Piezoelectric vibration device

Abstract

A crystal resonator (100) includes a crystal resonator piece (10) having a first excitation electrode (111) and a second excitation electrode (112) paired with the first excitation electrode (111), and a first sealing member (20) and a second sealing member (30) covering both main surfaces of the crystal resonator piece (10); a vibration portion (11) including the first excitation electrode (111) and the second excitation electrode (112) is hermetically sealed by the first sealing member (20) being joined to the crystal resonator piece (10) and the second sealing member (30) being joined to the crystal resonator piece (10); a second main surface (202) of the first sealing member (20) facing the vibration portion (11) includes a thin film thermistor (500); and a through hole penetrating from a first main surface (201) to the second main surface (202) is not provided.

Description

Technical Field

[0001] This invention relates to piezoelectric vibrators and other piezoelectric vibration devices. Background Technology

[0002] In recent years, various electronic devices have been developing towards higher operating frequencies and smaller (especially thinner) packages. Therefore, with the increase in frequency and miniaturization of packages, piezoelectric resonators (such as crystal resonators and crystal oscillators) are also required to increase in frequency and miniaturize their packages accordingly.

[0003] The housing of this piezoelectric vibrator is constructed from an approximately rectangular box-shaped encapsulation. As such a structure, prior art (see Patent Document 1) discloses a piezoelectric oscillator, which, for example, comprises a first and second sealing member made of glass or quartz crystal, and a piezoelectric vibrating plate made of quartz crystal with excitation electrodes formed on its two main surfaces; the first and second sealing members are stacked and joined together with the piezoelectric vibrating plate in between; the vibrating portion (excitation electrode) of the piezoelectric vibrating plate, disposed inside the encapsulation (internal space), is hermetically sealed. Hereinafter, this stacked configuration of the piezoelectric vibrator will be referred to as a sandwich structure.

[0004] However, existing technologies have also developed piezoelectric vibrating devices with integrated temperature sensors. For example, a thermistor is used as such a temperature sensor. The temperature sensor (thermometer) is used to detect the temperature of the vibrating part in the piezoelectric oscillator in order to adjust the oscillation frequency as it changes with temperature. Therefore, it is necessary to minimize the difference between the temperature of the vibrating part of the piezoelectric oscillator and the temperature measured by the temperature sensor.

[0005] [Patent Documents] [Patent Document 1]: Japanese Patent Application Publication No. 2022-97055 Summary of the Invention

[0006] In view of the above, the object of the present invention is to provide a piezoelectric vibration device that can further reduce the difference between the temperature of the vibrating part and the temperature measured by the temperature sensor.

[0007] This invention provides a piezoelectric vibrating device comprising a piezoelectric vibrating plate having a first excitation electrode formed on a main surface of a substrate and a second excitation electrode formed on the main surface of the substrate and paired with the first excitation electrode; and a first sealing member and a second sealing member covering the two main surfaces of the piezoelectric vibrating plate. An internal space is formed by the engagement of the first sealing member with the piezoelectric vibrating plate and the engagement of the second sealing member with the piezoelectric vibrating plate, thereby forming an airtight seal for the vibrating portion of the piezoelectric vibrating plate containing the first excitation electrode and the second excitation electrode. The first sealing member has a first main surface that does not face the vibrating portion. The first sealing member has a first main surface facing the vibration part and a second main surface facing the back of the first main surface of the first sealing member. The second main surface of the first sealing member has a thin-film thermistor. No through hole is provided from the first main surface of the first sealing member to the second main surface of the first sealing member. The second sealing member has a first main surface facing the vibration part and a second main surface facing the back of the first main surface of the second sealing member and not facing the vibration part. The second main surface of the second sealing member has an external terminal for the thermistor electrically connected to the thin-film thermistor and an external terminal for the excitation electrode electrically connected to the first excitation electrode and the second excitation electrode, respectively.

[0008] That is, the piezoelectric vibrating device of the present invention is configured such that a thin-film thermistor is provided on one main surface of the first sealing member facing the vibrating part (the second main surface of the first sealing member); no through hole is provided from one main surface to the other main surface (the first main surface of the first sealing member); and an external terminal for the thermistor and an external terminal for the excitation electrode are provided on one main surface of the second sealing member not facing the vibrating part (the second main surface of the second sealing member). Based on this structure, in the piezoelectric vibrating device of the present invention with a sandwich structure, the vibrating part and the thin-film thermistor, which serves as a temperature sensor, are positioned very close to each other, thereby reducing the temperature difference between the vibrating part and the thin-film thermistor, and reducing the difference between the temperature of the vibrating part and the temperature measured by the temperature sensor. In addition, the thin-film thermistor is not provided on the second sealing member with external terminals, but on the first sealing member, so that the heat conduction path from the external substrate on which the piezoelectric vibrating device is mounted can be brought closer to the vibrating part, thereby enabling the thin-film thermistor to measure a temperature closer to the temperature of the vibrating part.

[0009] In addition, as described above, the first sealing member has a structure with a thin-film thermistor on one of its main surfaces facing the vibrating part. The thin-film thermistor is not exposed to the outside of the piezoelectric vibrating device, thus preventing temperature changes and damage caused by external factors.

[0010] Furthermore, as described above, by employing a structure that does not provide a through hole extending from one main surface to another on the first sealing member, it is possible to prevent poor formation due to the presence of the through hole during the formation of the thin-film thermistor, thereby enabling stable manufacturing.

[0011] Furthermore, if a chip thermistor (such as a negative temperature coefficient thermistor) made of sintered body is used, the thickness will increase, making it difficult to achieve the thinness that is an advantage of the sandwich structure. However, with a thin film thermistor like the one of the present invention, both a temperature sensor can be mounted and a thin profile can be achieved.

[0012] Furthermore, preferably, with both the first sealing member and the second sealing member engaged with the piezoelectric vibrating plate, the thin-film thermistor and the external terminals for the thermistor are electrically connected to each other via wiring disposed inside the piezoelectric vibrating device. Based on this structure, damage to the conductivity of the thin-film thermistor due to external impacts can be prevented, and compared to the case where the wiring is disposed on the outer periphery of the piezoelectric vibrating device, heat conduction to the thin-film thermistor can be limited, allowing the thin-film thermistor to perform stably. Moreover, the electrical connection between the thin-film thermistor and the external terminals for the thermistor can be achieved without forming a through hole in the first sealing member.

