Crystal plate and crystal device

Abstract

A quartz crystal vibration plate capable of suppressing the formation of a recess in the base region of a holding portion on the outer frame side. [Solution] A quartz crystal vibration plate (2) includes an outer frame (23) and a vibrating portion (22) formed thinner than the outer frame (23), with a through portion (2a) formed between the outer frame (23) and the vibrating portion (22), and a retaining portion (24) formed thinner than the outer frame (23) connecting the outer frame (23) and the vibrating portion (22). A connecting portion (25) on one main surface of the outer frame (23) with the retaining portion (24) is provided with a flat region (25b) formed on the same plane as the retaining portion (24) and an inclined region (25a) inclined relative to the flat region (25b), and of an end (24a) of the retaining portion (24) on the connecting portion (25) side, at least regions (24b, 24c) on the through portion (2a) side are provided continuous with the flat region (25b), and the length of the flat region (25b) along the direction in which the retaining portion (24) extends is 1 μm to 30 μm.

Description

[Technical Field]

[0001] The present invention relates to a quartz crystal plate and a quartz crystal device. [Background technology]

[0002] In recent years, the operating frequencies of various electronic devices have been increasing and their packages have become smaller (especially lower profile). As a result, along with the increase in frequency and the miniaturization of packages, quartz crystal resonator devices (e.g., quartz crystal resonators, quartz crystal oscillators, etc.) are also being required to accommodate these increases in frequency and miniaturization of packages.

[0003] A so-called sandwich-structured crystal resonator device is known as a crystal resonator device suitable for miniaturization and low height. The housing of a sandwich-structured crystal resonator device is configured as a roughly rectangular parallelepiped package. This package is composed of a first sealing member and a second sealing member made of, for example, glass or quartz, and a crystal resonator plate with excitation electrodes formed on both main surfaces. The first sealing member and the second sealing member are stacked and bonded via the crystal resonator plate. The vibrating portion of the crystal resonator plate, which is disposed inside the package (internal space), is hermetically sealed by the first sealing member and the second sealing member (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-252051 Summary of the Invention [Problem to be solved by the invention]

[0005] The quartz crystal plate used in the sandwich-structure quartz crystal device described above has a vibrating section on which excitation electrodes are formed, an outer frame section surrounding the vibrating section, and a holding section that connects the vibrating section to the outer frame and holds it in place. AT-cut quartz crystal plates are widely used for this type of quartz crystal plate, as they are easy to process and have excellent frequency-temperature characteristics.

[0006] In such quartz crystal diaphragms, the vibrating portion and the holding portion are thinner than the outer frame portion, and a through hole is formed between the thick outer frame portion and the thin vibrating portion. However, when the outer shape of such a quartz crystal diaphragm is processed by etching, an anisotropic property of quartz crystal creates a tapered region in the outer frame portion that gradually thins from the thick outer frame portion to the thin holding portion. This tapered region is also formed at the connection between the outer frame portion and the holding portion. As a result, the tapered region intersects with the side surface of the holding portion (the surface that contacts the through hole), creating a problem of a recess formed in the base region of the holding portion on the outer frame side during etching, leading to concerns about the formation of such a recess, which can lead to breakage of the holding portion, or deterioration of the vibration characteristics of the vibrating portion due to breakage of the lead-out wiring or high resistance caused by thinning of the lead-out wiring.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a quartz vibration plate and a quartz vibration device that can prevent a recess from being formed in the base region of the outer frame portion of the holding portion. [Means for solving the problem]

[0008] The present invention provides a means for solving the above-mentioned problems as follows: That is, the present invention provides a quartz crystal vibrating plate including an outer frame and a vibrating portion formed thinner than the outer frame, with a through-hole formed between the outer frame and the vibrating portion, and the outer frame and the vibrating portion being connected by a holding portion formed thinner than the outer frame, wherein a connection portion between one main surface of the outer frame and the holding portion is provided with a flat region formed on the same plane as the holding portion and an inclined region inclined relative to the flat region, and at least a region of the end of the holding portion on the connection portion side that is on the through-hole side is provided continuous with the flat region.

[0009] According to the above configuration, a flat region is provided at the connection between the outer frame and the holding portion, and the inclined region does not directly intersect with the side surface of the holding portion. This prevents the formation of a recessed portion during etching in the base region of the holding portion on the outer frame side. This prevents the holding portion from breaking and the deterioration of the vibration characteristics of the vibrating portion due to disconnection or high resistance of the lead wiring. Furthermore, if there is a thickness difference between the outer frame and the holding portion, such as a step, forces (stresses and impacts) tend to concentrate in the thinner areas. However, the inclined region provided at the connection between the outer frame and the holding portion gradually weakens these forces. Thus, the inclined region can reduce external stress from the outer frame to the vibrating portion, improving the impact resistance of the holding portion, such as preventing breakage.

[0010] In the above configuration, it is preferable that the length of the flat region along the extension direction of the holding portion is greater than that of the inclined region, thereby effectively suppressing external stress from the outer frame (e.g., stress during solder mounting), and suppressing a shift in oscillation frequency and a deterioration in CI value.

[0011] In the above configuration, it is preferable that the length of the flat region along the extending direction of the holding portion is smaller than that of the inclined region, thereby ensuring a vibration area for the vibrating portion and improving impact resistance.

[0012] In the above configuration, it is preferable that the connection portion between the other main surface of the outer frame and the holding portion includes a flat region formed on the same plane as the holding portion and an end region of the outer frame, and the end of the holding portion on the connection portion side is connected to the flat region. In this case, by arranging at least a portion of the end region on the other main surface of the outer frame so as to overlap the inclined region on one main surface of the outer frame in a plan view, the influence of external stress from the outer frame (e.g., stress during solder mounting) can be reduced, thereby improving impact resistance. Furthermore, by arranging at least a portion of the flat region on the other main surface of the outer frame so as to overlap the flat region on one main surface of the outer frame in a plan view, the influence of external stress from the outer frame can be reduced, thereby improving stress balance in the outer frame.

