JP6523663B2 - Piezoelectric device - Google Patents

Description

  The present invention relates to piezoelectric devices such as crystal oscillators.

  There is known a crystal oscillator having a crystal vibrating element (piezoelectric element) and a package in which the crystal vibrating element is accommodated in a sealed space (for example, Patent Document 1). The characteristics of the crystal vibrating element change with temperature change. Therefore, when the temperature of the atmosphere around the crystal oscillator is unstable, the frequency of the oscillation signal output from the crystal oscillator is also unstable. In view of the above, there has also been proposed a thermostat-equipped crystal oscillator (piezoelectric device with a thermostat) in which a quartz oscillator is accommodated in a thermostat having a case and a heater (for example, Patent Document 2).

JP, 2014-093571, A Unexamined-Japanese-Patent No. 2013-211752

  Since the thermostat-equipped piezoelectric device is provided with a thermostat, it is large in size and expensive. Therefore, it is desirable to provide a piezoelectric device capable of at least one of miniaturization and cost reduction, and capable of reducing the influence of temperature changes in the surrounding atmosphere on the characteristics of the piezoelectric element.

  The piezoelectric device according to an aspect of the present invention includes a piezoelectric element and a contained piezoelectric device having a package for sealing the piezoelectric element, and the contained piezoelectric device is mounted on one main surface, and the other main surface A substrate having an external terminal electrically connected to the contained piezoelectric device, and a cover placed on the one main surface to accommodate the contained piezoelectric device, the cover comprising: The receiving piezoelectric device is surrounded by a gap and does not have a heater.

  Preferably, in the gap, a gas layer made of air or nitrogen and having a thickness of 30 mm or less surrounding the accommodated piezoelectric device is formed.

  Preferably, the gap is vacuum.

  Preferably, the cover and the substrate are joined along the entire circumference surrounding the contained piezoelectric device.

  Preferably, the cover is made of metal and is electrically connected to an external terminal to which a reference potential is applied among the plurality of external terminals.

  Preferably, the cover is made of an inorganic material.

  Preferably, the accommodated piezoelectric device further includes an integrated circuit element including a compensation circuit that compensates for the characteristic change due to the temperature change of the piezoelectric element.

  A piezoelectric device according to an aspect of the present invention includes a piezoelectric element, and an accommodated piezoelectric device having a package for sealing the piezoelectric element, a cover for accommodating the accommodated piezoelectric device, and the accommodated piezoelectric device and electricity. And an external terminal exposed to the outside of the cover, wherein the cover surrounds the accommodated piezoelectric device with a gap, and does not have a heater.

  According to the above configuration, at least one of downsizing and cost reduction is possible, and the influence of the temperature change of the surrounding atmosphere on the characteristics of the piezoelectric element can be reduced.

FIG. 1 is an exploded perspective view showing a configuration of a crystal oscillator according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view showing a configuration of a accommodated crystal oscillator in the crystal oscillator of FIG. 1. Sectional drawing in the III-III line of FIG. The perspective view which fractures | ruptures and shows one part the structure of the crystal oscillator which concerns on 2nd Embodiment of this invention.

  The drawings used in the following description are schematic, and dimensional ratios and the like in the drawings do not necessarily coincide with actual ones. The crystal oscillator may have any direction upward or downward, but hereinafter, for convenience, the orthogonal coordinate system xyz is defined and the positive side in the z direction is upward, such as the upper surface or the lower surface. We shall use the term. The x-axis, the y-axis and the z-axis are conveniently defined based on the shape of the member and the like, and do not mean the electrical axis, the mechanical axis and the optical axis of the piezoelectric body (quartz).

First Embodiment
FIG. 1 is an exploded perspective view showing the configuration of a crystal oscillator 1 according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view showing a configuration of a part of the crystal oscillator 1 (the accommodated oscillator 3). FIG. 3 is a cross-sectional view taken along line III-III of FIG.

  As shown in FIG. 1 and FIG. 3, the oscillator 1 is, for example, an electronic component which is generally in the form of a thin rectangular solid as a whole, and its dimensions may be appropriately set. For example, the length of the long side or the short side is 1 mm to 3 mm, and the thickness is 0.5 mm to 1 mm.

  The oscillator 1 has, for example, a plurality (four in the present embodiment) of external terminals 43 (one external terminal may be given an additional code of G) on its bottom surface. The bottom surface of the oscillator 1 is opposed to a circuit board or the like (not shown), and the plurality of external terminals 43 and a plurality of pads of the circuit board (not shown) are joined by bumps (for example, made of solder). The oscillator 1 is mounted on a circuit board (not shown). The oscillator 1 is supplied with power or the like through any of the plurality of external terminals 43, and outputs an oscillation signal through any one of the plurality of external terminals 43.

  The oscillator 1 has, for example, an accommodated oscillator 3 formed of a crystal oscillator, a substrate 5 on which the accommodated oscillator 3 is mounted, and a cover 7 which is covered on the substrate 5 so as to accommodate the accommodated oscillator 3. .

