JP7725962B2 - Crystal plate and crystal device - Google Patents

Description

The present invention relates to a quartz crystal vibration plate that is integrally formed with a vibrating section on which excitation electrodes are formed, a frame section that is arranged around the vibrating section, and a holding section that connects and holds the vibrating section to the frame section, and to a quartz crystal vibration device that uses this quartz crystal vibration plate.

In recent years, the operating frequencies of various electronic devices have become higher and their packages have become smaller (especially lower profile). As a result, along with these trends, there is a demand for quartz crystal resonator devices (e.g., quartz crystal resonators, quartz crystal oscillators, etc.) to also accommodate these higher frequencies and smaller packages.

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 plate-shaped first and second sealing members 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.

The quartz crystal vibration plate used in the above-mentioned three-layer quartz crystal vibration device is an AT-cut quartz crystal plate, and as described above, is integrally formed with a vibration part on which excitation electrodes are 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. See, for example, JP 2020-141358 (Patent Document 1).

Patent Document 1 discloses that when the frequency of a quartz crystal vibrating plate is increased, the thickness of the quartz crystal vibrating plate becomes thinner, and that 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 crystal plate uses the crystal axes of artificial 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 the resonant frequency is inversely proportional to the thickness.

Patent Publication No. 2020-141358

The quartz crystal vibration plate disclosed in Patent Document 1 mentioned above is designed to reinforce the strength of the vibration part with a thick section formed around the vibration part, preventing it from falling off, even when used at high frequencies. However, thickness-shear vibration excited in the vibration part propagates to the thick section, generating reflected waves and other problems, which can cause spurious (unwanted vibrations) or worsen the CI (series resonance resistance) value, impairing its function as a vibration device.

Furthermore, the vibrating section has excitation electrodes made of opposing metal films on the front and back, and these excitation electrodes must be connected externally via strip-shaped extraction electrodes made of metal films. However, the formation of steps due to the thick sections can reduce the conductivity of these extraction electrodes or cause them to break, thereby reducing the electrical characteristics of the quartz crystal vibration device.

The present invention was 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 support higher 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.

The quartz crystal vibration plate according to the present invention is an AT-cut quartz crystal vibration plate having a vibration portion having an excitation electrode formed on one main surface and an excitation electrode formed on the other main surface, and having corners and a generally rectangular shape in a plan view, on which extraction electrodes connected to the excitation electrodes are formed, a holding portion formed to protrude from the corners, and a frame portion that surrounds the outer periphery of the vibration portion via a through portion and is connected to the holding portion, wherein the vibration portion has a thick portion formed along at least one end side on which the holding portion is formed, and the other end side has the thickness of the vibration portion, and the holding portion is The present invention is characterized in that the thickness of the AT cut cutter is thicker than or equal to the thickness of the AT cut cutter, and a tapered portion is formed between the frame portion and the holding portion or between the thick portion and the vibrating portion at least in one of the two positions, the lead-out electrode is formed on the frame portion via the tapered portion, the holding portion is provided between the corner portion and the frame portion so as to protrude in opposite directions from both ends of at least one of the two positions, and the thick portion is provided on the one end, excluding a connection point with one of the holding portions provided on both ends of the one end . Note that by aligning the protruding direction of the holding portion in the Z'-axis direction of the AT cut, vibration leakage can be suppressed and the CI value (series resonance resistance value) can be improved.

With the above configuration, a thick portion is formed along almost the entire area of one end edge of the vibrating section where the holding portion is formed, while the other end edge is configured with a thin diaphragm thickness that corresponds to high frequencies. Therefore, vibrations excited by the diaphragm can be carried out in a state where they are less affected by the boundary conditions caused by the thick portion, resulting in a quartz crystal vibrating plate that is less likely to generate spurious signals and maintains a good CI value. The thick portion also improves the mechanical strength of the vibrating section. Furthermore, 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.

The holding portion is thicker than or the same thickness as 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 at least in one of the two locations. The extraction electrode extending from the excitation electrode to one edge of the quartz crystal plate is formed on this tapered portion and is configured not to pass through any sharp corners (steps), which prevents a decrease in electrode conductivity or electrode breakage. This allows for a quartz crystal plate with good electrical characteristics to be obtained.

