piezoelectric device

Abstract

The piezoelectric device comprises: an electronic component, a built-in piezoelectric component, a mounting plate, and a temperature sensor; a substrate, on which the piezoelectric component and the electronic component are mounted via the mounting plate; and a cover, which, by engaging with the substrate, at least seals the piezoelectric component and the mounting plate.

Description

Technical Field

[0001] This disclosure relates to piezoelectric devices having piezoelectric elements and electronic components. Background Technology

[0002] Piezoelectric devices incorporating both piezoelectric and electronic components are becoming increasingly common. The piezoelectric element's oscillation frequency changes with temperature, reflecting its frequency-temperature characteristics. The electronic component incorporates a temperature sensor, which, based on temperature information obtained from the sensor, controls the piezoelectric element's operation to ensure that the oscillation frequency remains constant despite temperature variations. Examples of such piezoelectric devices include, for instance, temperature-compensated crystal oscillators (TCXOs) (see, for example, Japanese Patent Application Laid-Open No. 2014-187641). A TCXO comprises a crystal resonating element as a piezoelectric element and an integrated circuit (IC) as an electronic component. Summary of the Invention

[0003] The piezoelectric device disclosed herein comprises: an electronic component, a mounting plate and a temperature sensor therein; a substrate, through which the piezoelectric component and the electronic component are mounted; and a cover, which, by engaging with the substrate, at least seals the piezoelectric component and the mounting plate. Attached Figure Description

[0004] Figure 1 This is an exploded perspective view of the piezoelectric device according to Embodiment 1.

[0005] Figure 2 This is an exploded perspective view showing the piezoelectric element and mounting plate in the piezoelectric device of Embodiment 1.

[0006] Figure 3 This is a top view showing the piezoelectric device according to Embodiment 1.

[0007] Figure 4 yes Figure 3 The cross-sectional view along line IV-IV in the diagram.

[0008] Figure 5 This is an exploded perspective view of a piezoelectric device for comparison.

[0009] Figure 6 This is a graph illustrating an example of the temperature change of the electronic component and the piezoelectric component when the ambient temperature of the piezoelectric device changes from T1 to T2 in the comparative example piezoelectric device.

[0010] Figure 7This is a graph showing an example of frequency change when the ambient temperature of the piezoelectric device in the comparative example changes.

[0011] Figure 8 This is a graph showing an example of frequency change when the ambient temperature of the piezoelectric device in Embodiment 1 changes.

[0012] Figure 9 This is a cross-sectional view showing the piezoelectric device of Embodiment 2.

[0013] Figure 10 This is a cross-sectional view showing the piezoelectric device of Embodiment 3.

[0014] Figure 11 This is a process diagram illustrating the first example of a general manufacturing method for piezoelectric devices.

[0015] Figure 12 This is a process diagram illustrating a second example of a general manufacturing method for piezoelectric devices.

[0016] Figure 13 This is a process diagram illustrating the manufacturing method of the piezoelectric device according to embodiments 1 to 3. Detailed Implementation

[0017] In typical piezoelectric devices, a sealed space is formed by a substrate and a cover. Within this sealed space, the piezoelectric element and electronic components are housed, mounted on the substrate. Mounting the piezoelectric element onto the substrate requires high-temperature treatments such as curing of the conductive adhesive and annealing to stabilize its properties. Therefore, as... Figure 11 As shown, if electronic components are first mounted on the substrate (S11), and then piezoelectric components (S12, S13) are mounted on the substrate, unnecessary high-temperature treatment is applied to the electronic components during the mounting of the piezoelectric components, which may affect the electrical characteristics of the electronic components. Conversely, if... Figure 12 As shown, if the piezoelectric element is first mounted on the substrate (S21, S22), and then the electronic component is mounted on the substrate (S23), there is a concern that dust may adhere to the piezoelectric element during the mounting of the electronic component, affecting the electrical characteristics of the piezoelectric element. In other words, the electrical characteristics of the piezoelectric device can sometimes be damaged due to the mounting sequence of the piezoelectric element and the electronic component onto the substrate.

[0018] Temperature changes around a piezoelectric device are transmitted to the piezoelectric element and electronic components via the substrate. The electronic components detect the changing temperature at regular intervals and control the operation of the piezoelectric element based on this temperature information. However, since the temperature of the piezoelectric element may not be consistent with the temperature of the electronic components, this can sometimes impair the frequency stability of the piezoelectric device.

