Crystal plate and crystal device

Abstract

To provide a crystal oscillating plate and a crystal oscillating device with improved oscillating characteristics of an oscillating portion while stabilizing the mechanical strength of the oscillating portion and a frame portion.SOLUTION: A crystal oscillating plate 1 is made of an AT-cut crystal oscillating plate and is a rectangular plate on the whole. The crystal oscillating plate 1 includes an oscillating portion 11, and holding portions 13, 13t connected to the oscillating portion, and a frame portion 12 arranged on the periphery of the oscillating portion and connected to the holding portion 13. Between the oscillating portion 11 and the frame portion 12, except for the holding portions 13, 13t, a circumferential through portion 14 is formed. The holding portion 13 is formed larger than the thickness of the holding portion 13t.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a quartz crystal vibration plate that is integrally formed with a vibrating portion on which an excitation electrode is formed, a frame portion that is arranged around the vibrating portion, and a holding portion that connects and holds the vibrating portion to the frame portion, and to a quartz crystal vibration device that uses this quartz crystal vibration plate. [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 three-layer crystal resonator device is known as a crystal resonator device suitable for miniaturization and low profile. The housing of a three-layer crystal resonator device is configured as a roughly rectangular parallelepiped package. This package is composed of a first and second sealing member, e.g., plate-shaped, made of glass or quartz crystal; a vibrating section with excitation electrodes formed on both main surfaces; and a crystal resonator plate in which a frame body is disposed around the periphery of the vibrating section via a through-hole and the vibrating section and the frame body are integrally formed by a holding section. The first and second sealing members are bonded to the top and bottom surfaces of the crystal resonator plate, forming a laminated structure. The vibrating section of the crystal resonator plate, located inside the package (internal space), is hermetically sealed by the first and second sealing members.

[0004] The quartz crystal vibration plate used in the above three-layer quartz crystal vibration device is an AT-cut quartz crystal plate, and as described above, it is integrally formed with a vibration part on which an excitation electrode is formed, a frame part arranged around the vibration part, and two holders that connect and hold the vibration part to the frame part. For example, see JP 2016-181880 (Patent Document 1).

[0005] As is well known, the crystal axes of an AT-cut quartz plate are represented by the X-, Y-, and Z-axes of the synthetic quartz, while the Y- and Z-axes of an AT-cut quartz crystal rotated 35°15' around the X-axis are represented by the Y'-axis and Z'-axis, respectively, and the resonant frequency is inversely proportional to the thickness. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2016-181880 Summary of the Invention [Problem to be solved by the invention]

[0007] Patent Document 1 discloses an example in which a vibrating section having excitation electrodes formed on both main surfaces is integrally formed with a frame section via two holding sections. In this configuration, the mechanical strength for holding the vibrating section can be improved compared to a configuration in which the holding section is formed in only one place. However, depending on the size of the vibrating section, forming multiple holding sections in multiple places can hinder its vibration, which can degrade the electrical characteristics of the quartz crystal vibrating device.

[0008] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a quartz crystal vibration plate and a quartz crystal vibration device that have a vibration part with excitation electrodes formed on both main surfaces, a frame part arranged on the outer periphery of the vibration part via a through part, and the vibration part and the frame part integrally formed by a holding part, in which the mechanical strength of the vibration part and the frame part are stabilized and the vibration characteristics of the vibration part are improved. [Means for solving the problem]

[0009] The quartz crystal vibration plate according to the present invention has an excitation electrode formed on one main surface and an excitation electrode formed on the other main surface, a vibration part having a generally rectangular shape in a plan view and having corners, on which extraction electrodes connected to each of the excitation electrodes are formed, holding parts formed to protrude from each of the corners, and a frame part surrounding the outer periphery of the vibration part via a through part and connected to each of the holding parts, wherein the extraction electrodes are extracted to the frame part, and the thickness of at least one holding part is smaller than the thickness of the other holding parts. The volume of at least one of the holding portions is smaller than the volume of the other holding portions. The quartz crystal plate may be an AT-cut quartz crystal plate, an XY-cut quartz crystal plate, or the like.

[0010] According to the above configuration, the frame and vibrating unit are connected by multiple holding parts, and at least one of the holding parts is thinner than the other holding parts. Therefore, the mechanical strength is stabilized by the multiple holding parts, and the provision of thin holding parts prevents the vibration of the vibrating unit from being impeded, resulting in a quartz crystal vibrating plate with excellent vibration characteristics. In a quartz crystal vibrating device using this quartz crystal vibrating plate, deterioration of electrical characteristics is suppressed, ensuring practical electrical performance.