The retaining portions may be provided at multiple locations between the corners of the vibrating portion and the frame portion. The retaining 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 retaining portions at the edge portions where the thick-walled portion is formed is preferable in terms of improving impact resistance.

By providing holding sections at multiple corners of the vibrating section, the mechanical strength between the vibrating section and the frame section is improved.

The thickened portion may also be provided contiguous to the other end edge or the other two end edges. For example, by providing it in an L-shape in plan view, the mechanical connection strength with the holding part can be improved, and by making the remaining two end edges of the vibrating part the same thickness as the vibrating part, an open area can be secured where boundary conditions for vibration are not formed. This makes it possible to maintain good vibration characteristics such as the generation of spurious signals from the diaphragm and deterioration of the CI value.

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

As mentioned above, by providing holding sections at diagonal corners or at three or four corners, deflection of the vibrating section in response to external shock is suppressed, thereby suppressing frequency fluctuations caused by deflection and improving frequency stability against external shock.

The diaphragm may have a tapered, thin section that is thinner than the thick section and thicker than the vibrating section formed on one end of the diaphragm parallel to the +X-axis direction and at the +Z'-axis direction. This configuration can improve the mechanical strength of the diaphragm.

However, when etching is performed on the +Z'-axis end of the edge along the X-axis of an AT-cut quartz crystal plate, the edge portion may become rough due to the anisotropic crystal, and may not be processed into the intended straight line. By adopting this low-thickness configuration, it becomes easier to maintain the straightness of the edge, which also has the effect of stabilizing electrical characteristics.

A quartz crystal vibration plate having any of the above configurations can be housed in a package with terminal electrodes, and each electrode on the quartz crystal vibration plate can be electrically and mechanically bonded to the mounting electrodes on the package to obtain a quartz crystal vibration device with terminal electrodes. For example, the quartz 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 then hermetically sealed with a lid.

Furthermore, the crystal vibration device may be characterized by using each of the crystal vibration plates and including 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.

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

The above configuration makes it possible to obtain a quartz crystal resonator device with excellent mechanical strength, suppressed spurious emissions, a good CI value, and excellent electrical characteristics.

With the quartz crystal vibration plate and quartz crystal vibration device of the present invention, vibrations excited by the vibration plate can be generated in a state where they are less affected by the boundary conditions caused by the thick portions, resulting in a quartz crystal vibration plate that is less likely to produce spurious signals and can maintain a good CI value. Furthermore, the thick portions can improve the mechanical strength of the vibration portion.

The holding portion is thicker than or the same thickness as 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. With this configuration, 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, preventing a decrease in electrode conductivity or electrode breakage. This allows for a quartz crystal plate with good electrical characteristics to be obtained.

As described above, the present invention makes it possible to obtain a quartz crystal vibration plate with stabilized and improved electrical characteristics and 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 and improve mechanical strength.

1 is an exploded perspective view showing each component of a quartz crystal resonator device according to an embodiment of the present invention; FIG. 2 is a schematic plan view of a quartz crystal plate of the quartz crystal device. 2 is a cross-sectional view taken along line AA in FIG. 1 when the components are assembled. FIG. 10 is a plan view of a quartz crystal plate according to a second embodiment. 5 is a cross-sectional view taken along the line B-B of FIG. 4. FIG. 10 is a cross-sectional view showing another modified example. FIG. 10 is a plan view of a quartz crystal plate according to a third embodiment. 8 is a cross-sectional view taken along the line CC in FIG. 7 . 8 is a cross-sectional view taken along the line DD in FIG. 7, showing a state in which the crystal vibration plate is bonded with a sealing member and an IC component is mounted. FIG. 10 is a plan view of a quartz crystal plate according to a fourth embodiment. FIG. 11 is a cross-sectional view taken along the line E-E of FIG. 10 . 11 is a cross-sectional view taken along the line F-F in FIG. 10 . FIG. 10 is a cross-sectional view showing a modified example of the fourth embodiment. 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment. 10A to 10C are diagrams illustrating a manufacturing process for a quartz crystal plate according to a fourth embodiment.

