JP2016012803A - Piezoelectric device with constant temperature oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric device with a constant temperature oven (an oven-controlled crystal oscillator) which promptly makes a temperature of a piezoelectric device constant.SOLUTION: An oven-controlled crystal oscillator includes: a mounting substrate 17 including a first mounting surface 24a and a second mounting surface 24b on the back surface of the first mounting surface 24a; a temperature compensated type crystal oscillator (TCXO) 3 mounted on the first mounting surface 24a; a heater 21 mounted on the second mounting surface 24b; and a case that houses the mounting substrate 17, the TCXO 3, and the heater 21. The mounting substrate 17 includes: an insulation substrate 24 forming the first mounting surface 24a and the second mounting surface 24b; and a heat transfer body 63 which is made of a material having heat conductivity higher than that of the insulation substrate 24, penetrates through the insulation substrate 24 to be exposed on the second mounting surface 24b side in an area overlapping with the heater 21 and exposed on the first mounting surface 24a side in an area overlapping with the TCXO 3, and is not electrically connected with the TCXO 3.

Description

  The present invention relates to a thermostatic chamber-equipped piezoelectric device.

  A piezoelectric device having a thermostatic chamber is known. For example, Patent Document 1 discloses a mounting substrate, a temperature compensated crystal oscillator (TCXO) mounted on one main surface of the mounting substrate, and a heater mounted on the other main surface of the mounting substrate. And an oven controlled crystal oscillator (OCXO) having a case for housing them. In addition, the thermostat is comprised by the heater and the case. The temperature around the TCXO is made constant by the thermostatic bath. This reduces the fluctuation of the frequency of the TCXO oscillation signal due to temperature.

JP2013-211752A

  In the technique of Patent Document 1, a mounting substrate is interposed between the piezoelectric device (TCXO) and the heater. Therefore, a part of the heat of the heater may move to the mounting substrate, and it may take time for the temperature of the piezoelectric device to reach a constant temperature. As a result, it may take time until the electrical characteristics of the piezoelectric device are stabilized.

  Therefore, it is desired to provide a piezoelectric device with a thermostatic chamber that can quickly bring the temperature of the piezoelectric device to a constant temperature.

  A thermostatic chamber-equipped piezoelectric device according to an aspect of the present invention includes a mounting substrate having a first mounting surface and a second mounting surface on the back thereof, a piezoelectric device mounted on the first mounting surface, and the second mounting surface A heater, and a case for housing the piezoelectric device, the mounting substrate, and the heater, and the mounting substrate includes an insulating substrate that constitutes the first mounting surface and the second mounting surface; The first mounting is made of a material having a higher thermal conductivity than the insulating base, penetrates the insulating base, is exposed to the second mounting surface side in a region overlapping the heater, and overlaps the piezoelectric device. And a heat transfer body exposed to the surface side and electrically disconnected from the piezoelectric device.

  Preferably, the heat transfer body includes a first heat transfer film provided on the first mounting surface and facing the piezoelectric device.

  Preferably, the heat transfer body includes a second heat transfer film provided on the second mounting surface and facing the heater.

  Preferably, a space is formed between the piezoelectric device and the first mounting surface, and the insulating substrate is disposed on the mounting substrate in a region overlapping the heater and the space. A hollow through hole penetrating from the side to the first mounting surface side and leading to the space is formed, and the heat transfer body includes an inner peripheral heat transfer film provided on an inner peripheral surface of the through hole. .

  Preferably, a space is formed between the piezoelectric device and the first mounting surface, and the heat transfer body is exposed to the first mounting surface side only in a region overlapping the space.

  Preferably, the piezoelectric device includes an element mounting member having a first concave portion and a second concave portion opening on opposite sides, a piezoelectric element accommodated in the first concave portion, and an integration accommodated in the second concave portion. And is mounted on the first mounting surface with the second recess side facing the first mounting surface, and the second recess constitutes at least a part of the first space.

  Preferably, the heat transfer body is provided on the second mounting surface and connected to a mounting pad joined to the heater via a bump.

  According to said structure, the temperature of a piezoelectric device can be rapidly made constant.

1 is a perspective view showing a schematic configuration of an OCXO according to an embodiment of the present invention with a part thereof broken. FIG. Sectional drawing in the II-II line of FIG. FIG. 3 is a partially enlarged view of FIG. 2. The top view and bottom view of the mounting base | substrate of OCXO of FIG. The block diagram which shows schematic structure of the signal processing system of OCXO of FIG.

  Hereinafter, OCXO according to an embodiment of the present invention will be described with reference to the drawings. Note that the drawings used in the following description are schematic, and the dimensional ratios and the like on the drawings do not necessarily match the actual ones.

  The OCXO may be set in any direction upward or downward, but hereinafter, for convenience, terms such as an upper surface and a lower surface are defined by defining the orthogonal coordinate system xyz and setting the positive side in the z direction upward. Shall be used.

  For the same or similar configuration, a number may be added to the beginning of the name and a capital letter may be added to the end of the code, such as “first external terminal 23A” and “second external terminal 23B”. In this case, the numbers and alphabets may be omitted and not distinguished, just like “external terminal 23”.

  When a conductor such as a wiring or a pad is simply connected without an electrical or thermal description, basically, the objects are in contact with each other, the objects are integrally formed, It refers to a connection in which the members are joined together via bumps or the like, and is accompanied by an electrical connection and a thermal connection. In the thermal connection, for example, the state in which the two objects are in direct contact with or integrally formed, and the material of the insulating base 24 described later and the gas in the case 19 are between the two objects. A state in which one or a plurality of members made of a material having a higher thermal conductivity than air (for example, air) is interposed to form a heat path.

  FIG. 1 is a perspective view showing a schematic configuration of an OCXO 1 according to an embodiment of the present invention, with a part thereof broken. 2 is a cross-sectional view taken along the line II-II in FIG.