[0011] Furthermore, when using an AT-cut quartz crystal plate, a thicker portion may be formed around the periphery of the vibrating portion, which is thicker than the vibrating portion. In this case, the holding portion and the thick portion may be formed continuously. By configuring the holding portion to extend in the Z'-axis direction of the AT-cut, the propagation of vibration energy from thickness-shear vibration can be suppressed, which has the advantage of stabilizing the electrical characteristics of the quartz crystal vibrating device.

[0012] The above configuration improves the mechanical strength of the diaphragm due to the thickened portion, even when the frequency is increased, and the configuration of the holding portion prevents the vibration of the vibrating portion from being inhibited, resulting in a quartz crystal diaphragm with good vibration characteristics. In a quartz crystal device using this quartz crystal diaphragm, deterioration of electrical characteristics is suppressed, and practical electrical performance can be ensured.

[0013] The present invention also provides a quartz crystal vibration plate comprising: a vibration section having an excitation electrode formed on one main surface and an excitation electrode formed on the other main surface, the vibration section having a generally rectangular shape in plan view with corners and having extraction electrodes connected to the excitation electrodes; holding sections each protruding from the corners; and a frame section surrounding the periphery of the vibration section via a through-hole and connected to each of the holding sections, wherein the extraction electrodes are extracted to the frame section, and the projected area of at least one holding section is smaller than the areas of the other holding sections. Note that the area is the product of the length and width dimensions (projected area) of the holding section in plan view.

[0014] According to the above configuration, the frame and the vibrating unit are connected by multiple holding parts, and at least one of the holding parts has a smaller area than the other holding parts. Therefore, the mechanical strength is stabilized by the multiple holding parts, and the small holding parts prevent the vibration of the vibrating unit from being hindered, resulting in a quartz crystal vibrating plate with good vibration characteristics. In a quartz crystal vibrating device using this quartz crystal vibrating plate, deterioration of electrical characteristics is suppressed and practical electrical performance can be ensured.

[0015] The volume (product of thickness and area) of at least one of the holding portions may be smaller than the volume (product of thickness and area) of the other holding portions. In this case, the mechanical strength is stabilized by the number of holding portions, and the provision of small-volume holding portions can prevent the vibration of the vibrating portion from being impeded, resulting in a quartz crystal vibrating plate with good vibration characteristics. In a quartz crystal vibrating device using this quartz crystal vibrating plate, degradation of electrical characteristics is suppressed, ensuring practical electrical performance.

[0016] In each of the above configurations, a thin portion having a tapered portion that is thinner than the thick portion and thicker than the vibrating portion may be formed on one end side of the diaphragm parallel to the +X-axis direction and at the +Z'-axis direction end. With the above configuration, the mechanical strength of the diaphragm can be improved.

[0017] However, when etching is performed on the +Z'-axis end of the side along the X-axis of an AT-cut quartz crystal plate, the edge may become rough due to the anisotropic crystal, and may not be processed to the intended straight line. By adopting this low-thickness structure, it becomes easier to maintain the straightness of the edge, and the electrical characteristics are also stabilized.

[0018] The crystal vibration plate of each of the above configurations can be housed in a package with terminal electrodes, and the electrodes of the crystal vibration plate can be electrically and mechanically bonded to the mounting electrodes on the package to obtain a crystal vibration device with terminal electrodes. For example, the crystal vibration plate can be conductively bonded to a ceramic package with a concave cross section and wired electrodes using a conductive bonding material or metal bumps, and the package can be hermetically sealed with a lid.

[0019] The crystal vibration device may also be characterized in that each of the crystal vibration plates is provided with a first sealing member that covers at least one main surface of the vibration portion of the crystal vibration plate, and a second sealing member that covers at least the other main surface of the vibration portion of the crystal vibration plate.

[0020] According to the above configuration, a quartz crystal resonator device having excellent mechanical strength and electrical characteristics can be obtained. [Effects of the Invention]

[0021] The quartz crystal plate of the present invention can stabilize its mechanical strength by being held by multiple holding parts. Furthermore, by providing thin holding parts, it is possible to prevent the vibration of the vibrating part from being inhibited, resulting in a quartz crystal plate with good vibration characteristics.

