Thermistor-mounted piezoelectric vibration device

Abstract

A thermistor-mounted piezoelectric vibration device (1) is provided with a sand device (2), and a thin-plate thermistor (5) which is mounted on an outside surface of a first sealing member (20) in the sand device (2). The thin-plate thermistor (5) is disposed so as to overlap with at least a portion of a vibration section (13) of the sand device (2) in plan view. Furthermore, a piezoelectric vibration plate (10) in the sand device (2) has the vibration section (13), an outer frame section (14) which encloses the outer periphery of the vibration section (13), and a retention section (15) which retains the vibration section (13) by linking the vibration section (13) and the outer frame section (14). The thin-plate thermistor (5) is disposed so as to overlap the outer frame section (14) on two mutually opposing sides of the sand device (2).

Description

Technical Field

[0001] The present invention relates to a thermistor-mounted piezoelectric vibration device in which a thermistor is mounted on a piezoelectric vibration device having a sandwich structure.

Background Art

[0002] In recent years, the operating frequencies of various electronic devices have been increasing, and the packages have been miniaturized (especially made thinner). Therefore, along with the increase in frequency and the miniaturization of the package, piezoelectric vibration devices (such as crystal resonators and crystal oscillators) are also required to cope with the increase in frequency and the miniaturization of the package.

[0003] In this type of piezoelectric vibration device, the housing is composed of a package having a substantially rectangular parallelepiped shape. This package is composed of, for example, a first sealing member and a second sealing member made of glass or crystal, and a piezoelectric vibration plate made of, for example, crystal and having exciting electrodes formed on both main surfaces. The first sealing member and the second sealing member are laminated and joined via the piezoelectric vibration plate. Then, the vibrating portion (exciting electrode) of the piezoelectric vibration plate arranged inside the package (internal space) is hermetically sealed. Hereinafter, such a laminated form of the piezoelectric vibration device is referred to as a sandwich structure. Further, a piezoelectric vibration device having a sandwich structure is referred to as a sandwich device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As piezoelectric vibration devices, thermistor-mounted piezoelectric vibration devices equipped with thermistors are also widely used (for example, Patent Documents 1 and 2). However, at present, there is no known product that mounts a thermistor in a sand device to form a thermistor-mounted piezoelectric vibration device. Note that the sand device has problems that occur significantly in the sand device. Even when a thermistor-mounted piezoelectric vibration device is formed in the sand device, it is necessary to solve the problems in the sand device.

[0006] For example, since the sand device is a low-profile thin device, the internal excitation electrodes are easily affected by external noise, and noise countermeasures are important. Even when a thermistor-mounted piezoelectric vibration device is formed in the sand device, it is required to solve such problems.

[0007] In addition, since the sand device is a low-profile thin device, there is a problem that the strength is relatively low. Even when a thermistor-mounted piezoelectric vibration device is formed in the sand device, it is required to solve such problems.

[0008] The present invention has been made in view of the above problems, and an object thereof is to use the mounted thermistor to solve the problems in the sand device when a thermistor-mounted piezoelectric vibration device is formed in the sand device. In particular, a first object of the present invention is to provide a thermistor-mounted piezoelectric vibration device with excellent noise countermeasures while using a sand device. Another object of the present invention is to provide a thermistor-mounted piezoelectric vibration device with measures taken in terms of strength while using a sand device.

Means for Solving the Problems

[0009] In order to solve the above problems, a thermistor-mounted piezoelectric vibration device according to a first aspect of the present invention includes a piezoelectric vibration plate having a first excitation electrode formed on a first main surface and a second excitation electrode formed on a second main surface, a first sealing member laminated so as to cover the first main surface side of the piezoelectric vibration plate, and a second sealing member laminated so as to cover the second main surface side of the piezoelectric vibration plate. The second sealing member is joined to form a sandwich-structured piezoelectric vibration device in which an internal space for hermetically sealing the vibration portion is formed, and a thin plate thermistor mounted on an outer surface of the first sealing member in the piezoelectric vibration device. The thin plate thermistor is arranged so as to overlap at least a part of the vibration portion in a plan view.

[0010] According to the above configuration, by arranging the thin plate thermistor so as to overlap the vibration portion of the piezoelectric vibration device, it can be used as a shield for the vibration portion.

[0011] Further, in the thermistor-mounted piezoelectric vibration device, the thin plate thermistor may be arranged so as to overlap the entire first excitation electrode and the entire second excitation electrode in a plan view.

[0012] According to the above configuration, by overlapping the thin plate thermistor with the entire first excitation electrode and the entire second excitation electrode, the shielding effect of the thin plate thermistor can be maximally exerted.

[0013] Further, in the thermistor-mounted piezoelectric vibration device, the thin plate thermistor may have a common electrode formed on one main surface of a single-plate thermistor flat plate and divided electrodes formed on the other main surface, and the common electrode may be formed on substantially the entire surface of the thermistor flat plate.

[0014] According to the above configuration, by making the common electrode in the thin plate thermistor have a large area, the thin plate thermistor becomes advantageous as a shield.

[0015] Further, in the thermistor-mounted piezoelectric vibration device, the thin-plate thermistor has a common electrode formed on one main surface of a single-plate thermistor flat plate, and a divided electrode formed on the other main surface, and the divided electrode can be formed over an area of half or more of the thermistor flat plate.

[0016] According to the above configuration, by making the divided electrode in the thin-plate thermistor have a large area, the thin-plate thermistor becomes excellent as a shield.

[0017] Further, in order to solve the above problems, a thermistor-mounted piezoelectric vibration device according to a second aspect of the present invention includes a piezoelectric vibration plate having a first excitation electrode formed on a first main surface and a second excitation electrode formed on a second main surface, a first sealing member laminated so as to cover the first main surface side of the piezoelectric vibration plate, and a second sealing member laminated so as to cover the second main surface side of the piezoelectric vibration plate, and a sandwich-structured piezoelectric vibration device in which an internal space for hermetically sealing the vibration portion is formed by joining the first and second sealing members, and a thin-plate thermistor mounted on an outer surface of the first sealing member in the piezoelectric vibration device. The piezoelectric vibration plate has a vibration portion, an outer frame portion surrounding the outer periphery of the vibration portion, and a holding portion that holds the vibration portion by connecting the vibration portion and the outer frame portion. The thin-plate thermistor is characterized in that it is disposed so as to overlap the outer frame portion on two sides of the piezoelectric vibration device that face each other.

[0018] According to the above configuration, by joining the thin-plate thermistor to the outer peripheral portion of the piezoelectric vibration device, that is, by disposing it so as to overlap the outer frame portion, the strength as a thermistor-mounted piezoelectric vibration device can be ensured.

[0019] Further, in the thermistor-mounted piezoelectric vibration device, the electrical connection between the thin-plate thermistor and the piezoelectric vibration device can be made with a conductive resin adhesive, and the gap between the thin-plate thermistor and the piezoelectric vibration device can be filled with a non-conductive resin adhesive.

[0020] According to the above configuration, the thin plate thermistor is surface-bonded to the piezoelectric vibration device by the conductive resin adhesive and the non-conductive resin adhesive, and the thermal conductivity between the thin plate thermistor and the piezoelectric vibration device can be improved. Thereby, the thin plate thermistor can be maintained at a temperature close to that of the vibrating portion of the piezoelectric vibration device. Further, the surface bonding between the piezoelectric vibration device and the thin plate thermistor can also improve the strength of the thermistor-mounted piezoelectric vibration device.

[0021] Further, in the thermistor-mounted piezoelectric vibration device, the conductive resin adhesive can be configured to have higher thermal conductivity than the non-conductive resin adhesive.

[0022] According to the above configuration, the thermal conductivity between the thin plate thermistor and the piezoelectric vibration device can be further improved.