Embodiments of the present invention will be described in detail below with reference to the drawings.

First Embodiment As shown in FIG. 1, the quartz crystal vibrating device Xtl according to the first embodiment comprises a quartz crystal vibrating plate 1, a first sealing member 2, and a second sealing member 3, and is configured by stacking the first sealing member 2, the quartz crystal vibrating plate 1, and the second sealing member 3 in this order.

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 consists of a vibrating portion 11, holding portions 13 connected to the corners of the vibrating portion 11, and a frame portion 12 arranged 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.

The vibrating section 11 is rectangular with opposing long sides and opposing short sides and has four corners. However, 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) approximately in 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 edge (the corners of the vibrating section). These extraction electrodes are extracted to the frame section 12 via the holding section 13 and ultimately to terminal electrodes formed on the second sealing member 3, which will be described later.

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

These excitation electrodes 111, 112 and extraction electrodes 111a, 112a are made of multiple layers of metal films, and have a multi-layer 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.

A thick portion 11a is formed on one end edge of the vibrating portion 11. This thick portion 11a is formed on one end edge in the X-axis direction, extending in the Z'-axis direction and spanning the entire end edge. The thick portion 11a is formed to be thicker than the vibrating portion 11.

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, holding portion 13, and 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.

As shown in Figures 1 and 3, the holding portion 13 is thicker than the vibrating portion 11 and the thick portion 11a. A sloped taper T2 (an obtuse angle relative to the top surface of the holding portion 13) is formed from the thick portion 11a to the top surface of the holding portion 13, and a sloped taper T3 (an obtuse angle relative to the top surface of the holding portion 13) 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 (an obtuse angle relative to the top surface of the frame portion 12) is formed from the holding portion 13 to the top 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. The formation of these tapers allows the boundaries to have obtuse angles. As will be described later, the extraction electrodes 111a and 112a are formed on the top surface of the frame portion 12, passing from the vibrating portion 11 through the top surface of the holding portion 13 (or via the side or top surface of the thick portion 11a), thereby allowing the electrodes to be extracted.

An example of the specific dimensions of the quartz crystal vibration plate is shown below. The quartz crystal vibration plate is a rectangular AT-cut quartz crystal plate in plan view, with external dimensions of 1.2 mm long sides and 1.0 mm short sides, 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 that the thick portion be at least 10 μm thicker than the vibrating portion in order 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 portion has a long side width of 0.15 mm and a short side width of 0.05 mm, and the square vibrating portion has a side width of 0.7 mm.

In this embodiment, a configuration is adopted in which the quartz crystal plate 1 is thinned from only one of its main surfaces. For example, etching is used to thin only one of its main surfaces to the desired frequency (thickness). In this case, the other main surface is not etched, so degradation of vibration characteristics due to surface roughening caused by etching can be suppressed.

Sealing films S11 and S21 (not shown) are formed around the outer periphery of the front and back edges of the frame body 12. Similar to the electrode film described above, these sealing films have a multilayer structure in which a Ti film is formed in contact with the quartz crystal plate and an Au film is formed on top of that.

The first sealing member 2 is made of a rectangular, plate-shaped 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.

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 are 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 are elongated in the X-axis direction, and are arranged opposite 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.

In addition, 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 aforementioned 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, with the extraction electrode 111a ultimately connected to the terminal electrode 31, and the extraction electrode 112a ultimately connected to the terminal electrode 32 via the metal via V3.

As shown in Figure 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 made of a quartz crystal plate, and its surface is mirror-polished to a smooth surface. As a specific example, an average surface roughness Ra of 0.3 to 0.1 nm is preferred. By forming sealing films S11, S12, S21, and S22 on such a smooth surface, the metal film on the surface (the top layer Au film) also has an extremely smooth surface.

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 pressure bonding using a diffusion bonding method after surface treatment of the Au in the metal film. As a result, the vibration portion 11 of the quartz crystal plate 1 is hermetically sealed, covered (surrounded) by the sealing portions S1 (S11, S12) and S2 (S21, S22) of the sealing members 2 and 3 and the frame portion 12.