[0022] Furthermore, the crystal resonator device of the present invention can stabilize mechanical strength and ensure practical electrical performance. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is an exploded perspective view showing each component of a quartz crystal resonator device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a plan view of a quartz crystal plate of the quartz crystal device. [Figure 3] 2 is a cross-sectional view taken along the line AA in FIG. 1 when the components are assembled. [Figure 4] FIG. 10 is a plan view of a quartz crystal plate according to a second embodiment. [Figure 5] 5 is a cross-sectional view of FIG. 4 taken along line B-B. [Figure 6] FIG. 10 is a cross-sectional view showing another modified example. [Figure 7] FIG. 10 is a plan view of a quartz crystal plate according to a third embodiment. [Figure 8] 8 is a cross-sectional view taken along CC in FIG. 7. [Figure 9] 8 is a DD cross-sectional view of the crystal vibration plate of FIG. 7 bonded with a sealing member and having an IC component mounted thereon. [Figure 10] FIG. 10 is a plan view of a quartz crystal plate according to a fourth embodiment. [Figure 11] 11 is a cross-sectional view of FIG. 10 taken along E-E axis. [Figure 12] FIG. 11 is a cross-sectional view of FIG. 10 taken along the line F-F. [Figure 13] FIG. 10 is a cross-sectional view showing a modified example of the fourth embodiment. [Figure 14] 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. [Figure 15] 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. [Figure 16] 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. [Figure 17] 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. [Figure 18] 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0025] First embodiment As shown in FIG. 1, the quartz crystal vibration device Xtl according to the first embodiment comprises a quartz crystal vibration plate 1, a first sealing member 2, and a second sealing member 3, which are stacked in the order of the first sealing member 2, the quartz crystal vibration plate 1, and the second sealing member 3.

[0026] The quartz crystal oscillating plate 1 is an AT-cut quartz crystal oscillating plate, and is a rectangular plate overall. The quartz crystal oscillating plate 1 comprises a vibrating portion 11, holding portions 13 and 13t connected to two corners of the vibrating portion 11, and a frame portion 12 disposed on the outer periphery of the vibrating portion and connected to the holding portions 13 and 13t. A through-hole 14 is formed around the periphery between the vibrating portion 11 and the frame portion 12, except for the holding portions 13 and 13t.

[0027] The vibrating section 11 is rectangular with opposing long sides and opposing short sides and has four corners. The vibrating section may also be square. Rectangular excitation electrodes 111 and 112 are formed on one and the other main surfaces (front and back main surfaces) at approximately the center of the vibrating section 11. Strip-shaped extraction electrodes 111a and 112a are connected to the corners of each excitation electrode 111 and 112, and are extracted toward both ends of one side (corners of the vibrating section). The extraction electrode 111a is extracted to the frame body via the holding section 13, and the extraction electrode 112a is extracted to the frame body via the holding section 13t, and finally to terminal electrodes 31 and 32 formed on the second sealing member 3, which will be described later.

[0028] Specifically, the extraction electrode 111a passes through the surface of the holding portion 13, is extracted to the other main surface through a metal via (through metal) V1 formed in the frame portion 12, and is connected to a metal via V2 formed in the second sealing member 3 described below. The metal via V2 is electrically connected to a terminal electrode 31 formed on the other main surface of the second sealing member 3. The extraction electrode 112a passes through the back surface of the holding portion 13t, is extracted to the other surface of the quartz crystal vibrating plate 1, and is electrically connected to a metal via V3 formed in the opposing second sealing member 3. The metal via V3 is electrically connected to a terminal electrode 32 formed on the other main surface of the second sealing member 3.

[0029] These excitation electrodes 111, 112 and extraction electrodes 111a, 112a are made of multiple metal films, and have a multilayer structure in which, for example, a Ti film is formed in contact with the quartz crystal plate and an Au film is formed on top of that. Specific examples of the thickness of each metal film include a Ti film of 5 nm and an Au film of 200 nm, but these can be changed depending on the desired characteristics.

[0030] A thick portion 11a is formed on one end side of the vibrating portion 11. The thick portion 11a is formed on one end side in the X-axis direction, extends in the Z'-axis direction, and is formed over the entire end side. The thick portion 11a is formed to be thicker than the vibrating portion 11.

[0031] 2, a holder 13 is provided at one corner C1 of the vibrating section 11, and the holder 13 is connected to the frame section 12. In this embodiment, the vibrating section, holder, and frame section are integrally formed from a quartz crystal plate using photolithography and wet etching techniques. Note that dry etching may be used instead of wet etching.