[0013] The present invention may also be a quartz crystal vibration device including a quartz crystal vibration plate having any of the above configurations, characterized in that it includes a first sealing member covering one main surface of the vibrating portion of the quartz crystal vibration plate and a second sealing member covering the other main surface of the vibrating portion of the quartz crystal vibration plate, and the first sealing member is bonded to the quartz crystal vibration plate and the second sealing member is bonded to the quartz crystal vibration plate to seal the vibrating portion of the quartz crystal vibration plate. A quartz crystal vibration device including a quartz crystal vibration plate having the above configuration can achieve the same effects as the quartz crystal vibration plate described above. That is, when a quartz crystal vibration plate with a frame in which the vibrating portion and the outer frame are connected by a holding portion is used, it is possible to reduce the size and height of the quartz crystal vibration device, and in such a small and thin quartz crystal vibration device, it is possible to prevent the formation of a recess in the base area of ​​the holding portion on the outer frame side. [Effects of the Invention]

[0014] The quartz crystal vibrating plate and quartz crystal vibrating device of the present invention have a flat region at the connection between the outer frame and the holder, and the sloped region does not directly intersect with the side of the holder, which prevents the formation of a recess in the base region of the holder on the outer frame side during etching. This prevents the holder from breaking and the deterioration of the vibration characteristics of the vibrating unit due to breakage or high resistance of the lead wiring. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing each component of a crystal oscillator according to an embodiment of the present invention; [Figure 2] 2 is a schematic plan view of the first main surface side of the first sealing member of the crystal oscillator. FIG. [Figure 3] 3 is a schematic plan view of the second main surface side of the first sealing member of the crystal oscillator. FIG. [Figure 4] 2 is a schematic plan view of a first main surface side of a quartz crystal plate of the quartz crystal oscillator. FIG. [Figure 5] 2 is a schematic plan view of the second main surface side of the crystal vibration plate of the crystal oscillator. FIG. [Figure 6] 3 is a schematic plan view of the first main surface side of the second sealing member of the crystal oscillator. FIG. [Figure 7] 4 is a schematic plan view of the second main surface side of the second sealing member of the crystal oscillator. FIG. [Figure 8] 3 is a schematic plan view showing the configuration of the second main surface side of the quartz crystal plate. FIG. [Figure 9] 9 is a cross-sectional view taken along the line D1-D1 in FIG. 8. [Figure 10] 10 is a perspective view showing the configuration of the second main surface side of the connection portion between the holder and outer frame of the quartz crystal plate. FIG. [Figure 11] 10 is a schematic plan view showing the configuration of the second main surface side of the quartz crystal plate according to Modification 1. FIG. [Figure 12] 10 is a schematic plan view showing the configuration of the first main surface side of a quartz crystal plate according to Modification 2. FIG. [Figure 13] 13 is a cross-sectional view taken along line D2-D2 in FIG. 12. [Figure 14]FIG. 10 is a schematic plan view of the second main surface side of a tuning-fork type crystal vibrating plate of a crystal oscillator according to another embodiment. [Figure 15] 10 is a schematic plan view showing the configuration of the first main surface side of a quartz crystal plate according to Modification 3. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a crystal vibration device to which the present invention is applied is described as a crystal oscillator. Note that the crystal vibration device to which the present invention is applicable is not limited to a crystal oscillator, and the present invention may also be applied to a crystal resonator.

[0017] 1, the crystal oscillator 101 according to this embodiment is configured to include a crystal diaphragm 2, a first sealing member 3, a second sealing member 4, and an IC chip 5. In this crystal oscillator 101, the crystal diaphragm 2 is bonded to the first sealing member 3, and the crystal diaphragm 2 is bonded to the second sealing member 4, thereby forming a package 12 with a substantially rectangular parallelepiped sandwich structure. The IC chip 5 is mounted on the main surface of the first sealing member 3 opposite to the surface bonded to the crystal diaphragm 2. The IC chip 5, which serves as an electronic component, is a one-chip integrated circuit element that, together with the crystal diaphragm 2, forms an oscillator circuit.

[0018] In the quartz crystal vibration plate 2, a first excitation electrode 221 is formed on one of the principal surfaces, that is, a first principal surface 211, and a second excitation electrode 222 is formed on the other principal surface, that is, a second principal surface 212. In the quartz crystal oscillator 101, a first sealing member 3 and a second sealing member 4 are bonded to both of the principal surfaces (first principal surface 211, second principal surface 212) of the quartz crystal vibration plate 2, respectively, to form an internal space of the package 12, and a vibrating part 22 (see FIGS. 4 and 5) including the first excitation electrode 221 and the second excitation electrode 222 is hermetically sealed in the internal space.

[0019] The crystal oscillator 101 according to this embodiment has a package size of, for example, 1.0 × 0.8 mm, and is designed to be compact and low-profile. In addition, in order to achieve the miniaturization, the package 12 does not have castellations, but rather uses through-holes (described later) to achieve electrode conduction.

[0020] Next, the crystal vibration plate 2, the first sealing member 3, and the second sealing member 4 of the crystal oscillator 101 will be described with reference to Figures 1 to 7. Note that the following description focuses on the individual components that are not joined together and are configured as individual components.