[0023] Further, in the thermistor-mounted piezoelectric vibration device, the non-conductive resin adhesive can be configured to have higher hardness than the conductive resin adhesive.

[0024] According to the above configuration, the stress between the thin plate thermistor and the piezoelectric vibration device can be relaxed, and the package strength of the thermistor-mounted piezoelectric vibration device can be improved.

[0025] Further, in the thermistor-mounted piezoelectric vibration device, the first sealing member and the second sealing member can be configured to be made of a brittle material.

Advantages of the Invention

[0026] The thermistor-mounted piezoelectric vibration device according to the first aspect of the present invention can be used as a shield for the vibrating portion by superimposing and arranging a thin plate thermistor having a wide-area electrode on the vibrating portion, and an excellent noise-countermeasure thermistor-mounted piezoelectric vibration device can be obtained while using a sand device.

[0027] In addition, in the thermistor-mounted piezoelectric vibration device according to the second aspect of the present invention, by bonding the thin-film thermistor to the outer peripheral portion of the sand device, that is, by arranging it so as to overlap the outer frame portion, while using the sand device, a thermistor-mounted piezoelectric vibration device with measures taken in terms of strength can be obtained, which has the effect described above.

Brief Description of the Drawings

[0028]

Figure 1

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Figure 16

Embodiments for Carrying Out the Invention

[0029] 〔Embodiment 1〕 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a thermistor-mounted piezoelectric vibration device (hereinafter referred to as this device) 1 according to this embodiment. FIG. 2 is a cross-sectional view of this device 1 (cross-sectional view taken along line A-A in FIG. 1). As shown in FIGS. 1 and 2, this device 1 is a device in which a thin plate thermistor 5 is mounted on a sandwich device (piezoelectric vibration device having a sandwich structure) 2.

[0030] First, the configuration of the sandwich device 2 will be described. As shown in FIG. 2, the sandwich device 2 includes a piezoelectric vibration plate 10, a first sealing member 20, and a second sealing member 30. In the sandwich device 2, the piezoelectric vibration plate 10 and the first sealing member 20 are joined, and the piezoelectric vibration plate 10 and the second sealing member 30 are joined, thereby forming a package having a substantially rectangular parallelepiped sandwich structure.

[0031] FIG. 3 is a plan view showing a first main surface 11 which is one main surface (joint surface with the first sealing member 20) of the single piezoelectric vibration plate 10 before joining. FIG. 4 is a plan view showing a second main surface 12 which is the other main surface (joint surface with the second sealing member 30) of the single piezoelectric vibration plate 10 before joining. The piezoelectric vibration plate 10 is a piezoelectric substrate made of a piezoelectric material such as quartz, and both of its main surfaces (the first main surface 11 and the second main surface 12) are formed as flat and smooth surfaces (mirror finish). In this embodiment, an AT-cut quartz plate that performs thickness-shear vibration is used as the piezoelectric vibration plate 10.

[0032] In FIGS. 3 to 8, the longitudinal directions of the piezoelectric diaphragm 10, the first sealing member 20, and the second sealing member 30 are indicated by directions A1 and A2, and the short-side directions are indicated by directions B1 and B2. In the piezoelectric diaphragm 10, both main surfaces of the piezoelectric diaphragm 10 are the XZ' plane, the direction parallel to the short-side direction is the X-axis direction, and the direction parallel to the longitudinal direction is the Z'-axis direction.

[0033] The piezoelectric diaphragm 10 has a vibration portion 13 formed in a substantially rectangular shape, an outer frame portion 14 surrounding the outer periphery of the vibration portion 13, and a holding portion 15 that holds the vibration portion 13 by connecting the vibration portion 13 and the outer frame portion 14. Note that between the vibration portion 13 and the outer frame portion 14, except for the formation location of the holding portion 15, there is a cutout portion (an opening that penetrates the piezoelectric diaphragm 10 in the thickness direction). Thereby, the piezoelectric diaphragm 10 has a configuration in which the vibration portion 13, the outer frame portion 14, and the holding portion 15 are integrally provided. On the first main surface 11 and the second main surface 12 of the piezoelectric diaphragm 10, a pair of exciting electrodes (a first exciting electrode 111 and a second exciting electrode 121) are formed.

[0034] In the present embodiment, the holding portion 15 is provided only at one location between the vibration portion 13 and the outer frame portion 14. Also, the vibration portion 13 and the holding portion 15 are formed thinner than the outer frame portion 14. Due to such a difference in thickness between the outer frame portion 14 and the holding portion 15, the natural vibration frequencies of the piezoelectric vibration of the outer frame portion 14 and the holding portion 15 are different, and it becomes difficult for the outer frame portion 14 to resonate with the piezoelectric vibration of the holding portion 15. Note that the formation location of the holding portion 15 is not limited to one location, and the holding portion 15 may be provided at two locations between the vibration portion 13 and the outer frame portion 14.

[0035] The first excitation electrode 111 is provided on the first main surface 11 side of the vibrating portion 13, and the second excitation electrode 121 is provided on the second main surface 12 side of the vibrating portion 13. Lead wires (first lead wire 112, second lead wire 122) for connecting these excitation electrodes to external electrode terminals are connected to the first excitation electrode 111 and the second excitation electrode 121. The first lead wire 112 is drawn from the first excitation electrode 111 and is connected to a connection bonding pattern 114 formed on the outer frame portion 14 via the holding portion 15. The second lead wire 122 is drawn from the second excitation electrode 121 and is connected to a connection bonding pattern 124 formed on the outer frame portion 14 via the holding portion 15.

[0036] Bonding patterns for bonding the piezoelectric vibrating plate 10 to the first sealing member 20 and the second sealing member 30 are formed on the first main surface 11 and the second main surface 12 of the piezoelectric vibrating plate 10. This bonding pattern includes a sealing pattern for hermetically sealing the internal space of the package and a conductive pattern for conducting wiring and electrodes. In FIGS. 3, 4, 6, and 7, the bonding region where the bonding pattern is formed is indicated by diagonal hatching.

[0037] As the sealing pattern in the piezoelectric vibrating plate 10, a first vibration-side bonding pattern 113 is formed on the first main surface 11, and a second vibration-side bonding pattern 123 is formed on the second main surface 12. The first vibration-side bonding pattern 113 and the second vibration-side bonding pattern 123 are provided on the outer frame portion 14 and are formed in an annular shape in plan view. The region inside the first vibration-side bonding pattern 113 and the second vibration-side bonding pattern 123 becomes the sealing region (the region that becomes the internal space of the package after bonding) of the vibrating portion 13. The first excitation electrode 111 and the second excitation electrode 121 are not electrically connected to the first vibration-side bonding pattern 113 and the second vibration-side bonding pattern 123.

[0038] As a conductive pattern on the piezoelectric diaphragm 10, on the first main surface 11, four connection bonding patterns 115 are formed outside the sealing region (outside the vibration-side first bonding pattern 113), and connection bonding patterns 114 and 116 are formed inside the sealing region (inside the vibration-side first bonding pattern 113). Also, on the second main surface 12, four connection bonding patterns 125 are formed outside the sealing region (outside the vibration-side second bonding pattern 123), and a connection bonding pattern 124 is formed inside the sealing region (inside the vibration-side first bonding pattern 113). The connection bonding patterns 115 and 125 are provided in regions near the four corners (corner portions) of the outer frame portion 14.

[0039] Further, in the piezoelectric diaphragm 10, a plurality of through holes 16 are formed between the first main surface 11 and the second main surface 12, and through electrodes for achieving electrical continuity between the first main surface 11 and the second main surface 12 are formed on the inner wall surfaces of the respective through holes 16. Specifically, four through holes 16 (and through electrodes) are formed to achieve electrical continuity between the connection bonding pattern 115 and the connection bonding pattern 125, and one through hole 16 (and through electrode) is formed to achieve electrical continuity between the connection bonding pattern 116 and the connection bonding pattern 124.