[0032] As shown in FIGS. 1 and 3, the holding portion 13 is thicker than the vibrating portion 11 and the thick portion 11a. A sloped taper T2 (the angle formed with the upper surface of the holding portion 13 is an obtuse angle) is formed from the thick portion 11a to the upper surface of the holding portion 13, and a sloped taper T3 (the angle formed with the upper surface of the holding portion 13 is an obtuse angle) is also formed from the vibrating portion 11 to the holding portion 13. The holding portion 13 is connected to the frame portion 12, and a taper T1 (the angle formed with the upper surface of the frame portion 12 is an obtuse angle) is formed from the holding portion 13 to the upper surface of the frame portion 12. With this configuration, the thicknesses of the respective portions are set as follows: vibrating portion < thick portion < holding portion < frame portion. The thicknesses of the thick portion 11a and holding portion 13 may be equal. By forming these tapers, the boundary regions can be made obtuse.

[0033] An example of the specific dimensions of the quartz crystal vibrating plate is shown below. The quartz crystal vibrating plate is an AT-cut quartz crystal plate that is rectangular in plan view, with external dimensions of 0.6 mm long and 0.5 mm short, with a frame thickness of 0.04 mm, a holding portion thickness of 0.03 mm, a thick portion thickness of 0.017 mm (17 μm), and a vibrating portion thickness of 0.005 mm (5 μm). It is preferable for the thick portion to be at least a dozen μm thicker than the vibrating portion thickness to ensure mechanical strength.

[0034] In this embodiment, the crystal plate 1 is thinned from only one of its main surfaces, for example, by etching only one of its main surfaces until it reaches the desired frequency (thickness). In this case, the other main surface is not etched, so that deterioration of vibration characteristics due to surface roughening caused by etching can be suppressed.

[0035] Seal films S11 and S21 are formed around the outer peripheral edges of the front and back of the frame body portion 12, and like the electrode film described above, these seal films have a multilayer structure in which a Ti film is formed in contact with the quartz vibration plate and an Au film is formed on top of that.

[0036] The first sealing member 2 is made of a rectangular, plate-like AT-cut quartz crystal plate, and has the same external shape and size as the quartz crystal vibration plate 2. On the surface of the first sealing member 2 facing the quartz crystal vibration plate 1, a circumferential sealing film S12 corresponding to the sealing film S11 is formed.

[0037] The second sealing member 3 is made of a rectangular, plate-shaped AT-cut quartz crystal plate and has the same external shape and size as the quartz crystal plate 2. A peripheral sealing film S22 corresponding to the sealing film S21 is formed on the surface of the second sealing member 3 facing the quartz crystal plate 1. A pair of terminal electrodes 31, 32 is formed on the surface of the second sealing member 3 that does not face the quartz crystal plate 1. These terminal electrodes 31, 32 have a constant width and extend in the X-axis direction, and are arranged facing each other in the Z'-axis direction. The metal films that make up these terminal electrodes are layered structures of Ti, NiTi, and Au films.

[0038] Furthermore, a metal via V2 is formed in the second sealing member 3 near the area corresponding to the holding portion 13, penetrating from the front to the back, and is electrically connected to the metal via V1 described above. A metal via V3 is also formed in the second sealing member 3 near the area corresponding to the holding portion 13t, penetrating from the front to the back. With this configuration, the extraction electrode 111a formed on the quartz crystal plate is connected to the terminal electrode 31, and the extraction electrode 112a is connected to the terminal electrode 32 via the metal via V3.

[0039] As shown in FIG. 3, the quartz crystal resonator device Xtl is constructed by stacking a first sealing member 2, a quartz crystal plate 1, and a second sealing member 3 in this order. As mentioned above, each of these components is made of a quartz crystal plate, and its surface is mirror-polished to a smooth surface. Specifically, the average surface roughness Ra is preferably 0.3 to 0.1 nm. By forming the sealing films S11, S12, S21, and S22 on such a smooth surface, the metal film (top layer Au film) on the surface also has an extremely smooth surface.

[0040] The first sealing member 2 and the quartz crystal plate 1, and the quartz crystal plate and the second sealing member 3 are bonded by pressure bonding using a diffusion bonding method after surface treatment of the Au of the metal film. As a result, the vibration part of the quartz crystal plate is hermetically sealed within the sealing members 2 and 3 and the frame part 12 by the seal parts S1 (S11, S12) and S2 (S21, S22).

