Crystal plate and crystal device

Abstract

To provide a crystal oscillating plate with improved oscillating characteristics of an oscillating portion while stabilizing the mechanical strength of the oscillating portion and a frame portion even when the crystal oscillating plate is compatible with high frequencies, and to provide a crystal oscillating device with stable electrical characteristics.SOLUTION: A quartz oscillating plate 1 is an AT-cut quartz oscillating plate. The quartz oscillating plate 1 consists of an oscillating portion 11, a holding portion 13 connected to the oscillating portion 11, and a frame portion 12 arranged on the periphery of the oscillating portion 11 and connected to the holding portion 13. Between the oscillating portion 11 and the frame portion 12, except for the holding portion 13, a circumferential through portion 14 is formed. The holding portion 13 is formed thicker than the oscillating portion 11 and a thick-walled portion 11a. A sloping taper T2 is formed from the thick-walled portion 11a to the top surface of the holding portion 13. A sloping taper T3 is formed from the oscillating portion 11 to the holding portion 13. A taper T1 is formed from the holding portion 13 to the top surface of the frame portion 12.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 height. A three-layer crystal resonator device has a housing configured as a roughly rectangular parallelepiped package. This package is composed of a first and second sealing member, each made of, for example, glass or quartz, a vibrating section with excitation electrodes formed on both main surfaces, and a crystal resonator plate with a frame portion formed around the periphery of the vibrating section via a connecting portion. 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 a single holding part that connects and holds the vibration part to the frame part. For example, see JP 2020-141358 (Patent Document 1).

[0005] Patent Document 1 discloses a structure in which, when the frequency of a quartz crystal plate is increased, the thickness of the quartz crystal plate becomes thinner, and a thick portion is formed around the entire outer periphery of the vibrating portion to reinforce its strength. It is well known that, in terms of the crystal axis designation, an AT-cut quartz plate uses the crystal axes of synthetic quartz as the X-axis, Y-axis, and Z-axis, while the Y-axis and Z-axis of an AT-cut quartz crystal rotated 35°15' around the X-axis are used as the Y'-axis and Z'-axis, respectively, and its resonant frequency is inversely proportional to its thickness. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2020-141358 Summary of the Invention [Problem to be solved by the invention]

[0007] The quartz crystal diaphragm disclosed in Patent Document 1 has a structure in which a thick portion formed around the vibrating portion provides strength reinforcement and prevents the vibrating portion from falling off, even when it is adapted to high frequencies. However, thickness-shear vibration excited in the vibrating portion propagates to the thick portion, generating reflected waves and the like, which can cause spurious (unwanted vibrations) or deteriorate the CI (series resonance resistance) value, impairing the function of the vibrating device.

[0008] Furthermore, excitation electrodes made of opposing metal films are formed on the front and back of the vibrating part, and these excitation electrodes must be connected externally by strip-shaped extraction electrodes made of metal films.However, the formation of steps due to the thick parts can reduce the conductivity of these extraction electrodes or cause them to break, which can degrade the electrical characteristics of the quartz vibration device.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a quartz crystal vibration plate that stabilizes the mechanical strength between the vibrating part and the frame part, even when the quartz crystal vibration plate is made to correspond to high frequencies, and that improves the vibration characteristics of the vibrating part, as well as to provide a quartz crystal vibration device with stable electrical characteristics. [Means for solving the problem]

[0010] The quartz crystal vibration plate according to the present invention is an AT-cut quartz crystal vibration plate having a vibration part that has an excitation electrode formed on one main surface and an excitation electrode formed on the other main surface, and has corners and is generally rectangular in plan view, on which extraction electrodes connected to the excitation electrodes are formed, a holding part that protrudes from the corners, and a frame part that surrounds the outer periphery of the vibration part via a through part and is connected to the holding part, is before The memory storage section is formed at least one end Around A thick section is formed along the others the end side of the holding portion has a thickness equal to or thicker than the thick portion, and a tapered portion is formed between the frame portion and the holding portion or between the thick portion and the vibrating portion, and the extraction electrode is formed on the frame portion via the tapered portion, The holding portions are provided between the corner portion and the frame portion at least on both ends of the one end side so as to protrude in opposite directions, and the thick portion is provided on the one end side and is formed except for a connection point with one of the holding portions provided on both ends of the one end side. Furthermore, by aligning the protruding direction of the holding portion with the Z' axis direction of the AT cut, it is possible to suppress vibration leakage and improve the CI value (series resonance resistance value).