  The contained oscillator 3 is an electronic component that generates and outputs an oscillation signal. The housed oscillator 3 is housed in the outer shell 8 (see FIG. 3) composed of the substrate 5 and the cover 7 so that the housed oscillator 3 is thermally insulated with respect to the surrounding atmosphere to suppress the temperature change, and hence, , The frequency of the oscillation signal is stabilized. In addition, the oscillator 1 does not have a heater for heating the atmosphere around the contained oscillator 3 which is provided in the oscillator with a thermostat.

  For example, the contained oscillator 3 is generally configured in a substantially rectangular parallelepiped shape, and has a plurality of (four in the present embodiment) internal terminals 33 on the bottom surface thereof. The internal terminal 33 is a terminal serving as an external terminal for the contained oscillator 3. The accommodated oscillator 3 is supplied with power and the like via any of the plurality of internal terminals 33, and outputs an oscillation signal through any one of the plurality of internal terminals 33.

  For example, as shown in FIG. 2 and FIG. 3, the contained oscillator 3 applies a voltage to the quartz crystal vibrating element (piezoelectric element) 9 and the quartz crystal vibrating element 9 to generate an oscillation signal, and And the element mounting member 15 and the cover member 17 which comprise the package 13 (code | symbol is FIG.1 and FIG.3) which accommodates.

  The crystal vibrating element 9 generates natural vibration when an alternating voltage is applied. The integrated circuit element 11 is configured to include an oscillation circuit, applies a voltage to the crystal vibrating element 9, and generates an oscillation signal using natural vibration in the crystal vibrating element 9. The package 13 contributes to the protection of the crystal vibrating element 9 and the integrated circuit element 11 and the input / output of electrical signals to these.

  The quartz crystal vibrating element 9 includes, for example, a quartz crystal piece 19, a pair of excitation electrodes 21 for applying a voltage to the quartz crystal piece 19, and a pair of lead-out electrodes for mounting the quartz crystal vibrating element 9 on the element mounting member 15. And 23).

  The crystal piece 19 is formed, for example, in a substantially rectangular plate shape. The crystal piece 19 is made of, for example, an AT cut crystal piece. The pair of excitation electrodes 21 is, for example, provided in layers on the center sides of both main surfaces of the quartz piece 19. The pair of extraction electrodes 23 is, for example, extracted from the pair of excitation electrodes 21 and provided at one end side portion in the longitudinal direction of the quartz piece 19. The pair of excitation electrodes 21 and the pair of extraction electrodes 23 extend in the longitudinal direction of the crystal piece 19 so that, for example, either of the main surfaces of the crystal vibrating element 9 may be mounted. It is formed in a 180 ° rotational symmetric shape with respect to the line.

  The integrated circuit element 11 is formed, for example, in a substantially thin rectangular parallelepiped shape, and has a plurality of (six in the present embodiment) IC terminals 25 on the top surface. The plurality of IC terminals 25 are arranged, for example, along the two long sides of the rectangular shape of the integrated circuit element 11 in plan view (a total of two rows are provided).

  The number and role of the IC terminals 25 may be appropriately set in accordance with the function and the like required of the integrated circuit element 11 (oscillator 1). For example, one of six IC terminals 25 is for supplying ground potential GND, which is a reference potential, to integrated circuit element 11, and one is for integrating power supply voltage Vcc (potential different from the reference potential). Two for supplying voltage to the circuit element 11, two for applying a voltage from the integrated circuit element 11 to the crystal vibrating element 9, and one for outputting the generated oscillation signal Vout One is for inputting a control signal Vcon for adjusting the frequency of the oscillation signal Vout to the integrated circuit element 11. Instead of the control signal Vcon, for example, an enable / disable signal EN instructing generation or stop of the oscillation signal Vout by the integrated circuit element 11 may be input.

  As described above, the integrated circuit element 11 is configured to include the oscillation circuit. The oscillation circuit is, for example, of a feedback type. In addition, the integrated circuit element 11 may include a temperature sensor and a temperature compensation circuit that compensates for the characteristic change of the crystal vibrating element 9 due to the temperature change based on the temperature detected by the temperature sensor. The temperature compensation circuit, for example, although not particularly shown, is a variable capacitance element disposed between the crystal vibrating element 9 and the reference potential portion (ground portion), and a voltage according to the temperature detected by the temperature sensor. And a compensation signal generation circuit applied to the By changing the load capacitance of the quartz crystal vibrating element 9 according to the temperature, the characteristic change of the quartz crystal vibrating element 9 due to the temperature change is compensated. This stabilizes the frequency of the oscillation signal. The integrated circuit element 11 may be packaged or may be a bare chip.