[0040] In the piezoelectric diaphragm 10, the first excitation electrode 111, the second excitation electrode 121, the first lead wiring 112, the second lead wiring 122, the vibration-side first bonding pattern 113, the vibration-side second bonding pattern 123, and the connection bonding patterns 114 to 116, 124, and 125 can be formed in the same process. Specifically, these can be formed from an underlying film (Ti film) formed by physical vapor deposition on both main surfaces of the piezoelectric diaphragm 10 and a bonding film (Au film) formed by physical vapor deposition and laminated on the underlying film. Also, the configuration of the laminated film forming the bonding pattern is not limited to a two-layer structure of a Ti film and an Au film, and may be a three-layer or more structure including other films (for example, a barrier film formed between the Ti film and the Au film).

[0041] FIG. 5 is a plan view showing a first main surface 21 which is one of the main surfaces (outer surface) of the single first sealing member 20 before joining. FIG. 6 is a plan view showing a second main surface 22 which is the other main surface (joining surface with the piezoelectric vibrating plate 10) of the single first sealing member 20 before joining. The first sealing member 20 is a rectangular parallelepiped substrate formed from a single glass wafer or quartz wafer, and the second main surface 22 of the first sealing member 20 is formed as a flat and smooth surface (mirror finish).

[0042] On the first main surface 21 of the first sealing member 20, as shown in FIG. 5, two electrode patterns 211 and wiring patterns 212 and 213 are formed. The electrode pattern 211 is a mounting pad for mounting the thin-film thermistor 5 (see FIG. 1). The wiring pattern 212 is a wiring pattern that forms part of the wiring path for connecting the first exciting electrode 111 to the external electrode terminal 321 (see FIG. 8). The wiring pattern 213 is a wiring pattern that forms part of the wiring path for connecting the second exciting electrode 121 to the external electrode terminal 321.

[0043] On the second main surface 22 of the first sealing member 20, as shown in FIG. 6, a joining pattern for joining the first sealing member 20 to the piezoelectric vibrating plate 10 is formed. This joining pattern includes a sealing pattern for hermetically sealing the internal space of the package and a conductive pattern for conducting wiring and electrodes.

[0044] As the sealing pattern in the first sealing member 20, a sealing-side first joining pattern 221 is formed. The sealing-side first joining pattern 221 is formed in an annular shape in plan view, and the inner region thereof becomes the sealing region. As the conductive pattern in the first sealing member 20, four connection joining patterns 222 are formed near the four corners (corner portions) outside the sealing region (outside the sealing-side first joining pattern 221), and connection joining patterns 223 to 225 are formed inside the sealing region (inside the sealing-side first joining pattern 221). Incidentally, the connection joining pattern 224 and the connection joining pattern 225 are connected by a wiring pattern 226.

[0045] Further, in the first sealing member 20, a plurality of through holes 23 are formed between the first main surface 21 and the second main surface 22, and through electrodes for achieving electrical continuity between the first main surface 21 and the second main surface 22 are formed on the inner wall surfaces of the respective through holes 23. Specifically, four through holes 23 (and through electrodes) are formed to achieve electrical continuity between the electrode pattern 211 or the wiring patterns 212, 213 and the connection bonding pattern 222, and one through hole 23 (and through electrode) is formed to achieve electrical continuity between the wiring pattern 212 and the connection bonding pattern 223, and one through hole 23 (and through electrode) is formed to achieve electrical continuity between the wiring pattern 213 and the connection bonding pattern 225.

[0046] In the first sealing member 20, the sealing-side first bonding pattern 221, the connection bonding patterns 222 to 225, and the wiring pattern 226 can be formed in the same process. Specifically, these can be formed from an underlying film (Ti film) formed by physical vapor deposition on the second main surface 22 of the first sealing member 20 and a bonding film (Au film) laminated by physical vapor deposition on the underlying film.

[0047] FIG. 7 is a plan view showing the first main surface 31, which is one of the main surfaces (bonding surface with the piezoelectric vibrating plate 10), of the single second sealing member 30 before bonding. FIG. 8 is a plan view showing the second main surface 32, which is the other main surface (outer surface), of the single second sealing member 30 before bonding. The second sealing member 30 is a rectangular parallelepiped substrate formed from a single glass wafer or quartz wafer, and the first main surface 31 of this second sealing member 30 is formed as a flat and smooth surface (mirror finish).

[0048] As shown in FIG. 7, a bonding pattern for bonding the second sealing member 30 to the piezoelectric vibrating plate 10 is formed on the first main surface 31 of the second sealing member 30. This bonding pattern includes a sealing pattern for hermetically sealing the internal space of the package and a conductive pattern for electrically connecting wirings and electrodes.

[0049] As the sealing pattern in the second sealing member 30, a second bonding pattern 311 on the sealing side is formed. The second bonding pattern 311 on the sealing side is formed in an annular shape in a plan view, and the inner region thereof becomes the sealing region. As the conductive pattern in the second sealing member 30, four connection bonding patterns 312 are formed near the four corners (corner portions) outside the sealing region (outside the second bonding pattern 311 on the sealing side).

[0050] As shown in FIG. 8, four external electrode terminals 321 for electrically connecting the present device 1 to the outside are provided on the second main surface 32 of the second sealing member 30. The external electrode terminals 321 are respectively located at the four corners (corner portions) of the second sealing member 30.

[0051] Further, a plurality of through holes 33 are formed in the second sealing member 30 between the first main surface 31 and the second main surface 32, and through electrodes for achieving electrical continuity between the first main surface 31 and the second main surface 32 are formed on the inner wall surfaces of the respective through holes 33. Specifically, four through holes 33 (and through electrodes) are formed to achieve electrical continuity between the connection bonding pattern 312 and the external electrode terminal 321.

[0052] In the second sealing member 30, the second bonding pattern 311 on the sealing side and the connection bonding pattern 312 can be formed by the same process. Specifically, these can be formed from an underlying film (Ti film) formed by physical vapor deposition on the first main surface 31 of the second sealing member 30 and a bonding film (Au film) laminated by physical vapor deposition on the underlying film.

[0053] In the SAW device 2, the piezoelectric diaphragm 10 and the first sealing member 20 are diffusion-bonded in a state where the vibration-side first bonding pattern 113 and the sealing-side first bonding pattern 221, which are sealing patterns, are overlapped, and the piezoelectric diaphragm 10 and the second sealing member 30 are diffusion-bonded in a state where the vibration-side second bonding pattern 123 and the sealing-side second bonding pattern 311, which are sealing patterns, are overlapped, thereby manufacturing a package having a sandwich structure. That is, the vibration-side first bonding pattern 113 and the sealing-side first bonding pattern 221 are joined to form a sealing pattern layer between the piezoelectric diaphragm 10 and the first sealing member 20, and the vibration-side second bonding pattern 123 and the sealing-side second bonding pattern 311 are joined to form a sealing pattern layer between the piezoelectric diaphragm 10 and the second sealing member 30. Thereby, the internal space of the package, that is, the accommodation space of the vibrating portion 13 is hermetically sealed.

[0054] At this time, the connection bonding patterns, which are conductive patterns, are also joined to each other, and the joined conductive patterns form a conductive pattern layer between the piezoelectric diaphragm 10 and the first sealing member 20 or between the piezoelectric diaphragm 10 and the second sealing member 30. In the SAW device 2, electrical conduction is obtained between the first excitation electrode 111 and the second excitation electrode 121 and the external electrode terminals 321 (at the lower right and upper left in FIG. 8). Further, the thin-film thermistor 5 mounted on the SAW device 2 is configured to obtain electrical conduction with the external electrode terminals 321 (at the upper right and lower left in FIG. 8).

