Thermostatic bath piezoelectric oscillator

Abstract

This invention provides a thermostatic bath type piezoelectric oscillator. In this thermostatic bath type piezoelectric oscillator (1), the core (5) includes at least an oscillator IC (51), a piezoelectric vibrator (50), and a heater IC (52). The core (5) is sealed inside a heat-insulating package (2) in a closed state. The core (5) is supported in the package (2) by a core substrate (4). When viewed from above, the core substrate (4) is connected to the package (2) at a location further outward than the area where the core (5) is located. Based on the structure of this invention, the heat generated by the heater required to maintain the temperature of the core can be minimized.

Description

Technical Field

[0001] This invention relates to a thermostatic bath type piezoelectric oscillator. Background Technology

[0002] Piezoelectric oscillators, such as crystal resonators, have inherent frequency-temperature characteristics, with their vibration frequency changing according to temperature. Therefore, in the prior art, oven-controlled piezoelectric oscillators (OCXOs) have been developed, where the piezoelectric oscillator is enclosed in a temperature-controlled oven to maintain a constant temperature around it (see, for example, Patent Document 1). An OCXO is configured, for example, to have a core consisting of an oscillator IC, a piezoelectric oscillator, a heater IC, etc., sealed in a heat-insulating package, with the core fixed to the package by a core substrate. In the OCXO, the temperature of the core is maintained at approximately constant by controlling the heat generated by the heating element (heat source) of the heater IC (heater heat output).

[0003] In the OCXO described above, the core substrate is fixed to the package body, for example, by a conductive adhesive, and an electrical connection is established between the core substrate and the package body through the conductive adhesive. In this case, heat from the core may move (leak) to the package body side through the connection between the core substrate and the package body. To compensate for the heat that moves to the package body side through the connection, the heat generated by the heater required to maintain the temperature of the core will increase, resulting in increased energy consumption.

[0004] [Patent Document 1]: Japanese Patent No. 6376681 Summary of the Invention

[0005] In view of the above, the object of the present invention is to provide a thermostatic tank piezoelectric oscillator that can minimize the amount of heat generated by the heater required to maintain the temperature of the core.

[0006] As a technical solution to the above-mentioned technical problems, the present invention has the following structure. That is, the thermostatic tank piezoelectric oscillator of the present invention is a thermostatic tank piezoelectric oscillator in which at least an oscillator IC, a piezoelectric vibrator, and a heater IC are sealed in a heat-insulating package in a hermetically sealed state. The core portion is characterized in that: the core portion is supported in the package by a core substrate, and when viewed from above, the core substrate is connected to the package at a location further outward than the area where the core portion is located. In this case, it is preferable that the core substrate is connected to the package by a mechanical connection.

[0007] Based on the above structure, the connection between the core substrate and the package is not located where it overlaps with the core in a top view, but rather at a position away from the core. Therefore, heat from the core is less likely to move (leak) to the package side through the connection between the core substrate and the package, allowing most of the heat generated by the heater IC's heating element to remain in the core. This minimizes the heater heat output required to maintain the core's temperature, thereby reducing the OCXO's energy consumption. Furthermore, since the core is fixed within the package by the core substrate, stress from the mounting substrate on which the OCXO is mounted is less likely to be transmitted to the core, thus protecting the core.

[0008] In the above structure, preferably, a gap is provided between the core substrate and the inner bottom surface of the package.

[0009] Based on the above structure, the heat insulation of the core can be improved by utilizing the gap between the core substrate and the inner bottom surface of the package. This further reduces the heat generated by the heater required to maintain the temperature of the core, thereby further reducing the energy consumption of the OCXO.

[0010] In the above structure, preferably, the core substrate is bonded to the package body by an adhesive, and the gap is formed by the adhesive sandwiched between the core substrate and the package body.

[0011] Based on the above structure, a gap can be formed between the core substrate and the inner bottom surface of the package using a simple method such as an adhesive that bonds the core substrate to the package.

[0012] In the above structure, preferably, a pair of opposing stepped portions are formed inside the package, and the gap is formed by a recess formed between the pair of stepped portions.

[0013] Based on the above structure, by providing the stepped portion, the gap between the core substrate and the inner bottom surface of the package can be reliably ensured. Furthermore, even if the adhesive used to bond the core substrate to the package flows out onto the inner bottom surface of the package, the adhesive will flow into the recess, thereby preventing short circuits caused by the adhesive coming into contact with each other.

[0014] In the above structure, preferably, the recess is formed at a position corresponding to the core portion when viewed from above.

[0015] Based on the above structure, since the recess is located at a position corresponding to the core (e.g., below), the heat insulation of the core can be further improved by utilizing the recess.

[0016] In the above structure, preferably, the piezoelectric vibrator includes a first sealing component and a second sealing component made of glass or crystal, and a piezoelectric vibrating plate made of crystal. The piezoelectric vibrating plate has a vibrating portion with excitation electrodes formed on two main surfaces. The first sealing component and the second sealing component are stacked and joined across the piezoelectric vibrating plate, and the vibrating portion of the piezoelectric vibrating plate disposed inside is hermetically sealed.

[0017] Based on the above structure, since a sandwich-structure piezoelectric oscillator with the vibrating part hermetically sealed inside, as described above, is used as the core piezoelectric oscillator, the core can be miniaturized and reduced in size, thereby reducing the heat capacity of the core. This suppresses the heat generation of the OCXO heater, thus reducing energy consumption. Furthermore, it improves the temperature tracking performance of the core and enhances the stability of the OCXO. In addition, in the sandwich-structure piezoelectric oscillator, since the vibrating part is hermetically sealed without adhesive, the adverse effects of heat convection caused by outgassing from the adhesive can be suppressed. That is, within the hermetically sealed space of the vibrating part, outgassing from the adhesive circulates and generates heat convection, potentially hindering high-precision temperature control of the vibrating part. However, in the sandwich-structure piezoelectric oscillator, since such outgassing does not occur, high-precision temperature control of the vibrating part can be achieved.