  The element mounting member 15 includes, for example, an insulating member 27 and various conductors provided on the surface or inside of the insulating member 27. The conductor is, for example, a pair of element pads 29 on which the crystal vibrating element 9 is mounted, a plurality (six in this embodiment) of IC pads 31 (FIG. 3) on which the integrated circuit element 11 is mounted, Internal terminals 33, and wiring (not shown) for connecting them.

  The insulating member 27 (element mounting member 15) constitutes, for example, a so-called H-type package. That is, the insulating member 27 has a first recess 27 a which opens upward and accommodates the crystal vibrating element 9, and a second recess 27 b (FIG. 3) which opens downward and accommodates the integrated circuit device 11. There is. In another viewpoint, the insulating member 27 includes the substrate portion 27c, a first frame portion 27d located on one main surface of the substrate portion 27c, and a second frame portion located on the other main surface of the substrate portion 27c. And 27e.

  The insulating member 27 is formed, for example, by stacking a plurality of layered members made of ceramic such as alumina. The number of layered members and the thickness of each layer may be appropriately set according to the shape and dimensions of the insulating member 27 and the position and shape of the conductors disposed in the insulating member 27. The first frame portion 27d may be formed of metal.

  The pair of element pads 29 is, for example, a layered conductor formed on the bottom of the first recess 27a, and is arranged along one short side of the first recess 27a. The pair of element pads 29 and the pair of extraction electrodes 23 of the quartz crystal element 9 are joined, for example, by a pair of conductive adhesives 35 (FIG. 3). Thus, the quartz crystal vibrating element 9 is fixed to the element mounting member 15 like a cantilever and electrically connected to the element mounting member 15.

  The plurality of IC pads 31 are, for example, layered conductors formed on the bottom surface of the second recess 27b, and are arranged in two rows along opposing two sides (for example, two long sides) of the second recess 27b. There is. The plurality of IC pads 31 and the plurality of IC terminals 25 of the integrated circuit element 11 are joined by, for example, a plurality of bumps 37 (FIG. 3). Thereby, the integrated circuit element 11 is fixed to the element mounting member 15 and electrically connected (that is, mounted). The bumps 37 are made of, for example, solder.

  The plurality of internal terminals 33 are, for example, layered conductors formed on the lower surface of the second frame 27e, and are provided at the four corners of the second frame 27e.

  Two of the plurality of IC pads 31 are connected to a pair of element pads 29 via wires (not shown) of the element mounting member 15. The remaining four (corresponding to Vcc, GND, Vout and Vcon) of the plurality of IC pads 31 are connected to the four internal terminals 33 via unshown wirings of the element mounting member 15. The wiring of the element mounting member 15 is formed of, for example, a via conductor penetrating the layered member constituting the insulating member 27 in the vertical direction, and a layered conductor stacked on the layered member.

  The lid member 17 is joined to the upper surface of the first frame portion 27d and seals the first recess 27a. Therefore, the crystal vibrating element 9 is accommodated in the closed space. The lid member 17 may be made of a conductive material such as metal, may be made of an insulating material, or may be made of a composite material in which an insulating layer and a conductive layer are laminated. For example, the lid member 17 is formed of a metal plate, and the metal plate is joined to the first frame portion 27d by seam welding or the like. When the lid member 17 includes a conductor, the conductor is electrically connected to the internal terminal 33 to which the reference potential (ground potential) is applied through the wiring provided on the surface or inside of the insulating member 27. It is also good.

  As shown in FIGS. 1 and 3, the substrate 5 is made of, for example, a rigid printed wiring board, and includes an insulating substrate 39 and various conductors provided on the insulating substrate 39. The various conductors are, for example, a plurality of (four in the present embodiment) internal pads 41 for mounting the contained oscillator 3 and a plurality of external terminals 43 described above.

  The insulating substrate 39 (substrate 5) is, for example, a substantially rectangular plate, and has a first major surface 39a and a second major surface 39b on the back surface thereof. The insulating substrate 39 may be made of ceramic, or may be a substrate made of glass fiber or the like impregnated with a resin such as epoxy resin.

  The plurality of internal pads 41 are, for example, layered conductors formed on the first major surface 39a, and are located on the four corners of the first major surface 39a. The plurality of internal pads 41 and the internal terminal 33 of the accommodated oscillator 3 are joined by, for example, a plurality of bumps 45 (FIG. 3). Thereby, the contained oscillator 3 is fixed to the substrate 5 and electrically connected (i.e. mounted). The bumps 45 are made of, for example, solder.

  The plurality of external terminals 43 are, for example, layered conductors formed on the second main surface 39b, and are located at four corners of the second main surface 39b.

  The plurality of internal pads 41 and the plurality of external terminals 43 are connected via the wiring of the substrate 5. The wiring of the substrate 5 is constituted by, for example, a through conductor 47 (FIG. 3) penetrating the insulating substrate 39. The through conductor 47 may be filled in a hole penetrating the insulating substrate 39 or may be formed in a film shape on the inner surface of the hole. Note that, instead of the through conductor 47, a wire made of a layered conductor may be formed on the side surface (for example, in a castellation) of the insulating substrate 39. A part of the wiring of the substrate 5 may be constituted by a layered conductor on the first major surface 39 a and / or in the insulating substrate 39.