[0019] Therefore, the first objective of this disclosure is to provide a piezoelectric device that improves electrical characteristics by eliminating problems caused by the mounting sequence of the piezoelectric element and electronic components onto the substrate. The second objective of this disclosure is to provide a piezoelectric device that improves frequency stability by eliminating problems caused by the temperature difference between the piezoelectric element and the electronic components.

[0020] According to the piezoelectric device disclosed herein, by employing a structure in which the piezoelectric element is mounted via a mounting plate, only the piezoelectric element and the mounting plate are subjected to high-temperature treatment during piezoelectric element mounting. This avoids unnecessary high-temperature treatment of the electronic component during piezoelectric element mounting, which could affect the electrical characteristics of the electronic component. Furthermore, since unnecessary high-temperature treatment is not applied to the electronic component even if the electronic component is mounted first and then the mounting plate with the attached piezoelectric element is mounted, dust adhesion to the piezoelectric element is prevented during electronic component mounting. Therefore, problems arising from the mounting sequence of the piezoelectric element and electronic component to the substrate are eliminated, thereby improving the electrical characteristics of the piezoelectric device.

[0021] Furthermore, according to the piezoelectric device disclosed herein, by employing a structure in which the piezoelectric element is mounted via a mounting plate, the time lag between the ambient temperature of the piezoelectric device and the temperature of the electronic component can be reduced by the amount of the mounting plate. Therefore, even when the temperature change of the piezoelectric element is faster than that of the electronic component, the temperature difference between the two can be reduced. Consequently, the problem caused by the temperature difference between the piezoelectric element and the electronic component can be eliminated, thereby improving the frequency stability of the piezoelectric device.

[0022] The following description, with reference to the accompanying drawings, illustrates methods for implementing this disclosure (hereinafter referred to as "implementation"). Furthermore, in this specification and the drawings, repetitive descriptions are omitted by using the same reference numerals for substantially identical structural elements. The shapes depicted in the drawings may not necessarily correspond to actual dimensions or proportions due to their priority of visibility and ease of description.

[0023] <Implementation Method 1>

[0024] First, based on Figures 1 to 4 The structure of the piezoelectric device 11 in Embodiment 1 will be briefly described below. Additionally, in Figure 1 In the image, a portion of the substrate 50 is shown missing.

[0025] The piezoelectric device 11 includes: a piezoelectric element 20; a mounting plate 30; an electronic component 40 with a built-in temperature sensor 41; a base 50 on which the piezoelectric element 20 and the electronic component 40 are mounted via the mounting plate 30; and a cover 70 that seals at least the piezoelectric element 20 and the mounting plate 30 by engaging with the base 50.

[0026] Furthermore, in this embodiment 1, the following structure is adopted. The substrate 50 includes: a substrate portion 60 having a first bottom surface 51 for mounting electronic components 40; a first frame portion 61 having a second bottom surface 52 for mounting piezoelectric components 20 via a mounting plate 30 and located at the periphery of the first bottom surface 51; and a second frame portion 62 located at the periphery of the second bottom surface 52. The cover 70 seals the piezoelectric components 20, the mounting plate 30, and the electronic components 40 by engaging with the second frame portion 62.

[0027] Next, the structure of the piezoelectric device 11 in this embodiment 1 will be described in more detail.

[0028] The piezoelectric element 20, viewed from above, is approximately quadrilateral in shape and is a crystal resonator. It comprises a crystal wafer 27 having an upper surface 21 and a lower surface 22 in a face-to-back relationship; and electrodes 23 and 24 extending from the upper surface 21 to the lower surface 22 of the crystal wafer 27. The crystal wafer 27 may contain, for example, an AT-cut plate. The electrodes 23 and 24 are insulated from each other and are respectively designated as excitation electrodes, lead-out electrodes, and pad electrodes, extending from the upper surface 21 across the side to the lower surface 22. Thus, the piezoelectric element 20 is a thickness-slip resonator, but a tuning fork-type bending resonator or a contour-slip resonator may be used instead. Furthermore, a piezoelectric element containing ceramic or the like may be used instead of a crystal resonator. The planar shape of the piezoelectric element 20 is not limited to a quadrilateral shape and can be any shape, such as a circle, an ellipse, or a polygon.