[0021] As shown in Figures 4 and 5, the quartz crystal vibrating plate 2 is a piezoelectric substrate made of quartz crystal, and both of its main surfaces (first main surface 211 and second main surface 212) are flat and smooth (mirror-finished). In this embodiment, an AT-cut quartz crystal plate that vibrates in thickness-shear mode is used as the quartz crystal vibrating plate 2. In the quartz crystal vibrating plate 2 shown in Figures 4 and 5, both main surfaces 211 and 212 of the quartz crystal vibrating plate 2 are in the XZ' plane. In this XZ' plane, the direction parallel to the short side (short side) of the quartz crystal vibrating plate 2 is the X-axis direction, and the direction parallel to the long side (long side) of the quartz crystal vibrating plate 2 is the Z'-axis direction. Note that AT-cut is a processing technique in which artificial quartz crystal is cut at an angle of 35°15' around the X-axis with respect to the Z-axis, one of the three crystal axes of the artificial quartz crystal: the electrical axis (X-axis), the mechanical axis (Y-axis), and the optical axis (Z-axis). In an AT-cut quartz crystal plate, the X-axis coincides with the crystal axis of the quartz crystal. The Y' and Z' axes are inclined 35°15' from the Y and Z crystal axes of the quartz. The Y' and Z' axis directions correspond to the cutting direction when cutting an AT-cut quartz plate.

[0022] A pair of excitation electrodes (first excitation electrode 221, second excitation electrode 222) are formed on both main surfaces 211, 212 of the quartz crystal vibration plate 2. The quartz crystal vibration plate 2 has a substantially rectangular vibrating portion 22, an outer frame portion 23 that surrounds the outer periphery of the vibrating portion 22, and a holding portion 24 that holds the vibrating portion 22 by connecting the vibrating portion 22 and the outer frame portion 23. In other words, the quartz crystal vibration plate 2 is configured such that the vibrating portion 22, the outer frame portion 23, and the holding portion 24 are integrally provided, and a through portion 2a (see FIG. 8) is formed between the outer frame portion 23 and the vibrating portion 22.

[0023] In this embodiment, the holding portion 24 is provided at only one location between the vibrating portion 22 and the outer frame portion 23. Furthermore, the vibrating portion 22 and the holding portion 24 are formed to be thinner than the outer frame portion 23. Due to this difference in thickness between the outer frame portion 23 and the holding portion 24, the natural frequencies of the piezoelectric vibrations of the outer frame portion 23 and the holding portion 24 differ, making it difficult for the outer frame portion 23 to resonate with the piezoelectric vibration of the holding portion 24. Note that the location where the holding portion 24 is formed is not limited to one location, and the holding portion 24 may be provided at two locations between the vibrating portion 22 and the outer frame portion 23 (for example, on both sides in the -Z'-axis direction).

[0024] The holding portion 24 extends (protrudes) in the -Z' direction from only one corner of the vibrating portion 22, which is located in the +X direction and the -Z' direction. In this way, the holding portion 24 is provided at a corner of the outer periphery of the vibrating portion 22, where the displacement of the piezoelectric vibration is relatively small. Therefore, compared to when the holding portion 24 is provided at a portion other than the corner (the center of the side), it is possible to prevent the piezoelectric vibration from leaking to the outer frame portion 23 via the holding portion 24, and it is possible to more efficiently piezoelectrically vibrate the vibrating portion 22. Furthermore, compared to when two or more holding portions 24 are provided, it is possible to reduce the stress acting on the vibrating portion 22, thereby reducing the frequency shift of the piezoelectric vibration caused by such stress and improving the stability of the piezoelectric vibration.

[0025] The first excitation electrode 221 is provided on the first main surface 211 side of the vibrating section 22, and the second excitation electrode 222 is provided on the second main surface 212 side of the vibrating section 22. Lead wiring (first lead wiring 223, second lead wiring 224) for connecting these excitation electrodes to external electrode terminals is connected to the first excitation electrode 221 and the second excitation electrode 222. The first lead wiring 223 is led out from the first excitation electrode 221 and connected to a connection bonding pattern 27 formed on the outer frame section 23 via the holding section 24. The second lead wiring 224 is led out from the second excitation electrode 222 and connected to a connection bonding pattern 28 formed on the outer frame section 23 via the holding section 24. In this way, the first lead wiring 223 is formed on the first main surface 211 side of the holding section 24, and the second lead wiring 224 is formed on the second main surface 212 side of the holding section 24.

[0026] Both main surfaces (first main surface 211 and second main surface 212) of the quartz crystal plate 2 are provided with vibration-side sealing portions for bonding the quartz crystal plate 2 to the first sealing member 3 and the second sealing member 4, respectively. The vibration-side sealing portion on the first main surface 211 is formed with a vibration-side first bonding pattern 251 for bonding to the first sealing member 3. The vibration-side sealing portion on the second main surface 212 is formed with a vibration-side second bonding pattern 252 for bonding to the second sealing member 4. The vibration-side first bonding pattern 251 and the vibration-side second bonding pattern 252 are provided on the outer frame portion 23 and are formed in an annular shape in a plan view. The first excitation electrode 221 and the second excitation electrode 222 are not electrically connected to the vibration-side first bonding pattern 251 and the vibration-side second bonding pattern 252.

[0027] As shown in FIGS. 4 and 5, the quartz crystal vibration plate 2 has five through holes formed between the first main surface 211 and the second main surface 212. Specifically, the four first through holes 261 are provided in the four corner regions of the outer frame portion 23. The second through hole 262 is provided in the outer frame portion 23 on one side in the Z′-axis direction of the vibration portion 22 (on the +Z′-direction side in FIGS. 4 and 5). A connection bonding pattern 253 is formed around each of the first through holes 261. Furthermore, a connection bonding pattern 254 is formed on the first main surface 211 side around the second through hole 262, and a connection bonding pattern 28 is formed on the second main surface 212 side around the second through hole 262.