[0055] FIG. 9(a) is a top view of the thin-film thermistor 5, and FIG. 9(b) is a bottom view of the thin-film thermistor 5. The thin-film thermistor 5 is an NTC thermistor thinned to be suitable in combination with the SAW device 2. A common electrode 52 serving as a relay electrode is formed on one main surface of the thermistor flat plate 51 which is a single plate, and a divided electrode 53 serving as an operating electrode is formed on the other main surface. In the present device 1, while the thickness of the SAW device 2 is about 120 μm, the thickness of the thin-film thermistor 5 can be set to be less than half of the thickness of the SAW device 2 (about 50 μm).

[0056] As the thermistor flat plate 51, for example, a manganese-based semiconductor ceramic plate is used. More specifically, an Mn-Fe-Ni-based material is made into a slurry together with a binder or the like, and a wafer-shaped thermistor flat plate 51 is formed into a green sheet using a thick film forming technique such as screen printing technology or doctor blade technology, and this is sintered and formed into a wafer of the thermistor flat plate 51 by a firing technique. Note that not only Mn-Fe-Ni-based materials but also Mn-Co-based or Fe-Ni-based materials may be used.

[0057] The common electrode 52 is formed on the entire surface (or almost the entire surface) of the thermistor flat plate 51. The divided electrodes 53 are arranged at two positions at both ends along one direction (preferably the longitudinal direction) of the thermistor flat plate 51, and are formed on an area of more than half of the thermistor flat plate 51. Each electrode forms an electrode film (metal film) on the thermistor flat plate 51 by sputtering and performs patterning using photolithography technology. As a specific metal material, a laminated structure of a Ti film, a NiTi film, and an Au film may be adopted, or other metal film configurations may be used. When the laminated structure of the Ti film, the NiTi film, and the Au film is adopted, when the thin plate thermistor 5 is finally soldered to the mounting substrate (in this case, the first sealing member 20), solder erosion is less likely to occur and stable conductive bonding can be performed.

[0058] In this way, since the thin plate thermistor 5 has a wide-area metal electrode (common electrode 52 and divided electrode 53), it can act advantageously as a shielding member for the sand device 2. In order to also use the thin plate thermistor 5 as a shielding member, in a plan view of the present device 1, the thin plate thermistor 5 is arranged so as to at least partially overlap with the vibrating portion 13 of the sand device 2 (see FIG. 1). Further, if the thin plate thermistor 5 is arranged so as to overlap with the entire first excitation electrode 111 and the second excitation electrode 121 in a plan view, the shielding effect of the thin plate thermistor 5 can be maximally exerted, which is more preferable.

[0059] Further, the thin plate thermistor 5 is arranged such that both ends thereof overlap the outer frame portion 14 at least on two opposite sides of the sand device 2. The first sealing member 20 and the second sealing member 30 in the sand device 2 are extremely thin substrates, and brittle materials such as glass and crystal are used. For this reason, the strength of the sand device 2 is particularly low in the central portion (the region where the outer frame portion 14 does not exist in the piezoelectric vibrating plate 10). In such a sand device 2, if the thin plate thermistor 5 is arranged in the region of the central portion of the sand device 2, there is a risk that the first sealing member 20 may crack due to the pressing force when mounting the thin plate thermistor 5.

[0060] On the other hand, by joining the thin plate thermistor 5 to the outer peripheral portion of the sand device 2 (the region where the outer frame portion 14 exists in the piezoelectric vibrating plate 10), that is, by arranging the end portions of the thin plate thermistor 5 so as to overlap the outer frame portion 14, cracking of the first sealing member 20 can be suppressed, and the strength of the present device 1 can be ensured. In particular, by making the thin plate thermistor 5 overlap the sealing portion of the sand device 2 (a sealing pattern such as the vibration-side first bonding pattern 113), the present device 1 becomes more stable in terms of strength. In FIGS. 1 and 2, an example is shown in which both ends of the thin plate thermistor 5 are arranged so as to overlap the outer frame portion 14 on two sides facing each other in the short side direction of the sand device 2. However, the thin plate thermistor 5 may overlap the outer frame portion 14 on two sides facing each other in the long side direction of the sand device 2. Alternatively, the thin plate thermistor 5 may be arranged so as to overlap not only two opposite sides of the sand device 2 but also three sides or four sides.

[0061] The thin-film thermistor 5 has a split electrode 53 on its lower surface (the joint surface with the sand device 2), and the split electrode 53 is electrically joined to the electrode pattern 211 of the first sealing member 20 and mounted on the sand device 2. At this time, it is preferable that the split electrode 53 and the electrode pattern 211 are electrically joined by a conductive resin adhesive 61 (see FIG. 2). However, the present invention is not limited to this, and the split electrode 53 and the electrode pattern 211 may be joined by Au (gold) bumps. Further, the gap between the thin-film thermistor 5 and the sand device 2 (the gap where the conductive resin adhesive 61 does not exist) is preferably filled with a non-conductive resin adhesive 62 (see FIG. 2). The non-conductive resin adhesive 62 may not only be filled on the lower surface of the thin-film thermistor 5 but also be a sealing resin that seals the entire thin-film thermistor 5. Incidentally, a silicone-based resin can be preferably used as the conductive resin adhesive 61, and an epoxy-based resin can be preferably used as the non-conductive resin adhesive 62.

[0062] Thus, when the thin-film thermistor 5 is surface-joined to the sand device 2 by the conductive resin adhesive 61 and the non-conductive resin adhesive 62, the thermal conductivity between the thin-film thermistor 5 and the sand device 2 can be improved. Thereby, the thin-film thermistor 5 can be held at a temperature close to the vibrating portion 13 of the sand device 2. Also, the surface joining of the sand device 2 and the thin-film thermistor 5 has the merit of improving the strength of the present device 1.

[0063] When the conductive resin adhesive 61 and the non-conductive resin adhesive 62 are used for joining the thin-film thermistor 5, it is preferable that the conductive resin adhesive 61 has higher thermal conductivity than the non-conductive resin adhesive 62. Thereby, the thermal conductivity between the thin-film thermistor 5 and the sand device 2 can be further improved. Also, it is preferable that the non-conductive resin adhesive 62 has higher hardness than the conductive resin adhesive 61. Thereby, the stress between the thin-film thermistor 5 and the sand device 2 can be relaxed, and the package strength of the present device 1 can be improved.

[0064] The embodiments disclosed this time are illustrative in all respects and are not a basis for limiting interpretation. Therefore, the technical scope of the present invention is not construed only by the above-described embodiments, but is defined based on the description of the claims. Also, all changes within the meaning and scope equivalent to the claims are included.

[0065] For example, the present device 1 in the above description has a structure mounted on the thin-film thermistor 5 of the sand device 2 and exemplifies a device used as a piezoelectric vibrator. However, it may be a device used as a piezoelectric oscillator having an IC chip further mounted on the thin-film thermistor 5.

[0066] The embodiments disclosed this time are illustrative in all respects and are not a basis for limiting interpretation. Therefore, the technical scope of the present invention is not construed only by the above-described embodiments, but is defined based on the description of the claims. Also, all changes within the meaning and scope equivalent to the claims are included.

[0067] For example, the present device 1 in the above description has a structure mounted on the thin-film thermistor 5 of the sand device 2 and exemplifies a device used as a piezoelectric vibrator. However, it may be a device used as a piezoelectric oscillator having an IC chip further mounted on the thin-film thermistor 5.