  The OCXO 1 includes, for example, a TCXO 3 and a thermostatic chamber 5 for maintaining an atmosphere around the TCXO 3 at a predetermined temperature and mediating electrical connection between the TCXO 3 and an external device.

  The TCXO 3 includes, for example, an element mounting member 7, a vibration element 9 (FIG. 2) and an IC 11 (FIG. 2) mounted on the element mounting member 7, and a lid 13 for sealing the vibration element 9. ing.

  The element mounting member 7 includes, for example, an insulating member 15 and various wirings and pads provided on or inside the insulating member 15.

  As shown in FIG. 2, the insulating member 15 (element mounting member 7) includes a first concave portion 15 a that opens upward and accommodates the vibration element 9, and a second concave portion 15 b that opens downward and accommodates the IC 11. Have. In another aspect, the insulating member 15 includes a substrate portion 15c, a first frame portion 15d positioned on one main surface (first mounting surface 15ca) of the substrate portion 15c, and the other main surface of the substrate portion 15c ( And a second frame portion 15e located on the second mounting surface 15cb).

  The insulating member 15 is formed by stacking a plurality of layered members made of ceramic such as alumina, for example. In the example of FIG. 2, the insulating member 15 includes four layered members constituting the substrate portion 15c, a layered member constituting the first frame portion 15d, and a layered member constituting the second frame portion 15e. Overlaid and formed.

  The wiring and pads of the element mounting member 7 are constituted by, for example, a via conductor that penetrates the layered member constituting the insulating member 15 in the vertical direction, and a layered conductor superimposed on the layered member. These conductors are made of a metal such as Cu, for example, and have a higher thermal conductivity than the insulating member 15.

  The vibration element 9 includes, for example, a plate-shaped piezoelectric element plate 10 (FIG. 2) and a pair of excitation electrodes 32 (see FIG. 5) provided on both main surfaces of the piezoelectric element plate 10. The piezoelectric element plate 10 is made of, for example, a quartz material such as quartz, cut at a predetermined angle with respect to a crystal axis, and has a rectangular shape in plan view. When a voltage is applied to the pair of excitation electrodes 32, the piezoelectric base plate 10 generates a thickness shear vibration at a predetermined frequency. The vibration element 9 is mounted on the element mounting member 7 by, for example, a lead electrode (not shown) extending from the excitation electrode 32 being bonded to a pad (not shown) on the first mounting surface ca by a bump.

  For example, the IC 11 is mounted on the second mounting surface cb by being bonded to a pad (not shown) provided on the second mounting surface cb by a bump. The IC 11 is electrically connected to the thermostatic chamber 5 (more specifically, a mounting substrate 17 to be described later) and also electrically connected to the vibration element 9 through wiring and pads provided on the element mounting member 7. ing.

  The lid 13 is bonded to the upper surface of the first frame portion 15d and seals the first recess 15a. The lid 13 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 stacked. For example, the lid 13 is made of a metal plate, and this metal plate is joined to the first frame portion 15d by seam welding or the like, and the lid 13 is provided on the surface or inside of the insulating member 15. The wiring is electrically connected to the second device pad 25B (see FIG. 5).

  For example, the thermostatic chamber 5 mounts the mounting base 17 on which the TCXO 3 is mounted, the case 19 that houses the TCXO 3, the heater 21 (FIG. 2) for heating the atmosphere in the case 19, and the OCXO 1 to an external device. And a plurality (four in this embodiment) of external terminals 23 (first external terminal 23A to fourth external terminal 23D). In addition to the TCXO 3 and the heater 21, various electronic components (for example, a power supply IC) may be mounted on the mounting substrate 17.

  The mounting substrate 17 is made of, for example, a printed wiring board, and includes an insulating substrate 24 and various conductors provided on the insulating substrate 24. The insulating substrate 24 (mounting substrate 17) has a first mounting surface 24a and a second mounting surface 24b on the back surface thereof. TCXO3 is mounted on the first mounting surface 24a, and the heater 21 is mounted on the second mounting surface 24b. That is, the mounting substrate 17 is interposed between the TCXO 3 and the heater 21. The insulating base 24 is made of, for example, a glass epoxy material.

  The case 19 is made of, for example, a metal material, and houses the TCXO 3, the mounting substrate 17, and the heater 21. Although not particularly illustrated, the case 19 is configured, for example, by fixing a member constituting the lower surface of the case 19 and members constituting the upper surface and the outer peripheral surface of the case 19. Both members are preferably joined in an airtight manner (the inside of the case 19 is sealed).

  For example, the heater 21 is mounted on the second mounting surface 24b of the mounting substrate 17 at a position overlapping the TCXO3. For example, the heater 21 is configured by sealing a conductor (resistor) extending in a predetermined pattern with an insulating material, and generates heat corresponding to a voltage applied via the mounting substrate 17.

  The plurality of external terminals 23 are, for example, pin-shaped terminals, and one end side is inserted into a hole formed in the mounting base 17 and is fixed to the mounting base 17 with solder or the like and electrically connected thereto. The other end sides of the plurality of external terminals 23 extend from, for example, the lower surface of the case 19. The plurality of external terminals 23 are fixed to the case 19 and may contribute to fixing the mounting base 17 and the case 19 while securing a space between the mounting base 17 and the lower surface of the case 19. .

  FIG. 3 is a partially enlarged view of FIG. In FIG. 3, the portion related to the mounting of the TCXO 3 and the heater 21 on the mounting base 17, the configuration of the mounting base 17, and the like are shown in more detail than FIG.