[0028] In the first through hole 261 and the second through hole 262, a through electrode for achieving electrical continuity between the electrodes formed on the first main surface 211 and the second main surface 212 is formed along the inner wall surface of each through hole. In addition, the central portion of each of the first through hole 261 and the second through hole 262 is a hollow through portion that penetrates between the first main surface 211 and the second main surface 212.

[0029] In the quartz crystal plate 2, the first excitation electrode 221, the second excitation electrode 222, the first escape wiring 223, the second escape wiring 224, the first bonding pattern 251, the vibration-side second bonding pattern 252, and the connection bonding patterns 253, 254, 27, and 28 can be formed in the same process. Specifically, these can be formed from base films formed by physical vapor deposition on both main surfaces 211 and 212 of the quartz crystal plate 2, and bonding films formed by physical vapor deposition on the base films. In this embodiment, Ti (or Cr) is used for the base films, and Au is used for the bonding films.

[0030] 2 and 3, the first sealing member 3 is a rectangular parallelepiped substrate formed from a single quartz crystal wafer, and the second main surface 312 (the surface that bonds to the quartz crystal vibration plate 2) of this first sealing member 3 is formed as a flat, smooth surface (mirror-finished). As shown in Fig. 2, six electrode patterns 37 including mounting pads for mounting the IC chip 5, which is an oscillator circuit element, are formed on the first main surface 311 (the surface on which the IC chip 5 is mounted) of this first sealing member 3. The IC chip 5 is bonded to the electrode patterns 37 using metal bumps (e.g., Au bumps) 38 (see Fig. 1) by FCB (Flip Chip Bonding).

[0031] As shown in FIGS. 2 and 3, the first sealing member 3 has six through holes formed therein, each connected to one of the six electrode patterns 37 and penetrating between the first main surface 311 and the second main surface 312. Specifically, four third through holes 322 are provided in the four corner regions of the first sealing member 3. The fourth and fifth through holes 323 and 324 are provided in the A2 and A1 directions in FIGS. 2 and 3, respectively. The A1 and A2 directions in FIGS. 2, 3, 6, and 7 correspond to the -Z' and +Z' directions in FIGS. 4 and 5, respectively, and the B1 and B2 directions in FIGS. 2, 3, 6, and 7 correspond to the -X and +X directions in FIGS. 4 and 5, respectively.

[0032] In the third through hole 322 and the fourth and fifth through holes 323, 324, through electrodes for achieving electrical continuity between the electrodes formed on the first main surface 311 and the second main surface 312 are formed along the inner wall surfaces of the respective through holes. In addition, the central portions of the third through hole 322 and the fourth and fifth through holes 323, 324 form hollow through portions that penetrate between the first main surface 311 and the second main surface 312.

[0033] A sealing-side first bonding pattern 321 is formed on the second main surface 312 of the first sealing member 3 as a sealing-side first sealing portion for bonding to the quartz-crystal vibrating plate 2. The sealing-side first bonding pattern 321 is formed in a ring shape in a plan view.

[0034] Furthermore, on the second main surface 312 of the first sealing member 3, a connection joint pattern 34 is formed around each of the third through holes 322. A connection joint pattern 351 is formed around the fourth through hole 323, and a connection joint pattern 352 is formed around the fifth through hole 324. Furthermore, a connection joint pattern 353 is formed on the opposite side of the long axis direction of the first sealing member 3 from the connection joint pattern 351 (A2 direction side), and the connection joint pattern 351 and the connection joint pattern 353 are connected by a wiring pattern 33. Note that the connection joint pattern 353 is not connected to the connection joint pattern 352.

[0035] In the first sealing member 3, the sealing-side first bonding pattern 321, the connection bonding patterns 34, 351 to 353, and the wiring pattern 33 can be formed by the same process. Specifically, these can be formed from an underlayer formed by physical vapor deposition on the second main surface 312 of the first sealing member 3, and a bonding film formed by physical vapor deposition on the underlayer. In this embodiment, Ti (or Cr) is used for the underlayer, and Au is used for the bonding film.

[0036] 6 and 7, the second sealing member 4 is a rectangular parallelepiped substrate formed from a single quartz crystal wafer, and the first main surface 411 of this second sealing member 4 (the surface that bonds to the quartz crystal vibration plate 2) is formed as a flat, smooth surface (mirror-finished). A sealing-side second bonding pattern 421 is formed on the first main surface 411 of this second sealing member 4 as a sealing-side second sealing portion for bonding to the quartz crystal vibration plate 2. The sealing-side second bonding pattern 421 is formed in a ring shape in a plan view.

[0037] Four external electrode terminals 43 for electrical connection to the outside are provided on the second main surface 412 (the outer main surface not facing the quartz crystal plate 2) of the second sealing member 4. The external electrode terminals 43 are located at the four corners (corner portions) of the second sealing member 4, respectively.

[0038] As shown in FIGS. 6 and 7 , the second sealing member 4 has four through holes formed therein that penetrate between the first main surface 411 and the second main surface 412. Specifically, the four sixth through holes 44 are provided in the four corner (corner) regions of the second sealing member 4. In the sixth through holes 44, through electrodes for ensuring electrical connection between the electrodes formed on the first main surface 411 and the second main surface 412 are formed along the inner wall surfaces of the sixth through holes 44. Furthermore, the central portions of each sixth through hole 44 form hollow through portions that penetrate between the first main surface 411 and the second main surface 412. Furthermore, in the first main surface 411 of the second sealing member 4, connection bonding patterns 45 are formed around each sixth through hole 44.