[0041] According to this embodiment, the vibrating portion 11 has a thick portion 11a formed along almost the entire area of one end edge where the holding portions 13 and 13t are formed, while the other end edge has a thin diaphragm thickness suitable for high frequencies. Therefore, the vibration excited by the vibrating portion 11 can be caused to vibrate in a state where it is less affected by the boundary conditions caused by the thick portion 11a, thereby obtaining a quartz crystal vibrating plate that is less likely to generate spurious signals and maintains a good CI value (series resonance resistance). The thick portion 11a also improves the mechanical strength of the vibrating portion 11.

[0042] As mentioned above, the holding portion 13 is thicker than or the same thickness as the thick portion 11a, and tapered portions are formed between the frame portion 12 and the holding portion 13, and between the thick portion 11a and the vibrating portion 11. As mentioned above, this tapering allows the boundaries to be made obtuse. As a result, the extraction electrodes 111a and 112a, which are extracted from the excitation electrodes 111 and 112 to one edge of the quartz crystal vibrating plate, are formed on this tapered portion and do not pass through any sharp corners (step portions), preventing a decrease in electrode conductivity and electrode breakage. This allows for a quartz crystal vibrating plate with good electrical characteristics.

[0043] In this embodiment, the metal film of the excitation electrode and the metal film for sealing are exemplified as a multilayer structure of Ti and Au, but the metal film is not limited to this. For example, a multilayer structure of Ti, Ru (ruthenium), and Au may be used.

[0044] Although the bonding between each sealing member and the quartz crystal plate was performed using a diffusion bonding method, brazing using an AuSn alloy brazing material, or other brazing materials such as Sn alloy brazing material, may also be used. In this case, the metal film configuration may also be different, for example, a configuration in which an Ag or Cu film is formed on a Cr underlayer, or a configuration in which an Au alloy film is formed on the Cr underlayer.

[0045] In the above description, quartz plates are used as the material for the first and second sealing members, but glass or ceramic materials may be used instead of quartz plates. Furthermore, while a plate-like structure has been exemplified, a recess may be provided in a position facing the quartz vibration plate. Providing such a recess reduces the chance of contact between the vibration part and the sealing members, thereby stabilizing the characteristics of the quartz vibration device.

[0046] Furthermore, at least one of the sealing members may be made of a resin film. For example, a resin film may be attached to the thick frame portion so as to bridge the frame portion. The resin film contributes to the reduction in thickness, allowing for an ultra-thin crystal resonator device to be obtained.

[0047] According to this embodiment, the frame portion 12 and the vibrating portion 11 are connected by a plurality of holding portions 13, 13t, but the thickness of the holding portion 13t is smaller than the thickness of the holding portion 13. Therefore, the mechanical strength is stabilized by the holding by a plurality of holding portions, and by providing a holding portion with a small thickness (thin), it is possible to prevent the vibration of the vibrating portion from being hindered. This prevents the deterioration of the electrical characteristics of the quartz crystal vibrating device, and ensures practical electrical performance.

[0048] Second embodiment The second embodiment also comprises a quartz crystal plate 1, a first sealing member 2, and a second sealing member 3, which are stacked in this order. Compared to the first embodiment, the configurations of the vibrating portion 11 of the quartz crystal plate, the frame portion 12, the holding portions 13, 13t, and the thick portion 11 are different. The first sealing member 2 and the second sealing member 3 have similar configurations to those of the first embodiment, so a description thereof will be omitted.

[0049] The vibrating section 11 is rectangular, and has holding sections 13, 13t formed at both ends of one side (the holding sections are arranged left and right reversely compared to the first embodiment). Thick section 11b formed on the vibrating section is formed between the holding sections, but the thick section does not extend up to holding section 13. Therefore, as shown in Figure 5, the thickness decreases from thick section 11b to vibrating section 11, then increases at holding section 13, and then further increases at the frame section.

[0050] Furthermore, the holding portion 13t is thinned by forming a slit 16a from the other main surface of the quartz crystal plate, thereby achieving the relationship that the thickness of the holding portion 13 is greater than the thickness of the holding portion 13t. Furthermore, the frame portion 12 on the holding portion 13t side has a thin portion 12a that is thinner than the frame portion. This thin portion 12a continues to the taper T1 from the holding portion, and by forming an extraction electrode 113a in this portion, the angle of the edge at the boundary between the taper T1 and the frame portion can be made obtuse, thereby preventing breaks in the electrode wiring.