[0029] The mounting plate 30, viewed from above, is approximately quadrilateral in shape, having a first main surface 31 and a second main surface 32 in a face-back relationship, and, for example, contains a laminated ceramic plate obtained by stacking and firing multiple green sheets. Figure 2 As shown, piezoelectric element pads 33 and 34 are located on the first main surface 31, and mounting plate electrodes 35, 36, 37, and 38 are located on the second main surface 32. Piezoelectric element pads 33 and 34 are positioned opposite to electrodes 23 and 24 of the piezoelectric element 20, and are electrically connected to electrodes 23 and 24 via piezoelectric element bonding materials 25 and 26. The piezoelectric element bonding materials 25 and 26 are, for example, conductive adhesives such as silver-coated epoxy resin, and are fluid before curing. Figure 2As shown, mounting plate electrodes 35, 36, 37, and 38 are located at the four corners of the second main surface 32. The piezoelectric element pads 33 and 34 on the first main surface 31 and the mounting plate electrodes 35 and 36 on the second main surface 32 are electrically connected via internal wiring (not shown). This internal wiring may contain, for example, conductor patterns printed on the green film or via conductors. The mounting plate electrodes 37 and 38 are not electrically connected anywhere else, but are mechanically connected to the substrate 50. The piezoelectric element pads 33 and 34, as well as the mounting plate electrodes 35, 36, 37, and 38, may have an Au (gold) layer on the surface and a Ni (nickel) layer on the substrate. Alternatively, the mounting plate 30 may replace a ceramic plate with a crystal plate or the like. The planar shape of the mounting plate 30 is not limited to a quadrilateral shape; it can be any shape, such as a circle, ellipse, triangle, or polygon with pentagonal or larger shapes.

[0030] Electronic component 40 is an IC that functions as a temperature sensor 41 and an oscillation circuit for the piezoelectric element 20, and is a flip chip (FC) with bumps forming the connection terminals 42. These bumps, for example, contain gold or solder and are electrically connected to the electronic component pads 53. The number of connection terminals 42 and electronic component pads 53 is the same. That is, the electronic component 40 is mounted to the substrate 50 via the connection terminals 42 with the circuitry of the connection terminals 42 of the electronic component 40 facing downwards onto the electronic component pads 53, which are oriented towards the first bottom surface 51. The temperature sensor 41 is, for example, a temperature sensor utilizing the forward voltage of a pn junction formed within the IC. The higher the temperature, the lower the forward voltage of the pn junction. Therefore, by flowing a certain current through the pn junction and measuring the forward voltage, voltage information can be obtained. By converting this voltage information, the temperature information of the electronic component 40 and, consequently, the piezoelectric element 20, can be obtained. Alternatively, the electronic component 40 may be configured to contain only a temperature sensor, such as a thermistor or a diode. The portion of the connecting terminal 42 can also replace the bump with a metal wire containing aluminum or gold.

[0031] The substrate portion 60, the first frame portion 61, and the second frame portion 62 constituting the substrate 50 include, for example, a laminated ceramic plate obtained by stacking and firing multiple green sheets. The first frame portion 61 is arranged in a ring around the periphery of the substrate portion 60, and the second frame portion 62 is arranged in a ring around the periphery of the first frame portion 61. The internal wiring (not shown) includes, for example, conductor patterns or via conductors printed on the green sheets. A pad 53 for electronic components is provided on the first bottom surface 51 of the recessed space 63, and pads 55, 56, 57, and 58 for mounting plates are provided on the second bottom surface 52. The pads 53 for electronic components and the pads 55, 56, 57, and 58 for mounting plates include, for example, an Au (gold) layer on the surface and a Ni (nickel) layer on the substrate.

[0032] Pads 55, 56, 57, and 58 of the mounting plate are provided on the mounting plate electrodes 35, 36, 37, and 38 of the mounting plate 30. Figure 2 The mounting plates are electrically connected to the mounting plate electrodes 35, 36, 37, and 38 at opposite positions via mounting plate bonding materials 65, 66, 67, and 68. The mounting plate bonding materials 65, 66, 67, and 68 are, for example, conductive adhesives such as silver-coated epoxy resin, and are fluid before curing. External terminals 54 for surface mounting are provided on the protruding ends at the four corners of the substrate portion 60. These external terminals 54 include, for example, frequency control terminals, ground terminals, output terminals, and power supply voltage terminals. Furthermore, the mounting plate pads 55 and 56, the electronic component pads 53, and the external terminals 54 are electrically connected to each other via internal wiring (not shown). The mounting plate pads 57 and 58 are not electrically connected to any other location. Alternatively, the mounting plate bonding materials 65, 66, 67, and 68 can be replaced with solder or similar materials instead of conductive adhesives.