[0039] In the second sealing member 4, the sealing-side second bonding pattern 421 and the connection bonding pattern 45 can be formed by the same process. Specifically, they can be formed from an underlayer formed by physical vapor deposition on the first main surface 411 of the second sealing member 4, and a bonding film formed by physical vapor deposition on the underlayer. In this embodiment, Ti (or Cr) is used for the underlayer, and Au is used for the bonding film.

[0040] In the crystal oscillator 101 including the crystal vibrating plate 2, first sealing member 3, and second sealing member 4 configured as described above, the crystal vibrating plate 2 and the first sealing member 3 are diffusion bonded together with the first vibration-side bonding pattern 251 and the first sealing-side bonding pattern 321 overlapping each other, and the crystal vibrating plate 2 and the second sealing member 4 are diffusion bonded together with the second vibration-side bonding pattern 252 and the second sealing-side bonding pattern 421 overlapping each other, thereby producing the sandwich-structured package 12 shown in Fig. 1. This hermetically seals the internal space of the package 12, i.e., the space housing the vibrating unit 22.

[0041] At this time, the above-mentioned connection bonding patterns are also diffusion bonded together while overlapping each other. By bonding the connection bonding patterns together, electrical continuity is obtained among the first excitation electrode 221, the second excitation electrode 222, the IC chip 5, and the external electrode terminal 43 in the crystal oscillator 101.

[0042] Specifically, the first excitation electrode 221 is connected to the IC chip 5 via the first escape wiring 223, the junction between the connection junction pattern 27 and the connection junction pattern 353, the wiring pattern 33, the connection junction pattern 351, the through electrode in the fourth through hole 323, and the electrode pattern 37, in that order. The second excitation electrode 222 is connected to the IC chip 5 via the second escape wiring 224, the connection junction pattern 28, the through electrode in the second through hole 262, the junction between the connection junction pattern 254 and the connection junction pattern 352, the through electrode in the fifth through hole 324, and the electrode pattern 37, in that order. In addition, the IC chip 5 is connected to the external electrode terminal 43 via the electrode pattern 37, the through electrode in the third through hole 322, the joint between the connection junction pattern 34 and the connection junction pattern 253, the through electrode in the first through hole 261, the joint between the connection junction pattern 253 and the connection junction pattern 45, and the through electrode in the sixth through hole 44, in that order.

[0043] In the sandwich-structured package 12 manufactured as described above, there is a gap of 1.00 μm or less between the first sealing member 3 and the quartz crystal plate 2, and a gap of 1.00 μm or less between the second sealing member 4 and the quartz crystal plate 2. In other words, the thickness of the bonding material between the first sealing member 3 and the quartz crystal plate 2 is 1.00 μm or less, and the thickness of the bonding material between the second sealing member 4 and the quartz crystal plate 2 is 1.00 μm or less (specifically, 0.15 μm to 1.00 μm for the Au-Au bonding of this embodiment). For comparison, the thickness of a conventional metal paste sealing material using Sn is 5 μm to 20 μm.

[0044] In this embodiment, in the quartz crystal vibration plate 2 configured as described above, the vibrating portion 22 and the holding portion 24 are formed thinner than the outer frame portion 23, and the holding portion 24 extends in the Z'-axis direction. A connection portion 25 between the holding portion 24 and one of the main surfaces of the outer frame portion 23 (here, the second main surface 212) is provided with a flat region 25b formed on the same plane as the holding portion 24 and an inclined region 25a inclined relative to the flat region 25b. Of the end portion 24a of the holding portion 24 on the connection portion 25 side, at least the regions 24b and 24c on the through portion 2a side are continuous with the flat region 25b. This point will be described below with reference to FIGS. 4, 5, 8 to 10. Note that FIGS. 8 to 10 omit illustrations of electrodes, through holes, and the like formed on the quartz crystal vibration plate 2.

[0045] Here, the quartz crystal vibration plate 2 is formed into the outer shape shown in FIGS. 4, 5, and 8 by performing two types of etching processes on the rectangular quartz crystal plate: frequency adjustment etching and outline formation etching. In the frequency adjustment etching, the thicknesses of the vibrating portion 22 and the holding portion 24 are adjusted to set the oscillation frequency of the quartz crystal oscillator 101 to a predetermined value. In the outline formation etching, through-holes 2a (see FIG. 8) are formed in the rectangular quartz crystal plate, and the outer shapes of the vibrating portion 22, outer frame portion 23, and holding portion 24 are formed. The through-holes in the quartz crystal vibration plate 2 are also formed in the outline formation etching.

[0046] When the outer shape of the quartz crystal vibration plate 2 is formed by etching, an anisotropic property of quartz crystal creates a sloped region in the outer frame 23 that gradually thins from the thick outer frame 23 to the thin holding portion 24. In such a sloped region, the resist may not be straight, and the amount of resist applied may vary compared to a flat region, resulting in an inaccurate pattern and uneven portions after etching. This creates a problem: the sloped region intersects with the side surface of the holding portion 24 (the surface that contacts the through-hole 2a), creating a recess in the base region of the holding portion 24 on the outer frame 23 side, leading to the inside of the holding portion 24.

[0047] 8 to 10, in the present embodiment, flat regions 25b are formed in the same plane as the second main surface 212 of the retaining portion 24 at the connecting portions 25 between the outer frame portion 23 and the retaining portion 24. The flat regions 25b are formed so as to be in the same plane as the second main surface 212 of the retaining portion 24 during frequency adjustment etching. By providing such flat regions 25b, inclined regions 25a are formed in the connecting portions 25 between the outer frame portion 23 and the retaining portion 24 together with the through portions 2a during contour formation etching, but the inclined regions 25a do not directly intersect with the side surfaces of the retaining portion 24 (side surfaces on the ±X direction sides).