In this embodiment, the vibrating portion 11 has a thick portion 11a formed along almost the entire area of one end edge where the holding portion 13 is formed, while the other end edge is configured with a thin diaphragm thickness that corresponds to high frequencies. Therefore, the vibrations excited by the vibrating portion 11 can be caused to vibrate in a state that is less affected by the boundary conditions caused by the thick portion 11a, resulting in a quartz crystal vibrating plate that is less likely to produce 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.

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 drawn from the excitation electrodes 111 and 112 to one edge of the quartz crystal vibrating plate, are formed on this tapered portion and extend to the frame portion 12 via the holding portion 13. As a result, the extraction electrodes 111a and 112a do not pass through acute corner areas (step portions), which prevents reduced electrode conductivity and electrode breakage. This enables a quartz crystal vibrating plate with good electrical characteristics to be obtained.

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

In addition, while the bonding of each sealing member to the quartz crystal plate was performed using the diffusion bonding method, brazing using, for example, 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 Cr base layer may have an Ag or Cu film formed thereon, or an alloy film with Au formed thereon.

In the above explanation, quartz plates were used as the material for the first and second sealing members, but glass or ceramic materials may also be used instead of quartz plates. Furthermore, while a plate-like structure was exemplified, a recess may be provided in a position facing the quartz vibration plate. Providing a recess in this way reduces the chance of contact between the vibration part and the sealing member, thereby stabilizing the characteristics of the quartz vibration device.

Furthermore, a resin film material may be used for at least one of the two sealing members. For example, a resin film may be attached to a thick frame portion so as to span the frame portion. Since the resin film contributes to the reduction in thickness, an ultra-thin crystal resonator device can be obtained.

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.

The vibrating part 11 is rectangular in plan view, with holding parts 13 and 15 formed on both ends of one edge. The thick part 11b formed on the vibrating part is formed between the holding parts, but does not extend up to the holding part 15. This configuration improves the holding strength of the vibrating part, thereby improving the impact resistance of the quartz crystal vibrating device.

Furthermore, 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 those 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.

Furthermore, the extraction electrode 114a formed on the other main surface can be extracted to the frame portion 12 via the holding portion 15, allowing electrical connection to the terminal electrode formed on the frame portion over a relatively short distance. This suppresses the formation of unnecessary parasitic capacitance, thereby improving the electrical characteristics of the quartz crystal resonator device.

The frame body 12 is a rectangular plate overall when viewed from above, with castellations C, C cut out in the width direction of the frame body at the center of the opposing outer edges. 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, this promotes the creeping of solder material onto the castellations, thereby improving the joint strength during mounting.

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

As described above, the second embodiment can improve the impact resistance and electrical characteristics of the quartz crystal resonator device.

A modified example of the second embodiment is shown in Figure 6. In this modified example, the configuration of the excitation electrode formed on the vibrating portion 11 of the quartz crystal plate and the configuration of the second sealing member are different.

The electrode configuration that vibrates (excites) the vibration portion 11 of the quartz crystal 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, in 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, maintaining an appropriate distance between the vibration portion 11 and the excitation electrode 116.

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

The vibrating part 11 has a configuration similar to that of the second embodiment, with two holding parts 13 and 16 formed on both ends of one side. Furthermore, a thick part 11c is formed between the holding parts 13 and 16 of the vibrating part 11, and a thick part 11d is formed from one end of the thick part 11c in a direction perpendicular to the thick part 11c, so that overall, the thick parts are formed in an inverted L shape on two consecutive sides of the vibrating part.

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

In this embodiment, the extraction electrodes 117a, 118a drawn from the opposing excitation electrodes 117, 118 are configured to fan out toward the ends of the vibrating section. When aiming for higher frequencies, there is a trend toward thinner excitation electrodes made of metal films in order to efficiently excite without impeding vibration, which in turn leads to similarly thinner extraction electrodes. In such cases, thinner extraction electrodes increase the likelihood of breakage midway through the wiring. To prevent such defects from occurring, the width of the extraction electrodes is increased with increasing distance from the excitation electrodes, thereby reducing the chance of breakage. In particular, in the present invention, thicker sections are formed in the vibrating section, resulting in multiple steps. However, by adopting this embodiment, the chance of breakage due to the thicker sections is reduced, resulting in a highly reliable quartz vibration device (quartz resonator, quartz oscillator, etc.).