  In the present embodiment, the substrate 5 is used only for electrically connecting the contained oscillator 3 to the outside while accommodating the contained oscillator 3 with the cover 7. Therefore, for example, electronic components other than the contained oscillator 3 are not mounted on the substrate 5. Also, for example, in the substrate 5, the internal pad 41 and the external terminal 43 are simply electrically connected, and are interposed between them, and are formed of the conductor of the substrate 5, a resistor, an inductor Alternatively, no electronic element such as a capacitor is provided. However, other electronic components may be mounted on the substrate 5, or the conductors in the substrate 5 may constitute an electronic element.

  The cover 7 is formed in, for example, a substantially rectangular box shape, and the cover oscillator 7 is accommodated by facing the opening downward and covering the substrate 5 and the accommodated oscillator 3. As shown in FIG. 3, for example, the cover 7 and the contained oscillator 3 (package 13) are not in contact with each other throughout. That is, the cover 7 may be referred to as four first gaps G1 on the side of the contained oscillator 3 and a second gap G2 above the contained oscillator 3 (hereinafter, these may be referred to as gaps G without distinction. ) Encloses the contained oscillator 3. By forming the gap G, the heat insulation between the atmosphere around the oscillator 1 and the contained oscillator 3 is improved.

  The gap G may or may not be sealed. When the gap G is sealed, the inside thereof may or may not be vacuum (in a state of being decompressed below atmospheric pressure). When a gas is sealed in the gap G, the gas may be air or an appropriate gas such as nitrogen. In the case where the gap G is not sealed and in the case where a gas is sealed in the gap G, the cover 7 surrounds the accommodated oscillator 3 through the gas layer.

  In the present embodiment, since the outer shape of the accommodated oscillator 3 and the inside of the cover 7 have a substantially rectangular parallelepiped shape, the thickness of each gap G (the distance between the accommodated oscillator 3 and the cover 7. Arrows with G1 and G2 ) Is generally constant in each gap G. The thicknesses of the plurality of gaps G may be identical to one another or may be different from one another. The specific thickness of the gap G may be set as appropriate.

  The thickness of the air layer (gap G) when the cover 7 surrounds the accommodated oscillator 3 via the air layer because the gap G is not sealed or air is enclosed in the gap G The length is preferably 30 mm or less. If the air layer is 30 mm or less, convection is unlikely to occur due to viscous resistance, and improvement of the heat insulating effect by the air layer is expected. The value of 30 mm is demonstrated in the technical field of paired glass of buildings. Furthermore, from the viewpoint of downsizing the oscillator 1, the gap G is preferably 1 mm or less.

In addition, the nitrogen layer (the gap G) has a thickness of 30 mm even when the cover 7 encloses the accommodated oscillator 3 via the nitrogen layer by sealing the nitrogen (N ₂ ) in the gap G. It is preferable that it is the following. Nitrogen accounts for 80% of air, and its viscosity is close to that of air (eg, at 20 ° C. and 1 atm, the viscosity of air is 18.2 × 10 ⁻⁶ Pa · s, the viscosity of nitrogen is 17 6 × 10 ⁻⁶ Pa · s), the same effect as described above is expected.

  Also, even when air and a gas other than nitrogen are sealed in the gap G, the thickness of the gas layer may be appropriately set so that convection does not easily occur as described above. For example, if it is a gas whose viscosity is higher than that of air and the thickness of the gas layer is 30 mm or less, the same effect as described above can be expected.

  The material of the cover 7 may be appropriate. For example, the cover 7 may be formed of a conductor such as metal, may be formed of an insulator such as ceramic, glass, or polymer resin, or may be formed of a laminate of a metal and an insulator. Good. If metal is used, the cover 7 can be expected to have a shielding function. Further, when an insulator is used, generally, since the insulator has higher heat insulation than a conductor, improvement of the heat insulation effect by the cover 7 is expected.

  For example, the lower part of the side surface portion (wall portion) of the cover 7 is fixed to the substrate 5. Fixing may be realized, for example, by bonding, screw fastening, insertion of the claws of the cover 7 into the slits of the substrate 5, or a combination thereof. Bonding is preferable from the viewpoint of fixing firmly at low cost.

  The bonding may be performed by an (insulating) adhesive, may be performed by a conductive bonding material such as solder, or may be welding. Also, as described above, since the gap G may or may not be sealed, bonding may be performed over the entire periphery of the cover 7 or over the entire periphery. There is no need (it may be done discretely).