[0011] According to the above configuration, the vibrating section has a thickened section formed along almost the entire edge of one end where the support section is formed, while the other end is configured with a thin diaphragm thickness corresponding to high frequencies. Therefore, vibrations excited by the diaphragm can be generated in a state where they are less affected by the boundary conditions caused by the thickened section, resulting in a quartz crystal vibrating plate that is less likely to generate spurious signals and maintains a good CI value. The thickened section also improves the mechanical strength of the vibrating section. Furthermore, by configuring the support section 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 holding portion is thicker than or equal to the thick portion, and a tapered portion is formed between the frame portion and the holding portion, or between the thick portion and the vibrating portion. The extraction electrode extending from the excitation electrode to one edge of the quartz crystal plate is formed on this tapered portion and does not pass through any sharp corners (steps), which prevents a decrease in electrode conductivity or electrode breakage. This results in a quartz crystal plate with excellent electrical characteristics.

[0013] The holding portions may be provided at a plurality of locations between the corners of the vibrating portion and the frame portion. The holding portions may be provided at the corners of the vibrating portion at both ends in the elongated direction of the thick-walled portion, or at diagonal corners of the vibrating portion. Providing the holding portions at the edge portions where the thick-walled portion is formed is preferable in terms of improving impact resistance.

[0014] By providing the holding portions at a plurality of corners of the vibrating portion, the mechanical strength between the vibrating portion and the frame portion is improved.

[0015] The thickened portion may be provided on the other end side or the other two end sides in a continuous manner. For example, by providing the thickened portion in an L-shape in a plan view, the mechanical connection strength with the holding part can be improved, and by making the remaining two end sides of the vibrating part the same thickness as the vibrating part, an open area where boundary conditions are not formed in vibration can be secured. This allows for maintaining good vibration characteristics such as the generation of spurious signals from the diaphragm and a deterioration in the CI value.

[0016] The thickened portions may also be provided on the other two edges. In this case, the holding portions can be connected to the three corners of the vibrating portion, which is an effective configuration when shock resistance is required.

[0017] As mentioned above, by providing holding portions at the diagonal corners or at three or four corners, the deflection of the vibrating portion in response to external shock is suppressed, thereby suppressing frequency fluctuations due to deflection and improving frequency stability against external shock.

[0018] The vibration plate may have a tapered portion formed on one end thereof parallel to the +X-axis direction and in the +Z'-axis direction, the tapered portion being thinner than the thick portion and thicker than the vibrating portion. This configuration can improve the mechanical strength of the vibration plate.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] Specifically, the sealing portion of the sealing member is bonded to both the front and back main surfaces of the frame body of the quartz vibration plate via a bonding member, so that both main surfaces of the vibration part are airtightly covered by the first sealing member and the second sealing member.

[0023] According to the above configuration, it is possible to obtain a crystal resonator device that has excellent mechanical strength, suppresses spurious signals, has a good CI value, and is excellent in electrical characteristics. [Effects of the Invention]

[0024] The quartz crystal vibrating plate and quartz crystal vibrating device of the present invention can vibrate in a state where the vibration excited by the vibrating plate is less affected by the boundary conditions caused by the thickened portion, thereby making it possible to obtain a quartz crystal vibrating plate that is less likely to generate spurious signals and maintains a good CI value. Furthermore, the thickened portion can improve the mechanical strength of the vibrating portion.

[0025] The holding portion is thicker than or equal to the thick portion, and a tapered portion is formed between the frame portion and the holding portion, or between the thick portion and the vibrating portion. This configuration allows the extraction electrode extending from the excitation electrode to one edge of the quartz crystal plate to be formed on this tapered portion and not pass through any sharp corners, preventing poor electrode conductivity or electrode breakage. This allows for the production of a quartz crystal plate with excellent electrical characteristics.