[0033] The cover 70 is made of a metal such as Kovar or ceramic, and is a rectangular flat plate. Furthermore, the cover 70 is joined to the base 50 by spot welding or a glass seal to airtightly seal the recessed space 63.

[0034] The space surrounded by the substrate portion 60, the first frame portion 61, the second frame portion 62, and the cover 70 is a recessed space 63. That is, the recessed space 63 is formed in the base 50 and houses the piezoelectric element 20, the mounting plate 30, and the electronic component 40.

[0035] The piezoelectric device 11 is constructed such that the base 50 and the cover 70 are hermetically sealed within the recessed space 63 by seam welding or glass sealing, with the piezoelectric element 20, mounting plate 30, and electronic component 40 mounted on the base 50. Thus, the piezoelectric device 11 is a surface-mount crystal oscillator incorporating the piezoelectric element 20. Since the crystal oscillator serves as the reference clock signal source for the device, it requires higher reliability than other electronic components.

[0036] Next, the assembly method of piezoelectric device 11 will be explained.

[0037] (First step:) Figure 13 S1, S2) such as Figure 2As shown, on the first main surface 31 of the mounting plate 30, piezoelectric element bonding materials 25 and 26 containing conductive adhesive are applied to the piezoelectric element pads 33 and 34. Then, the electrodes 23 and 24 of the piezoelectric element 20 are placed on the piezoelectric element bonding materials 25 and 26, and subjected to heat treatment at a high temperature of 300–350°C for 10–30 minutes, thereby hardening the piezoelectric element bonding materials 25 and 26. Since the piezoelectric element 20 is fixed in a cantilever beam shape, the piezoelectric element bonding materials 25 and 26 are hardened at high temperature in one go, so that the piezoelectric element 20 does not tilt and contacts and is fixed to the upper and lower components. Thus, the piezoelectric element 20 is mounted to the mounting plate 30. Next, in order to stabilize the characteristics of the piezoelectric element 20, the mounting plate 30 on which the piezoelectric element 20 is mounted is subjected to an annealing treatment at a high temperature of 300–350°C for 5–15 minutes, for example.

[0038] (Second process:) Figure 13 In step S3), separate from the first step, the forming surface of the connection terminal 42 of the electronic component 40 is oriented toward the first bottom surface 51 of the recessed space 63. The positions of the electronic component pad 53 and the connection terminal 42 are aligned, the connection terminal 42 is pressed onto the electronic component pad 53, and heat or ultrasonic waves are applied. As a result, the connection terminal 42 is bonded to the electronic component pad 53.

[0039] (Third process:) Figure 13 (S4) After the first and second processes, on the second bottom surface 52, mounting plate bonding materials 65, 66, 67, and 68, acting as conductive adhesives, are applied to the mounting plate pads 55, 56, 57, and 58. Then, mounting plate electrodes 35, 36, 37, and 38 of the mounting plate 30 are placed on the mounting plate bonding materials 65, 66, 67, and 68. Figure 2 The mounting plate is then hardened using bonding materials 65, 66, 67, and 68 at room temperature or high temperature. Since the tilt of the mounting plate 30 can be disregarded, the hardening temperature can be lower than in the first process.

[0040] (Fourth step) After the third step, the recessed space 63 of the substrate 50 is sealed by the cover 70. Thus, the piezoelectric device 11 is completed.

[0041] Next, the function and effect of the piezoelectric device 11 will be explained.

[0042] First, let me explain Figure 5 The comparative example shown is as follows. In the piezoelectric device 10 of the comparative example, there is no mounting plate 30 as in Embodiment 1. That is, the piezoelectric element 20 is directly mounted to the base 50 without the mounting plate 30. Apart from this, the structure is the same as that of the piezoelectric device 11 of Embodiment 1.

[0043] (1) In the piezoelectric device 10 of the comparative example, in the structure where the electronic component 40 is located in the recessed space 63 at a depth greater than that of the piezoelectric component 20, the electronic component 40 needs to be installed before the piezoelectric component 20. Figure 11 Therefore, after the electronic component 40 is mounted onto the substrate 50 ( Figure 11 S11), the piezoelectric element 20 is mounted onto the substrate 50. Figure 11 S12), the piezoelectric element 20 is subjected to high-temperature treatment. Figure 11 (S13). At this time, there is concern that applying unnecessary high-temperature treatment to the electronic component 40 during the installation of the piezoelectric element 20 may affect the electrical characteristics of the electronic component 40.