[0048] More specifically, as shown in FIG. 8 , the end 24a of the holding portion 24 on the −Z′ direction side is connected to a flat region 25b that is substantially rectangular in plan view, and the flat region 25b is connected to the inclined region 25a. The flat region 25b is interposed between the holding portion 24 and the inclined region 25a. At the end 24a of the holding portion 24 on the connection portion 25 side (the end on the −Z′ direction side), the entire region from the region 24b on the −X direction side to the region 24c on the +X direction side is connected to the flat region 25b. The width of the flat region 25b in the X-axis direction is larger than the width of the end 24a of the holding portion 24 on the connection portion 25 side. The flat region 25b is formed in a part of the inner end of the outer frame portion 23 on the side that contacts the through portion 2a, and recesses having shapes corresponding to the flat region 25b and the inclined region 25a are provided in the outer frame portion 23. The ends of the flat region 25b on the ±X direction sides are connected to the inclined regions 26a and 26b.

[0049] The flat region 25b is formed by setting back the rectangular opening formed during frequency adjustment etching toward the outer frame portion 23 by the area corresponding to the flat region 25b. In this case, the setback amount toward the outer frame portion 23 is preferably 20 μm or more. The contour formation etching then forms the through-hole 2a and the inclined regions 25a, 26a, and 26b in the area of ​​the outer frame portion 23 on the through-hole 2a side (the area on the +Z′ direction side). However, in the area where the holding portion 24 is formed, the holding portion 24 is not directly connected to the inclined region 25a but is connected via the flat region 25b. In the configuration of this embodiment in which the holding portion 24 is connected in the −Z′ direction, the inclined regions 25a, 26a, and 26b are formed on the second main surface 212 side of the quartz crystal plate 2 but are not formed on the first main surface 211 side of the quartz crystal plate 2.

[0050] According to this embodiment, the flat region 25b is provided at the connection portion 25 between the outer frame portion 23 and the holding portion 24, and the inclined region 25a does not directly intersect with the side surface (side surface in the ±X direction) of the holding portion 24. This prevents the formation of a recessed portion during etching in the base region of the holding portion 24 on the outer frame portion 23 side. This prevents the holding portion 24 from breaking and the deterioration of the vibration characteristics of the vibrating portion 22 due to disconnection or high resistance of the second escape wiring 224 (see FIG. 5). Furthermore, if there is a thickness difference, such as a step, between the outer frame portion 23 and the holding portion 24, force (stress or impact) concentrates in the thinner portion. However, the inclined region 25a provided at the connection portion 25 between the outer frame portion 23 and the holding portion 24 gradually weakens this force. Thus, the provision of the inclined region 25a can reduce external stress from the outer frame portion 23 to the vibrating portion 22, improving the impact resistance of the holding portion 24, such as preventing breakage.

[0051] Here, the length Lb along the direction (Z'-axis direction) in which the holding portion 24 of the flat region 25b extends only needs to be at least 1 μm. In order to realize miniaturization of the crystal vibrating plate 2 and secure the area of the vibrating portion 22, it is preferably 1 μm to 30 μm. In this case, by making the length Lb in the Z'-axis direction of the flat region 25b larger than the length La in the Z'-axis direction of the inclined region 25a, external stress from the outer frame portion 23 (for example, stress during solder mounting) can be effectively suppressed, and shift of the oscillation frequency and deterioration of the CI value can be suppressed. Such a dimensional relationship (Lb > La) is effective, for example, in a relatively low-frequency crystal oscillator 101 with an oscillation frequency of 48 MHz or the like.

[0052] On the other hand, by making the length Lb in the Z'-axis direction of the flat region 25b smaller than the length La in the Z'-axis direction of the inclined region 25a, it is possible to secure the vibration area of the vibrating portion 22 or improve the shock resistance. Such a dimensional relationship (Lb < La) is effective, for example, in a relatively high-frequency crystal oscillator 101 with an oscillation frequency of 60 MHz or higher.

[0053] The inclination angle α1 of the inclined region 25a with respect to the flat region 25b can be, for example, 28°, but in the case of an AT-cut crystal vibrating plate, it is preferably 25° to 35°.

[0054] In the present embodiment, the crystal vibrating plate 2 includes a vibrating portion 22, an outer frame portion 23 surrounding the outer periphery of the vibrating portion 22, and a holding portion 24 connecting the vibrating portion 22 and the outer frame portion 23. A through portion 2a penetrating in the thickness direction is provided between the vibrating portion 22 and the outer frame portion 23. When using such a framed crystal vibrating plate 2 in which the vibrating portion 22 and the outer frame portion 23 are connected by the holding portion 24, it is possible to achieve miniaturization and low profile of the crystal oscillator 101. Even in such a miniaturized and thinned crystal oscillator 101, the same operational effects as those of the crystal vibrating plate 2 described above can be obtained.

[0055] The present invention can be embodied in various other forms without departing from its spirit, essence, or main features. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as limiting. The scope of the present invention is defined by the claims and is not limited to the text of the specification. Furthermore, all modifications and variations within the equivalent range of the claims are within the scope of the present invention.

[0056] In the above embodiment, an AT-cut quartz crystal plate that performs thickness-shear vibration is used as the quartz crystal plate, but other quartz crystal plates (such as an SC-cut quartz crystal plate or a Z-cut quartz crystal plate (quartz Z-plate)) may also be used. For example, the present invention can also be applied to a tuning-fork type quartz crystal plate that uses a Z-cut quartz crystal plate as shown in FIG.