[0051] In this embodiment, the holding portion 13t is thinned by forming the slit 16a on the other main surface side, so that the thinned portions are formed on both the front and back sides of the vibrating portion 11 and the holding portion 13t as shown in Fig. 5. This configuration has the effect of providing a cushioning function for the entire vibrating portion.

[0052] The excitation electrodes 113, 114 formed on the vibrating part are rectangular, and the extraction electrodes 113a, 114a extending from the excitation electrodes 113, 114 are extended from the center of two opposing sides in a direction perpendicular to the two sides, and then extend toward the respective holding parts 13, 13t. This extraction electrode configuration can suppress adverse effects on the excitation operation of the vibrating part, and can also suppress deterioration of electrical characteristics such as CI.

[0053] The frame 12 is a rectangular plate overall, and castellations C, C are formed in the center of the opposing outer edges, cut out in the width direction of the frame. By forming a metal film for electrodes on the side surfaces of the castellations C, C, when joining to a mounting board (not shown), for example, by soldering, the solder material can be promoted to creep up to the castellations, thereby improving the joining strength during mounting.

[0054] As described above, according to the second embodiment, it is possible to improve the impact resistance and electrical characteristics of the quartz crystal resonator device.

[0055] Modification of the second embodiment A modified example of the second embodiment is shown in Fig. 6. In this modified example, the configuration of the excitation electrodes formed on the vibrating portion 11 of the quartz crystal vibrating plate and the configuration of the second sealing member are different.

[0056] The electrode configuration that vibrates (excites) the vibration portion 11 of the quartz crystal vibration plate is such that the excitation electrode 115 formed on one main surface is a metal film formed directly on the vibration portion 11, while the other main surface is vibrated using an air gap method. Specifically, an excitation electrode 116 of the same shape is formed on the surface of the second sealing member facing the vibration portion, at a position opposite the portion where the excitation electrode 115 is formed. The vibration portion 11 is vibrated by applying an AC electric field to both excitation electrodes 115, 116. In addition, a thin portion 3a is formed on the surface of the second sealing member facing the vibration portion, so that the distance between the vibration portion 11 and the excitation electrode 116 is kept appropriate.

[0057] Third embodiment The third embodiment will be described with reference to Figures 7 to 9. The main features of this embodiment are that the vibrating section is thinned from both sides (front and back) of the quartz crystal vibrating plate in the thickness direction, that holding sections are provided in two locations, that thick sections are formed across two continuous sides, that the extraction electrodes are configured to spread out in a fan shape toward the ends on the vibrating section plate surface, and that an IC chip for the oscillation circuit is mounted on the top surface of the quartz crystal vibrating device to form a quartz crystal oscillator.

[0058] Vibrating section 11 is configured to be thinned on both the front and back sides, and two holding sections 13, 13t are formed on both ends of one end side of vibrating section 11 configured in this way, with the thickness of holding section 13t being smaller than the thickness of holding section 13. Furthermore, thick section 11c is formed between holding sections 13, 13t of vibrating section 11, and thick section 11d is formed from one end of thick section 11c in a direction perpendicular to thick section 11c, so that as a whole, thick sections are formed in an inverted L shape on two consecutive sides of the vibrating section.

[0059] It is known that in thickness-shear vibration of an AT-cut quartz crystal plate, the area involved in the vibration becomes smaller as the frequency increases. When vibrating at higher frequencies, even an inverted L-shaped thick section as shown in this embodiment does not impede the vibration. However, as the frequency increases, the thickness of the vibrating section decreases, which tends to reduce mechanical strength. However, by forming the thick sections on two consecutive sides, mechanical strength can be improved, resulting in a high-frequency quartz crystal vibration device with excellent impact resistance.

[0060] In this embodiment, the extraction electrodes 117a, 118a, which are respectively extracted from the opposing excitation electrodes 117, 118, are configured to fan out toward the ends of the vibrating section. To achieve higher frequencies, excitation electrodes made of metal films tend to be thinner to efficiently excite vibration without impeding it, which also leads to the extraction electrodes being similarly thinner. In such cases, the thinner extraction electrodes increase the likelihood of wire breakage along the wiring. To prevent such defects, the width of the extraction electrodes is increased with increasing distance from the excitation electrodes, thereby reducing the chance of wire breakage. In particular, in the present invention, thicker portions are formed in the vibrating section, resulting in multiple steps. However, by adopting this embodiment, the chance of wire breakage due to the thicker portions is reduced, resulting in a highly reliable crystal vibrating device (crystal resonator, crystal oscillator, etc.).