[0044] In contrast, according to the piezoelectric device 11 of this embodiment 1, by adopting a structure in which the piezoelectric element 20 is mounted via the mounting plate 30, high-temperature treatment during the mounting of the piezoelectric element 20 can be performed only on the piezoelectric element 20 and the mounting plate 30. Figure 13 Therefore, unnecessary high-temperature treatment of the electronic component 40 during the installation of the piezoelectric element 20 can be avoided, thus preventing any impact on the electrical characteristics of the electronic component 40. Consequently, problems arising from the installation sequence of the piezoelectric element 20 and the electronic component 40 onto the substrate 50 can be eliminated, thereby improving the electrical characteristics of the piezoelectric device 11.

[0045] (2) Alternatively, the thermal time constant for the heat transferred from the substrate 50 to the electronic component 40 can be set as τs( Figure 6 The thermal time constant for heat transfer from the substrate 50 to the piezoelectric element 20 via the mounting plate 30 is set as τx1. This is in the case where the piezoelectric element 20 is directly mounted to the substrate 50 without passing through the mounting plate 30 (see reference). Figure 5 (Comparative example) The thermal time constant for the heat transferred from the substrate 50 to the piezoelectric element 20 is set as τx2 ( Figure 6 When |τs-τx1|<|τs-τx2|, it holds true.

[0046] The thermal time constant can be set as the time it takes for the electronic component 40 and the piezoelectric component 20 to reach {T1+(T2-T1)×0.632} from T1 when the ambient temperature of the piezoelectric device 11 changes from T1 to T2.

[0047] In this case, such as Figure 6 As shown, in the comparative example piezoelectric device 10, the thermal time constant τx2 of the piezoelectric element 20 becomes much smaller than the thermal time constant τs of the electronic element 40. Therefore, as Figure 7 As shown, when the ambient temperature of the piezoelectric device 10 is increased (-40℃→85℃) and decreased (85℃--40℃), deviations occur in the frequency change (df / f0).

[0048] In contrast, according to the piezoelectric device 11 of this embodiment 1, by adopting a structure in which the piezoelectric element 20 is mounted via the mounting plate 30, the thermal time constant τx1 of the piezoelectric element 20 can be increased to make it closer to the thermal time constant τs of the electronic element 40. Therefore, as Figure 8 As shown, when the ambient temperature of the piezoelectric device 11 is increased (-40℃→85℃) and decreased (85℃→-40℃), the deviation of the frequency change (df / f0) becomes more pronounced than... Figure 7 Small.

[0049] As described above, according to the piezoelectric device 11 of this embodiment 1, by employing a structure in which the piezoelectric element 20 is mounted via the mounting plate 30, the time delay between the transfer of ambient temperature of the piezoelectric device 11 to the piezoelectric element 20 and the mounting plate 30 can be reduced. Therefore, the temperature difference between the two can be reduced when the temperature change of the piezoelectric element 20 is faster than that of the electronic element 40. Consequently, the problem caused by the temperature difference between the piezoelectric element 20 and the electronic element 40 can be eliminated, thereby improving the frequency stability of the piezoelectric device 11. In addition, to obtain the actual temperature of the piezoelectric element 20, there are methods such as measuring it using a thermocouple, measuring it using a radiation thermometer by making a small hole in the substrate 50 or the cover 70, or calculating it using computer simulation.

[0050] (3) Alternatively, when viewed from above, the piezoelectric element 20 and the electronic element 40 can be arranged to overlap with the mounting plate 30. In this case, miniaturization can be achieved because the area occupied by the piezoelectric device 11 can be reduced. In addition, by covering the electronic element 40 with the electrodes 23 and 24 of the piezoelectric element 20, noise of the signal applied to the electronic element 40 can be reduced.

[0051] (4) Alternatively, when viewed from above, the mounting plate 30 may be the same size as or contain the piezoelectric element 20. In this case, since the heat capacity of the mounting plate 30 increases, or the mounting plate 30 functions as a shield against radiant heat from the substrate 50, the thermal time constant τx1 of the piezoelectric element 20 can be further increased.