  The element mounting member 7 includes, for example, a plurality (four in the present embodiment) of device pads 25 (first device pad 25A to fourth device pad 25D provided on the lower surface of the second frame portion 15e. See also FIG. 5). have. The device pad 25 is electrically connected to the IC 11 through the wiring of the element mounting member 7. The arrangement position, planar shape, and area of the plurality of device pads 25 in the lower surface of the second frame portion 15e may be set as appropriate. For example, the plurality of device pads 25 are provided at the four corners of the second frame portion 15e.

  The TCXO 3 is disposed with the lower surface of the second frame portion 15e facing the first mounting surface 24a of the mounting substrate 17. The plurality of device pads 25 are a plurality of device mounting pads 27 provided on the first mounting surface 24a (first device mounting pad 27A to fourth device mounting pad 27D; see also FIG. 4A). Are joined by a plurality of bumps 26. Thereby, the TCXO 3 is fixed and electrically connected to the mounting substrate 17. The bump 26 is made of, for example, solder (including lead-free solder) or a conductive adhesive.

  Since the second recess 15b is formed in the element mounting member 7 and the bumps 26 are interposed between the element mounting member 7 and the mounting base 17, the TCXO 3 and the mounting base 17 are interposed. The first space S1 is configured. The first space S <b> 1 communicates with the outside of the element mounting member 7 through gaps between the plurality of bumps 26. However, the first space S <b> 1 may be hermetically sealed by arranging resin around the element mounting member 7 or between the plurality of bumps 26.

  The heater 21 has, for example, a plurality (two in this embodiment) of heater pads 28 on the surface facing the second mounting surface 24b. The heater pad 28 is for receiving power supply, for example, and is provided on both sides of the heater 21 in the longitudinal direction. The plurality of heater pads 28 are bonded to the plurality of heater mounting pads 30 (the first heater mounting pad 30A and the second heater mounting pad 30B) provided on the second mounting surface 24b by the plurality of bumps 29. The Thereby, the heater 21 is fixed and electrically connected to the mounting substrate 17. The bump 29 is made of, for example, solder (including lead-free solder) or a conductive adhesive.

  The heater 21 is further fixed to the mounting substrate 17 by an adhesive 31. For example, the adhesive 31 is provided so as to cover the heater 21. That is, the adhesive 31 is in close contact with the side surface (for example, four or two side surfaces) of the heater 21 and the surface of the heater 21 opposite to the mounting substrate 17 and around the heater 21 on the second mounting surface 24b. It is in close contact with the area. The adhesive 31 may be in close contact with the heater 21 only on the side surface of the heater 21. Further, the adhesive 31 may not be provided.

  The heater 21 and the second mounting surface 24b are separated by the thickness of the bump 29, and the adhesive 31 does not flow between them except for the outer peripheral side. Accordingly, a second space S2 is formed between the two. For example, the second space S <b> 2 is sealed by providing the adhesive 31 so as to surround the outer periphery of the heater 21. However, the second space S <b> 2 may communicate with the space outside the heater 21 by providing an adhesive so as to cover only two of the four side surfaces of the heater 21.

  In the mounting substrate 17, a plurality of through holes 61 are formed in a region overlapping the TCXO 3 and the heater 21 in order to optimize the temperature rise of the TCXO 3. The plurality of through holes 61 communicate the first space S1 and the second space S2. The number, arrangement, shape, and size of the plurality of through holes 61 may be set as appropriate. When a through hole for connecting the conductive layers of the mounting substrate 17 is provided in the mounting substrate 17, the through hole 61 is the same as the through hole as long as it has the same shape and size as the through hole. It is convenient to form.

  In addition, the mounting substrate 17 includes a heat transfer body 63 that penetrates the insulating substrate 24 and is exposed to the first mounting surface 24a and the second mounting surface 24b in order to optimize the temperature increase in the first space S1. Yes. The heat transfer body 63 is, for example, provided on the first mounting surface 24a, the first heat transfer film 63a facing the TCXO3, and the second heat transfer film 63b provided on the second mounting surface 24b and facing the heater 21. And an inner peripheral heat transfer film 63c that is provided on the inner peripheral surface of the through hole 61 and connects the first heat transfer film 63a and the second heat transfer film 63b.

  For example, the second heat transfer film 63b is connected to one of the two heater mounting pads 30 (may be regarded as including the heater mounting pad 30). Therefore, the heat transfer body 63 is thermally connected to the heater 21 (heater pad 28) via the heater mounting pad 30 and the bump 29. The heat transfer body 63 is made of, for example, a metal such as Cu, and has a higher heat transfer rate than the insulating base 24. The heat transfer body 63 is electrically disconnected from the TCXO 3.

  4A is a plan view of the first mounting surface 24a, and FIG. 4B is a plan view of the second mounting surface 24b. However, FIG. 4B is a view seen through the second mounting surface 24b from the first mounting surface 24a side. That is, the upper, lower, left, and right sides of FIG. 4A correspond to the upper, lower, left, and right sides of FIG. 4B (see the coordinate system xyz).

  In FIG. 4A, TCXO3 is indicated by a two-dot chain line, and in FIG. 4B, the control IC 50 for controlling the heater 21 and the heater 21 is indicated by a two-dot chain line.

  The mounting substrate 17 has a plurality of holes into which a plurality (four) of external terminals 23 are inserted, and a plurality of connection terminals 65 (first connection terminals 65A to fourth connection terminals) connected to the plurality of external terminals 23. 65D). The plurality of holes and the plurality of connection terminals 65 are provided, for example, on the outer peripheral side of the mounting substrate 17, more specifically at the four corners. The plurality of connection terminals 65 are formed, for example, by providing a metal film around the inner peripheral surface of the plurality of holes and the holes on the first mounting surface 24a and the second mounting surface 24b.