[0068] 〔Embodiment 2〕 Hereinafter, other embodiments of the present invention will be described in detail with reference to the drawings. In this embodiment, a case where the thermistor-mounted piezoelectric vibration device of the present invention is suitable for a crystal vibration device with a thermistor is exemplified. In addition, in the present Embodiment 2, members having the same functions and configurations as the thermistor-mounted piezoelectric vibration device 1 according to Embodiment 1 are given the same member numbers (even if the shapes exemplified in the drawings are different).

[0069] The crystal oscillator device with a thermistor according to this embodiment consists of a crystal oscillator device Xtl and a thermistor (corresponding to the thin-film thermistor 5). As shown in FIG. 10, the crystal oscillator device Xtl consists of a crystal oscillation plate (corresponding to the piezoelectric oscillation plate 10), a first sealing member 20, and a second sealing member 30, and is configured by laminating and stacking them in the order of the first sealing member 20, the piezoelectric oscillation plate 10, and the second sealing member 30. Further, the thermistor 5 is electrically joined to the upper surface of the crystal oscillator device Xtl.

[0070] The piezoelectric oscillation plate 10 is made of an AT-cut crystal oscillation plate and is rectangular plate-shaped as a whole. The piezoelectric oscillation plate 10 consists of a vibration part 13, holding parts 15 and 15t connected to two corner parts of the vibration part 13, and an outer frame part 14 arranged on the outer periphery of the vibration part and connected to the holding parts 15 and 15t. Note that a through part 17 is formed in a circumferential shape between the vibration part 13 and the outer frame part 14 except for the holding parts 15 and 15t.

[0071] The vibration part 13 is rectangular with opposing long sides and short sides and has four corner parts. Note that the vibration part may be square when viewed in plan. Also, a rectangular first excitation electrode 111 and a second excitation electrode 121 are formed on one main surface and the other main surface (front and back main surfaces) at approximately the center of the vibration part 13. Strip-shaped first lead electrodes 112 and second lead electrodes 122 are connected to the respective corner parts of the first excitation electrode 111 and the second excitation electrode 121 and are drawn out toward both ends of one side (the corner part of the vibration part). Note that the first lead electrode 112 is drawn out to the outer frame part 14 via the holding part 15, and the second lead electrode 122 is drawn out to the outer frame part 14 via the holding part 15t, and finally is drawn out to the external electrode terminals 321a and 321b formed on the second sealing member 30 described later.

[0072] Specifically, the first lead electrode 112 passes through the surface of the holding portion 15, is drawn out to the other main surface through a metal via (through metal) V1 formed in the outer frame portion 14, and is further connected to a metal via V2 formed in a second sealing member 30 described later. The metal via V2 is electrically connected to an external electrode terminal 321a formed on the other main surface of the second sealing member 30. Also, the second lead electrode 122 passes through the back surface of the holding portion 15t, is drawn out to the other surface of the piezoelectric vibrating plate 10, and is electrically connected to a metal via V3 formed in the opposing second sealing member 30. The metal via V3 is electrically connected to an external electrode terminal 321b formed on the other main surface of the second sealing member 30.

[0073] The first excitation electrode 111, the second excitation electrode 121, the first lead electrode 112, and the second lead electrode 122 are composed of a plurality of metal films. For example, a Ti film is formed in contact with the piezoelectric vibrating plate 10, and a multi-layer structure with an Au film formed on top thereof. As an example of the thickness of each specific metal film, for example, a Ti film of 5 nm and an Au film of 200 nm can be given, but these may be changed according to desired characteristics.

[0074] A thick portion 13a is formed on one end side of the vibrating portion 13. The thick portion 13a is at one end side in the X-axis direction and is formed over the entire one end side extending in the Z'-axis direction. The thick portion 13a is formed thicker than the thickness of the vibrating portion 13.

[0075] As shown in FIG. 11, a holding portion 15 is provided at one corner C1 of the vibrating portion 13, and a holding portion 15t is provided at another corner C2. Each of the holding portions 15, 15t is connected to the outer frame portion 14. In the present embodiment, the vibrating portion, the holding portion, and the frame portion are integrally formed from a crystal plate using photolithography technology and wet etching technology. Note that dry etching technology may be used instead of wet etching.

[0076] As shown in FIGS. 10 and 13, the holding portion 15 is configured to be thicker than the vibrating portion 13 and the thick portion 13a, and a taper T2 on an inclined surface is formed from the thick portion 13a to the upper surface of the holding portion 15, and a taper T3 on an inclined surface is formed from the vibrating portion 13 to the holding portion 15, respectively. Further, although the holding portion 15 is connected to the outer frame portion 14, a taper T1 is formed on the upper surface of the outer frame portion 14 from the holding portion 15. With such a configuration, the respective thicknesses are set as the vibrating portion < thick portion < holding portion < frame body portion. Note that the thicknesses of the thick portion 13a and the holding portion 15 may be equal. By forming these respective tapers, the boundary region can be rounded. Note that when the step of the boundary region is small or when the risk of disconnection is low, there is no practical problem even if the taper is not formed.

[0077] A specific dimensional example of the piezoelectric vibrating plate 10 is shown below. The piezoelectric vibrating plate 10 uses a rectangular AT-cut crystal plate, and its outer dimensions are 1.2 mm in width and 1.0 mm in length. The outer dimensions of the vibrating portion 13 are 0.7 mm in width and 0.7 mm in length. The width of the outer frame portion 14 is 0.2 mm in width and 0.1 mm in length. The dimensions of the holding portion 15 are 0.05 mm in width and 0.15 mm in length. Regarding the thickness of each component, the thickness of the outer frame portion 14 is 0.04 mm, the thickness of the holding portion 15 is 0.03 mm, the thickness of the thick portion 13a is 0.017 mm (17 μm), and the thickness of the vibrating portion 13 is 0.005 mm (5 μm). Note that it is preferable that the thickness of the thick portion 13a is greater than the thickness of the vibrating portion 13 by 10 or more μm in terms of ensuring mechanical strength.

[0078] Note that in the present embodiment, a configuration in which thinning is performed only on one main surface of the piezoelectric vibrating plate 10 is adopted. For example, thinning is performed to a desired frequency (thickness) by an etching technique only from one main surface side. In this case, since etching is not performed on the other main surface side, a decrease in vibration characteristics due to roughening of the surface by etching can be suppressed. Note that a configuration in which thinning is performed from both main surfaces may be adopted.

[0079] On the front and back outer peripheral ends of the outer frame portion 14, a circumferential seal film (corresponding to the vibration-side first bonding pattern 113 and the vibration-side second bonding pattern 123) is formed. These seal films, similar to the aforementioned electrode film, are in a multilayer structure where a Ti film is formed in contact with the piezoelectric diaphragm 10, and an Au film is formed on top of it.

[0080] Also, at a position away from the holding portion 15 of the outer frame portion 14 and on the inner peripheral side, connection electrodes 141 and 142 are formed. The connection electrodes 141 and 142 each consist of a strip-shaped metal film formed from the upper surface of the outer frame portion 14 through the inner surface to the lower surface of the outer frame portion 14. These connection electrodes 141 and 142 are electrically connected to the electrode pads (corresponding to the divided electrodes 53) of the thermistor 5 described later, and are also electrically connected to the external electrode terminals 321c and 321d of the second sealing member 30.

[0081] The first sealing member 20 is made of a rectangular plate-shaped AT-cut crystal plate and has the same outer shape and outer size as the piezoelectric diaphragm 10. On the other main surface (the surface facing the piezoelectric diaphragm 10) of the first sealing member 20, a circumferential seal film (corresponding to the sealing-side first bonding pattern 221) corresponding to the vibration-side first bonding pattern 113 is formed.

[0082] Also, on one main surface of the first sealing member 20, a pair of rectangular electrode pads (corresponding to the electrode pattern 211) having long sides and short sides are provided in parallel, and electrodes of each electrode pad 211 are drawn out to the other main surface through metal vias from the connection electrode 211a.