[0026] According to the present invention, it is possible to obtain a quartz crystal vibration plate that has stabilized and improved electrical characteristics as well as improved mechanical strength, and in a quartz crystal vibration device using this quartz crystal vibration plate, it is possible to stabilize and improve electrical characteristics as well as improve mechanical strength. [Brief explanation of the drawings]

[0027] [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 schematic 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

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0029] 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.

[0030] 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 connected to the 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 portion 13. A through-hole 14 is formed around the periphery between the vibrating portion 11 and the frame portion 12, except for the holding portion 13.

[0031] 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, 112 are formed on the front and back surfaces (one main surface and the other main surface) at approximately the center of the vibrating section 11. Strip-shaped extraction electrodes 111a, 112a are connected to the corners of each excitation electrode 111, 112 and are extracted toward both ends of one side (the corners of the vibrating section). These extraction electrodes are extracted to the frame section 12 via the holding section 13 and are ultimately extracted to terminal electrodes formed on the second sealing member 3, which will be described later.

[0032] Specifically, the extraction electrode 111a passes through the surface of the holding part 13, is extracted to the other main surface (rear surface) through a metal via (through metal) V1 formed in the frame body part 12, and is connected to a metal via V2 formed in the second sealing member 3 described below. The extraction electrode 112a passes through the rear surface of the holding part, is extracted to the other main surface of the frame body part 12, and is connected to a metal via V3 formed in the second sealing member 3 described below through metal wiring (not shown).

[0033] 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.

[0034] 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.

[0035] As shown in Figure 2, a holding portion 13 extending in the Z'-axis direction is provided at one corner C1 of the vibrating portion 11, and the holding portion 13 is connected to the frame portion 12. In this embodiment, the vibrating portion 11, the holding portion 13, and the frame portion 12 are integrally formed from a quartz plate using photolithography and wet etching techniques. Note that dry etching may be used instead of wet etching.

[0036] As shown in FIGS. 1 and 3, the holding portion 13 is configured to be 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 the holding portion 13 may be equal. By forming these tapers, the angles of the respective boundary regions can be made obtuse. As will be described later, the extraction electrodes 111a, 112a are formed on the upper surface of the frame body portion 12 through the upper surface of the holding portion 13 from the vibrating portion 11 (sometimes via the side or upper surface of the thick portion 11a), thereby allowing the electrodes to be extracted.

[0037] An example of the specific dimensions of the quartz crystal vibrating plate is shown below. The quartz crystal vibrating plate is a rectangular AT-cut quartz crystal plate in plan view, with external dimensions of 1.2 mm long and 1.0 mm short sides, 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 that the thick portion be at least 10 μm thicker than the vibrating portion thickness to ensure mechanical strength. The rectangular frame body has a long side width of 0.2 mm and a short side width of 0.1 mm, the rectangular holding part has a long side width of 0.15 mm and a short side width of 0.05 mm, and the square vibrating part has a side width of 0.7 mm.

[0038] 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.

[0039] Seal films S11, S21 (not shown) are formed around the outer periphery of the front and back sides of the frame body 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.

[0040] The first sealing member 2 is made of a rectangular, plate-like AT-cut quartz crystal plate in a plan view, and has the same external shape and size as the quartz crystal vibration plate 2. A peripheral sealing film S12 corresponding to the sealing film S11 is formed on the surface of the first sealing member 2 facing the quartz crystal vibration plate 1.

[0041] The second sealing member 3 is made of a rectangular, plate-shaped AT-cut quartz crystal plate in a planar view, 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 fixed 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.

[0042] Furthermore, a metal via V2 is formed in the second sealing member 3, penetrating from the front to the back, and is electrically connected to the above-mentioned metal via V1. Although not shown, the extraction electrode 112a is also extracted to the other main surface of the frame body portion 12 via the holding portion 113, and ultimately the extraction electrode 111a is connected to the terminal electrode 31, and the extraction electrode 112a is connected to the terminal electrode 32 via the metal via V3.