  In the example shown in FIGS. 1 and 3, the case where the cover 7 is joined to the substrate 5 over the entire circumference of the cover 7 by the conductive bonding material 49 is illustrated. An annular bonding pad 51 made of a conductor and extending to surround the plurality of internal pads 41 is formed on the first major surface 39 a of the substrate 5 in order to strengthen the bonding between the conductive bonding material 49 and the substrate 5. Is provided. Similar bonding pads may be provided on the lower surface of the side surface portion of the cover 7.

  Moreover, FIG.1 and FIG.3 has illustrated the case where the cover 7 is comprised by the conductor and the reference electric potential is provided. For example, the external terminal 43G shown on the right side of the drawing in FIG. 3 is a terminal to which a reference potential is applied, and the external terminal 43G and the bonding pad 51 described above are via the conductor of the substrate 5 (for example, the through conductor 47). Are connected electrically.

  As described above, in the present embodiment, the oscillator 1 includes the accommodated oscillator 3, the substrate 5, and the cover 7. The housed oscillator 3 has a crystal vibrating element 9 and a package 13 for sealing the crystal vibrating element 9. The substrate 5 has the accommodated oscillator 3 mounted on the first main surface 39a, and has an external terminal 43 electrically connected to the accommodated oscillator 3 on the second principal surface 39b. The cover 7 is placed on the first major surface 39 a so as to receive the accommodated oscillator 3. In addition, the cover 7 surrounds the accommodated oscillator 3 via the gap G. The oscillator 1 does not have a heater.

  In another aspect, the oscillator 1 includes the accommodated oscillator 3, the cover 7, and the external terminal 43. The housed oscillator 3 has a crystal vibrating element 9 and a package 13 for sealing the crystal vibrating element 9. The cover 7 accommodates the contained oscillator 3. The external terminal 43 is electrically connected to the accommodated oscillator 3 and exposed to the outside of the cover 7. The cover 7 surrounds the accommodated oscillator 3 via the gap G. The oscillator 1 does not have a heater.

  Therefore, for example, the possibility that the atmosphere around the oscillator 1 is directly in contact with the accommodated oscillator 3 by the cover 7 is reduced. As a result, for example, the temperature change of the accommodated oscillator 3 due to the temperature change of the surrounding atmosphere is alleviated, and the frequency of the oscillation signal is stabilized. That is, the oscillator 1 can reduce the influence of the temperature change of the surrounding atmosphere on the characteristics of the crystal vibrating element 9. On the other hand, since the oscillator 1 does not have a heater, miniaturization and cost reduction are expected. The cover 7 is only covered on the first major surface 39 a and does not accommodate the substrate 5. Therefore, the miniaturization is remarkable as compared with the second embodiment described later.

  By making the configuration as described above, by enclosing the contained oscillator 3 with the cover 7, it is possible to suppress the contact of the gas flowing to the contained oscillator 3 and alleviate the temperature change of the contained oscillator 3. There is. Therefore, the effect of alleviating the above-mentioned temperature change is particularly remarkable when there is a fan in the housing of the device accommodating the oscillator 1 and the gas flow around the oscillator 1. Further, the stabilization of the frequency of the oscillation signal is effective in a situation where the oscillator 1 is provided in a flowing gas, for example, in a case where it is used in a GPS mounted on an automobile part or the like. That is, by stabilizing the reference signal, it is expected to improve the accuracy of the position information.

  Moreover, in the present embodiment, for example, in the gap G, a gas layer made of air or nitrogen and having a thickness of 30 mm or less surrounding the accommodated oscillator 3 is configured.

  Thus, for example, as already mentioned, the occurrence of air or nitrogen convection can be reduced. As a result, for example, the temperature change of the accommodated oscillator 3 caused by the temperature change of the atmosphere around the oscillator 1 can be mitigated. If the gas is air, for example, it is not necessary to prepare a special gas, and the gap G may not necessarily be sealed. Therefore, for example, cost reduction is expected. Also, if the gas is nitrogen, it is expected to suppress the oxidation of the conductor, and nitrogen is relatively inexpensive compared to other inert gases and the like.

  Further, in the present embodiment, the gap G may be vacuum instead of the above-described configuration of the gas layer.

  In this case, the heat insulating effect by the gap G can be improved as compared with the case where the gas is present in the gap G at a pressure higher than the atmospheric pressure. However, compared to the case where a gas layer having a pressure equal to the atmospheric pressure is used, for example, the sealing property is improved and the strength for resisting the pressure difference between the inside and outside of the cover 7 is required. Preferably, the gas layer is formed.

  Further, in the present embodiment, the cover 7 and the substrate 5 are joined along the entire circumference surrounding the contained oscillator 3.