This embodiment also illustrates an example of a crystal oscillator. An IC component (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 connection electrode pads for 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 substrate 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 on the inside of 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 substrate connection surface of the second sealing member. Note that only two terminals, terminal electrodes 33 and 34, are shown in Figure 9.

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 the holding part is provided in one location, 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.

The excitation electrode 119 formed on one main surface of the vibrating section is rotated 45 degrees around the center of both excitation electrodes, while the excitation electrode 120 formed on the other main surface is rotated 45 degrees around the center of both excitation electrodes. This configuration has the effect of suppressing spurious (unwanted vibrations) that tend to occur at higher frequencies.

In addition to the inverted L-shaped thick sections 11e and 11f, the vibrating section has a low-thick section 11g that extends parallel to the thick section 11e from the other end of the thick section 11e. Forming a thick section is effective in improving the mechanical strength of the vibrating section, but it may also limit the vibration area. By forming a low-thick section 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.

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 exterior shape of a quartz 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 it may not be possible to process the edges in a straight line. By configuring a low-thickness portion as in this embodiment, it is possible to suppress variations in the exterior shape processing, resulting in a quartz crystal resonator device with stable electrical characteristics.

A modified example of the fourth embodiment will be described with reference to Figure 13. In this modified example, the thick and thin sections formed on the outer periphery of the diaphragm 11 have different configurations. The thick section 11h is wider than the configuration shown in Figure 12, and is 17 μm thick. The thin section 11i is also wider than the configuration shown in Figure 12, and is 0.5 μm to 1.5 μm thicker than the thickness of the vibrating section 11. The slope of the tapered section formed by the thin section 11i and the vibrating section is also smaller. The thickness of the vibrating section is determined by the set frequency.

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

The above modified example is less likely to adversely affect electrical characteristics when the frequency is high, as in the example dimensions above, because the vibration region is narrow. Furthermore, in the above verification example, the thickness of the low-thickness portion relative to the vibration portion was not large, so no deterioration in electrical characteristics was observed. Furthermore, the wide width of the thick and low-thickness portions in the Z'-axis direction also improves mechanical strength.

In addition, in this embodiment, the holding portion 13 is formed in the same position as in the first embodiment. This holding portion may also be formed at the diagonal portion of the rectangular vibrating portion 11. Specifically, the holding portion 13 is formed following the intersection of the thick portions 11e and 11f, and the holding portion formed at the diagonal portion is formed following the end 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 just one side, so when an impact is applied to the quartz crystal vibrating device, deflection can be suppressed and frequency fluctuations can be reduced.

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 multi-piece manufacturing process is carried out using a quartz crystal wafer to obtain a large number of quartz crystal vibrating plates, but this explanation will focus on one quartz crystal vibrating plate portion.

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. Exposure is then performed using a specified mask pattern, and a resist mask pattern is formed on the front and back surfaces 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.

Next, as shown in Figure 16, photolithography and wet etching techniques are used to form a metal film mask pattern on the quartz crystal vibration plate for the second etching. The second etching is also performed from the backside, and finally, as shown in Figure 18, a quartz crystal vibration plate is obtained with thick portions 11f and thin portions 11g formed, taking advantage of the anisotropy of the quartz crystal.

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 based on the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included.

REFERENCE SIGNS LIST 1 quartz crystal plate 11 vibration portion 111, 112, 113, 114, 115, 116, 117, 118, 119, 120 excitation electrodes 111a, 112a, 113a, 114a, 117a, 118a, 119a, 120a extraction electrodes 12 frame portion 13, 15, 16 holding portion 14 penetration portion 2 first sealing member 3 second sealing member 4 IC chip S11, S12 sealing film S1, S2 sealing portion T1, T2, T3 tapered portion V1, V2, V3 metal via

Claims (3)

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 . A quartz crystal vibration plate as described in claim 1, characterized in that the thick portion is provided contiguous with the other end edge or the other two end edges. 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.