 10a of the package 10. Also, the recess 10a does not have to be rectangular in plan view. For example, the corners of the inner surface of the recess 10a may be rounded. In addition, the package 10 may have other recesses besides the recess 10a.

[0032] Furthermore, the bottom and sides of package 10 may be a single unit, or they may be separate components joined together.

[0033] Furthermore, the piezoelectric vibrator 1 may contain other electronic components in addition to the piezoelectric vibrating element 20 within the recess 10a or within other recesses. Furthermore, the specific details such as structure, configuration, materials, and size shown in the above embodiments may be modified as appropriate without departing from the spirit of this disclosure. The scope of the present invention includes the scope of the invention as described in the claims and its equivalents. [Industrial applicability]

[0034] This disclosure can be used for piezoelectric vibration elements and piezoelectric vibrators. [Explanation of symbols]

[0035] 1. Piezoelectric vibrator 10 packages 10a recess 11 electrode pads 12 External connection pads 15 Joining members 20 Piezoelectric vibration elements 21 Crystal piece 211 Vibration section 212 Thick wall part 22 Excitation electrode 23 Mounted electrodes 231 Top part 24 Test electrodes 25, 251~253 Connecting conductors 26 Metal Patterns 261 Top part 262 Side view 263 Below 30. Cover

Claims

1. A piezoelectric plate having a vibrating portion and a thick-walled portion located along at least a part of the vibrating portion and being thicker than the vibrating portion, A pair of excitation electrodes located on both sides of the vibrating section, A pair of mounted electrodes are located on the thickened portions on each of the two sides of the piezoelectric plate and connected one to each of the pair of excitation electrodes, A conductor pattern extending across both sides of the thickened portion, which is not electrically connected to either the mounted electrode or the excitation electrode, A piezoelectric vibration element equipped with the following features.

2. The piezoelectric vibrating element according to claim 1, wherein the pair of mounted electrodes are located diagonally opposite the piezoelectric plate in a planar perspective view.

3. The piezoelectric vibrating element according to claim 2, wherein the conductor pattern is located at a corner of the thickened portion where the pair of mounted electrodes are not located.

4. A piezoelectric vibration element according to any one of claims 1 to 3, A package having a recess and an electrode surface located within the recess, Equipped with, The piezoelectric vibration element is located within the recess, and the mounted electrode is bonded to the electrode surface via a conductive bonding member. Piezoelectric vibrator.

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