[0013] Furthermore, preferably, the substrates of the first sealing member, the piezoelectric vibrator, and the second sealing member are each made of quartz crystal. Based on this structure, heat transferred from the external substrate of the piezoelectric vibrator to the second sealing member via external terminals can be uniformly conducted to the piezoelectric vibrator and the first sealing member. More specifically, by making the substrates of each component constituting the piezoelectric vibrator the same material (quartz crystal), the thermal conductivity of each component can be made equal. Therefore, the difference between the temperature of the vibrating part and the temperature measured by the temperature sensor can be further reduced.

[0014] <Invention Effects> Based on the piezoelectric vibration device of the present invention, it is possible to provide a piezoelectric vibration device that further reduces the difference between the temperature of the vibrating part and the temperature measured by the temperature sensor. Attached Figure Description

[0015] Figure 1 is a side view of the crystal resonator in this embodiment.

[0016] Figure 2 is a schematic top view of the first main surface side of the first sealing member of the crystal resonator in this embodiment.

[0017] Figure 3 is a schematic top view of the second main surface side of the first sealing member of the crystal resonator in this embodiment.

[0018] Figure 4 is a schematic top view of the first main surface of the crystal resonator in this embodiment.

[0019] Figure 5 is a schematic top view of the second main surface of the crystal resonator in this embodiment.

[0020] Figure 6 is a schematic top view of the first main surface side of the second sealing member of the crystal resonator in this embodiment.

[0021] Figure 7 is a schematic top view of the second main surface side of the second sealing member of the crystal resonator in this embodiment.

[0022] Figure 8 is a magnified view of the area near the thin-film thermistor in Figure 3.

[0023] Figure 9 is a cross-sectional view of the thin-film thermistor in Figure 8 along line A-A.

[0024] Figure 10 is a schematic top view of the second main face side of the second sealing member in the modified example.

[0025] Figure 11 is a cross-sectional view of the through hole of the second sealing member in Figure 10. Detailed Implementation

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the following embodiments will describe the case where the piezoelectric resonator of the present invention is a crystal resonator.

[0027] First, the basic structure of the crystal resonator 100 in this embodiment (first embodiment) will be described. As shown in FIG1, the crystal resonator 100 adopts a structure having a crystal vibrating plate (piezoelectric vibrating plate) 10, a first sealing member 20, and a second sealing member 30. In this crystal resonator 100, the crystal vibrating plate 10 and the first sealing member 20 are joined by a sealing part (sealing channel) 115, and the crystal vibrating plate 10 and the second sealing member 30 are joined by a sealing part (sealing channel) 116, thus forming an approximately rectangular sandwich structure package. That is, in the crystal resonator 100, by joining the first sealing member 20 and the second sealing member 30 on the two main surfaces of the crystal vibrating plate 10 respectively, an internal space (cavity) of the package is formed, and the vibrating part 11 (refer to FIG4 and FIG5) is hermetically sealed in this internal space.

[0028] Hereinafter, referring to FIGS. 1 to 7, the components of the crystal resonator 100, the crystal oscillator 10, the first sealing member 20, and the second sealing member 30 will be described. Furthermore, the components of each individual unit structure that are not yet joined will be described here. FIGS. 2 to 7 merely show one structural example of each of the crystal oscillator 10, the first sealing member 20, and the second sealing member 30, and are not intended to limit the present invention.

[0029] In this embodiment, as shown in Figures 4 and 5, the crystal oscillator 10 is an AT-cut quartz wafer subjected to thickness shear vibration. In the crystal oscillator 10 shown in Figures 4 and 5, the two main surfaces (101, 102) of the crystal oscillator 10 are XZ' planes. In this XZ' plane, the direction parallel to the short side of the crystal oscillator 10 is the X-axis direction, and the direction parallel to the long side of the crystal oscillator 10 is the Z'-axis direction. Furthermore, AT cutting refers to a processing method in which the three crystal axes of a quartz crystal—the electrical axis (X-axis), mechanical axis (Y-axis), and optical axis (Z-axis)—are cut at an angle approximately 35°15′ relative to the Z-axis around the X-axis. In the AT-cut quartz wafer, the X-axis coincides with the crystal axis of the quartz crystal. The Y' and Z' axes are aligned with the Y' and Z' axes of the quartz crystal relative to the crystal axis by approximately 35°15′ (this cutting angle can be appropriately changed within the adjustment range of the frequency-temperature characteristics of the AT-cut crystal oscillator). The Y' and Z' axis directions correspond to the cutting orientation when the AT-cut quartz wafer is cut out. In addition, the two main surfaces (first main surface 101 and second main surface 102) of the crystal oscillator 10 are configured as flat and smooth surfaces with a mirror finish, for example, by polishing.

[0030] The crystal oscillator 10 is configured to include a vibrating portion 11 that is approximately rectangular, an outer frame portion 12 surrounding the outer periphery of the vibrating portion 11, and a holding portion 13 that supports the vibrating portion 11 by connecting the vibrating portion 11 and the outer frame portion 12. That is, the crystal oscillator 10 is constructed by integrating the vibrating portion 11, the outer frame portion 12, and the holding portion 13 as a single unit. The holding portion 13 extends (protrudes) from only one corner of the vibrating portion 11 located in the +X and -Z' directions towards the outer frame portion 12 in the -Z' direction. Furthermore, a hollow portion 10a, formed by hollowing out the crystal oscillator 10, is provided between the vibrating portion 11 and the outer frame portion 12. In this embodiment, only one holding portion 13 connecting the vibrating portion 11 and the outer frame portion 12 is provided on the crystal oscillator 10, and the hollow portion 10a is continuously formed to surround the periphery of the vibrating portion 11.