  Therefore, for example, the gap G of the cover 7 is sealed, and the possibility of the atmosphere around the oscillator 1 flowing into the gap G is reduced. As a result, for example, the temperature change of the accommodated oscillator 3 caused by the temperature change of the atmosphere around the oscillator 1 can be mitigated. In addition, for example, the cover 7 reduces the risk of the substrate 5 being bent. As a result, for example, peeling between the internal terminal 33 and the internal pad 41 due to the bending of the substrate 5 is reduced. Further, for example, when the bending of the substrate 5 is suppressed by the cover 7, the possibility of the substrate 5 vibrating due to the vibration of the quartz crystal vibrating element 9 is reduced. By reducing the vibration of the substrate 5, the frequency of the oscillation signal of the accommodated oscillator 3 is stabilized, and the possibility of the unnecessary vibration being applied to the electronic components around the oscillator 1 is also reduced.

  Further, in the present embodiment, the cover 7 is made of metal and is electrically connected to the external terminal 43 </ b> G to which the reference potential is applied among the plurality of external terminals 43.

  Thus, for example, as already mentioned, the cover 7 can also be used as a shield. As a result, for example, it is expected that noise penetration is reduced and the frequency of the oscillation signal is stabilized. Since the cover 7 encloses the contained oscillator 3, the cover 7 has a large area capable of blocking noise from the contained oscillator 3 or noise from the contained oscillator 3 and is suitable as a shield.

  Further, in the present embodiment, the cover 7 may be made of an inorganic material instead of being made of metal.

  In this case, heat conduction by phonons is dominant in inorganic materials such as glass and ceramic, and heat conduction by conductive electrons such as metal materials is not the type of heat conduction by conduction electrons, compared to the case where metal materials are used, The heat insulation of the cover 7 can be enhanced. Thus, the highly thermally insulating cover 7 reduces the transfer of the temperature of the atmosphere around the oscillator 1. As a result, for example, the temperature change of the gap G is suppressed, and in turn, the temperature change of the accommodated oscillator 3 is suppressed. Also, the transfer of heat from the substrate 5 to the cover 7 is reduced.

  The housed oscillator 3 further includes an integrated circuit element 11 including a compensation circuit that compensates for the characteristic change due to the temperature change of the crystal vibrating element 9.

  Therefore, the compensation circuit operates under the condition that the temperature change of the accommodated oscillator 3 is mitigated. As a result, the occurrence of overshoot or undershoot of the frequency with respect to the target frequency due to the time delay or the like of the compensation circuit is reduced.

Second Embodiment
FIG. 4 is a partially broken perspective view showing a crystal oscillator 201 according to a second embodiment of the present invention.

  In the description of the second embodiment, the same or similar components as or to those of the first embodiment may be denoted by the same reference numerals as those of the first embodiment, and the description thereof may be omitted. In the configuration corresponding to (similar to) the configuration of the first embodiment and to which the reference numeral different from the reference numeral of the first embodiment is attached, matters not specifically mentioned are similar to the configuration of the first embodiment.

  Similar to the oscillator 1 of the first embodiment, the oscillator 201 includes the accommodated oscillator 3, the substrate 205 on which the accommodated oscillator 3 is mounted, the cover 207 that accommodates the accommodated oscillator 3, the accommodated oscillator 3, and the electricity. And an external terminal 243 exposed to the outside of the cover 207. However, for example, the oscillator 201 is different from the oscillator in the following points.

  First, in the oscillator 201, the cover 207 accommodates not only the contained oscillator 3 but also the substrate 205. Specifically, for example, the cover 207 is configured in a substantially rectangular parallelepiped shape, and encloses the accommodated oscillator 3 and the substrate 205 by six sides. Although not particularly illustrated, the cover 207 is configured by, for example, fixing (for example, bonding) a member constituting the upper surface side and a member constituting the lower surface side. The cover 207 may be made of an insulator or may be made of a conductor.

  The upper surface and the four side surfaces of the cover 207 surround the accommodated oscillator 3 via the gap G, as in the first embodiment. That the gap G may or may not be sealed, that a specific gas may be enclosed in the gap G, that the gap G may be vacuum, a gas layer of 30 mm or less is formed in the gap G That it may be the same as in the first embodiment.

  The four side surfaces and the lower surface of the cover 207 may be in contact with the substrate 205 or may not be in contact (it may be opposed to each other via a gap). In the example of FIG. 4, the lower surface of the cover 207 is opposed to the substrate 205 via the gap G3. In this case, since the atmosphere on the lower surface side of the oscillator 201 and the substrate 205 are thermally insulated by the gap G3, it is expected that the temperature change of the accommodated oscillator 3 due to the temperature change of the substrate 205 is alleviated.

  Further, in the oscillator 201, the external terminal 243 is not a pad formed on the main surface of the substrate 205 but a conductive pin. For example, one end of the external terminal 243 is inserted into a hole formed in the substrate 205, and is joined to a conductor (not shown) formed around the hole by a conductive bonding material (not shown) such as solder. There is. Thus, the external terminal 243 is fixed to the substrate 205 and electrically connected, and in turn, is electrically connected to the accommodated oscillator 3. The other end of the external terminal 243 extends from the hole (not shown) formed on the lower surface of the cover 207 to the outside of the cover 207, for example.