[0057] The tuning-fork-type quartz crystal vibrating plate 6 shown in Fig. 14 includes a vibrating portion 62 formed in a tuning-fork shape, an outer frame portion 63 surrounding the outer periphery of the vibrating portion 62, and a holding portion 64 connecting the vibrating portion 62 to the outer frame portion 63 to hold the vibrating portion 62. The tuning-fork-type quartz crystal vibrating plate 6 is configured such that the vibrating portion 62, the outer frame portion 63, and the holding portion 64 are integrally formed, and a through portion 6a is formed between the outer frame portion 63 and the vibrating portion 62. Note that Fig. 14 shows the second main surface 612 of the tuning-fork-type quartz crystal vibrating plate 6. The first and second excitation electrodes formed on the vibrating portion 62 and the lead-out wiring connected to the first and second excitation electrodes are not shown.

[0058] The vibrating unit 62 includes two legs 62a and 62b extending along the Y′-axis direction and a base 62c to which the ends of the legs 62a and 62b are connected. The legs 62a and 62b extend in the −Y′ direction from the −Y′-direction end of the base 62c. Recesses 62d and 62e are formed in the first and second main surfaces 612 of the legs 62a and 62b, respectively, so that the cross sections of the legs 62a and 62b are formed in a substantially H-shape. The holding unit 64 is provided at only one location between the vibrating unit 62 and the outer frame 63. The holding unit 64 extends in the +Y′-direction end of the base 62c of the vibrating unit 62 from the center of the base 62c in the X-axis direction to the outer frame 63 in the +Y′-direction.

[0059] The vibrating portion 62 and the holding portion 64 are formed thinner than the outer frame portion 63, and the holding portion 64 extends in the Y′-axis direction. A connection portion 65 between the holding portion 64 and one of the main surfaces (here, the second main surface 612) of the outer frame portion 63 is provided with a flat region 65b formed on the same plane as the holding portion 64 and an inclined region 65a inclined relative to the flat region 65b. Of the end portion 64a of the holding portion 64 on the connection portion 65 side, at least the regions 64b and 64c on the through portion 6a side are provided continuous with the flat region 65b. Specifically, as shown in FIG. 14 , the end portion 64a on the −Y′-direction side of the holding portion 64 is connected to the flat region 65b, which is substantially rectangular in plan view, and the flat region 65b is connected to the inclined region 65a. The flat region 65b is interposed between the holding portion 64 and the inclined region 65a. A flat region and an inclined region may be provided at connection portion 65 between outer frame portion 63 and holding portion 64 on the other main surface (first main surface) side.

[0060] In the above embodiment, the flat region 25b is formed only in a portion of the inner end of the outer frame portion 23 on the side that contacts the through-hole 2a, but the flat region 25b may also be formed over the entire inner end of the outer frame portion 23 on the side that contacts the through-hole 2a, as shown in variant example 1 of Figure 11, for example.

[0061] In the above embodiment, as shown in variant example 2 in Figures 12 and 13, a flat region 25c formed on the same plane as the retaining portion 24 and an end region 23a of the outer frame portion 23 may be provided at the connection portion 25 with the retaining portion 24 on the other main surface (here, the first main surface 211) of the outer frame portion 23, and the end portion 24a of the retaining portion 25 side may be connected to the flat region 25c.

[0062] In Modification 2 shown in Figures 12 and 13, a flat region 25c is formed in the same plane as the first main surface 211 of the holding portion 24 at the connection portion 25 between the outer frame portion 23 and the holding portion 24. The flat region 25c is formed so as to be in the same plane as the first main surface 211 of the holding portion 24 during frequency adjustment etching. The end portion 24a on the -Z' direction side of the holding portion 24 is connected to the flat region 25c which has a substantially triangular shape in plan view. A partial region of the end portion 24a of the holding portion 24 on the connection portion 25 side (the end portion on the -Z' direction side) is connected to the flat region 25c. The width in the X-axis direction of the flat region 25c is smaller than the width in the X-axis direction of the end portion 24a of the holding portion 24 on the connection portion 25 side.

[0063] The flat region 25c is formed in a part of the inner end of the outer frame portion 23 on the side that contacts the through portion 2a, and a substantially triangular recess corresponding to the flat region 25c is provided in the outer frame portion 23. Note that in this configuration in which the holding portion 24 is connected in the -Z' direction, unlike the example in FIG. 8, no inclined region connected to the flat region 25c is provided on the first main surface 211 side of the outer frame portion 23, and the flat region 25c is connected to a wall surface (step surface) that extends in the vertical direction. The flat region 25c is connected to the end region 23a of the outer frame portion 23 via this wall surface.

[0064] 13, at least a portion of end region 23a of outer frame portion 23 may be provided at a position that overlaps in plan view with inclined region 25a on second main surface 212 of outer frame portion 23. With this configuration, the influence of external stress from outer frame portion 23 (for example, stress during solder mounting) can be reduced, and impact resistance can be improved.

[0065] Furthermore, flat region 25c may be configured so that at least a portion of flat region 25c overlaps flat region 25b in a plan view. This configuration can reduce the influence of external stress from outer frame portion 23, thereby improving the stress balance in outer frame portion 23.

[0066] 12 and 13, flat region 25c, which is formed on the same plane as first main surface 211 of retaining portion 24, is formed only in a portion of the inner end of outer frame portion 23 on the side that contacts through portion 2a. However, as in Modification 3 shown in FIG. 15, flat region 25d may be formed over half or more of the inner end of outer frame portion 23 on the side that contacts through portion 2a. In Modification 3, a substantially trapezoidal recess corresponding to flat region 25d is provided in outer frame portion 23, and flat region 25d is larger than flat region 25c in FIGS. 12 and 13. As a result, intersection portion 25e between first main surface 211 of retaining portion 24 and outer frame portion 23 is included in flat region 25d, making it less likely that complex crystal planes will form at this intersection portion 25e, thereby suppressing cracks and the like in retaining portion 24.