[0031] The thickness of the substrate of the crystal resonator 10 can be, for example, approximately 40 μm or approximately 60 μm. Furthermore, it is preferable that the vibrating portion 11 in the crystal resonator 10 is thinner than the outer frame portion 12; more preferably, the thickness of the vibrating portion 11 is about half the thickness of the outer frame portion 12. In this case, it is preferable that the first main surface 101 of the outer frame portion 12 and the first main surface 101 of the vibrating portion 11 are positioned differently in the thickness direction (Y' direction). Additionally, the thickness of the vibrating portion 11 is related to the vibration characteristics of the crystal resonator 100. Therefore, in order to obtain a crystal resonator 100 with the desired characteristics, the thickness of the vibrating portion 11 can be appropriately adjusted.

[0032] On the two main surfaces (101, 102) of the crystal oscillator 10, a pair of excitation electrodes (first excitation electrode 111, second excitation electrode 112) are formed. The first excitation electrode 111 is disposed on the first main surface 101 side of the oscillator 11, and the second excitation electrode 112 is disposed on the second main surface 102 side of the oscillator 11. Lead wires (first lead wire 113, second lead wire 114) for connecting these excitation electrodes to external electrode terminals are connected to the first excitation electrode 111 and the second excitation electrode 112. The first lead wire 113 is led out from the first excitation electrode 111 and connected to the connection engagement pattern 12a formed on the first main surface 101 side of the outer frame 12 via the holding part 13; furthermore, the connection engagement pattern 12a is connected to the connection engagement pattern 12e formed on the second main surface 102 side of the outer frame 12 via the second roundabout wire 18 formed on the inner wall surface of the outer frame 12. In addition, the second lead wire 114 is led out from the second excitation electrode 112 and connected to the connection bonding pattern 12d formed on the second main surface 102 side of the outer frame portion 12 via the holding portion 13.

[0033] Furthermore, as shown in Figures 4 and 5, vibrating plate-side sealing portions for engaging the crystal vibrating plate 10 with the first sealing member 20 and the second sealing member 30 are respectively provided on the two main surfaces (first main surface 101 and second main surface 102) of the crystal vibrating plate 10. The vibrating plate-side sealing portion of the first main surface 101 has a first engagement pattern 121; the vibrating plate-side sealing portion of the second main surface 102 has a second engagement pattern 122. The first engagement pattern 121 and the second engagement pattern 122 are provided on the outer frame portion 12 and are configured to be annular when viewed from above. The outer periphery of the first engagement pattern 121 is positioned close to the outer periphery of the first main surface 101 of the crystal vibrating plate 10 (outer frame portion 12). The outer periphery of the second engagement pattern 122 is positioned close to the outer periphery of the second main surface 102 of the crystal vibrating plate 10 (outer frame portion 12). In this embodiment, the first bonding pattern 121 on the vibrating plate side and the second bonding pattern 122 on the vibrating plate side are connected by a first inner and outer meandering wiring 17 formed on the inner wall surface of the outer frame portion 12. The first inner and outer meandering wiring 17 is provided on the inner wall surface of the outer frame portion 12 formed along the Z' axis direction, that is, on the inner wall surface on the -X direction side.

[0034] Furthermore, a first through hole 161 is formed on the outer frame portion 12, extending through the thickness direction of the crystal oscillator 10 (between the first main surface 101 and the second main surface 102). Specifically, on the outer frame portion 12, the first through hole 161 is provided on the inner periphery of the first bonding pattern 121 and the second bonding pattern 122 on the oscillator side. Around the first through hole 161, a connecting bonding pattern 12b is formed on the first main surface 101 side, and a connecting bonding pattern 12g is formed on the second main surface 102 side. In addition, as a further connecting bonding pattern, a connecting bonding pattern 12c is formed on the first main surface 101 side and a connecting bonding pattern 12f is formed on the second main surface 102 side on the outer frame portion 12.

[0035] In the first through hole 161, a through electrode is formed along the inner wall surface of the first through hole 161 to enable conduction between the electrodes formed on the first main surface 101 and the second main surface 102. Furthermore, the middle portion of the first through hole 161 is a hollow through portion that passes between the first main surface 101 and the second main surface 102. However, conduction between the electrodes on the first main surface 101 and the second main surface 102 can also be achieved by means other than the through electrode of the through hole (e.g., wiring formed on the inner wall surface of the outer frame portion 12).

[0036] As shown in Figures 2 and 3, the first sealing member 20 is constructed from a cuboid substrate made of an AT-cut quartz wafer. The first main surface 201 and the second main surface 202 (the surfaces that engage with the crystal oscillator 10) of the first sealing member 20 are configured as flat, smooth surfaces (mirror-finished). Furthermore, although the first sealing member 20 does not have a vibrating section, it is preferably made of an AT-cut quartz wafer, similar to the crystal oscillator 10. In this embodiment, the X-axis, Y-axis, and Z'-axis directions of the first sealing member 20 are the same as those of the crystal oscillator 10. Moreover, it is preferable that the thickness of the first sealing member 20 is the same as that of the crystal oscillator 10.

[0037] Furthermore, no through hole is provided on the first sealing member 20 to pass through the first main surface 201 and the second main surface 202. Therefore, in this embodiment, the first main surface 201 (the upper surface of the crystal resonator 100) of the first sealing member 20 is a smooth surface on which the quartz crystal of the substrate constituting the first sealing member 20 is completely exposed.

[0038] As shown in FIG3, a first sealing member side engagement pattern 24, serving as a sealing member side first sealing portion for engaging with the crystal oscillator 10, is formed on the second main surface 202 of the first sealing member 20. The first sealing member side engagement pattern 24 is configured to be annular when viewed from above. The outer periphery of the first sealing member side engagement pattern 24 is set to be close to the outer periphery of the second main surface 202 of the first sealing member 20. In addition, a connecting engagement pattern 22a for engaging with a connecting engagement pattern 12a formed on the first main surface 101 of the outer frame portion 12 of the crystal oscillator 10, a connecting engagement pattern 22b for engaging with a connecting engagement pattern 12b formed on the first main surface 101 of the outer frame portion 12 of the crystal oscillator 10, and a connecting engagement pattern 22c for engaging with a connecting engagement pattern 12c formed on the first main surface 101 of the outer frame portion 12 of the crystal oscillator 10 are formed on the second main surface 202 of the first sealing member 20.