[0018] Invention effects:

[0019] In the thermostatic bath piezoelectric oscillator of this invention, the connection portion between the core substrate and the package is not located at a position overlapping the core when viewed from above, but rather at a position away from the core. Therefore, heat from the core is less likely to move to the package side via the connection portion between the core substrate and the package, thus allowing most of the heat generated by the heating element of the heater IC to remain in the core. This minimizes the amount of heat generated by the heater required to maintain the core temperature, thereby reducing energy consumption. Attached Figure Description

[0020] Figure 1 This is a cross-sectional view showing the general structure of the OCXO involved in this embodiment.

[0021] Figure 2 It means Figure 1 A cross-sectional view of the core component and core substrate of the OCXO.

[0022] Figure 3 It means Figure 2 Top view of the core component and core substrate.

[0023] Figure 4 It is a schematic representation Figure 2A schematic diagram of the constituent components of the core crystal oscillator (crystal resonator and oscillator IC).

[0024] Figure 5 yes Figure 4 A top view of the first main face side of the first sealing component of the crystal oscillator.

[0025] Figure 6 yes Figure 4 A top view of the second main face side of the first sealing component of a crystal oscillator.

[0026] Figure 7 yes Figure 4 A top view of the first main surface of the crystal oscillator of a crystal oscillator.

[0027] Figure 8 yes Figure 4 A top view of the second main surface of the crystal oscillator of a crystal oscillator.

[0028] Figure 9 yes Figure 4 A top view of the first main face side of the second sealing component of a crystal oscillator.

[0029] Figure 10 yes Figure 4 A top view of the second main face side of the second sealing component of the crystal oscillator.

[0030] Figure 11 This is a cross-sectional view showing the general structure of the OCXO involved in the first modified example.

[0031] Figure 12 It means Figure 11 A top view of the OCXO.

[0032] Figure 13 This is a cross-sectional view showing the general structure of the OCXO involved in the second variation.

[0033] <Explanation of Figure Labels>

[0034] 1. Thermostatic bath type piezoelectric oscillator

[0035] 2 Package

[0036] 4 Core substrates

[0037] 5. Core Department

[0038] 7 Adhesives

[0039] 7a Connection part

[0040] 50 Crystal resonator (piezoelectric oscillator)

[0041] 51 Oscillator IC

[0042] 52 Heater IC Detailed Implementation

[0043] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0044] like Figure 1 As shown, the OCXO1 of this embodiment is configured such that a core portion 5 is disposed inside a roughly rectangular package (shell) 2 made of ceramic or the like, and is hermetically sealed by a cover 3. The dimensions of the package 2 are, for example, 7.0 × 5.0 mm. A recess 2a with an upward opening is formed on the package 2, and the core portion 5 is hermetically sealed inside the recess 2a. A peripheral wall portion 2b surrounds the recess 2a, and the cover 3 is fixed to the top surface of the peripheral wall portion 2b by a sealing material 8, thus the interior of the package 2 is sealed (hermetically sealed). As the sealing material 8, it is preferable to use a metallic sealing material such as Au-Su alloy or solder, but a sealing material such as low-melting-point glass can also be used. Preferably, the interior space of the package 2 is a vacuum, or an atmosphere with low thermal conductivity such as low-pressure nitrogen or argon.

[0045] On the inner wall surface of the peripheral wall portion 2b of the package 2, a stepped portion 2c is formed along a row of connecting terminals (not shown). The core portion 5 is connected to the connecting terminals formed on the stepped portion 2c via a plate-shaped core substrate 4. The core substrate 4 is made of crystal, for example. Alternatively, the core substrate 4 may be made of a heat-resistant and flexible resin material such as polyimide.

[0046] The core substrate 4 is configured to be positioned between a pair of opposing stepped portions 2c within the package 2, with a gap 2d formed on the lower side of the core substrate 4 between the pair of stepped portions 2c. Furthermore, connection terminals formed on the stepped surfaces of the stepped portions 2c are connected to connection terminals (not shown) formed on the bottom surface 4b of the core substrate 4 via a conductive adhesive 7. Additionally, external terminals (not shown) of each component formed on the core portion 5 are connected to connection terminals 4c formed on the top surface 4a of the core substrate 4 via wires 6a and 6b through wire bonding. The conductive adhesive 7 is, for example, a polyimide adhesive or an epoxy adhesive.

[0047] Below, refer to Figure 2 , Figure 3 The core part 5 will be explained. Figure 2 , Figure 3 This shows the state in which the core part 5 is mounted on the core substrate 4. Figure 2 Show along Figure 3 The cross-section after cutting the short side of the core substrate 4 ( Figure 1Similarly, the core section 5 is a component that integrates various electronic components used in the OCXO1, employing a three-layer structure (stacked structure) where the oscillator IC51, crystal resonator 50, and heater IC52 are stacked sequentially from top to bottom. Viewed from above, the areas of the oscillator IC51, crystal resonator 50, and heater IC52 gradually decrease from bottom to top. The core section 5 is configured to stabilize the oscillation frequency of the OCXO1, particularly by adjusting the temperatures of the temperature-sensitive crystal resonator 50, oscillator IC51, and heater IC52. Here, the various electronic components of the core section 5 are not sealed with sealing resin, but they can be sealed with sealing resin depending on the packaging environment.

[0048] Crystal oscillator 100 is composed of crystal resonator 50 and oscillator IC51. Oscillator IC51 is connected by several metal bumps 51a (see reference). Figure 4 The crystal oscillator 100 is mounted on the crystal resonator 50. The oscillation frequency of the OCXO1 is controlled by controlling the piezoelectric vibration of the crystal resonator 50 using the oscillator IC51. The crystal oscillator 100 will be described in detail later.