  In the plurality of connection terminals 65, the relationship between the position and the role may be set as appropriate. In the present embodiment, the first connection terminal 65A is a terminal to which a control voltage Vcon for controlling the frequency of the oscillation signal generated by the TCXO3 is input, and the second connection terminal 65B is connected to the ground serving as a reference potential. The third connection terminal 65C is a terminal for outputting the oscillation signal Vout generated by the TCXO3, and the fourth connection terminal 65D is supplied with the power supply voltage Vcc for driving the TCXO3 and the thermostatic chamber 5. Terminal.

  The plurality of (four) device mounting pads 27 are provided at the four corners of the TCXO3 arrangement region in correspondence with the device pads 25 of the TCXO3 being provided at the four corners of the TCXO3. Further, the plurality of device mounting pads 27 are arranged, for example, such that the center of the TCXO 3 is positioned at the center of the first mounting surface 24a.

  The center is, for example, the center of gravity of the planar shape. The same applies to the center of a heater 21 and the like which will be described later.

  The first device mounting pad 27A to the fourth device mounting pad 27D are electrically connected to the first connection terminal 65A to the fourth connection terminal 65D through, for example, wiring provided on the mounting base 17. . In FIG. 4, the arrangement positions of the first device mounting pads 27A to the fourth device mounting pads 27D and the arrangement positions of the first connection terminals 65A to the fourth connection terminals 65D correspond to each other. It does not have to be compatible.

  The plurality (two) of heater mounting pads 30 are provided on both sides of the heater 21 in the longitudinal direction corresponding to the heater pads 28 provided on both sides of the heater 21 in the longitudinal direction. . In addition, the plurality of heater mounting pads 30 are located, for example, such that the center of the heater 21 is located closer to the second connection terminal 65B that is electrically connected to the ground that is the reference potential than the center of the second mounting surface 24b. Has been placed.

  For example, a drive signal is input to the first heater pad 30 </ b> A from the control IC 50 mounted on the mounting substrate 17. The second heater pad 30 </ b> B is electrically connected to the second connection terminal 65 </ b> B that is electrically connected to the ground that is the reference potential, for example, via a wiring provided on the mounting substrate 17.

  The control IC 50 includes a second connection terminal 65B that is electrically connected to the ground that is a reference potential, a fourth connection terminal 65D that is supplied with a power supply voltage, and a first heater pad that is electrically connected to the heater 21. It is electrically connected to 30A through the wiring of the mounting substrate 17.

  The first heat transfer film 63a is formed, for example, so that a short circuit is not caused by the plurality of device mounting pads 27 and the bumps 26 and the like and the overlap with the TCXO 3 is as large as possible. For example, the first heat transfer film 63a has a shape (for example, a rectangle) similar to the planar shape of the second recess 15b, and is slightly smaller than the planar shape of the second recess 15b.

  For example, the second heat transfer film 63b does not cause a short circuit with a wiring having a different potential from the second heat transfer film 63b on the second mounting surface 24b, and the overlap with the heater 21 is as large as possible. Is formed. For example, the second heat transfer film 63 b has the same width (x direction) as the heater 21 and is formed to have an area of 2/3 or more of the heater 21. Further, the second heat transfer film 63b is formed in a size and a shape so that the first heat transfer film 63a can be accommodated in, for example, a plan view.

  The plurality of through-holes 61 are, for example, the central side of a region that overlaps the first space S1 and the heater 21 (in this embodiment, the heater 21 is wider than the first space S1, and thus is the same as the region that overlaps the first space S1). A first through hole 61A located on the outer periphery of a region overlapping the first space S1 and the heater 21, and a plurality of (four) second through holes 61B surrounding the first through hole 61A. Yes. The plurality of second through holes 61B are located at, for example, the four corners of the rectangular first space S1.

  The central side of the region overlapping the first space S1 and the heater 21 is, for example, a range closer to the center of the region than the outer peripheral edge of the region (a half range of the central side), and the outer peripheral side is the A range closer to the outer periphery than the center (half range on the outer periphery). More preferably, the central side is a position closer to the center than the intermediate position between the center and the outer peripheral edge (a quarter of the center side), and the outer peripheral side is more than the intermediate position. It is a range (1/4 range on the outer peripheral edge side) position close to the outer peripheral edge.

  In order to make it easier to transfer the heat of the heater 21 to the second connection terminal 65B electrically connected to the ground serving as the reference potential, the mounting substrate 17 has a heat transfer wiring 67 (see FIG. 4B) on the second mounting surface 24b. )have. The heat transfer wiring 67 is connected to the second connection terminal 65B and overlaps the heater 21 in a plan view. However, the heat transfer wiring 67 is not electrically connected to the heater 21. Alternatively, the heat transfer wiring 67 is electrically connected to the heater 21 via an electronic element such as a resistor, a capacitor, or an inductor with respect to the heater 21 (heater mounting pad 30), and is not directly connected. . The other end of the heat transfer wiring 67 on the second connection terminal 65B side may or may not be electrically connected to an electronic element other than the heater 21 when not electrically connected to the heater 21. It does not have to be. The heat transfer wiring 67 desirably extends integrally from the second connection terminal 65 </ b> B to the heater 21, but an electronic element that does not hinder heat transfer may be disposed in the middle of the heat transfer wiring 67. For example, the heat transfer wiring 67 extends between the two heater mounting pads 30 so as to cross the heater 21.

  Further, the mounting substrate 17 has a dummy pad 69 (see FIG. 4) on the first mounting surface 24a in order to easily transfer the heat of the heater 21 to the second device mounting pad 27B electrically connected to the ground serving as the reference potential. (A)). The dummy pad 69 is formed, for example, by widening a part of the wiring (for example, the tip), and with respect to the device wiring 71 that connects the second connection terminal 65B and the second device mounting pad 27B. The second device mounting pads 27B are connected. The dummy pad 69 is not electrically connected to the TCXO 3. For example, the bump 26 is not provided on the dummy pad 69, and the dummy pad 69 is not bonded to the TCXO3. Alternatively, the dummy pad 69 is bonded by a dummy device pad 25 and a bump 26 that are not electrically connected to any electronic element of the TCXO 3 such as the IC 11 and the vibration element 9 and is thermally connected to the TCXO 3. It is connected but not electrically connected.