[0039] Additionally, a thin-film thermistor 500, functioning as a temperature sensor, is provided on the second main surface 202 of the first sealing member 20. In this embodiment, the thin-film thermistor 500 is disposed approximately in the middle of the second main surface 202, and appears approximately rectangular when viewed from above. The thin-film thermistor 500 is connected to the bonding pattern 22b via a first thermistor connection electrode 25, and to the first bonding pattern 24 on the sealing member side via a second thermistor connection electrode 26.

[0040] Figure 8 is an enlarged view of the vicinity of the thin-film thermistor 500 in Figure 3, and Figure 9 is a cross-sectional view of the thin-film thermistor 500 along line A-A in Figure 8. The thin-film thermistor 500 consists of a pair of thermistor electrodes (501, 502), a resistive film 503, and a protective film 504. The thickness of the thin-film thermistor 500 can be in the range of 1–10 μm.

[0041] A pair of thermistor electrodes (501, 502) are each configured as a comb shape with protrusions. These electrodes are arranged facing each other with the protrusions of one (501) and the other (502) staggered and separated by a predetermined gap, without contacting each other. Furthermore, an upper resistive film 503 extends into the gap. That is, the resistive film 503 is disposed within the facing gap between the pair of thermistor electrodes (501, 502), and the width of the resistive film 503 is consistent with the facing gap between the pair of thermistor electrodes (501, 502). One thermistor electrode 501 is connected to the first thermistor connection electrode 25, and the other thermistor electrode 502 is connected to the second thermistor connection electrode 26.

[0042] The resistive film 503 is a thin film made of insulating material that covers at least a portion of a pair of thermistor electrodes (501, 502). In this embodiment, the resistive film 503 is configured to be approximately rectangular. However, it is preferable that the resistive film 503 completely covers the pair of thermistor electrodes (501, 502). As the insulating material constituting the resistive film 503, for example, an oxide of an alloy can be used, and more specifically, a MnCoNi-based alloy can be used.

[0043] The protective film 504 is a thin film made of insulating material that covers a pair of thermistor electrodes (501, 502) and the resistive film 503. In this embodiment, the protective film 504 is configured to be approximately rectangular. For example, a SiO2-based material can be used as the insulating material constituting the protective film 504.

[0044] Furthermore, the characteristics of the thin-film thermistor 500, such as its B constant and resistance value, vary depending on the material composition, area, and shape of the pair of thermistor electrodes (501, 502) and the resistive film 503. Moreover, the desired B constant and resistance value depend on the application and characteristics of the crystal resonator 100. Therefore, the material composition, area, and shape of the pair of thermistor electrodes (501, 502) and the resistive film 503 can be appropriately modified according to the application and characteristics of the crystal resonator 100.

[0045] As shown in Figures 6 and 7, the second sealing member 30 is constructed from a cuboid substrate made of an AT-cut quartz wafer. Furthermore, the first main surface 301 (the surface that engages with the crystal resonator 10) and the second main surface 302 (the bottom surface of the crystal resonator 100) of the second sealing member 30 are configured as flat, smooth surfaces (mirror finish). Preferably, the second sealing member 30, like the crystal resonator 10, uses an AT-cut quartz wafer; the directions of the X-axis, Y-axis, and Z'-axis are also the same as those of the crystal resonator 10. Further preferably, the thickness of the second sealing member 30 is the same as that of the crystal resonator 10 and the first sealing member 20.

[0046] As shown in Figure 7, four external electrode terminals (32a, 32b, 32c, 32d) are provided on the second main surface 302 (the main surface not facing the outer side of the crystal resonator 10) of the second sealing member 30, which are electrically connected to an external circuit board disposed outside the crystal resonator 100. Each external electrode terminal (32a, 32b, 32c, 32d) is configured as an approximate rectangle and is located at the four corners of the second main surface 302 of the second sealing member 30. When viewed from above, each external electrode terminal (32a, 32b, 32c, 32d) is positioned overlapping the outer frame portion 12 of the crystal resonator 10.

[0047] As shown in Figures 6 and 7, four through holes are formed on the second sealing member 30, connecting the first main surface 301 and the second main surface 302. Specifically, the second through hole 162, the third through hole 163, the fourth through hole 164, and the fifth through hole 165 are respectively provided on the second sealing member 30.

[0048] In the second through hole 162, the third through hole 163, the fourth through hole 164, and the fifth through hole 165, through electrodes for conducting the electrodes formed on the first main surface 301 and the second main surface 302 are formed along their respective inner wall surfaces. Furthermore, the middle portion of each of the second through hole 162, the third through hole 163, the fourth through hole 164, and the fifth through hole 165 forms a hollow through portion that passes between the first main surface 301 and the second main surface 302. The through electrode of the second through hole 162 is electrically connected to the external electrode terminal 32a, the through electrode of the third through hole 163 is electrically connected to the external electrode terminal 32b, the through electrode of the fourth through hole 164 is electrically connected to the external electrode terminal 32c, and the through electrode of the fifth through hole 165 is electrically connected to the external electrode terminal 32d.

[0049] As shown in Figure 6, a second sealing member-side engagement pattern 31 is formed on the first main surface 301 of the second sealing member 30, serving as a second sealing portion for engaging with the crystal oscillator 10. The second sealing member-side engagement pattern 31 is configured to be annular in plan view. The outer periphery of the second sealing member-side engagement pattern 31 is positioned close to the outer periphery of the first main surface 301 of the second sealing member 30. Furthermore, on the first main surface 301 of the second sealing member 30, a connecting engagement pattern 33a is formed around the second through hole 162, a connecting engagement pattern 33b is formed around the fourth through hole 164, and a connecting engagement pattern 33c is formed around the fifth through hole 165. Further, a connecting engagement pattern 33d is formed on the side opposite to the connecting engagement pattern 33b in the Z' direction of the second sealing member 30, and the connecting engagement pattern 33b and the connecting engagement pattern 33d are connected by a wiring pattern 34.