[0049] A non-conductive adhesive (bottom filler) 53 is sandwiched between the opposing surfaces of the crystal resonator 50 and the oscillator IC 51, thus fixing the opposing surfaces of the crystal resonator 50 and the oscillator IC 51 together. In this case, the top surface of the crystal resonator 50 (the first main surface 201 of the first sealing member 20) and the bottom surface of the oscillator IC 51 are joined by the non-conductive adhesive 53. For example, a polyimide adhesive or an epoxy adhesive is used as the non-conductive adhesive 53. Furthermore, the external terminals formed on the top surface of the crystal resonator 50 (…) Figure 5 The electrode pattern 22 shown is connected to the connection terminal 4c formed on the top surface 4a of the core substrate 4 via wire bonding through the wire 6a.

[0050] Viewed from above, the area of ​​oscillator IC51 is smaller than that of crystal resonator 50, and the entire oscillator IC51 is located within the area of ​​crystal resonator 50. The entire bottom surface of oscillator IC51 is bonded to the top surface of crystal resonator 50 (first main surface 201 of first sealing member 20).

[0051] The heater IC52 is, for example, a structure that integrates a heating element (heat source), a control circuit (current control circuit) for controlling the temperature of the heating element, and a temperature sensor for detecting the temperature of the heating element into one unit. By using the heater IC52 to control the temperature of the core 5, the temperature of the core 5 can be maintained at approximately a constant temperature, thereby stabilizing the oscillation frequency of the OCXO1.

[0052] A non-conductive adhesive 54 is sandwiched between the opposing surfaces of the crystal resonator 50 and the heater IC 52, thus fixing them together. In this case, the bottom surface of the crystal resonator 50 (the second main surface 302 of the second sealing member 30) and the top surface of the heater IC 52 are joined by the non-conductive adhesive 54. For example, a polyimide adhesive or an epoxy adhesive is used as the non-conductive adhesive 54. An external terminal (not shown) formed on the top surface of the heater IC 52 is connected to a connection terminal 4c formed on the top surface 4a of the core substrate 4 via a wire 6b through wire bonding.

[0053] Viewed from above, the area of ​​the crystal resonator 50 is smaller than that of the heater IC52, and the entire crystal resonator 50 is located within the area of ​​the heater IC52. The entire bottom surface of the crystal resonator 50 (the second main surface 302 of the second sealing member 30) is bonded to the top surface of the heater IC52.

[0054] A conductive adhesive 55 is sandwiched between the opposing surfaces of the heater IC 52 and the core substrate 4, thus fixing the opposing surfaces of the heater IC 52 and the core substrate 4 together. In this case, the bottom surface of the heater IC 52 and the top surface 4a of the core substrate 4 are joined by the conductive adhesive 55. Therefore, the heater IC 52 is grounded via the conductive adhesive 55 and the core substrate 4. For example, a polyimide adhesive or an epoxy adhesive can be used as the conductive adhesive 55. Furthermore, if the heater IC 52 is grounded, for example, via a wire, a non-conductive adhesive similar to the non-conductive adhesives 53 and 54 described above can be used instead of the conductive adhesive.

[0055] As described above, a plurality of connection terminals 4c are formed on the top surface 4a of the core substrate 4. Furthermore, a plurality of ( Figure 3 There are two 4d chip capacitors (bypass capacitors). There are no particular restrictions on the size or number of the 4d chip capacitors.

[0056] As described above, a plurality of connection terminals are formed on the bottom surface 4b of the core substrate 4 and are connected to the connection terminals formed on the package 2 via conductive adhesive 7. Figure 3In the diagram, the double-dotted line shows the connection portion 7a connecting the core substrate 4 and the package 2 via conductive adhesive 7. Connection terminals on the bottom surface 4b of the core substrate 4 are positioned corresponding to the connection terminals 4c on the top surface 4a of the core substrate 4. The connection terminals on the bottom surface 4b of the core substrate 4, which are used to connect to the connection terminals of the package 2, are coated with conductive adhesive 7, and the portions coated with conductive adhesive 7 constitute the connection portion 7a. Viewed from above, the connection portions 7a using conductive adhesive 7 are located at the periphery of the core substrate 4. More specifically, the connection portions 7a are arranged at predetermined intervals along a pair of opposing long sides adjacent to the core substrate 4. These areas along the pair of opposing long sides adjacent to the core substrate 4 are located above a pair of opposing stepped portions 2c of the package 2.

[0057] There is no particular limitation on the type of crystal resonator 50 used in the core part 5, but it is preferable to use a sandwich structure device that is easy to make the device thinner. The sandwich structure device includes a first sealing member and a second sealing member made of glass or crystal, and a piezoelectric vibrating plate made of crystal, for example, having a vibrating part with excitation electrodes formed on two main surfaces. The first sealing member and the second sealing member are stacked and joined across the piezoelectric vibrating plate, and the vibrating part of the piezoelectric vibrating plate disposed inside is hermetically sealed.

[0058] For a crystal oscillator 100 that integrates the crystal resonator 50 with the oscillator IC51 in such a sandwich structure, refer to... Figures 4 to 10 Please provide an explanation.

[0059] like Figure 4 As shown, the crystal oscillator 100 includes a crystal resonator (piezoelectric resonator) 10, a first sealing member 20, a second sealing member 30, and an oscillator IC51. In this crystal oscillator 100, the crystal resonator 10 is engaged with the first sealing member 20, and simultaneously with the second sealing member 30, thereby forming a sandwich-structure package with an approximately rectangular parallelepiped structure. That is, in the crystal oscillator 100, the first sealing member 20 and the second sealing member 30 are respectively engaged with the two main surfaces of the crystal resonator 10 to form the internal space (cavity) of the package, and the vibrating part 11 (see reference) Figure 7 , Figure 8 It is airtightly sealed in this internal space.