  Further, in the oscillator 201, electronic components 253 other than the contained oscillator 3 are also mounted on the substrate 205. For example, the electronic component 253 may be interposed between the external terminal 243 and the contained oscillator 3, and a signal from any one of the external terminals 243 is input separately from the contained oscillator 3, A signal may be output to any one of the external terminals 243. For example, the electronic component 253 is a resistor, an inductor, a capacitor, or a driver IC interposed between the external terminal 243 and the contained oscillator 3. Also, for example, the electronic component 253 is a temperature sensor that detects the temperature around the accommodated oscillator 3 and outputs the detection result to the accommodated oscillator 3 or the external terminal 243. The electronic component 253 may be mounted on any of the main surfaces of the substrate 205. The number and position of the electronic components 253 may be appropriately set. In the same manner as in the first embodiment, the substrate 205 is merely for connecting the internal terminal 33 and the external terminal 243 without providing the electronic component 253 and the electronic element formed of the conductor in the substrate 205. May be

  As described above, in the second embodiment, as in the first embodiment, the oscillator 201 is electrically connected to the accommodated oscillator 3, the cover 207 that accommodates the accommodated oscillator 3, and the accommodated oscillator 3. And an external terminal 243 exposed to the outside of the cover 207. The cover 207 surrounds the accommodated oscillator 3 via the gap G without a heat source. That is, the oscillator 201 does not have a heater which is a heat source.

  Therefore, the same effect as that of the first embodiment is achieved. For example, the possibility of direct contact with the atmosphere around the oscillator 201 is reduced by the cover 207. As a result, the temperature change of the accommodated oscillator 3 is alleviated, and the frequency of the oscillation signal is stabilized. That is, the influence of the temperature change of the atmosphere around the oscillator 201 on the characteristics of the crystal vibrating element 9 can be reduced. Furthermore, on the other hand, unlike the heat source for causing the gap G to function as a thermostat, specifically, the piezoelectric oscillator having a heater, the oscillator 1 generates a heat source for causing the gap G to function as a thermostat Specifically, miniaturization and cost reduction are expected because there is no heater.

  In the first and second embodiments described above, the crystal oscillators 1 and 201 are each an example of a piezoelectric device, the accommodated oscillator 3 is an example of an accommodated piezoelectric device, and the crystal vibrating element 9 is a piezoelectric element. It is an example.

  The present invention is not limited to the above embodiments, and may be implemented in various aspects.

  The structure of the piezoelectric device may be changed as appropriate. For example, as in the first embodiment, when the cover is placed on one main surface of the substrate and the external terminal is provided on the other main surface side, even if the electronic component is mounted on the other main surface of the substrate Good. However, in this case, for example, the external terminal needs to be a pin shape, or a recess or an opening for housing the electronic component on the circuit board on which the piezoelectric device is mounted is required so that the mounting of the piezoelectric device is there. Also, for example, when the cover is placed on one main surface of the substrate as in the first embodiment, an opening may be formed in the substrate. Further, for example, in the case where the substrate is accommodated in the cover as in the second embodiment, a plurality of substrates may be accommodated in the cover in a layered manner via the spacer. The number of external terminals and the arrangement thereof may be appropriately set according to the function required of the piezoelectric device. Also, for example, without providing a substrate on which the housed piezoelectric device is mounted, an external terminal provided on the package of the housed piezoelectric device as an external terminal is exposed to the outside of the cover, or an external terminal fixed to the cover May be fixed directly to the internal terminals of the accommodated piezoelectric device. However, as in the first and second embodiments, the structure in which the contained piezoelectric device is mounted on the substrate is easier to manufacture, and the existing piezoelectric device may be used as the contained piezoelectric device. It is easy.

  The accommodated piezoelectric device is not limited to the piezoelectric oscillator. For example, the contained piezoelectric device may be a piezoelectric element having a piezoelectric element and a package for containing the piezoelectric element in a sealed space, and not having an oscillation circuit (integrated circuit element). Also, for example, the contained piezoelectric device may be an elastic wave device having a piezoelectric substrate, an excitation electrode provided on the upper surface thereof, and a cover for accommodating the excitation electrode. In this elastic wave device, the piezoelectric element is constituted by the upper surface portion of the piezoelectric substrate and the excitation electrode, and the package is constituted by the other portion of the piezoelectric substrate and the cover.

  In the case where the contained piezoelectric device is a piezoelectric vibrator that does not have an oscillation circuit, the entire piezoelectric device including the contained piezoelectric device and the cover may be a piezoelectric vibrator that does not have an oscillating circuit. It may be a piezoelectric oscillator having a circuit. In the case where the entire piezoelectric device is a piezoelectric vibrator, for example, the accommodated piezoelectric device (piezoelectric vibrator) and the external terminal are directly connected. In the case where the entire piezoelectric device is a piezoelectric oscillator, for example, an integrated circuit element including an oscillation circuit is mounted on a substrate (either inside or outside the cover). Further, for example, an opening is formed in a region overlapping the accommodated piezoelectric device (piezoelectric vibrator) of the substrate, and an integrated circuit element including an oscillation circuit is disposed in the opening and mounted on a package of the accommodated piezoelectric device. It is also good.