[0050] In the crystal resonator 100 comprising the crystal oscillator 10, the first sealing member 20, and the second sealing member 30, the crystal oscillator 10 and the first sealing member 20 are diffusely bonded in a state where the first bonding pattern 121 on the oscillator side and the first bonding pattern 24 on the sealing member side overlap; the crystal oscillator 10 and the second sealing member 30 are diffusely bonded in a state where the second bonding pattern 122 on the oscillator side and the second bonding pattern 31 on the sealing member side overlap, thereby forming a sandwich-structured package. Thus, the internal space of the package, i.e., the storage space of the vibrating part 11 and the thin-film thermistor 500, is hermetically sealed.

[0051] At this time, the vibrating part 11 and the thin-film thermistor 500 are arranged facing each other. More specifically, for example, if the thickness of the crystal vibrating plate 10 (outer frame 12), the first sealing member 20, and the second sealing member 30 is set to approximately 40 μm, and the thickness of the vibrating part 11 is set to be thinner than that of the outer frame 12 (approximately 20 μm), the distance between the vibrating part 11 and the second main surface 202 of the first sealing member 20 is approximately 10 μm. Therefore, in this case, the distance between the thin-film thermistor 500, which has a thickness of 1 to 10 μm, and the vibrating part 11 is approximately 9 μm or less, thereby arranging them in a close proximity state. The distance between the vibrating part 11 and the thin-film thermistor 500 is only required to prevent the vibrating part 11 from contacting the thin-film thermistor 500, preferably 10 μm or less.

[0052] Furthermore, at this time, the aforementioned connection bonding patterns also diffuse and bond with each other in an overlapping state. Thus, through the bonding of the connection bonding patterns, electrical conduction can be achieved between the first excitation electrode 111 and the external electrode terminal 32a, and between the second excitation electrode 112 and the external electrode terminal 32c in the crystal resonator 100. Specifically, the first excitation electrode 111 is connected to the external electrode terminal 32a sequentially via the first lead wire 113, the connection bonding pattern 12a, the second roundabout wire 18, the connection bonding pattern 12e, the connection bonding pattern 33a, and the through electrode of the second through hole 162. The second excitation electrode 112 is connected to the external electrode terminal 32c sequentially via the second lead wire 114, the connection bonding pattern 12d, the connection bonding pattern 33d, the wire pattern 34, the connection bonding pattern 33b, and the through electrode of the fourth through hole 164.

[0053] Furthermore, in the crystal resonator 100 of this embodiment, a sealing portion (sealing channel) is formed to hermetically seal the vibrating portion 11 of the crystal oscillator 10. The sealing channel is composed of a first sealing channel 115 formed by diffusion bonding (Au-Au bonding) between the first bonding pattern 121 on the vibrator side and the first bonding pattern 24 on the sealing member side, and a second sealing channel 116 formed by diffusion bonding (Au-Au bonding) between the second bonding pattern 122 on the vibrator side and the second bonding pattern 31 on the sealing member side. The first sealing channel 115 and the second sealing channel 116 are not electrically connected to the electrical conduction path between the first excitation electrode 111, the second excitation electrode 112 and the external electrode terminals 32a and 32c. Specifically, the first sealing channel 115 is connected to the second sealing channel 116 via the first inner and outer bypass wiring 17; furthermore, the second sealing channel 116 is connected to the external electrode terminal 32b via the through electrode of the third through hole 163. In addition, the external electrode terminal 32b in this embodiment is grounded. That is, the external electrode terminal 32b in this embodiment functions as a grounding terminal.

[0054] Furthermore, the thin-film thermistor 500 is connected to the connection bonding pattern 22b via the first thermistor connection electrode 25. The connection bonding pattern 22b is then connected to the external electrode terminal 32d via the connection bonding pattern 12b, the through electrode of the first through hole 161, and the through electrode of the fifth through hole 165. Therefore, the thin-film thermistor 500 is electrically connected to the external electrode terminal 32d. Further, the thin-film thermistor 500 is connected to the first bonding pattern 24 on the sealing member side via the second thermistor connection electrode 26. Therefore, the thin-film thermistor 500 achieves a ground connection.

[0055] Alternatively, preferably, the thin-film thermistor 500 is configured such that, when viewed from above (from the Y' direction), it overlaps at least a portion of the oscillating part 11, the first excitation electrode 111, and the second excitation electrode 112.

[0056] In the crystal resonator 100, the various bonding patterns described above are formed by stacking multiple layers on a quartz wafer. Starting from the bottom layer, Ti (titanium) and Au (gold) layers are formed sequentially using evaporation or sputtering processes. Furthermore, if other wiring and electrodes formed on the crystal resonator 100 also employ a structure consistent with the bonding patterns, the bonding patterns, wiring, and electrodes can be patterned simultaneously. However, the various bonding patterns, wiring, and electrodes described above can also be formed using photolithography.

[0057] Furthermore, the pair of thermistor electrodes (501, 502) of the thin-film thermistor 500, like the various bonding patterns in the crystal resonator 100, are formed by stacking multiple layers on a quartz wafer, with Ti (titanium) and Au (gold) layers formed from the bottommost layer by vapor deposition or sputtering processes. However, the pair of thermistor electrodes (501, 502) of the thin-film thermistor 500 can also be formed by photolithography. In this case, spin coating is preferred for photolithography. By spin coating, the photoresist film can be coated thinly and uniformly. Therefore, patterning can be reliably implemented when forming the components of the thin-film thermistor 500, such as the thermistor electrodes (501, 502), the resistive film 503, and the protective film 504, through photolithography.

[0058] Furthermore, the wiring patterns connecting the thin-film thermistor 500 to the external electrode terminal 32d are not arranged on the outer periphery of the crystal resonator 100. That is, preferably, the wiring patterns connecting the thin-film thermistor 500 to the external electrode terminal 32d are arranged inside the crystal resonator 100. Further, in the first sealing member 20 having the thin-film thermistor 500, preferably, the first main surface 201 on the side without the thin-film thermistor 500 and the peripheral surface connecting the first main surface 201 and the second main surface 202 do not have electrodes or wiring. Additionally, in the crystal resonator 100 of this embodiment, all wiring is arranged inside the sealed state, and electrodes and wiring other than the four external electrode terminals (32a, 32b, 32c, 32d) are not arranged on the outer periphery of the crystal resonator 100.