[0061] This embodiment also illustrates an example of a crystal oscillator. An IC component (single-chip IC) 4 constituting an oscillator circuit and the like is mounted on the top surface of the crystal resonator. Although not shown, the second sealing member 2 is formed with multiple electrode pads for mounting the IC component 4 and a wiring pattern connecting these electrode pads. The wiring pattern also includes electrode pads for connection to the crystal resonator device, and is wired to connect the crystal terminals of the crystal resonator to the oscillator circuit. The terminals of the IC component 4 are also wired so that they can be drawn out, ultimately leading to the mounting board connection surface (back side) of the second sealing member as terminal electrodes. Connection electrodes 121, 122, 123, and 124 are formed in the through-hole 14 inside the frame body. These connection electrodes connect the above-mentioned wiring pattern from the second sealing member to the second sealing member. The wiring formed on this crystal resonator device forms four terminal electrodes that function as a crystal oscillator on the mounting board connection surface of the second sealing member. Note that only two terminals, terminal electrodes 33 and 34, are shown in FIG. 9.

[0062] Fourth embodiment The fourth embodiment will be described with reference to Figures 10 to 12. This embodiment constitutes a quartz crystal resonator, and is characterized in that the excitation electrodes formed on one main surface of the vibrating part and the other main surface are not directly opposite each other, but the excitation electrode on the other main surface is rotated by 45 degrees, that holding parts are provided in two places, and the thicknesses of the holding parts are equal but the areas (projected areas) are different, and that in addition to the thick parts on two sides, low thick parts that are lower in height than the thick parts are formed.

[0063] The excitation electrode 119 formed on one main surface of the vibrating section 11 is rotated 45 degrees around the center of the two excitation electrodes as an axis, while the excitation electrode 120 formed on the other main surface is rotated 45 degrees around the center of the two excitation electrodes. This configuration has the effect of suppressing spurious (unwanted vibrations) that tend to occur at higher frequencies. Furthermore, when the frequency is increased, the vibration area becomes smaller, which suppresses spurious that may occur when excited vibrations are reflected by the thick portion, thereby improving the vibration characteristics of the quartz crystal vibrating device.

[0064] In addition to the inverted L-shaped thick portions 11e and 11f, the vibrating portion has a thin portion 11g extending from the other end of the thick portion 11e in parallel to the thick portion 11f. Forming a thick portion is effective in improving the mechanical strength of the vibrating portion, but it may also limit the vibration range. By forming the thin portion 11g with a reduced thickness as in this embodiment, it is possible to minimize operational interference with the quartz crystal vibrating device and increase its shock resistance. Furthermore, combined with the spurious suppression effect achieved by the excitation electrode configuration described above, the electrical characteristics of the quartz crystal vibrating device can be improved.

[0065] In this embodiment, the low-thickness portion 11g has a tapered portion that is inclined when viewed in cross section, and extends in the +X direction at the end in the +Z' direction. When etching is used to process the contour of a quartz plate, the region at the +Z' end, i.e., the region extending in the +X direction at the end in the +Z' direction, is prone to processing variations, and linear processing may not be possible relative to the processing of the edges. By configuring a low-thickness portion as in this embodiment, it is possible to suppress variations in the contour processing, resulting in a quartz crystal resonator device with stable electrical characteristics.

[0066] A modified example of the fourth embodiment will be described with reference to Fig. 13. In this modified example, the thick and thin portions formed on the outer periphery of the diaphragm 11 have different configurations. The thick portion 11h is wider than the configuration shown in Fig. 12, and has a thickness of 17 µm. The thin portion is also wider than the configuration shown in Fig. 12, and is 0.5 µm to 1.5 µm thicker than the thickness of the vibrating portion 11. The slope of the tapered portion formed by the thin portion and the vibrating portion is also small. The thickness of the vibrating portion is determined by the set frequency.

[0067] As a specific example of dimensions, when the operating frequency of the quartz crystal resonator device is 312 MHz, the vibrating part is approximately 5.3 μm thick and the thin part is set to 6.2 μm, resulting in a thickness difference of 0.9 μm. When the operating frequency is approximately 2 GHz, the vibrating part is approximately 0.7 μm thick and the thin part is set to 1.3 μm, resulting in a thickness difference of 0.6 μm. The width of the thick part in the +Z'-axis direction is 0.1 mm, and the width of the thin part in the +Z'-axis direction is 0.1 mm.