[0043] 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 that order. As mentioned above, each of these components is 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 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.

[0044] The first sealing member 2 and the quartz crystal plate 1, and the quartz crystal plate 1 and the second sealing member 3 are bonded by applying pressure to the two together using a diffusion bonding method after surface treatment of the Au in the metal film. As a result, the vibration part 11 of the quartz crystal plate 1 is hermetically sealed, covered (surrounded) by the sealing parts S1 (S11, S12) and S2 (S21, S22) and the sealing members 2 and 3 and the frame part 12.

[0045] According to this embodiment, the vibrating portion 11 has a thick portion 11a formed along almost the entire area of one end side where the holding portion 13 is formed, and the other end side has a thin diaphragm thickness corresponding to 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 making it possible to obtain a quartz crystal vibrating plate that is less likely to generate spurious signals and can maintain a good CI value (series resonance resistance). The thick portion 11a also improves the mechanical strength of the vibrating portion 11.

[0046] 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 extend via the holding portion 13 to the frame portion 12. As a result, the extraction electrodes 111a and 112a do not pass through sharp corner areas (step portions), which prevents reduced electrode conductivity and electrode breakage. This results in a quartz crystal vibrating plate with excellent electrical characteristics.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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. The configurations of the vibrating portion 11, frame portion 12, holding portion 13, and thick portion 11 of the quartz crystal plate are different from those of the first embodiment. The first sealing member 2 and second sealing member 3 have similar configurations to those of the first embodiment, so a description thereof will be omitted.

[0052] The vibrating section 11 is rectangular in plan view, and has holding sections 13 and 15 formed on both ends of one side. The thick section 11b formed on the vibrating section is formed between the holding sections, but does not extend up to the holding section 15. This configuration can improve the holding strength of the vibrating section, and can improve the impact resistance of the quartz crystal vibrating device.

[0053] The excitation electrodes 113, 114 formed on the vibrating part 11 are rectangular in plan view, 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 each holding part. This extraction electrode configuration can suppress adverse effects on the excitation operation of the vibrating part 11, and can also suppress deterioration of electrical characteristics such as CI.

[0054] Furthermore, the extraction electrode 114a formed on the other main surface can be extracted to the frame portion 12 via the holding portion 15, and can be electrically connected to the terminal electrode formed on the frame portion over a relatively short distance. This makes it possible to suppress the formation of unnecessary parasitic capacitance, thereby improving the electrical characteristics of the quartz crystal resonator device.

[0055] The frame 12 is a rectangular plate overall in a plan view, 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.

[0056] Furthermore, a step 12a that is thinner than the thickness of the frame 12 is formed in the frame 12 near the holder 13. This step 12a continues to the taper T1 from the holder, and forming the extraction electrode 113a in this portion connects the taper T1 and the step 12a. Therefore, the angle of the edge at the boundary between them is made obtuse, which makes it possible to prevent breaks in the electrode wiring.

[0057] 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.

[0058] 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.

[0059] The electrode configuration that vibrates (excites) the vibration portion 11 of the quartz crystal vibration plate 1 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 3 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 step 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.

[0060] 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.

[0061] Similar to the second embodiment, vibrating section 11 has two holding sections 13 and 16 formed at both ends of one side. A thick section 11c is formed between holding sections 13 and 16 of vibrating section 11, and a thick section 11d is formed from one end of thick section 11c in a direction perpendicular to thick section 11c, so that the thick sections are formed in an inverted L shape on two consecutive sides of the vibrating section as a whole.

[0062] 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.

[0063] In this embodiment, the extraction electrodes 117a, 118a, which are 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 vibration device (crystal resonator, crystal oscillator, etc.).

[0064] This embodiment also illustrates an example of a crystal oscillator. An IC component (a single-chip IC) that constitutes an oscillator circuit is mounted on the top surface of the crystal resonator device. Although not shown, the first sealing member 2 is formed with multiple electrode pads for mounting the IC component and a wiring pattern connecting these electrode pads. The wiring pattern also includes electrode pads for connecting the crystal resonator device and is wired to connect the crystal terminals of the crystal resonator device to the oscillator circuit. The terminals of the IC component 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. These electrodes connect the wiring pattern from the first 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.