  When the contained piezoelectric device is a piezoelectric oscillator, the piezoelectric oscillator may be, for example, a clock oscillator, a voltage controlled oscillator (VCXO), or a temperature compensated oscillator (TCXO). May be The same applies to the case where the entire piezoelectric device including the accommodated piezoelectric device and the cover is a piezoelectric oscillator. When the contained piezoelectric device is a piezoelectric vibrator, the piezoelectric vibrator may have an electronic element other than the piezoelectric element such as a thermistor. The same applies to the case where the entire piezoelectric device including the accommodated piezoelectric device and the cover is a piezoelectric vibrator.

  In the case where the contained piezoelectric device is a piezoelectric oscillator, the package is not limited to one having a so-called H-type element mounting member. For example, the contained piezoelectric device includes an element substrate on which the piezoelectric element and the integrated circuit element are mounted on the same main surface, an element cover for housing the piezoelectric element, and a resin for sealing the element cover and the integrated circuit element. It may be an oscillator having Further, for example, the contained piezoelectric device includes a first recess in which the piezoelectric element is accommodated, a second recess which is opened in the bottom of the first recess, and in which the integrated circuit element is accommodated, and a lid member which closes the first recess. And may be an oscillator having

  The piezoelectric body constituting the piezoelectric element is not limited to quartz, and may be, for example, ceramic. When the piezoelectric element is a quartz crystal vibrating element, the quartz crystal vibrating element is not limited to a rectangular flat plate, and may be, for example, a tuning fork type. Further, the flat plate-shaped crystal vibrating element is not limited to one in which a pair of electrodes is provided on both main surfaces of the piezoelectric body, and, for example, one pair of piezoelectric vibrators like a SAW type crystal vibrating element The electrode of may be provided.

  The piezoelectric device of the present invention is characterized by not having a heater. Here, the heater indicates, for example, a heater provided mainly for heating. That is, even if an element whose main purpose is an action other than heating generates heat, and the heat intentionally or unintentionally affects the characteristics of the piezoelectric element, the element is not a heater. For example, even if an integrated circuit element (including an oscillation circuit or a driver) or a resistor or inductor for impedance matching is provided adjacent to the piezoelectric element so that the piezoelectric element can be heated, the heater may be used. Absent. Therefore, the fact that the implemented product does not fall within the technical scope of the present invention does not necessarily mean that the component that performs the above-described additional heating action is provided in the implemented product. Conversely, for example, in the prior art, in the case where a heater is provided mainly for heating, the present invention is disclosed in the prior art even if the heater secondarily contributes to impedance matching No heater is provided).

  It should be noted that although the piezoelectric device with a thermostat has a heater, the piezoelectric device of the present invention does not have a heater in particular, but the piezoelectric device of the present invention is similarly cooled There is also no means or means for both heating and cooling. That is, the present invention does not have temperature control means for performing at least one of heating and cooling. It is the same as the above-mentioned heater whether it corresponds to these means.

  DESCRIPTION OF SYMBOLS 1 ... crystal oscillator (piezoelectric device), 3 ... accommodation oscillator (accommodation piezoelectric device), 5 ... board | substrate, 7 ... cover, 9 ... crystal oscillation element (piezoelectric element) 13 ... package, 43 ... external terminal, G1 and G2 ... gap.

Claims (5)

A piezoelectric element, a front Symbol detainee piezoelectric device having a package sealing the piezoelectric elements, and the electronic elements other than the piezoelectric element is accommodated in the package,
A substrate on which only the contained piezoelectric device is mounted on one main surface, and an external terminal electrically connected to the contained piezoelectric device on the other main surface;
A cover placed on the one main surface to accommodate the accommodated piezoelectric device;
The cover surrounds the accommodated piezoelectric device through a gap;
In the gap, a gas layer made of air or nitrogen and surrounding the accommodated piezoelectric device and having a thickness of 30 mm or less is configured, or the gap is vacuum.
Piezoelectric device that does not have a heater. The piezoelectric device according to claim 1 , wherein the cover and the substrate are joined along an entire circumference surrounding the contained piezoelectric device. The cover is made of a metal, a plurality of the external piezoelectric device according to claim 1 or 2 are external terminals electrically connected to a reference potential is applied among the terminals. The cover, piezoelectric device according to claim 1 or 2 made of an inorganic material. The piezoelectric device according to any one of claims 1 to 4 , wherein the contained piezoelectric device further includes an integrated circuit element including a compensation circuit that compensates for a characteristic change due to a temperature change of the piezoelectric element.

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