[0068] In the above-mentioned modified example, when the frequency is high, the vibration area is narrowed as in the above-mentioned dimension example, so it is unlikely to have a negative impact on the electrical characteristics. Also, in the above-mentioned verification example, the thickness of the thin-walled portion relative to the vibrating portion is not large, so no deterioration in the electrical characteristics was observed. Furthermore, the wide width of the thick-walled portion and the thin-walled portion can also improve the mechanical strength.

[0069] In this embodiment, the thicknesses of the holders 13 and 13t are set to be approximately the same, but the areas are different. That is, the dimensions of the holders 13 and 13t in the Z-axis direction are the same, but the dimension of the holder 13 in the X-axis direction is set to be larger than that of the holder 13t. This stabilizes the mechanical strength by the holding by multiple holders, and by providing holders with small areas, it is possible to prevent the vibration of the vibrating part from being hindered, thereby preventing a decrease in the electrical characteristics of the quartz crystal vibrating device and ensuring practical electrical performance.

[0070] The holding portions 13, 13t may be formed at diagonal corners of the rectangular vibrating portion 11. Specifically, the holding portion 13 is formed following the intersection of the thick portions 11e, 11f, and the holding portion formed at the diagonal corner is formed following the end of the thin portion 11g. When the holding portions are arranged diagonally in this manner, the vibrating portion is supported not only on one side but also on both sides of the diagonal, so that when an impact is applied to the quartz crystal resonator device, the deflection can be suppressed and frequency fluctuations can be reduced.

[0071] Manufacturing example Next, a manufacturing example of forming the above-mentioned low-thickness portion 11g using photolithography and wet etching techniques will be described with reference to Figures 14 to 18. In actual manufacturing, a quartz crystal wafer is used to manufacture multiple quartz crystal vibrating plates, but this explanation will focus on one quartz crystal vibrating plate portion.

[0072] First, a metal film is formed on the entire front and back surfaces of the quartz crystal vibration plate (quartz crystal wafer) by sputtering or other methods. Here, a Ti film is used as a base film, and an Au film is formed on top of that. A resist film is then applied to the entire front and back surfaces of the metal film using a film-forming device such as a spinner. After that, exposure is performed using a specified mask pattern, and a resist mask pattern is formed on the front and back of the quartz crystal vibration plate 1. This resist mask pattern is used to etch away unnecessary metal film, obtaining a metal film mask pattern M (see Figure 14). Wet etching is performed using this metal film mask pattern, resulting in quartz etching as shown in Figure 15.

[0073] Next, a metal film mask pattern for the second etching is formed on the quartz crystal vibrating plate using photolithography and wet etching techniques, as shown in Figure 16. The second etching is also performed from the back side, and finally, as shown in Figure 18, a quartz crystal vibrating plate is obtained with thick portions 11f and thin portions 11g formed, due to the anisotropy of the quartz crystal.

[0074] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments, but should be defined by the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. [Explanation of symbols]

[0075] 1 Crystal diaphragm 11 Vibration unit 111,112,113,114,115,116,117,118,119,120 Excitation electrode 111a, 112a, 113a, 114a, 117a, 118a, 119a, 120a Extraction electrode 12 Frame body part 13, 13t holding part 14 Penetration 2 First sealing member 3 Second sealing member 4 IC chip S11, S12 sealing membrane S1, S2 seal part T1, T2, T3 tapered section V1, V2, V3 metal vias

Claims

1. a vibration section having excitation electrodes formed on one main surface and excitation electrodes formed on the other main surface, and having extraction electrodes connected to the excitation electrodes, the vibration section being substantially rectangular in plan view and having corners; holding portions formed to protrude from the plurality of corner portions; a frame portion that surrounds the outer periphery of the vibrating portion via a through-hole and is connected to each of the holding portions, the extraction electrodes are drawn out to the frame portion, and the thickness of at least one of the holding portions is smaller than the thickness of the other holding portions; A quartz crystal plate, characterized in that at least one of the holding portions has a volume smaller than the volume of the other holding portions.

2. A thick portion is formed on one end of the vibrating portion, The thick portion is formed on one end side of the vibrating portion where a plurality of holding portions are formed. The quartz crystal plate according to claim 1.

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