  FIG. 5 is a block diagram showing a schematic configuration of the signal processing system of OCXO1.

  As described above, the OCXO 1 includes the TCXO 3 and the thermostatic chamber 5, which are electrically connected by bonding a plurality of device pads 25 and a plurality of device mounting pads 27 with bumps 26. It is connected to the. In addition, various signals are input to the plurality of device pads 25 of the TCXO 3 via the plurality of external terminals 23 of the thermostat 5 or various signals are output.

  As described above, the TCXO 3 includes the vibration element 9 and the IC 11 that is electrically connected to the vibration element 9. The IC 11 includes, for example, an oscillation circuit 33 that generates a oscillation signal by applying a voltage to the vibration element 9, a temperature compensation circuit 35 that compensates for a temperature change of the oscillation signal, and a temperature compensation held by the temperature compensation circuit 35. And a rewriting circuit (not shown) for rewriting the contents of the data. The configuration of these circuits may be the same as a known configuration.

  For example, the oscillation circuit 33 is not particularly illustrated, but an inverter whose input side and output side are electrically connected to the vibration element 9, a feedback resistor electrically connected to the input side and output side of the inverter, and the input side of the inverter And a variable capacitance element disposed between the output side of the inverter and the ground portion.

  In addition, for example, the temperature compensation circuit 35 includes a variable capacitance element 39 disposed between the vibration element 9 and the ground portion, a compensation signal generation circuit 41 electrically connected to the variable capacitance element 39, and a compensation signal generation. A ROM 43, a RAM 45, and a first temperature sensor 47 that are electrically connected to the circuit 41 are included.

  Note that the variable capacitance element 39 of the temperature compensation circuit 35 may also be used as a variable capacitance element included in the oscillation circuit 33 in order to change the frequency of the oscillation signal in accordance with the control voltage Vcon. Further, the ROM 43 and the RAM 45 may be used also as a ROM and a RAM that hold information used by the oscillation circuit 33. The first temperature sensor 47 may be provided separately from the IC 11.

  The compensation signal generation circuit 41 applies a voltage corresponding to the temperature detected by the first temperature sensor 47 to the variable capacitance element 39 based on information stored in the ROM 43 or RAM 45. Thereby, the load capacity of the vibration element 9 changes according to the temperature, and the frequency of the oscillation signal is temperature-compensated.

  In addition to the heater 21 described above, the thermostat 5 controls the heater 21 based on, for example, a second temperature sensor 49 that detects the temperature at an appropriate position in the case 19 and the temperature detected by the second temperature sensor 49. Temperature control circuit 51 (control IC 50). For example, the temperature control circuit 51 feedback-controls the heater 21 so that the temperature detected by the second temperature sensor 49 is maintained at a preset temperature.

  Some TCXOs can output the temperature detected by the first temperature sensor 47 from the device pad 25. When such TCXO is selected as TCXO 3, the heater 21 may be controlled based on the temperature detected by the first temperature sensor 47 without providing the second temperature sensor 49.

  In FIG. 4A, the plurality of external terminals 23 exposed from the thermostat 5 and the plurality of device pads 25 of the TCXO 3 are connected by wiring of the mounting substrate 17 without interposing electronic elements. However, an appropriate electronic element may be interposed. For example, an amplifier or an element for impedance matching may be interposed. However, it is preferable that the second external terminal 23B (second connection terminal 65B) electrically connected to the ground serving as the reference potential and the second device pad 25B are connected without interposing an electronic element. .

  The OCXO 1 of the present embodiment described above exhibits, for example, the effects of the first to third aspects described below.

  In the first aspect, the OCXO 1 of the present embodiment includes a mounting substrate 17 having a first mounting surface 24a and a second mounting surface 24b on the back surface thereof, a TCXO 3 mounted on the first mounting surface 24a, and a second mounting surface. It has a heater 21 mounted on 24b and a case 19 for housing them. A first space S1 is formed between the TCXO 3 and the first mounting surface 24a. The mounting substrate 17 has a hollow through hole 61 that penetrates the mounting substrate 17 from the second mounting surface 24b side to the first mounting surface 24a side in a region overlapping the heater 21 and the first space S1 and communicates with the first space S1. Is formed.

  Therefore, the gas (for example, air) in the first space S <b> 1 can directly touch the heater 21 through the through hole 61 without passing through the mounting substrate 17. As a result, the temperature of the first space S1 is easily raised by the heater 21, and as a result, the temperature of the TCXO 3 can be quickly made constant by the heater 21. That is, it is possible to shorten the startup time until the characteristics of the OCXO1 are stabilized.

  In the present embodiment, a second space S2 is formed between the heater 21 and the second mounting surface 24b, and the first space S1 and the second space S2 are communicated with each other through the through hole 61.

  Usually, when the second space S2 is formed by mounting the heater 21 with the bumps 29, the heat transfer from the heater 21 to the mounting substrate 17 is lowered, and as a result, it is difficult to raise the temperature of the TCXO3. However, in the present embodiment, since the gas in the second space S2 can flow into the first space S1 through the through-hole 61, the second space S2 directly heats up the gas in the first space S1 by the heater 21. It will function as a space to let you. As a result, a decrease in heat transfer due to the formation of the second space S2 can be reduced, or the heat transfer can be improved as compared with the case where the second space S2 is not formed.

  In the present embodiment, the first space S <b> 1 and the second space S <b> 2 are communicated with each other through the plurality of through holes 61.