[0083] The second sealing member 30 is made of a rectangular plate-shaped AT-cut crystal plate and has the same outer shape and outer size as the piezoelectric diaphragm 10. On the surface of the second sealing member 30 facing the piezoelectric diaphragm 10, a circumferential seal film (corresponding to the sealing-side second bonding pattern 311) corresponding to the vibration-side second bonding pattern 123 is formed.

[0084] On the surface of the second sealing member 30 that does not face the piezoelectric diaphragm 10, external electrode terminals 321a to 321d are formed. The external electrode terminals 321a to 321d are rectangular in shape and are formed at the respective corners of the second sealing member 30. The external electrode terminals 321a and 321b are electrically connected to the first excitation electrode 111 and the second excitation electrode 121, respectively, and the external electrode terminals 321c and 321d are electrically connected to the terminals 53 and 53 of the thermistor 5. Note that the metal film constituting these external electrode terminals 321 has a laminated structure of a Ti film, a NiTi film, and an Au film.

[0085] In addition, in the second sealing member 30, a metal via V2 that penetrates through from the front to the back is formed in the vicinity of the region corresponding to the holding portion 15 and is electrically connected to the aforementioned metal via V1. Also, a metal via V3 that penetrates through from the front to the back is formed in the vicinity of the region corresponding to the holding portion 15t. With such a configuration, the first lead-out electrode 112 formed on the piezoelectric diaphragm 10 is connected to the external electrode terminal 321a via the metal via V2, and the second lead-out electrode 122 is connected to the external electrode terminal 321b via the metal via V3. Furthermore, metal vias V4 and V5 corresponding to the connection electrodes 141 and 142 are formed, and the metal vias V4 and V5 are electrically connected to the external electrode terminals 321c and 321d, respectively. With such a configuration, the external electrode terminals 321a and 321b for the crystal vibration device and the external electrode terminals 321c and 321d for the thermistor are arranged side by side on the long side and face each other. Note that, depending on the design change of the electrode wiring, the two external electrode terminals 321a and 321b for the crystal vibration device Xtl and the two external electrode terminals 321c and 321d for the thermistor may be arranged diagonally.

[0086] The thermistor 5 is electrically and mechanically connected to the electrode pads 211 and 211 of the first sealing member 20. The thermistor 5 is a rectangular plate-shaped NTC thermistor. The rectangular plate-shaped thermistor element (corresponding to the thermistor flat plate 51) has a thickness G2. A common electrode 52 is formed on the entire one main surface of the thermistor element 51, and rectangular electrode pads 53 and 53 are formed on the other main surface at a constant interval G1 in the long side direction.

[0087] The thermistor 5 forms terminals as a resistor with a pair of electrode pads 53, 53 formed on the thermistor element 51. However, the conductive path flows from one electrode pad 53 through the common electrode 52 to the other electrode pad 53. With such a configuration, the cross-sectional area of the conductive path is greatly increased, and since it can be made into a path where the surfaces of the electrode pads 53, 53 and the common electrode 52 face each other, the resistance value can be lowered with a small area, the characteristics are likely to be stable, and the withstand voltage can also be improved.

[0088] By the way, when the electrode pads 53, 53 are configured to be close to each other, although it depends on the applied voltage, the flow path between the electrode pads 53, 53 becomes dominant in the conductive path, and there were cases where the desired resistance value could not be obtained. Therefore, in implementation, the distance G2a between one electrode pad 53 and the common electrode 52, the distance G2b between the other electrode pad 53 and the common electrode 52, and the distance G1 between the electrode pads 53, 53 are set such that G2a + G2b < G1. With such a setting, the desired resistance value can be obtained, and the accuracy as a thermistor can be stabilized.

[0089] The larger the contact area of the thermistor 5 with the crystal vibration device Xtl, the more accurately the temperature related to the crystal vibration device Xtl can be detected. Therefore, the electrode pads 53, 53 formed on the thermistor 5 are preferably larger with respect to the area of the thermistor 5. However, if they are too large, short circuits between adjacent electrode pads or short circuits due to conductive bonding materials are likely to occur. When the contact area becomes small, the temperature detection accuracy of the crystal vibration device Xtl decreases. Therefore, depending on the desired resistance value, if the total area of each electrode pad 53 is 40% to 85% of the area of the thermistor 5, stable temperature detection can be performed. If it is 40% or less, the electrode pads of the thermistor 5 become too small, and the temperature information of the crystal vibration device Xtl cannot be accurately detected, and its resistance value becomes too high, which may reduce the temperature detection ability as the thermistor 5. Also, if it is 85% or more, the risk of short circuits including the conductive bonding material increases, and when a short circuit occurs, the thermistor 5 stops functioning.

[0090] Specific dimension examples are shown below. The outer dimensions of the thermistor 5 (the outer dimensions of the thermistor element 51) are 0.8 mm for the long side, 0.6 mm for the short side, and 0.05 mm for the thickness, and its area is 0.48 mm 2 2. Also, the outer dimensions of each electrode pad 53 formed on the thermistor element 51 are 0.52 mm for the long side (the short side of the thermistor element 51) and 0.3 mm for the short side (the long side of the thermistor element 51), and its area is 0.156 mm 2 2. With such a configuration, the total area of each electrode pad 53 is set to about 65% of the area of the thermistor 5. Also, the distances G2a and G2b between the electrode pad 53 and the common electrode 52 are 0.05 mm each, and the distance G1 between the electrode pads is set to 0.12 mm, and it is set so that G2a + G2b < G1 holds.

[0091] Another specific example is shown below. The outer dimensions of the thermistor 5 (the outer dimensions of the thermistor) are 0.7 mm for the long side, 0.6 mm for the short side, and 0.04 mm for the thickness, and its area is 0.42 mm 2 2. Also, the outer dimensions of each electrode pad 53 formed on the thermistor element 51 are 0.58 mm for the long side (the short side of the thermistor element 51) and 0.3 mm for the short side (the long side of the thermistor element 51), and its area is 0.174 mm 2 2. With such a configuration, the total area of each electrode pad 53 is set to about 83% of the area of the thermistor 5. Also, the distances G2a and G2b between the electrode pad 53 and the common electrode 52 are 0.04 mm each, and the distance G1 between the electrode pads is set to 0.09 mm, and it is set so that G2a + G2b < G1 holds. Note that the above dimensions may be appropriately designed according to the size and characteristics of the crystal oscillator device Xtl and the required specifications of the crystal oscillator device with a thermistor.

[0092] The plate-shaped thermistor is made, for example, by making a Mn-Fe-Ni-Ti-based material into a slurry together with a binder or the like, creating a green sheet of the thermistor wafer using a thick film forming technique such as screen printing technology or doctor blade technology, and sintering and molding the plate-shaped thermistor wafer by a firing technique.

[0093] For this plate-shaped thermistor wafer, an electrode film (metal film) is formed by sputtering, and patterning is performed using photolithography technology. As a specific metal material, a laminated structure of a Ti film, a NiTi film, and an Au film similar to the metal film constituting the terminal electrode may be adopted, or other metal film structures may be used. When the laminated structure of the Ti film, the NiTi film, and the Au film is adopted, when the thermistor is finally soldered to the mounting substrate, solder erosion is less likely to occur and stable conductive bonding can be performed. Also, the metal film structure of the electrode pads 53, 53 and the metal film structure of the common electrode 52 may be made different. For example, the metal film structure of the electrode pads 53, 53 may be a laminated structure of the Ti film, the NiTi film, and the Au film, and the metal film structure of the common electrode 52 may be a laminated structure of the Ti film and the Au film.