[0065] Fourth embodiment The fourth embodiment will be described with reference to Figures 10 to 12. This embodiment configures a quartz crystal resonator, and its main features are 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 a holding part is provided in one location, and that in addition to thick parts on two sides, low thick parts that are lower in height than the thick parts are formed.

[0066] The excitation electrode 119 formed on one main surface of the vibrating part is rotated 45 degrees around the center of both excitation electrodes as an axis with respect to the excitation electrode 120 formed on the other main surface. This configuration has the effect of suppressing spurious (unwanted vibrations) that tend to occur at higher frequencies.

[0067] In addition to the inverted L-shaped thick portions 11e and 11f, the vibrating portion has a thin portion 11g extending parallel to the thick portion 11e from the other end of the thick portion 11e. While forming a thick portion is effective in improving the mechanical strength of the vibrating portion, it may also limit the vibration range. By forming a thin portion with a reduced thickness, as in this embodiment, it is possible to increase the impact resistance without impeding the operation of the quartz crystal vibrating device. Furthermore, combined with the spurious suppression effect of the excitation electrode configuration described above, it is possible to improve the electrical characteristics of the quartz crystal vibrating device.

[0068] In this embodiment, the low-thickness portion 11g has a tapered portion 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 crystal plate, the region, 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.

[0069] A modification of the fourth embodiment will be described with reference to FIG. 13. In this modification, the configuration of the thick portion and the thin portion formed on the outer periphery of the diaphragm 11 is different. The thick portion 11h is wider than the configuration shown in FIG. 12, and has a thickness of 17 μm. The thin portion 11i 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 11i and the vibrating portion is made smaller. The thickness of the vibrating portion is determined by the set frequency.

[0070] 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.

[0071] In the above-mentioned modified example, when the frequency is high, the vibration area is narrowed, so that the electrical characteristics are less likely to be adversely affected. Furthermore, in the above-mentioned verification example, the thickness of the low-thickness portion relative to the vibration portion is not large, so no deterioration in the electrical characteristics was observed. Furthermore, the wide width of the high-thickness portion and the low-thickness portion in the Z'-axis direction also improves the mechanical strength.

[0072] Furthermore, in this embodiment, the holding portions 13 are formed in the same positions as in the first embodiment. These holding portions may be formed at diagonal portions of the rectangular vibrating portion 11. Specifically, the holding portions 13 are formed contiguous to the intersection of the thick portions 11e and 11f, and the holding portions formed at the diagonal portions are formed contiguous to the end portions of the thin portion 11g. When such a diagonal arrangement of the holding portions is adopted, the vibrating portion is supported on both sides rather than cantilevered on only one side. Therefore, when an impact is applied to the quartz crystal vibrating device, the deflection can be suppressed and frequency fluctuations can be reduced.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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]

[0077] 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, 15, 16 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; a holding portion formed to protrude from the corner portion; a frame portion that surrounds the outer periphery of the vibrating portion via a through-hole and is connected to the holding portion; a thick portion is formed along at least one end side of the vibration portion where the holding portion is formed, the other end side has the thickness of the vibrating part, the holding portion has a thickness that is thicker than or equal to the thick portion, and a tapered portion is formed between the frame portion and the holding portion and / or between the thick portion and the vibrating portion, and the extraction electrode is formed on the frame portion via the tapered portion, the holding portions are provided between the corner portions and the frame portion at least on both ends of the one end side so as to protrude in opposite directions; The thick portion is provided on the one end side, and is formed except for the connection point with one of the holding portions provided on both ends of the one end side.

2. 2. The quartz crystal plate according to claim 1, wherein the thick portion is provided on the other end side or the other two end sides in a continuous manner with the thick portion.

3. 3. The quartz crystal vibration plate according to claim 1, wherein a thin portion is formed on one end side of the vibrating portion parallel to the +X-axis direction in the +Z'-axis direction, the thin portion being thinner than the thick portion and thicker than the vibrating portion, and having a tapered portion.

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