  Accordingly, the flow of gas from the second space S2 to the first space S1 via any of the plurality of through holes 61, and the second space from the first space S1 to any other of the plurality of through holes. A gas flow to S2 may occur. As a result, suitable convection occurs in the first space S1 and the second space S2, and the temperature of the first space S1 is likely to rise.

  In the present embodiment, the plurality of through holes 61 include a first through hole 61 </ b> A (center side through hole) located on the center side of a region overlapping the first space S <b> 1 and the heater 21, and the first space S <b> 1 and the heater 21. And a plurality of second through holes 61B (outer through holes) surrounding the first through hole 61A.

  Therefore, the above-described convection is preferably easily generated. For example, in the first space S1, the outer peripheral side is in contact with the second frame portion 15e, the central side is in contact with the IC 11, and the members that affect the temperature of both are different. However, the temperature tends to be higher than the other. As a result, a gas flow tends to occur from the center side to the outer periphery side of the first space S1 or from the outer periphery side to the center side of the first space S1. By arranging the first through-hole 61A and the second through-hole 61B at a position corresponding to the flow, gas easily flows through these through-holes 61, and thus convection is preferably generated. Further, in the heater 21, a temperature difference is likely to occur between the center side and the outer peripheral side, and convection is more likely to occur if the center side of the TCXO 3 and the center side of the heater 21 substantially coincide.

  In the present embodiment, the TCXO 3 includes the element mounting member 7 having the first concave portion 15a and the second concave portion 15b that are open on opposite sides, the vibration element 9 (piezoelectric element) housed in the first concave portion 15a, IC 11 (integrated circuit element) housed in the second recess 15b, and is mounted on the first mounting surface 24a with the second recess 15b side facing the first mounting surface 24a. The 2nd recessed part 15b comprises at least one part of 1st space S1, and the through-hole 61 is located in the area | region which overlaps with the 2nd recessed part 15b.

  Therefore, in the so-called H-type element mounting member 7, the temperature of the second recess 15b can be quickly raised. As a result, it is possible to reduce the H-shaped disadvantage that it is difficult to raise the temperature of the first recess 15a from the second recess 15b side.

  In a second aspect, the OCXO 1 of the present embodiment includes a mounting substrate 17 having a first mounting surface 24a and a second mounting surface 24b on the back surface thereof, and a TCXO 3 (piezoelectric device) mounted on the first mounting surface 24a. And a heater 21 mounted on the second mounting surface 24b, and a case 19 for housing them. The mounting substrate 17 is made of an insulating substrate 24 constituting the first mounting surface 24a and the second mounting surface 24b, and a material having a higher thermal conductivity than the insulating substrate 24, and penetrates the insulating substrate 24 and overlaps the heater 21. A heat transfer body 63 that is exposed to the second mounting surface 24b side and exposed to the first mounting surface 24a side in a region that overlaps the TCXO3, and is electrically disconnected from the TCXO3. Yes.

  Therefore, compared with the case where only the insulating base 24 is interposed between the heater 21 and the TCXO 3, the heat of the heater 21 is easily transmitted to the TCXO 3. As a result, the temperature of the TCXO 3 can be quickly brought to a constant temperature by the heater 21. That is, it is possible to shorten the startup time until the characteristics of the OCXO1 are stabilized.

  In the present embodiment, the heat transfer body 63 includes a first heat transfer film 63a provided on the first mounting surface 24a and facing the TCXO3.

  Therefore, heat is transferred from the heat transfer body 63 to the TCXO 3 over a wide range while suppressing an increase in the volume of the heat transfer body 63 as compared with a case where a conductor (metal) penetrating the insulating base 24 is simply provided. it can. As a result, heat conductivity can be improved at low cost. Further, if the first heat transfer film 63a is electrically connected to the ground serving as the reference potential, it is expected that the first heat transfer film 63a functions as a shield and the electrical characteristics of the TCXO 3 are improved.

  In the present embodiment, the heat transfer body 63 includes a second heat transfer film 63 b provided on the second mounting surface 24 b and facing the heater 21.

  Therefore, heat is transmitted from the heater 21 to the heat transfer body 63 over a wide range while suppressing an increase in the volume of the heat transfer body 63 as compared with a case where a conductor (metal) penetrating the insulating base 24 is simply provided. be able to. As a result, heat conductivity can be improved at low cost. Similarly to the first heat transfer film 63a, the second heat transfer film 63b is expected to function as a shield that improves the electrical characteristics of the TCXO 3 by being electrically connected to the ground serving as the reference potential. The

  In the present embodiment, a first space S1 is formed between the TCXO 3 and the first mounting surface 24a. The mounting substrate 17 has a hollow through hole 61 that penetrates the mounting substrate 17 from the second mounting surface 24b side to the first mounting surface 24a side in a region overlapping the heater 21 and the first space S1 and communicates with the first space S1. Is formed. The heat transfer body 63 includes an inner peripheral heat transfer film 63 c provided on the inner peripheral surface of the through hole 61.

  Therefore, while obtaining the effect by heating the gas of 1st space S1 with the heater 21 demonstrated from the 1st viewpoint, the through-hole 61 for obtaining the said effect, the heat-transfer body 63, and the 2nd mounting surface 24b. To the first mounting surface 24a. As a result, the heat of the heater 21 can be effectively transferred to the TCXO 3 by a simple manufacturing method or configuration as a whole.

  In the present embodiment, a first space S1 is formed between the TCXO 3 and the first mounting surface 24a. The heat transfer body 63 is exposed to the first mounting surface 24a side only in the region overlapping the first space S1.