[0052] (5) Alternatively, the mounting plate 30 may contain the same material as the substrate 50 (e.g., ceramic). In this case, since the mounting plate 30 and the substrate 50 have the same coefficient of thermal expansion, the strain generated in the mounting plate 30 and the substrate 50 due to temperature changes can be reduced.

[0053] <Implementation Method 2>

[0054] like Figure 9As shown, the structure of the base 150 of the piezoelectric device 12 in Embodiment 2 differs from that in Embodiment 1. The base 150 includes: a substrate portion 160 having an inner surface 151 and an outer surface 152 in a front-back relationship, on which the piezoelectric element 20 is mounted via a mounting plate 30, and on which the electronic component 40 is mounted; and a frame portion 161 located at the periphery of the inner surface 151. Furthermore, the cover 170 seals the piezoelectric element 20, the mounting plate 30, and the electronic component 40 by engaging with the frame portion 161.

[0055] The space surrounded by the substrate portion 160, the frame portion 161, and the cover 170 is a recessed space 163. In this embodiment 2, the substrate 150 is concave and the cover 170 is flat, but it is also possible to reverse this and set the substrate 150 to be flat and the cover 170 to be concave.

[0056] In the piezoelectric device 12 of this embodiment 2, since the piezoelectric element 20 and the electronic component 40 are located on the same plane, i.e., the inner surface 151, within the recessed space 163, unlike in embodiment 1, the piezoelectric element 20 can be installed first. Figure 12 ), or you can install electronic components 40 ( Figure 11 But even if electronic components 40 are installed first... Figure 13 After S3), install the mounting plate 30 with the piezoelectric element 20. Figure 13 S4), and because unnecessary high-temperature treatment is not performed on electronic component 40, therefore, by first installing electronic component 40 ( Figure 13 After S3), install the mounting plate 30 with the piezoelectric element 20. Figure 13 S4), when electronic component 40 is installed ( Figure 13 S3), and will not cause dust to adhere to the piezoelectric element 20, etc.

[0057] Furthermore, since the piezoelectric element 20 and the electronic element 40 undergo heat conduction through the same substrate portion 160, their thermal time constants can be made closer. Other structures, functions, and effects of this embodiment 2 are the same as those of embodiment 1.

[0058] <Implementation Method 3>

[0059] like Figure 10As shown, the structure of the base 250 of the piezoelectric device 13 in Embodiment 3 differs from that in Embodiment 1. The base 250 includes: a substrate portion 260 having an inner surface 251 and an outer surface 252 in a front-back relationship, wherein the piezoelectric element 20 is mounted on the inner surface 251 via a mounting plate 30, and the electronic component 40 is mounted on the outer surface 252; a first frame portion 261 located at the periphery of the outer surface 252; and a second frame portion 262 located at the periphery of the inner surface 251. Furthermore, the cover 270 seals the piezoelectric element 20 and the mounting plate 30 by engaging with the second frame portion 262.

[0060] The space surrounded by the substrate portion 260, the second frame portion 262, and the cover 270 is a recessed space 263. In this embodiment 3, the second frame portion 262 is located on the side of the base 250, but the second frame portion 262 may also be located on the side of the cover 270. In other words, the cover 270 is flat, but it may also be recessed.

[0061] In the piezoelectric device 13 of this embodiment 3, since the piezoelectric element 20 is located on the inner surface 251 of the substrate portion 260 and the electronic component 40 is located on the outer surface 252, unlike embodiment 1, the piezoelectric element 20 can be installed first. Figure 12 ), or you can install electronic components 40 ( Figure 11 But even if electronic components 40 are installed first... Figure 13 After S3), install the mounting plate 30 with the piezoelectric element 20. Figure 13 S4), and will not subject electronic component 40 to unnecessary high-temperature treatment. Therefore, by first installing electronic component 40 ( Figure 13 After S3), install the mounting plate 30 with the piezoelectric element 20. Figure 13 S4), when electronic component 40 is installed ( Figure 13 (S3) will not cause dust to adhere to the piezoelectric element 20. The other structures, functions and effects of this embodiment 3 are the same as those of embodiment 1.