[0060] The crystal oscillator 100 is, for example, a package with a size of 1.0 × 0.8 mm, achieving miniaturization and low profile. Furthermore, to achieve miniaturization, castle-type terminals are not formed in the package; instead, electrode conductivity is achieved through through-holes. The oscillator IC 51, mounted on the first sealing member 20, is a single-chip integrated circuit element that, together with the crystal oscillator 10, constitutes an oscillation circuit. Additionally, the crystal oscillator 100 is mounted on the aforementioned heater IC 52 using a non-conductive adhesive 54.

[0061] like Figure 7 , Figure 8 As shown, the crystal oscillator 10 is a piezoelectric substrate made of crystal, and its two main surfaces (first main surface 101 and second main surface 102) are configured as flat and smooth surfaces (mirror finish). As the crystal oscillator 10, an AT water-cutting wafer that performs thickness shear vibration is used. Figure 7 , Figure 8 In the crystal oscillator 10 shown, the two principal surfaces of the crystal oscillator 10, namely the first principal surface 101 and the second principal surface 102, are in the XZ′ plane. In the XZ′ plane, the direction parallel to the short side of the crystal oscillator 10 is taken as the X-axis direction, and the direction parallel to the long side of the crystal oscillator 10 is taken as the Z′ axis direction.

[0062] A pair of excitation electrodes (first excitation electrode 111 and second excitation electrode 112) are formed on the two main surfaces of the crystal oscillator 10, namely the first main surface 101 and the second main surface 102. The crystal oscillator 10 includes a vibrating portion 11 configured as approximately rectangular, an outer frame portion 12 surrounding the outer periphery of the vibrating portion 11, and a holding portion 13 that holds the vibrating portion 11 by connecting the vibrating portion 11 to the outer frame portion 12. That is, the crystal oscillator 10 is constructed by forming the vibrating portion 11, the outer frame portion 12, and the holding portion 13 as a single unit. The holding portion 13 extends (protrudes into) the outer frame portion 12 only from one corner located in the +X direction and the -Z′ direction of the vibrating portion 11 in the -Z′ direction.

[0063] A first excitation electrode 111 is disposed on the first main surface 101 side of the vibration section 11, and a second excitation electrode 112 is disposed on the second main surface 102 side of the vibration section 11. Lead wires (first lead wire 113 and second lead wire 114) for connecting these excitation electrodes to external electrode terminals are connected to the first excitation electrode 111 and the second excitation electrode 112. The first lead wire 113 extends from the first excitation electrode 111 and is connected to a connection bonding pattern 14 formed on the outer frame section 12 via a holding portion 13. The second lead wire 114 extends from the second excitation electrode 112 and is connected to a connection bonding pattern 15 formed on the outer frame section 12 via a holding portion 13.

[0064] On the two main surfaces (first main surface 101 and second main surface 102) of the crystal oscillator 10, vibration-side sealing portions for engaging the crystal oscillator 10 with the first sealing member 20 and the second sealing member 30 are respectively provided. The vibration-side sealing portion of the first main surface 101 has a vibration-side first engagement pattern 121 formed; the vibration-side sealing portion of the second main surface 102 has a vibration-side second engagement pattern 122 formed. The vibration-side first engagement pattern 121 and the vibration-side second engagement pattern 122 are provided on the outer frame portion 12 and are annular in plan view.

[0065] In addition, such as Figure 7 , Figure 8 As shown, five through holes are formed on the crystal oscillator 10, penetrating the first main surface 101 and the second main surface 102. Specifically, four first through holes 161 are respectively provided in the four corners (corner areas) of the outer frame portion 12. Second through holes 162 are provided in the outer frame portion 12 and located on one side of the oscillator 11 in the Z′ axis direction. Figure 7 , Figure 8 (The center is the -Z′ direction side). Connecting patterns 123 are formed around the first through hole 161. In addition, connecting patterns 124 are formed on the first main surface 101 side and connecting patterns 15 are formed on the second main surface 102 side around the second through hole 162.

[0066] In the first through hole 161 and the second through hole 162, through electrodes are formed along the inner wall surface of each through hole. These through electrodes are used to enable the conduction of the electrodes formed on the first main surface 101 and the second main surface 102. In addition, the middle portion of each of the first through hole 161 and the second through hole 162 becomes a hollow through portion that passes through the first main surface 101 and the second main surface 102.

[0067] Secondly, such as Figure 5 , Figure 6 As shown, the first sealing member 20 is a cuboid substrate made of an AT water-cutting wafer. The second main surface 202 of the first sealing member 20 (the surface that engages with the crystal oscillator 10) is made into a flat and smooth surface (mirror finish). Furthermore, the first sealing member 20 does not have a vibrating section. By using an AT water-cutting wafer, similar to the crystal oscillator 10, the thermal expansion rates of the crystal oscillator 10 and the first sealing member 20 are the same, thereby suppressing thermal deformation of the crystal oscillator 100. In addition, the orientations of the X-axis, Y-axis, and Z′-axis in the first sealing member 20 are the same as those in the crystal oscillator 10.

[0068] like Figure 5As shown, on the first main surface 201 of the first sealing member 20, a six-electrode pattern 22 is formed, including a mounting pad for mounting an oscillator IC 51 as an oscillation circuit element. The oscillator IC 51 uses metal protrusions (e.g., Au protrusions, etc.) 51a (see reference). Figure 4 The electrode pattern 22 is bonded to the core substrate 4 via flip chip bonding (FCB). Furthermore, in this embodiment, the electrode patterns 22 located at the four corners (corner portions) of the first main surface 201 of the first sealing member 20 are connected to the connection terminals 4c formed on the top surface 4a of the core substrate 4 via wires 6a. Thus, the oscillator IC 51 is electrically connected to the outside via wires 6a, the core substrate 4, the conductive adhesive 7, the package 2, etc.

[0069] like Figure 5 , Figure 6 As shown, six through holes are formed on the first sealing member 20. These six through holes are respectively connected to six electrode patterns 22 and penetrate the first main surface 201 and the second main surface 202. Specifically, four third through holes 211 are provided in the four corner areas (corner portions) of the first sealing member 20. Fourth through holes 212 and fifth through holes 213 are respectively provided in... Figure 5 , Figure 6 The +Z′ direction and the -Z′ direction.