[0067] In the above embodiment, the quartz crystal vibration plate 2 is provided with only one holding portion 24 connecting the vibration portion 22 and the outer frame portion 23, but two or more holding portions 24 may be provided, in which case the configuration of the above embodiment may be applied to the connection portions 25 between each holding portion 24 and the outer frame portion 23.

[0068] In the above embodiment, the holding portion 24 is provided at a corner of the vibrating portion 22. Specifically, the holding portion 24 extends from a corner on the +X and -Z' side of the vibrating portion 22 toward the -Z' direction. However, this is not limiting, and the holding portion 24 may extend from a corner on the +X and +Z' side of the vibrating portion 22 toward the +Z' direction. Furthermore, the holding portion 24 may be provided not at a corner of the vibrating portion 22 but at an intermediate position in the X-axis direction or the Z'-axis direction of the vibrating portion 22.

[0069] In the above embodiment, at end 24a on the connection portion 25 side (end on the -Z' direction side) of holding portion 24, the entire region from region 24b on the -X direction side to region 24c on the +X direction side is connected to flat region 25b. However, this is not limiting, and it is sufficient that at least base regions 24b, 24c of end 24a on the connection portion 25 side of holding portion 24 are connected to flat region 25b, and the entire region from region 24b on the -X direction side to region 24c on the +X direction side does not have to be connected to flat region 25b.

[0070] In the above embodiment, the first sealing member 3 and the second sealing member 4 are formed from quartz plates. However, this is not limiting. The first sealing member 3 and the second sealing member 4 may be formed from, for example, glass. Furthermore, in the above embodiment, the first sealing member 3 and the quartz plate 2 are bonded together using Au-Au bonding, and the second sealing member 4 and the quartz plate 2 are bonded together using brazing material. Furthermore, in the above embodiment, the present invention is applied to a quartz crystal unit having a sandwich structure in which the quartz crystal plate 2 is sandwiched between the first and second sealing members 3 and 4. However, this is not limiting. For example, the present invention can also be applied to a quartz crystal unit having a structure in which a quartz crystal plate is mounted on a concave base substrate made of an insulating material such as ceramic and hermetically sealed with a lid member.

[0071] This application claims priority based on Japanese Patent Application No. 2022-120859, filed on July 28, 2022, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0072] 101 Crystal oscillator (crystal oscillator device) 2 Crystal diaphragm 2a Penetration 22 Vibration unit 23 Outer frame 24 Holding part 24a End of connection part 24b, 24c Area on the penetration side 25 Continuation part 25a Inclined area 25b Flat area 212 2nd Main Side

Claims

1. An outer frame portion and a vibration portion formed to be thinner than the outer frame portion, a quartz crystal oscillating plate in which a through-hole is formed between the outer frame portion and the vibrating portion, and the outer frame portion and the vibrating portion are connected by a holding portion that is thinner than the outer frame portion, a flat region formed on the same plane as the holding portion and an inclined region inclined relative to the flat region are provided at a connection portion between the holding portion and one main surface of the outer frame portion, At least a region of the end of the holding portion on the connection portion side that is on the penetration portion side is provided continuously with the flat region, A quartz crystal vibration plate, characterized in that the length of the flat region along the direction in which the holding portion extends is 1 μm to 30 μm.

2. 2. The quartz crystal plate according to claim 1, A quartz crystal vibration plate, characterized in that the inclined region has an inclination angle of 25° to 35° with respect to the flat region.

3. An outer frame portion and a vibration portion formed to be thinner than the outer frame portion, a quartz crystal oscillating plate in which a through-hole is formed between the outer frame portion and the vibrating portion, and the outer frame portion and the vibrating portion are connected by a holding portion that is thinner than the outer frame portion, a flat region formed on the same plane as the holding portion and an inclined region inclined relative to the flat region are provided at a connection portion between the holding portion and one main surface of the outer frame portion, At least a region of the end of the holding portion on the connection portion side that is on the penetration portion side is provided continuously with the flat region, A quartz crystal vibration plate, characterized in that the inclined region has an inclination angle of 25° to 35° with respect to the flat region.

4. The quartz crystal plate according to any one of claims 1 to 3, A quartz crystal vibration plate, characterized in that the length of the flat region along the direction in which the holding portion extends is greater than the length of the inclined region.

5. The quartz crystal plate according to any one of claims 1 to 3, A quartz crystal vibration plate, wherein the length of the flat region along the direction in which the holding portion extends is smaller than the length of the inclined region.

6. The quartz crystal plate according to any one of claims 1 to 3, a flat region formed on the same plane as the holding portion and an end region of the outer frame portion are provided at a connection portion between the holding portion and the other main surface of the outer frame portion, The quartz crystal plate is characterized in that the end of the holding portion on the connection portion side is connected to the flat region.

7. 7. The quartz crystal plate according to claim 6, A quartz crystal vibration plate characterized in that at least a portion of the end region on the other main surface of the outer frame portion is positioned so as to overlap the inclined region on one of the main surfaces of the outer frame portion in a planar view.

8. 7. The quartz crystal plate according to claim 6, A quartz crystal vibration plate characterized in that at least a portion of the flat region on the other main surface of the outer frame portion is positioned so as to overlap the flat region on one of the main surfaces of the outer frame portion in a planar view.

9. A quartz crystal resonator device comprising the quartz crystal resonator plate according to any one of claims 1 to 3, a first sealing member that covers one main surface side of the vibration portion of the quartz crystal vibration plate; a second sealing member that covers the other main surface side of the vibration portion of the quartz crystal vibration plate, A quartz crystal vibration device characterized in that the vibrating portion of the quartz crystal vibration plate is sealed by bonding the first sealing member to the quartz crystal vibration plate and bonding the second sealing member to the quartz crystal vibration plate.

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