[0094] In this way, by forming the metal films that become the electrode pads 53, 53 and the common electrode 52 on the single-layer plate-shaped thermistor element 51 by thin film forming means such as sputtering, an extremely thin plate-shaped thermistor can be obtained. Note that the surface roughness of the plate-shaped thermistor may be reduced by lapping and polishing the surface in the state of the thermistor wafer. With such a configuration, the electrode film (metal film) can be stably formed, the manufacturing accuracy can be improved, and thus the performance as the thermistor 5 can be made highly accurate.

[0095] As shown in FIG. 13, the crystal vibration device Xtl has a configuration in which a first sealing member 20, a piezoelectric vibration plate 10, and a second sealing member 30 are stacked in this order. As described above, each of these constituent members is made of a crystal plate, and its surface is a smooth surface by mirror polishing. As a specific example, the average surface roughness Ra is preferably 0.3 to 0.1 nm. By forming the seal film on such a smooth surface, the metal film (uppermost Au film) on the surface also has a very smooth surface state.

[0096] The joining of the first sealing member 20, the piezoelectric diaphragm 10, and the piezoelectric diaphragm 10 and the second sealing member 30 is performed by subjecting the Au of the metal film to surface treatment and then pressure-joining the two by the diffusion bonding method. As a result, the vibrating portion 13 of the piezoelectric diaphragm 10 is hermetically sealed in a state surrounded by the first and second sealing members 20 and 30 and the outer frame portion 14 by the seal portions S1 and S2 formed by joining the seal films. Note that the inside of the hermetic seal is a vacuum or an inert gas atmosphere.

[0097] A thermistor 5 is mounted on the upper surface of the crystal oscillator device Xtl having the above configuration, that is, one main surface of the first sealing member 20. Specifically, the electrode pads 211, 211 formed on the upper surface of the crystal oscillator device Xtl and the electrode pads 53, 53 formed on the thermistor 5 composed of a plate-shaped thermistor are surface-joined with conductive bonding materials (for example, conductive resin adhesives 61) R1, R1. The electrode pads 211, 211 are configured to have a larger area than the electrode pads 53, 53. As a result, the conductive bonding materials R1, R1 can conductively bond the crystal oscillator device Xtl and the thermistor 5 in a state having a fillet, so that the bonding strength between the two can be improved. The conductive bonding material R1 is configured by adding conductive fillers such as silver powder and silver flakes to a paste-like silicone-based resin bonding material, and has excellent thermal conductivity. This, combined with the fact that the electrode pads are surface-joined, results in good heat conduction, and the temperature of the crystal oscillator device Xtl by the thermistor 5 can be measured with high accuracy with little time lag. When the conductive bonding material R1 is a conductive resin adhesive 61, other resins such as urethane-based resins and epoxy-based resins may be used in addition to the silicone-based resin. Further, the conductive bonding material R1 is not limited to the conductive resin adhesive 61 and may be solder.

[0098] As shown in FIG. 13, in the present embodiment, the thermistor 5 composed of a plate-shaped thermistor is covered with a resin material R2. The resin material R2 is configured to cover the upper surface of the crystal oscillator device Xtl and is configured to cover the thermistor 5, the electrode pads 211, 211 provided on the crystal oscillator device Xtl, and the conductive bonding material R1. The resin material R2 used here is an epoxy-based resin with silica (SiO2 ) It has a structure with a filler added, and the thermal conductivity is lower than that of the conductive bonding material R1. Note that for the resin material R2, other resin materials such as urethane-based resins and silicone-based resins may be used in addition to epoxy-based resins. With such a structure, the effect of suppressing the heat detected by the thermistor 5 from escaping to the outside can be obtained.

[0099] With the above structure, the temperature fluctuation of the crystal vibration device Xtl can be detected by the thermistor 5 with little time lag through the electrode pads 211, 53 and the conductive bonding material R1. Also, since the thermistor 5 is coated with a resin material having a lower thermal conductivity than the conductive bonding material, the temperature absorbed by the thermistor 5 does not leak to the outside. As a result, the operating temperature of the crystal vibration device Xtl can be accurately detected, so that high-precision temperature detection can be performed. Note that in addition to the thermistor 5 on the upper surface of the crystal vibration device Xtl, an IC component equipped with an oscillation circuit and a temperature compensation circuit may be mounted and conductively bonded to the crystal vibration device Xtl and the thermistor 5. With such a structure, a crystal vibration device constituting a temperature compensation type crystal oscillator can be obtained.

[0100] According to the present embodiment, the thick portion 13a is formed along substantially the entire area of one end side where the holding portions 15, 15t are formed in the vibrating portion 13, and the other end sides have a thickness configuration of a thin vibrating plate corresponding to a high frequency. Therefore, the vibration excited in the vibrating portion 13 can vibrate in a state hardly affected by the boundary conditions due to the thick portion 13a, whereby spurious and the like are less likely to occur, and a piezoelectric vibrating plate 10 in which the CI value (series resonance resistance) can also be kept in a good state can be obtained. Also, the mechanical strength of the vibrating portion 13 can be improved by the thick portion 13a.

[0101] Also, as described above, the holding portion 15 has a thickness greater than or equal to that of the thick portion 13a, and a tapered portion is formed between the outer frame portion 14 and the holding portion 15, and between the thick portion 13a and the vibrating portion 13. As described above, the boundary can be rounded by this taper formation. Accordingly, the first and second lead electrodes 112 and 122 drawn from the first and second excitation electrodes 111 and 121 to one side edge of the piezoelectric vibrating plate 10 are formed on this tapered portion and do not pass through an acute corner region (step portion), so that a decrease in electrode conduction and electrode disconnection can be prevented. Thereby, a piezoelectric vibrating plate 10 having good electrical characteristics can be obtained.

[0102] According to the present embodiment, the outer frame portion 14 and the vibrating portion 13 are connected by a plurality of holding portions 15 and 15t, and the thickness of the holding portion 15t is smaller than the thickness of the holding portion 15. Therefore, the mechanical strength can be stabilized by holding with a plurality of holding portions, and by providing a holding portion with a small (thin) thickness, it is possible to suppress the inhibition of the vibration of the vibrating portion. Thereby, a decrease in electrical characteristics as the crystal vibration device Xtl can be suppressed, and practical electrical performance can be ensured. Further, not limited to the present embodiment, the vibrating portion 13 may be connected at only one location of the holding portion 15.

[0103] In the piezoelectric vibrating plate 10, this may be configured as a thin portion instead of the through portion 17. In this case, the vibrating portion is connected to the frame body portion by the holding portion and the thin portion.

[0104] In the present embodiment, an example of the metal film of the first and second excitation electrodes 111 and 121 and the metal film for sealing (i.e., the seal film) is a multilayer structure of Ti and Au, but it is not limited to this metal film. For example, a multilayer structure of Ti, NiTi, and Au may be used.

[0105] Also, the bonding between the first and second sealing members 20 and 30 and the piezoelectric diaphragm 10 was performed by the diffusion bonding method. However, for example, it may be brazing using an AuSn alloy brazing material, or other brazing materials such as Sn alloy brazing may be used. In the case of this brazing, the metal film structure is also different. For example, a structure in which an Ag or Cu film is formed on a Cr underlayer, or a structure in which an alloy film with Au is formed may be used.

[0106] In the above description, the materials of the first and second sealing members 20 and 30 used a crystal plate. However, a glass material or a ceramic material may be used instead of the crystal plate. Also, although the shape was exemplified as a plate-like structure, a recess may be provided at a position facing the piezoelectric diaphragm 10. When the recess is provided in this way, the chance of contact between the vibrating portion 13 and the first and second sealing members 20 and 30 can be reduced, so that the characteristics as the crystal vibration device Xtl can be stabilized.