  Therefore, for example, the possibility that a short circuit between the heat transfer body 63 and the device mounting pad 27 for mounting the TCXO 3 occurs is reduced. Further, the substrate portion 15c of the TCXO3 is mounted via the first space S1 on the outer peripheral portion that is thermally connected to the mounting substrate 17 by the conductor, the device pad 25, and the bump 26 in the second frame portion 15e. The heat of the heater 21 is not easily transmitted in the central portion facing the base 17. By exposing the heat transfer body 63 intensively in such a first space S1, it is expected that the heat of the heater 21 is transferred to the substrate portion 15c in a well-balanced manner.

  In the present embodiment, as described in the first aspect, at least a part of the first space S1 is constituted by the second recess 15b of the H-type element mounting member 7, and the above-described heat transfer body. 63, it is possible to reduce the H-shaped disadvantage that it is difficult to raise the temperature of the first recess 15a from the second recess 15b side.

  In the present embodiment, the heat transfer body 63 is provided on the second mounting surface 24 b and connected to the heater mounting pad 30 joined to the heater 21 via the bumps 29.

  Therefore, the heat transfer body 63 is thermally connected to the heater 21 and can suitably transfer the heat of the heater 21 to the TCXO 3 side. In addition, since the heat transfer body 63 is thermally connected to the heater 21 by the heater mounting pads 30 and the bumps 29 for mounting the heater 21, the configuration of the OCXO 1 is simplified as a whole.

  In a third aspect, the OCXO 1 of the present embodiment includes a mounting substrate 17 having a first mounting surface 24a and a second mounting surface 24b on the back surface thereof, a TCXO 3 mounted on the first mounting surface 24a, and a second The heater 21 mounted on the mounting surface 24b, a case 19 for housing these, and a plurality of external terminals 23 exposed to the outside of the case 19 are provided. The mounting substrate 17 is connected to the second connection terminal 65B (reference potential connection terminal) connected to any of the plurality of external terminals 23, the device wiring 71 extending from the second connection terminal 65B, and the device wiring 71. And a second device mounting pad 27B on which TCXO3 is mounted. In the plan view of the second mounting surface 24b, the center of the heater 21 is located closer to the second connection terminal 65B than the center of the mounting substrate 17.

  Since the second connection terminal 65B for reference potential, the device wiring 71, and the second device mounting pad 27B thermally connect the external terminal 23 and the TCXO3, the heat of the TCXO3 is released to the external terminal 23. It is easy to end up. However, the heater 21 is provided so that the center of the heater 21 is closer to the second connection terminal 65B than the center of the mounting substrate 17, and the temperature of the second connection terminal 65B and the second external terminal 23B is increased by the heater 21. Thus, the heat flow from the TCXO 3 to the second connection terminal 65B is reduced. As a result, the temperature of the TCXO 3 can be quickly brought to a constant temperature by the heater 21. That is, it is possible to shorten the startup time until the characteristics of the OCXO1 are stabilized.

  In the present embodiment, the mounting substrate 17 is provided in a region overlapping the heater 21 on the second mounting surface 24b, connected to the second connection terminal 65B, and electrically disconnected from the heater 21. Or it has the heat-transfer wiring 67 electrically connected through the electronic element.

  Therefore, heat can be transmitted from the heater 21 to the second connection terminal 65B via the heat transfer wiring 67, and the temperature of the second connection terminal 65B can be quickly raised. As a result, the heat flow from the TCXO 3 to the second connection terminal 65B is reduced.

  In the present embodiment, the mounting substrate 17 is provided in a region overlapping the heater 21 on the first mounting surface 24a, is connected to the device wiring 71 via the second device mounting pad 27B, and is electrically connected to the TCXO3. And a dummy pad 69 which is not connected.

  Accordingly, the temperature of the dummy pad 69 is raised by the heater 21 via the mounting substrate 17, and the heat is transmitted to the second device mounting pad 27B, whereby the second pad via the second device mounting pad 27B is transmitted from the TCXO3. The heat flow to the connection terminal 65B is reduced. Note that the dummy pad 69 may not overlap the TCXO 3 as long as it overlaps the heater 21. However, if it overlaps with TCXO3, the area of the first mounting surface 24a can be saved.

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

  The structure of OCXO may be changed as appropriate. For example, a circuit board facing the mounting base via a spacer is provided on the heater side of the mounting base, a piezoelectric device (TCXO), a mounting base, and a case for covering the surface of the circuit board on the mounting base are provided, The surface of the circuit board opposite to the mounting substrate may be exposed outside the case. A pad-like external terminal may be provided on the surface of the circuit board that is exposed outside the case. In another aspect, the reference potential connection terminal (in the embodiment, the second connection terminal 65B) of the mounting substrate connected to the external terminal is not directly and electrically connected to the external terminal. The circuit board may be electrically and thermally connected via wiring and terminals.

  The piezoelectric device is not limited to an oscillator, and may be a filter such as a SAW filter, for example. When the piezoelectric device is a SAW filter, the piezoelectric element is a piezoelectric substrate provided with an IDT electrode. The piezoelectric device may not have a temperature compensation function.

  The piezoelectric device is not limited to one having a so-called H-type element mounting member. For example, the piezoelectric device may be one in which the piezoelectric element is accommodated in an element mounting member (box-shaped element mounting member) having only one recess, or the piezoelectric element is mounted on a flat element mounting member. Alternatively, the surface on which the electrode of the piezoelectric substrate is provided may be resin-sealed (the device mounting member is not provided).

  The oscillator may input and output signals other than those exemplified in the embodiment. For example, the oscillator may be one that does not receive a control voltage (outputs an oscillation signal having a predetermined constant frequency), or one that receives an enable / disable signal. Alternatively, two oscillation signals having different frequencies or the same frequency may be output.

  The vibration element is not limited to one in which a pair of electrodes is provided on both main surfaces of the piezoelectric body, and a pair of electrodes is provided on one main surface of the piezoelectric body like a SAW type vibration element. Also good. The cut angle of the piezoelectric body may be set as appropriate. The piezoelectric body is not limited to quartz but may be ceramic, for example.