[0059] Based on the above structure, a piezoelectric resonator can be provided that further reduces the temperature difference between the vibrating part and the temperature measured by the temperature sensor. The crystal resonator 100 is configured such that the second main surface 202 of the first sealing member 20, facing the vibrating part 11, has a thin-film thermistor 500; no through hole is provided from the second main surface 202 to the first main surface 201; the second main surface 302 of the second sealing member 30, not facing the vibrating part 11, has an external electrode terminal 32d electrically connected to the thin-film thermistor 500, and external electrode terminals (32a, 32c) electrically connected to the excitation electrodes (111, 112). Based on this structure, in the crystal resonator 100 of the present invention with a sandwich structure, the vibrating part 11 and the thin-film thermistor 500, which serves as a temperature sensor, are positioned very close to each other, and the temperature difference between the vibrating part 11 and the thin-film thermistor 500 can be further reduced by radiating heat. Furthermore, the thin-film thermistor 500 is not disposed on the second sealing member 30 which has external terminals, but on the first sealing member 20. Therefore, the heat conduction path from the external substrate on which the crystal resonator 100 is mounted can be brought closer to the vibration section 11, thereby enabling the thin-film thermistor 500 to detect a temperature closer to the temperature of the vibration section 11.

[0060] Furthermore, as described above, the second main surface 202 of the first sealing member 20, facing the vibrating part 11, is equipped with a thin-film thermistor 500. The thin-film thermistor 500 is not exposed outside the crystal resonator 100, thereby preventing temperature changes or damage caused by external factors. Furthermore, it avoids insufficient clamping of the first sealing member 20 due to the unevenness of the thin-film thermistor 500 when it is joined to the crystal oscillator 10, thus enabling stable manufacturing.

[0061] Furthermore, as described above, by employing a structure in which no through-hole is provided on the first sealing member 20, extending from the second main surface 202 to the first main surface 201, it is possible to avoid poor formation due to the presence of through-holes when forming the thin-film thermistor 500, thereby enabling stable manufacturing. In particular, when forming the thin-film thermistor 500, it is preferable to use spin coating for photoresist application. However, if there are through-holes on the first sealing member 20 for forming the thin-film thermistor 500, it will affect the uniformity of the photoresist film formed by spin coating, making it difficult to achieve uniform photoresist coating. Based on the above structure, spin coating can be used, thereby reliably forming the thin-film thermistor 500. More specifically, photolithography can be used to form each component of the thin-film thermistor 500, such as the thermistor electrodes (501, 502), the resistive film 503, and the protective film 504, with high precision. In addition, even if the thin-film thermistor 500 is formed before forming the through-hole, a metal film needs to be formed again when forming the through-hole. Therefore, if a through hole is formed later, the shape of the electrode film of the thin-film thermistor 500 and the wiring led out from the thin-film thermistor 500 may change, and the characteristics of the thin-film thermistor 500 may also change, so it is not advisable to use it. That is, as described above, by adopting a structure in which no through hole is provided on the first sealing member 20 to penetrate from the second main surface 202 to the first main surface 201, a thin-film thermistor 500 with performance more suitable for the crystal resonator 100 can be stably formed.

[0062] Furthermore, if a chip thermistor (such as a negative temperature coefficient thermistor) made of sintered material is used, the thickness will increase, making it impossible to achieve the thinness advantage of the sandwich structure. To address this, the thin-film thermistor 500 of this invention can both house a temperature sensor and achieve a thinner profile. Moreover, by using the thin-film thermistor 500 of this invention, compared to chip thermistors, the heat capacity can be reduced, and the temperature change of the substrate (in this embodiment, a quartz crystal) can be quickly tracked. Furthermore, the sensitivity (resolution) is improved compared to other temperature sensors with smaller heat capacity (such as temperature sensors that reference the resistance value of a metal thin film).

[0063] Furthermore, in the state where the crystal resonator 100 is engaged with both the first sealing member 20 and the crystal oscillator 10, the thin-film thermistor 500 and the external electrode terminal 32d are electrically connected to each other through wiring disposed inside the crystal resonator 100. This structure prevents the conduction of the thin-film thermistor 500 from being damaged by external impacts, etc.; compared to the case where wiring is disposed on the outer periphery of the crystal resonator 100, heat conduction to the thin-film thermistor 500 can be limited, thereby enabling the thin-film thermistor 500 to perform stably. Additionally, the electrical connection between the thin-film thermistor and the external thermistor terminal can be achieved without providing a through hole in the first sealing member 20.

[0064] Furthermore, in the first sealing member 20 equipped with the thin-film thermistor 500, there are no electrodes or wiring protrusions on the first main surface 201 on the side without the thin-film thermistor 500, and on the side peripheral surface connecting the first main surface 201 and the second main surface 202. With this structure, no protrusions caused by wiring (electrodes) are formed on the clamping surface during the joining of the first sealing member 20, so there are no factors that hinder clamping, and stable manufacturing can be achieved.

[0065] Furthermore, the substrates of the first sealing member 20, the crystal resonator 10, and the second sealing member 30 are each made of AT-cut quartz crystal. With this structure, heat transferred from the external substrate housing the crystal resonator 100 to the second sealing member 30 via the external electrode terminals (32a, 32b, 32c, 32d) can be uniformly conducted to the crystal resonator 10 and the first sealing member 20, thereby further reducing the temperature difference between the vibrating part 11 and the thin-film thermistor 500. Additionally, the crystal resonator 10 and the first sealing member 20 have the same coefficient of thermal expansion, thereby suppressing thermal deformation within the crystal resonator 100.

[0066] In addition, the substrates of the first sealing member 20, the crystal resonator 10, and the second sealing member 30 are all made of AT-cut quartz crystals, and their thicknesses are also the same. With this structure, the heat transferred from the external substrate on which the crystal resonator 100 is mounted to the second sealing member 30 via the external electrode terminals (32a, 32b, 32c, 32d) can be more evenly conducted to the crystal resonator 10 and the first sealing member 20, thereby further reducing the temperature difference between the vibrating part 11 and the thin-film thermistor 500.