[0070] In the third through hole 211, the fourth through hole 212, and the fifth through hole 213, through electrodes are formed along the inner wall surface of each through hole. These through electrodes are used to enable conduction of the electrodes formed on the first main surface 201 and the second main surface 202. Furthermore, the middle portion of each of the third through hole 211, the fourth through hole 212, and the fifth through hole 213 becomes a hollow through portion that penetrates the first main surface 201 and the second main surface 202.

[0071] A sealing-side first engagement pattern 24 is formed on the second main surface 202 of the first sealing member 20. This sealing-side first engagement pattern 24 serves as a sealing-side first sealing portion for engaging with the crystal oscillator 10. When viewed from above, the sealing-side first engagement pattern 24 is annular.

[0072] Furthermore, on the second main surface 202 of the first sealing member 20, a connecting pattern 25 is formed around the third through hole 211. A connecting pattern 261 is formed around the fourth through hole 212, and a connecting pattern 262 is formed around the fifth through hole 213. A connecting pattern 263 is formed on the opposite side (-Z′ direction side) of the connecting pattern 261 in the long axis direction of the first sealing member 20, and the connecting patterns 261 and 263 are connected by a wiring pattern 27.

[0073] Secondly, such as Figure 9 , Figure 10 As shown, the second sealing member 30 is a cuboid substrate made of an AT water-cutting wafer. The first main surface 301 of the second sealing member 30 (the surface that engages with the crystal oscillator 10) is configured as a flat and smooth surface (mirror finish). Furthermore, in the second sealing member 30, it is preferable to use an AT water-cutting wafer, just like the crystal oscillator 10, and the orientation of the X-axis, Y-axis, and Z′-axis is the same as that of the crystal oscillator 10.

[0074] A second sealing-side engagement pattern 31 is formed on the first main surface 301 of the second sealing member 30. This second sealing-side engagement pattern 31 serves as a second sealing portion for engagement with the crystal oscillator 10. When viewed from above, the second sealing-side engagement pattern 31 is annular.

[0075] Four electrode terminals 32 are provided on the second main surface 302 of the second sealing member 30. The electrode terminals 32 are located at the four corners (corner portions) of the second main surface 302 of the second sealing member 30. In addition, in this embodiment, electrical connection with the outside is achieved through the electrode pattern 22 and the wire 6a as described above, but electrical connection with the outside can also be achieved using the electrode terminals 32.

[0076] like Figure 9 , Figure 10As shown, four through holes are formed on the second sealing member 30, penetrating the first main surface 301 and the second main surface 302. Specifically, four sixth through holes 33 are provided in the four corner areas (corner portions) of the second sealing member 30. A through electrode is formed along the inner wall surface of each of the sixth through holes 33, which is used to achieve conductivity between the electrodes formed on the first main surface 301 and the second main surface 302. Thus, through the through electrode formed on the inner wall surface of the sixth through hole 33, conductivity is achieved between the electrode formed on the first main surface 301 and the electrode terminal 32 formed on the second main surface 302. Furthermore, the middle portion of each of the sixth through holes 33 becomes a hollow through portion penetrating the first main surface 301 and the second main surface 302. Additionally, in the first main surface 301 of the second sealing member 30, connection patterns 34 are formed around the sixth through holes 33. Furthermore, if the electrode terminal 32 is not used to achieve electrical connection with the outside, a structure that does not include the electrode terminal 32, the sixth through hole 33, etc., can also be adopted.

[0077] In the crystal oscillator 100 comprising the aforementioned crystal oscillator 10, first sealing member 20, and second sealing member 30, the crystal oscillator 10 and the first sealing member 20 are diffusely bonded in a state where the first bonding pattern 121 on the vibration side and the first bonding pattern 24 on the sealing side overlap, and the crystal oscillator 10 and the second sealing member 30 are diffusely bonded in a state where the second bonding pattern 122 on the vibration side and the second bonding pattern 31 on the sealing side overlap, thereby forming a... Figure 4 The package has a sandwich structure as shown. Therefore, the internal space of the package, that is, the storage space for the vibrating part 11, is airtight.

[0078] At this time, the aforementioned bonding patterns also diffuse and bond together in an overlapping state. Furthermore, through the bonding of the bonding patterns, electrical conduction is achieved in the crystal oscillator 100 for the first excitation electrode 111, the second excitation electrode 112, the oscillator IC51, and the electrode terminal 32.

[0079] Specifically, the first excitation electrode 111 is connected to the oscillator IC51 via the first lead wire 113, the wiring pattern 27, the fourth through hole 212, and the electrode pattern 22 in sequence. The second excitation electrode 112 is connected to the oscillator IC51 via the second lead wire 114, the second through hole 162, the fifth through hole 213, and the electrode pattern 22 in sequence.

[0080] In the crystal oscillator 100, it is preferable that various bonding patterns are formed by stacking several layers on a crystal plate, and that a Ti (titanium) layer and an Au (gold) layer are deposited starting from the bottom layer side. Furthermore, it is preferable that other wiring or electrodes formed in the crystal oscillator 100 also adopt the same structure as the bonding patterns, thus enabling simultaneous formation of bonding patterns or wiring and electrode patterns.

[0081] In the crystal oscillator 100 configured as described above, the sealing portion (sealing path) 115 and sealing portion (sealing path) 116, which hermetically seal the vibrating part 11 of the crystal oscillator 10, are configured to be annular in plan view. The sealing path 115 is formed by diffusion bonding of the first bonding pattern 121 on the vibrating side and the first bonding pattern 24 on the sealing side, and the outer and inner edge shapes of the sealing path 115 are approximately octagonal. Similarly, the sealing path 116 is formed by diffusion bonding of the second bonding pattern 122 on the vibrating side and the second bonding pattern 31 on the sealing side, and the outer and inner edge shapes of the sealing path 116 are approximately octagonal.