  The second space may not be formed between the second mounting surface and the heater. For example, in the embodiment, an underfill may be filled between the heater and the second mounting surface. Further, for example, the heater is in close contact with the second mounting surface directly or indirectly through an adhesive, and the heater pad formed on the surface opposite to the second mounting surface and the mounting substrate for heater mounting The pad may be connected by a bonding wire.

  There may not be a plurality of through holes (through holes 61 in the embodiment) communicating with the first space provided in the mounting substrate. For example, the number of through holes may be only one, or only two for gas inflow and outflow. When a plurality of through holes are provided, the arrangement position may be set as appropriate. For example, in the embodiment, a large number of through holes may be formed along the short side and / or the long side as well as the four corners and the center of the first space S1. The shape of the through hole is not limited to a circle, and may be an ellipse or a rectangle.

  The material of the heat transfer body may not be a conductive material or a metal. However, in general, a conductive material or a metal has high thermal conductivity and is suitable as a material for a heat transfer body. In addition, if the material of the heat transfer body is a conductive material, it is possible to form the heat transfer body together with wirings or pads, which is convenient.

  The shape and arrangement of the heat transfer body may be set as appropriate. For example, the heat transfer body may be one in which the portion connecting the first heat transfer film and the second heat transfer film penetrates the insulating base in a region that does not overlap the piezoelectric device or the heater. In addition, for example, in the heat transfer body, the portion penetrating the insulating base may not be in the form of a film provided on the inner surface of the through hole, but in the form of a column filled in the through hole. Further, the heat transfer body is formed in a column shape penetrating the insulating base in a region overlapping with the piezoelectric device and the heater, does not have the first heat transfer film and the second heat transfer film, and the upper surface and the lower surface of the column are first mounted. It may be exposed to the surface and the second mounting side.

  The heat transfer body may be thermally connected to the piezoelectric device as long as it is not electrically connected to the piezoelectric device. For example, the heat transfer body may be provided via a bump to a dummy pad that is provided in the piezoelectric device and is not electrically connected to any electronic element of the piezoelectric device.

  In the embodiment, the heat transfer body is electrically and thermally connected to the heater. However, the heat transfer body may be thermally connected to the heater while being electrically disconnected from the heater. It may be disconnected electrically and thermally. In the embodiment, the heat transfer body is connected to the heater mounting pad for supplying a driving voltage to the heater, but is connected to the heater mounting pad for electrically connecting a ground that is a reference potential to the heater. May be. The heat transfer body may be electrically floated without being connected to the ground serving as the reference potential.

  From the viewpoint of obtaining the effect of the first aspect, the heat transfer body may not be provided, and the heater may not be provided near the reference potential connection terminal. From the viewpoint of obtaining the effect of the second aspect, the first space and the through hole may not be provided, and the heater may not be provided near the reference potential connection terminal. From the viewpoint of obtaining the effect of the third aspect, the first space, the through hole, and the heat transfer body may not be provided. Moreover, the various structures corresponding to the effect of the 1st-3rd viewpoint may be combined suitably.

  DESCRIPTION OF SYMBOLS 1 ... Crystal oscillator with a thermostat (OCXO, piezoelectric device with a thermostat), 3 ... Temperature compensation type crystal oscillator (TCXO, piezoelectric device), 17 ... Mounting base, 19 ... Case, 21 ... Heater, 23 ... External terminal, 24 ... Insulating substrate, 24a ... first mounting surface, 24b ... second mounting surface, 27B ... second device mounting pad, 61 ... through hole, 63 ... heat transfer body, 65B ... second connection terminal (reference potential connection terminal) , 71 ... Device wiring, S1 ... First space.

Claims (7)

A mounting substrate having a first mounting surface and a second mounting surface on the back thereof;
A piezoelectric device mounted on the first mounting surface;
A heater mounted on the second mounting surface;
A case housing the piezoelectric device, the mounting substrate and the heater;
Have
The mounting substrate is
An insulating base constituting the first mounting surface and the second mounting surface;
The first mounting is made of a material having a higher thermal conductivity than the insulating base, penetrates the insulating base, is exposed to the second mounting surface side in a region overlapping the heater, and overlaps the piezoelectric device. A piezoelectric device with a thermostatic chamber, comprising: a heat transfer body exposed to the surface side and electrically disconnected from the piezoelectric device. The piezoelectric device with a thermostat according to claim 1, wherein the heat transfer body includes a first heat transfer film provided on the first mounting surface and facing the piezoelectric device. The thermostat-equipped piezoelectric device according to claim 1, wherein the heat transfer body includes a second heat transfer film that is provided on the second mounting surface and faces the heater. A space is formed between the piezoelectric device and the first mounting surface,
The mounting base is formed with a hollow through hole penetrating the insulating base from the second mounting surface side to the first mounting surface side in a region overlapping with the heater and the space and leading to the space. ,
The piezoelectric device with a thermostat according to any one of claims 1 to 3, wherein the heat transfer body includes an inner peripheral heat transfer film provided on an inner peripheral surface of the through hole. A space is formed between the piezoelectric device and the first mounting surface,
The thermostat-equipped piezoelectric device according to any one of claims 1 to 3, wherein the heat transfer body is exposed to the first mounting surface only in a region overlapping with the space. The piezoelectric device is
An element mounting member having a first recess and a second recess that open on opposite sides;
A piezoelectric element housed in the first recess;
An integrated circuit element housed in the second recess,
Mounted on the first mounting surface with the second recess side facing the first mounting surface,
The piezoelectric device with a thermostat according to claim 4 or 5, wherein the second recess constitutes at least a part of the first space. The piezoelectric device with a thermostat according to any one of claims 1 to 6, wherein the heat transfer body is provided on the second mounting surface and connected to a mounting pad joined to the heater via a bump. .

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