[0067] Furthermore, the crystal oscillator 10 is configured such that the vibrating part 11 is thinner than the outer frame part 12. This structure allows for more freedom in setting the thickness of the thin-film thermistor 500. In other words, the degree of freedom in determining the characteristics of the obtained thin-film thermistor 500 is increased, thereby expanding the range of selectable characteristics for the crystal resonator 100.

[0068] However, the present invention is not limited to the structure of the above-described embodiments and can have various embodiments. For example, in this embodiment, the vibrating part 11 is approximately rectangular and has a first excitation electrode 111 on the first main surface 101 and a second excitation electrode 112 on the second main surface 102. However, the vibrating part 11 may also be a tuning fork shape, with the first excitation electrode 111 and the second excitation electrode 112 on each main surface of a pair of extended vibrating arms (corresponding to the vibrating part in each embodiment). In this case, the substrate of the crystal vibrating plate 10 having the vibrating part 11 is made of an X-Y cut quartz crystal. Furthermore, it is preferable that the substrates of the first sealing member 20 and the second sealing member 30 are also made of X-Y cut quartz crystals.

[0069] In addition, in this embodiment, a structure is adopted in which the crystal oscillator 10 is joined with the first sealing member 20 and the second sealing member 30 by diffusion bonding (Au-Au bonding), but a structure using solder bonding such as AuSn solder can also be adopted, for example.

[0070] Furthermore, in this embodiment, the substrates of the first sealing member 20 and the second sealing member 30 are made of quartz crystals. However, for example, the substrates of at least one of the first sealing member 20 and the second sealing member 30 may be made of either glass or silicon. Further, in this embodiment, the substrate of the crystal oscillator 10 is made of AT-cut quartz crystals. However, it may also be made of quartz crystals obtained with different cutting orientations. In this case, it is preferable that the substrates of the first sealing member 20 and the second sealing member 30, which are bonded to the crystal oscillator 10, are made of quartz crystals obtained with the same cutting orientation as the crystal oscillator 10.

[0071] Furthermore, when the crystal resonator 100 is mounted on an external substrate, the external electrode terminals (32a, 32b, 32c, 32d) formed on the second main surface 302 of the second sealing member 30 are bonded to the external substrate by solder. However, if the through electrodes in the second through holes 162 to the fifth through holes 165 formed on the second sealing member 30 have an Au film made of Au (gold), the solder may wet and spread (climb) along the Au film within the through electrodes. Due to the corrosive effect of such solder, the Au constituting the Au film may condense, which may lead to problems such as increased on-resistance and wire breakage, and may also cause poor airtightness of the first sealing channel 115 and the second sealing channel 116.

[0072] Furthermore, as in the modified examples shown in Figures 10 and 11, structures are provided to prevent solder erosion at the external electrode terminals (32a, 32b, 32c, 32d) and the through electrodes of the second through hole 162 to the fifth through hole 165 of the second sealing member 30. As shown in Figure 11, the second through hole 162 of the second sealing member 30 is configured to have an approximately hourglass shape with an inclined surface 162a in its cross-section. Specifically, the second through hole 162 is configured to have a through portion 162b at the middle part in the thickness direction of the second sealing member 30, and the opening area gradually decreases from the opening end side (the side of the first main surface 301 and the side of the second main surface 302) to the middle part. A through electrode 162c is formed on the inner wall surface (inclined surface 162a) of the second through hole 162. Through the through electrode 162c, the electrode (connection pattern) 33a formed on the first main surface 301 of the second sealing member 30 is connected to the external electrode terminal 32a formed on the second main surface 302. In addition, only the external electrode terminal 32a of the second sealing member 30 and the through electrode 162c of the second through hole 162 are shown in Figure 11, but the other external electrode terminals (32b, 32c, 32d) and the through electrodes of the third through hole 163 to the fifth through hole 165 also have the same structure.

[0073] The joining pattern 33a of the first main surface 301 of the second sealing member 30 includes a first metal film 33e formed on the first main surface 301, for example by vapor deposition of a first conductive metal, and an Au film 33f formed on the first metal film 33e, for example by vapor deposition of Au (gold). The external electrode terminal 32a of the second main surface 302 of the second sealing member 30 includes a first metal film 32e formed on the second main surface 302, for example by vapor deposition of a first conductive metal, a second metal film 32f formed on the first metal film 32e, for example by vapor deposition of a second conductive metal, and an Au film 32g formed on the second metal film 32f, for example by vapor deposition of Au (gold). The through electrode 162c of the second through hole 162 includes a first metal film 162d formed on the inclined surface 162a of the second through hole 162, for example, by vapor deposition of a first conductive metal; a second metal film 162e formed on the first metal film 162d, for example, by vapor deposition of a second conductive metal; and an Au film 162f formed on the second metal film 162e, for example, by vapor deposition of Au. The Au film 162f is formed only on the inclined surface 162a on the upper side (first main surface 301 side) of the second through hole 162, and not on the inclined surface 162a on the lower side (second main surface 302 side). In this case, the through electrode 162c of the second through hole 162 can be formed by removing a portion of the Au film formed on the entire inclined surface 162a of the second through hole 162, for example, by metal etching. In this example, the Au film is removed from the end of the external electrode terminal 32a to the middle portion in the depth direction beyond the through electrode 162c. However, the Au film may also be completely removed in the through electrode 162c of the second through hole 162.

[0074] Furthermore, the first metal film 33e of the connecting bonding pattern 33a, the first metal film 162d of the penetrating electrode 162c, and the first metal film 32e of the external electrode terminal 32a are integrally formed. Additionally, the second metal film 162e of the penetrating electrode 162c and the second metal film 32f of the external electrode terminal 32a are integrally formed. The Au film 33f of the connecting bonding pattern 33a and the Au film 162f of the penetrating electrode 162c are integrally formed. In this case, Ti (titanium) is used as the first conductive metal, and Ni (nickel) is used as the second conductive metal. However, the aforementioned first and second conductive metals are only examples; conductive metals other than those described above may also be used. Furthermore, the multilayer structure of the penetrating electrode 162c, the external electrode terminal 32a, and the connecting bonding pattern 33a is only one example, and there is no particular limitation on the number of layers for each electrode. For example, the bonding pattern 33a for connection can have a three-layer structure with a second metal film, the same as the external electrode terminal 32a; or, the external electrode terminal 32a can have a two-layer structure without a second metal film, the same as the bonding pattern 33a for connection.