[0062] <Other>

[0063] The piezoelectric device constructed as described above is mounted on the surface of a printed circuit board (PCB) constituting an electronic device by fixing the bottom surface of its external terminals to the PCB using soldering, Au bumps, or conductive adhesives. Furthermore, the piezoelectric device can be used as an oscillation source in various electronic devices such as personal computers, clocks, game consoles, communication devices, or navigation systems. Because such a piezoelectric device can reduce the difference between the temperature obtained by calculating the voltage output from a temperature sensor and the actual ambient temperature of the piezoelectric device, it is easily corrected by the IC of the electronic device, thus enabling the output of a stable oscillation frequency. Therefore, electronic devices equipped with the piezoelectric device described above can operate correctly with high reliability.

[0064] The present disclosure has been described above with reference to the aforementioned embodiments, but the present disclosure is not limited to the aforementioned embodiments. Various modifications that can be understood by those skilled in the art can be added to the detailed structure of the present disclosure. Furthermore, the present disclosure includes solutions obtained by suitably combining some or all of the structures of the aforementioned embodiments.

[0065] This application claims priority based on Japanese Application Special Hoc 2020-128278 filed on July 29, 2020, the entire disclosure of which is incorporated herein by reference.

Claims

1. A piezoelectric device comprising: piezoelectric elements; Mounting plate; Electronic components with built-in temperature sensors; The substrate, via the mounting plate, mounts the piezoelectric element and the electronic components; and The cover, by engaging with the substrate, at least seals the piezoelectric element and the mounting plate. The matrix comprises: The substrate portion has a first bottom surface on which the electronic components are mounted; The first frame portion has a second bottom surface on which the piezoelectric element is mounted via the mounting plate, and is located at the periphery of the first bottom surface; and The second frame portion is located at the periphery of the second bottom surface. The cover is configured to seal the piezoelectric element, the mounting plate, and the electronic components by engaging with the second frame portion.

2. A piezoelectric device, comprising: piezoelectric elements; Mounting plate; Electronic components with built-in temperature sensors; The substrate, via the mounting plate, mounts the piezoelectric element and the electronic components; and The cover, by engaging with the substrate, at least seals the piezoelectric element and the mounting plate. The matrix comprises: The substrate portion has an inner surface and an outer surface in a face-to-back relationship. The piezoelectric element is mounted on the inner surface via the mounting plate, and the electronic component is mounted on the outer surface. The first frame portion is located at the periphery of the outer surface; and The second frame portion is located at the periphery of the inner surface. The cover is configured to seal the piezoelectric element and the mounting plate by engaging with the second frame portion.

3. The piezoelectric device according to claim 1 or 2, wherein, The piezoelectric device is configured such that, when viewed from above, the piezoelectric element and the electronic element overlap, sandwiching the mounting plate.

4. A piezoelectric device, comprising: piezoelectric elements; Mounting plate; Electronic components with built-in temperature sensors; The substrate, via the mounting plate, mounts the piezoelectric element and the electronic components; and The cover, by engaging with the substrate, at least seals the piezoelectric element and the mounting plate. The matrix comprises: The substrate portion has an inner surface and an outer surface in a face-to-back relationship. The piezoelectric element is mounted on the inner surface via the mounting plate, and the electronic component is also mounted on the inner surface. The frame portion is located at the periphery of the inner surface. The cover is configured to seal the piezoelectric element, the mounting plate, and the electronic components by engaging with the frame.

5. The piezoelectric device according to any one of claims 1, 2, or 4, wherein, From a top view, the mounting plate is set to be the same size as the piezoelectric element or to include the piezoelectric element.

6. The piezoelectric device according to any one of claims 1, 2, or 4, wherein, The mounting plate contains the same material as the substrate.

7. A piezoelectric device comprising: piezoelectric elements; Mounting plate; Electronic components with built-in temperature sensors; The substrate, via the mounting plate, mounts the piezoelectric element and the electronic components; and The cover, by engaging with the substrate, at least seals the piezoelectric element and the mounting plate. Let the thermal time constant for the heat transferred from the substrate to the electronic component be τs. The thermal time constant for the heat transferred from the substrate to the piezoelectric element via the mounting plate is set as τx1. When the thermal time constant for heat transfer from the substrate to the piezoelectric element is set to τx2 when the piezoelectric element is directly mounted to the substrate without passing through the mounting plate, They have the relationship |τs-τx1| < |τs-τx2|.

8. The piezoelectric device according to claim 7, wherein, The thermal time constant is set as the time it takes for the electronic component and the piezoelectric component to reach {T1+(T2-T1)×0.632} from T1 when the ambient temperature of the piezoelectric device changes from T1 to T2.

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