[0107] A modification in the second embodiment will be described with reference to FIG. 16. In FIG. 16, the detailed configuration of the crystal vibration device Xtl is omitted. It is a configuration in which a thermistor 5 is mounted on the upper surface of the crystal vibration device Xtl, but the configuration and arrangement of the thermistor 5 are different.

[0108] Electrode pads 24 and 24 are formed on the upper surface of the first sealing member 20. These electrode pads 24 and 24 are formed offset to the left side in the drawing, different from the example in FIG. 13. As a result, a region where the electrode pads 24 and 24 are not formed can be secured on the upper surface of the first sealing member 20. This region can be used as an adjustment region 25. When the first sealing member 20 is made of a light-transmissive material, the adjustment region 25 can transmit an energy beam B such as a laser beam. Therefore, by irradiating the energy beam onto the metal film formed on the piezoelectric diaphragm 10 to partially remove these metal films, the frequency of the crystal vibration device Xtl can be adjusted.

[0109] Further, a metal film for adjustment is formed in advance inside the first sealing member 20, and by irradiating the metal film for adjustment with an energy beam, the metal film for adjustment is vaporized and adhered to the metal film formed on the piezoelectric diaphragm 10, whereby the frequency of the crystal vibration device Xtl can be adjusted.

[0110] The thermistor 5 has a configuration in which electrode pads 54, 54 are formed on the other main surface of the thermistor element, and an electrode gap G3 is formed, but no electrode film is formed on one main surface. Therefore, a conductive path is formed between the electrode pads 54, 54, and it functions as a thermistor.

[0111] By joining the electrode pads 54, 54 and the electrode pads 24, 24 with a conductive joining material R1 made of solder, the two electrode pads are conductively surface-joined, thereby joining the two in a state of good thermal conductivity. In the example of FIG. 16, an insulating resin material R3 with good thermal conductivity is filled between the conductive joining materials R1, R1. With these configurations, the other main surface of the thermistor 5 is in a state of being surface-joined to the crystal vibration device Xtl over the entire surface.

[0112] Then, the resin material R2 is formed covering the entire upper surface (one main surface) of the first sealing member 20. As a result, the entire thermistor 5 is also covered with the resin material R2. Note that the resin material R2 may be formed only in the mounting region of the thermistor 5. In this case, since the adjustment region 25 is not covered with the resin material R2, there is an advantage that frequency adjustment by the energy beam B can be performed after joining the thermistor.

[0113] According to this embodiment, since the thermistor 5 is joined to the crystal vibration device Xtl over substantially the entire other main surface with the conductive joining material (solder) R1 and the insulating resin material R3, the thermistor 5 can surely and accurately capture the temperature change of the crystal vibration device Xtl. Further, by covering with the resin material R2, heat dissipation can also be suppressed. With these configurations, a crystal vibration device with a thermistor capable of performing highly accurate temperature detection can be obtained. Furthermore, with the adjustment region 25, the frequency of the crystal vibration device Xtl can be adjusted after hermetic sealing or after mounting the thermistor 5, so that the electrical characteristics can be improved.

[0114] Incidentally, the configuration of the coating resin (resin material R2) in the second embodiment can naturally be combined with the thermistor-mounted piezoelectric vibration device 1 in the first embodiment.

[0115] This application claims priority based on Japanese Patent Application No. 2021-178744 filed in Japan on November 1, 2021 and Japanese Patent Application No. 2021-178745 filed in Japan on November 1, 2021. By referring to this, all of its contents are incorporated into this application.

Explanation of Reference Numerals

[0116] 1 Thermistor-mounted piezoelectric vibration device 2 Sand device (piezoelectric vibration device with a sandwich structure) 10 Piezoelectric vibration plate 11 First main surface (of the piezoelectric vibration plate) 111 First excitation electrode 112 First lead wiring 113 First joining pattern on the vibration side 114 - 116 Joining patterns for connection 12 Second main surface (of the piezoelectric vibration plate) 121 Second excitation electrode 122 Second lead wiring 123 Second joining pattern on the vibration side 124, 125 Joining patterns for connection 13 Vibration part 14 Outer frame part 15 Holding part 16 Through hole 20 First sealing member 21 First main surface (of the first sealing member) 211 Electrode pattern 212, 213 Wiring pattern 22 Second main surface (of the first sealing member) 221 Sealing side first bonding pattern 222 - 225 Connecting bonding pattern 226 Wiring pattern 23 Through hole 30 Second sealing member 31 First main surface (of the second sealing member) 311 Sealing side second bonding pattern 312 Connecting bonding pattern 32 Second main surface (of the second sealing member) 321 External electrode terminal 33 Through hole 5 Thin - film thermistor 51 Thermistor flat plate 52 Common electrode 53 Divided electrode 61 Conductive resin adhesive 62 Non - conductive resin adhesive S1, S2 Seal part T1, T2, T3 Taper part V1, V2, V3, V4, V5 Metal via R1 Conductive bonding material R2 Resin material R3 Insulating resin material

Claims

1. A piezoelectric vibration device having a vibration part in which a first excitation electrode is formed on a first main surface and a second excitation electrode is formed on a second main surface, a first sealing member laminated so as to cover the first main surface side of the piezoelectric vibration plate, and a second sealing member laminated so as to cover the second main surface side of the piezoelectric vibration plate are joined to form an internal space for hermetically sealing the vibration part, and a thin-film thermistor mounted on an outer surface of the first sealing member in the piezoelectric vibration device, the thin-film thermistor is arranged so as to overlap at least a part of the vibration part in a plan view, the thin-film thermistor has a common electrode formed on one main surface of a single thermistor flat plate and a divided electrode formed on the other main surface, and the common electrode is formed on substantially the entire surface of the thermistor flat plate, a thermistor-mounted piezoelectric vibration device, characterized in that the common electrode is arranged on the side opposite to the piezoelectric vibration device with respect to the thermistor flat plate.

2. The thermistor-mounted piezoelectric vibration device according to claim 1, wherein the thin-film thermistor is arranged so as to overlap the entire first excitation electrode and the entire second excitation electrode in a plan view.

3. The thermistor-mounted piezoelectric vibration device according to claim 1, wherein the thin-film thermistor has a common electrode formed on one main surface of a single thermistor flat plate and a divided electrode formed on the other main surface, and the divided electrode is formed on an area of more than half of the thermistor flat plate.

4. The thermistor-mounted piezoelectric vibration device according to claim 1, wherein the piezoelectric vibration plate has the vibration part, an outer frame part surrounding the outer periphery of the vibration part, and a holding part for holding the vibration part by connecting the vibration part and the outer frame part, the thin-film thermistor is arranged so as to overlap the outer frame part on two opposite sides of the piezoelectric vibration device.

5. The thermistor-mounted piezoelectric vibration device according to claim 1, A piezoelectric vibration device with a thermistor mounted thereon, characterized in that an electrical connection between the thin-film thermistor and the piezoelectric vibration device is made with a conductive resin adhesive, and a non-conductive resin adhesive is filled in a gap between the thin-film thermistor and the piezoelectric vibration device.

6. The piezoelectric vibration device with a thermistor mounted thereon according to claim 5, wherein the conductive resin adhesive has higher thermal conductivity than the non-conductive resin adhesive.

7. The piezoelectric vibration device with a thermistor mounted thereon according to claim 5, wherein the non-conductive resin adhesive has higher hardness than the conductive resin adhesive.

8. The piezoelectric vibration device with a thermistor mounted thereon according to claim 1, wherein the first sealing member and the second sealing member are made of a brittle material.

9. The piezoelectric vibration device with a thermistor mounted thereon according to claim 1, wherein when the distance between one of the divided electrodes and the common electrode is G2a, the distance between the other divided electrode and the common electrode is G2b, and the distance between the divided electrodes is G1, a relationship of G2a + G2b < G1 is satisfied.

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