[0082] As described above, in this embodiment, the core portion 5 is supported in the package 2 by the core substrate 4. When viewed from above, the core substrate 4 is connected to the package 2 at a location further outward than the area where the core portion 5 is located. Furthermore, in the heater IC 52, the temperature of the core portion 5 is regulated by controlling the current supplied to the heating element, thereby maintaining the temperature of the core portion 5 at approximately a constant temperature.

[0083] The core portion 5 adopts a stacked structure of oscillator IC51, crystal resonator 50, and heater IC52, and when viewed from above, the area of ​​each component gradually increases from top to bottom, in the order of oscillator IC51, crystal resonator 50, and heater IC52. The area where the core portion 5 is located when viewed from above refers to the bonding area where components of the core portion 5 directly bonded to the core substrate 4 are bonded to the core substrate 4; in this embodiment, it is the bonding area where the core substrate 4 is bonded to the heater IC52.

[0084] like Figure 3 As shown, the connection portion 7a, which connects the core substrate 4 and the package 2 via conductive adhesive 7, is located further outward than the area where the core portion 5 is located (the area where the heater IC 52 is located) when viewed from above. When viewed from above, the connection portion 7a is located at the periphery of the core substrate 4 and is positioned where it does not overlap with the area where the core portion 5 is located. The connection portion 7a is configured to be spaced at a predetermined interval from the area where the core portion 5 is located.

[0085] Based on this embodiment, the connecting portion 7a is not positioned overlapping the core portion 5 when viewed from above, but rather positioned away from the core portion 5. Therefore, heat from the core portion 5 is less likely to move (leak) to the package 2 side via the connecting portion 7a, thus allowing most of the heat generated by the heating element of the heater IC 52 to remain in the core portion 5. This minimizes the amount of heat generated by the heater required to maintain the temperature of the core portion 5, thereby reducing the energy consumption of the OCXO1. Furthermore, since the core portion 5 is fixed in the package via the core substrate 4, stress from the mounting substrate on which the OCXO1 is mounted is less likely to be transmitted to the core portion 5, thus protecting the core portion 5.

[0086] Furthermore, since a gap 2d is provided between the core substrate 4 and the inner bottom surface of the package 2, the heat insulation of the core portion 5 can be improved through this gap 2d. As a result, the heat generated by the heater required to maintain the temperature of the core portion 5 can be further reduced, thereby further reducing the energy consumption of the OCXO1.

[0087] Furthermore, a pair of opposing stepped portions 2c are formed inside the package 2, and a gap 2d is formed by a recess formed between the stepped portions 2c and the stepped portions 2c. The recess between the stepped portions 2c is formed at a position corresponding to the core portion 5 when viewed from above (in this case, the lower position). Specifically, when viewed from above, the recess between the stepped portions 2c is positioned overlapping the core portion 5, and the core portion 5 is entirely housed within the recess between the stepped portions 2c and the stepped portions 2c.

[0088] Thus, by providing a pair of stepped portions 2c inside the package 2, the gap 2d between the core substrate 4 and the inner bottom surface of the package 2 can be reliably ensured. Furthermore, even if the adhesive used to bond the core substrate 4 to the package 2 flows out to the inner bottom surface of the package 2, the adhesive will flow into the recess, thereby preventing short circuits caused by the adhesive coming into contact with each other. Moreover, since the recess between the pair of stepped portions 2c is located at a position corresponding to the core portion 5, the heat insulation of the core portion 5 can be further improved by this recess.

[0089] Furthermore, in this embodiment, the piezoelectric oscillator of the core 5 employs a sandwich structure crystal resonator 50, as described above, in which the vibrating part 11 is hermetically sealed internally, enabling a low-profile design. This allows for the miniaturization and reduction of the core 5's height and heat capacity. Consequently, the heat generated by the OCXO1 heater can be suppressed, thereby reducing energy consumption. Moreover, the temperature tracking performance of the core 5 can be improved, thus enhancing the stability of the OCXO1. In addition, as described above, the sandwich structure crystal resonator 50 hermetically seals the vibrating part 11 without using adhesive, thereby suppressing the adverse effects of heat convection caused by degassing from the adhesive. That is, within the hermetically sealed space of the vibrating part 11, heat convection occurs due to the circulation of degassing from the adhesive, which could potentially hinder high-precision temperature control of the vibrating part 11. However, in the sandwich structure crystal resonator 50, such degassing does not occur, thus enabling high-precision temperature control of the vibrating part 11.

[0090] Typically, using a heater substrate with a heater resistor as the heat source for the core portion 5 could lead to an enlarged heater substrate. However, based on this embodiment, the required heater heat output can be ensured without using such a large heater substrate, thereby enabling further miniaturization of the core portion 5 and further reduction of its heat capacity. However, a heater substrate with a heater resistor can also be used as the heat source for the core portion 5 without limiting its size.

[0091] Furthermore, the crystal oscillator 10 has a vibrating section 11 configured as approximately rectangular, an outer frame 12 surrounding the outer periphery of the vibrating section 11, and a holding section 13 connecting the vibrating section 11 and the outer frame 12. When viewed from above, at least a portion of the oscillator IC51 overlaps with the outer frame 12 of the crystal oscillator 10. As a result, the heat from the oscillator IC51 is easily transferred to the vibrating section 11 of the crystal oscillator 10 via the outer frame 12, thereby making it easier to achieve a more uniform temperature in the core section 5.

[0092] Typically, the encapsulation body 2 suffers from thermal damage or time-related damage due to sealing, aging, and the passage of time. Therefore, when using resin-based adhesives with low heat resistance (conductive adhesive 7, conductive adhesive 55, non-conductive adhesive 53, non-conductive adhesive 54) as adhesives, decomposition and softening can generate gas within the encapsulation body 2, potentially hindering the high-precision temperature control of the OCXO1. In this embodiment, polyimide-based adhesives and epoxy-based adhesives with low thermal conductivity and high heat resistance are used as the aforementioned adhesives to prevent these problems.