[0075] In this modified example, the Au film 33f of the connecting bonding pattern 33a and the Au film 32g of the external electrode terminal 32a are not integrally formed. The Au film is removed from the end of the external electrode terminal 32a side of the second through hole 162 to the middle portion beyond the depth direction, thereby severing the Au film inside the second through hole 162. The Au film 33f of the connecting bonding pattern 33a and the Au film 32g of the external electrode terminal 32a are connected by a first metal film 162d formed of a conductive metal other than Au. Furthermore, in addition to removing the Au film from the through electrode 162c of the second through hole 162, the Au film around the second through hole 162 (peripheral portion) of the external electrode terminal 32a of the second main surface 302 is also removed. As shown in FIG10, the Au film of the approximately rectangular portion of each external electrode terminal (32a-32d) is removed, exposing the second metal film 32f in that portion. Therefore, in each external electrode terminal (32a-32d), the Au film 32g is configured in an approximately L-shape.

[0076] As described above, the Au film, which could potentially become an erosion path for solder, is cut off from the external electrode terminal 32a of the second main surface 302 and the through electrode 162c of the second through hole 162. A first metal film 162d, formed of a conductive metal other than Au, is used to achieve conductivity between the bonding pattern 33a of the first main surface 301 of the second sealing member 30 and the external electrode terminal 32a of the second main surface 302. Thus, by removing the Au film, the erosion path of solder in the through electrode 162c can be cut off, preventing solder from wetting and spreading into the through electrode 162c, thereby avoiding problems such as increased conductivity resistance and wire breakage. Furthermore, it can prevent poor airtightness of the first sealing channel 115 and the second sealing channel 116 due to solder creep.

[0077] Furthermore, in this modified example, a structure can be further adopted in which the second through holes 162 to the fifth through holes 165 are filled with metal or a conductive resin made of metal and resin. With such a structure, for example, in addition to removing the Au film from the through electrode 162c of the second through hole 162, the Au film in the portion (peripheral portion) surrounding the second through hole 162 in the external electrode terminal 32a of the second main surface 302 is also removed. Therefore, in cases where the on-resistance increases and the electrical characteristics of the crystal resonator 100 deteriorate, the on-resistance can be reduced by utilizing the metal or conductive resin within the second through hole 162, preventing the electrical characteristics of the crystal resonator 100 from deteriorating. As the metal used to fill the second through holes 162 to the fifth through holes 165 and the metal mixed in the conductive resin, a metal other than gold (Au) can be used, for example, silver (Ag).

[0078] Regarding the present invention and this embodiment, the first main surface of the first sealing member of the present invention corresponds to the first main surface 201 of this embodiment. Similarly, the second main surface of the first sealing member corresponds to the second main surface 202, the first main surface of the second sealing member corresponds to the first main surface 301, the second main surface of the second sealing member corresponds to the second main surface 302, the external terminal of the thermistor corresponds to the external electrode terminal 32d, and the external terminal of the excitation electrode corresponds to the external electrode terminal 32a and the external electrode terminal 32c.

[0079] The embodiments disclosed herein are merely illustrative of all aspects and not intended as a basis for limiting interpretation. Therefore, the technical scope of this invention cannot be interpreted solely based on the above embodiments, but must be defined according to the claims. Furthermore, all modifications are included within the same sense and scope as the claims.

[0080] This application claims priority based on Japanese Patent Application No. 2024-034635, filed on March 7, 2024. It is self-evident that all contents of that application are incorporated herein by reference.

[0081] [Potential for industrial applications] The piezoelectric vibrating device of the present invention can be applied to the manufacturing and sales industry of piezoelectric vibrating devices with sandwich structures.

[0082] <Explanation of Figure Labels> 10 Crystal Vibrating Plate 111 First excitation electrode 112 Second excitation electrode 20 First sealing component 201 First Main Face 202 Second Main Face 30 Second sealing component 301 First Main Page 302 Second Main Face External electrode terminals 32a, 32b, 32c, 32d 100 Crystal Resonator 500 Thin Film Thermistor 501, 502 thermistor electrodes 503 resistive film 504 protective film

Claims

1. A piezoelectric vibrating device comprising a piezoelectric vibrating plate having a first excitation electrode formed on the main surface of a substrate and a second excitation electrode formed on the main surface of the substrate and paired with the first excitation electrode; The piezoelectric vibrating plate comprises a first sealing member and a second sealing member covering the two main surfaces of the piezoelectric vibrating plate. The first sealing member engages with the piezoelectric vibrating plate, and the second sealing member engages with the piezoelectric vibrating plate, thereby forming an airtight internal space that seals the vibrating portion of the piezoelectric vibrating plate containing the first excitation electrode and the second excitation electrode. The feature is that: The first sealing member has a first main surface that does not face the vibrating part, and a second main surface that is the back side of the first main surface and faces the vibrating part. The second main surface of the first sealing member is equipped with a thin-film thermistor; No through hole is provided, extending from the first main surface of the first sealing member to the second main surface of the first sealing member; The second sealing member has a first main surface facing the vibrating part and a second main surface that is the back side of the first main surface of the second sealing member and does not face the vibrating part; The second sealing member has a second main surface having an external terminal for a thermistor electrically connected to the thin-film thermistor, and an external terminal for an excitation electrode electrically connected to the first excitation electrode and the second excitation electrode respectively.

2. The piezoelectric vibration device as described in claim 1, characterized in that: With the first sealing member engaged with the piezoelectric vibrating plate and the second sealing member engaged with the piezoelectric vibrating plate, the thin-film thermistor and the thermistor are electrically connected to each other via wiring disposed inside the piezoelectric vibrating device through external terminals.

3. The piezoelectric vibration device as described in claim 1 or 2, characterized in that: The substrates of the first sealing member, the piezoelectric vibrating plate, and the second sealing member are each made of quartz crystal.

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