[0093] This invention can be modified in various ways without departing from its spirit, purpose, or main features. Therefore, the above embodiments are merely examples of various aspects and do not constitute a basis for limiting interpretation. The technical scope of this invention is defined by the claims, and not by the content of the specification. Furthermore, all modifications falling within the scope of the claims are within the scope of this invention.

[0094] In the above embodiment, a gap 2d is formed between the core substrate 4 and the inner bottom surface of the package 2 by providing a pair of stepped portions 2c inside the package 2. However, a structure that does not provide such stepped portions 2c inside the package 2 can also be used. For example, the core substrate 4 can be bonded to a connection terminal formed on the inner bottom surface of the package 2 by a conductive adhesive, and the gap 2d is formed between the core substrate 4 and the inner bottom surface of the package 2 by the conductive adhesive sandwiched between the core substrate 4 and the package 2. In this case, the conductive adhesive is applied to a state having a predetermined thickness, and the thickness of the conductive adhesive ensures the gap 2d between the core substrate 4 and the inner bottom surface of the package 2. Based on this structure, a gap 2d can be formed between the core substrate 4 and the inner bottom surface of the package 2 by using the simple method of bonding the core substrate 4 and the package 2 with an adhesive.

[0095] In the above embodiment, a sandwich-structured crystal resonator 50 is used as the piezoelectric oscillator, but it is not limited to this; other piezoelectric oscillators can also be used. Furthermore, the oscillator IC 51 is mounted to the crystal resonator 50 using FCB (Flip Chip Bonding) with metal protrusions, but it is not limited to this; wire bonding, conductive adhesives, etc., can also be used to mount the oscillator IC 51 to the crystal resonator 50. Furthermore, the heater IC 52 is mounted to the core substrate 4 using wire bonding, but it is not limited to this; FCB with metal protrusions, conductive adhesives, etc., can also be used to mount the heater IC 52 to the core substrate 4. Furthermore, the electrical connection between the crystal resonator 50 and the core substrate 4 is achieved using wire bonding, but it is not limited to this; FCB with metal protrusions, conductive adhesives, etc., can also be used to mount the crystal resonator 50 to the heater IC 52, thereby achieving the electrical connection between the crystal resonator 50 and the core substrate 4 through the heater IC 52.

[0096] In addition, for example, it can also be like Figure 11 , Figure 12 The first variant shown Figure 13As shown in the second variation, the electrical connection between the core 5 and the package 2 is achieved by wire bonding. Alternatively, although not shown, the electrical connection between the substrate 4 and the package 2 can also be achieved using the FCB method with metal protrusions. Thus, the electrical connection between the core substrate 4 and the package 2 can also be achieved using mechanical connection methods such as conductive adhesives, wire bonding, or the FCB method with metal protrusions.

[0097] When the core substrate 4 is mechanically connected to the inner bottom surface of the package 2, a pair of stepped portions 2c (see reference) are connected to the core substrate 4. Figure 1 Compared to the top surface structure of the core IC 52, this allows for a lower profile in the OCXO1. Furthermore, by connecting the core substrate 4 to the package 2 via a mechanical and insulating (non-conductive) connection, heat from the core 5 is less likely to move (leak) to the package 2, thus ensuring that most of the heat generated by the heater IC 52 remains in the core 5. This minimizes the amount of heat generated by the heater required to maintain the temperature of the core 5, thereby reducing the energy consumption of the OCXO1. Moreover, by connecting the core substrate 4 to the package 2 via a mechanical and insulating connection, the core 4 can be electrically connected to the package 2 simply by wire bonding.

[0098] The configuration of the connection portion 7a between the core substrate 4 and the package 2 described above is only one example. Other configuration structures can also be used, as long as the connection portion 7a is located further outward than the area where the core portion 5 is located when viewed from above. In other words, the connection portion 7a can also be located in a position other than the above-mentioned position, as long as it does not overlap with the core portion 5 when viewed from above.

[0099] In the above embodiments, the core part 5 adopts a structure in which at least the oscillator IC51, the crystal resonator 50, and the heater IC52 are stacked sequentially from the top. Conversely, the core part 5 may also adopt a structure in which at least the heater IC52, the crystal resonator 50, and the oscillator IC51 are stacked sequentially from the top.

[0100] The core portion 5 can be any structure having at least an oscillator IC51, a crystal resonator 50, and a heater IC52, or it can be a structure with an additional structure such as a heater substrate added to a stacked structure of the oscillator IC51, crystal resonator 50, and heater IC52. For example, it can be a four-layer structure in which the heater substrate, oscillator IC51, crystal resonator 50, and heater IC52 are stacked sequentially from top to bottom, or it can be a four-layer structure in which the heater IC52, crystal resonator 50, oscillator IC51, and heater substrate are stacked sequentially from top to bottom. In these cases, by stacking the heater substrate, which serves as a heat source, with the oscillator IC51, the temperature of the core portion 5 can be further homogenized.

[0101] Furthermore, in the case of a four-layer structure in which the heater substrate, oscillator IC51, crystal resonator IC50, and heater IC52 are stacked sequentially from top to bottom, the bonding area between the heater IC52 and the core substrate 4, which is directly bonded to the core substrate 4, is the area where the core portion 5 is provided. On the other hand, in the case of a four-layer structure in which the heater IC52, crystal resonator 50, oscillator IC51, and heater substrate are stacked sequentially from top to bottom, the bonding area between the heater substrate and the core substrate 4, which is directly bonded to the core substrate 4, is the area where the core portion 5 is provided.

[0102] Furthermore, the core portion 5 only needs to have at least an oscillator IC51, a crystal resonator 50, and a heater IC52, and may not have the stacked structure described above. For example, the core portion 5 may also have a structure that includes, in addition to the oscillator IC51, crystal resonator 50, and heater IC52, a heater substrate, multiple chip capacitors (bypass capacitors), etc. In this case, the bonding area between the constituent component (e.g., the heater substrate) directly bonded to the core substrate 4 and the core substrate 4 is the area where the core portion 5 is disposed.

[0103] In the above embodiment, the core portion 5 and the package 2 are electrically connected via the core substrate 4, but the core portion 5 and the package 2 may also be electrically connected without using the core substrate 4. That is, at least one of the oscillator IC51, crystal resonator 50, and heater IC52 constituting the core portion 5 may be electrically connected to the package 2 via a wire. (Refer to...) Figure 11 , Figure 12 The OCXO1 involved in this variation will be explained. Figure 11 This is a cross-sectional view showing the general structure of OCXO1 involved in the first modified example. Figure 12 yes Figure 11 Top view of OCXO1.

[0104] like Figure 11 , Figure 12As shown, the OCXO1 involved in the first modified example is configured such that a core portion 5 is disposed inside a roughly rectangular package (shell) 2 made of ceramic or the like, and is hermetically sealed by a cover 3. The dimensions of the package 2 are, for example, 5.0 × 3.2 mm. A recess 2a with an opening at the top is formed on the package 2, and the core portion 5 is sealed inside the recess 2a in a hermetically sealed state. A peripheral wall portion 2b surrounds the recess 2a, and the cover 3 is fixed to the top surface of the peripheral wall portion 2b by seam welding with a sealing material 8, so the interior of the package 2 is sealed (hermetically sealed). As the sealing material 8, it is preferable to use a metallic sealing material such as Au-Su alloy or solder, but a sealing material such as low-melting-point glass can also be used. Furthermore, it is not limited to this; as the sealing structure, the sealing can also be achieved by methods such as seam sealing using a metal ring, direct seam sealing without using a metal ring, beam sealing, etc. (Seam sealing is preferred in terms of not reducing the vacuum level). Preferably, the internal space of the package 2 is a vacuum (e.g., a vacuum level below 10 Pa), or a low-pressure atmosphere with low thermal conductivity such as nitrogen or argon. Furthermore, Figure 12 The image shows the state of OCXO1 after removing cover 3, and also shows the internal structure of OCXO1.

[0105] On the inner wall surface of the peripheral wall portion 2b of the package 2, a stepped portion 2c is formed along a row of connecting terminals (not shown). The core portion 5 is disposed on the bottom surface (inner bottom surface of the package 2) of the recess 2a located between the opposing pair of stepped portions 2c via a plate-shaped core substrate 4. Alternatively, the stepped portion 2c may be configured to surround the bottom surface of the recess 2a. The core substrate 4 is made of a heat-resistant and flexible resin material such as polyimide. Furthermore, the core substrate 4 may also be made of crystal.

[0106] The core substrate 4 is bonded to the bottom surface of the recess 2a (the inner bottom surface of the package 2) by a non-conductive adhesive 7b, and a gap 2d is formed on the lower side of the core substrate 4. Furthermore, external terminals (not shown) formed on each component of the core portion 5 are connected to connection terminals formed on the stepped surface of the stepped portion 2c via wires 6a and 6b through wire bonding. Spacer members 2f are provided inside the non-conductive adhesive 7b.

[0107] Two non-conductive adhesives 7b are respectively disposed at the two ends of the long side of the core substrate 4, and along the short side of the core substrate 4 (and...). Figure 12The spacers 2f are arranged in a straight line (perpendicular to the paper surface). Each spacer 2f is disposed adjacent to one side of the non-conductive adhesive 7b and is arranged in a straight line along the short side of the core substrate 4. Thus, on the inside of each non-conductive adhesive 7b, two spacers 2f are sandwiched between the inner bottom surface of the core substrate 4 and the package body 2. The two ends of the core substrate 4 in the long side direction are supported by two spacers 2f.

[0108] The core substrate 4 is made of a heat-resistant and flexible resin material such as polyimide. The spacer 2f is made of a paste-like material such as molybdenum or tungsten. Thus, a non-conductive adhesive 7b and a spacer 2f are provided between the core substrate 4 and the inner bottom surface of the package 2, easily ensuring the gap 2d between the core substrate 4 and the inner bottom surface of the package 2. Furthermore, the thickness of the non-conductive adhesive 7b applied to the inner bottom surface of the package 2 depends on the spacer 2f, therefore, the width of the gap 2d between the core substrate 4 and the inner bottom surface of the package 2 can be easily determined. The thickness of the spacer 2f is preferably 5–50 μm. There is no underfill material between the opposing surfaces of the crystal resonator 50 and the oscillator IC 51. The opposing surfaces of the crystal resonator 50 and the oscillator IC 51 are fixed by multiple metal protrusions 51a, thereby avoiding the stress caused by the underfill material. Alternatively, a structure in which a bottom filler is sandwiched between the opposing surfaces of the crystal resonator 50 and the oscillator IC51 can be used. Furthermore, a conductive adhesive 56 is sandwiched between the opposing surfaces of the crystal resonator 50 and the heater IC52, but a structure in which a non-conductive adhesive is sandwiched between the opposing surfaces of the crystal resonator 50 and the heater IC52 can also be used.

[0109] In the above embodiment, the package 2 is a single package, but the present invention is not limited to this; for example, it can also be a single package. Figure 13 The H-type package shown, or a package with two overlapping layers. Figure 13 This is a cross-sectional view showing the general structure of OCXO1 involved in the second variation.

[0110] Figure 13 The H-type package OCXO1 shown has a package body 2, which has a recess 2a with an upper opening and a recess 2e with a lower opening. In the recess 2e formed on another main surface opposite to the mounting surface of the core part 5 (the main surface where the recess 2a is formed), circuit elements such as a chip capacitor 4d (e.g., circuit elements mounted by soldering) used as adjustment electronic components in combination with the heater IC 52 can be arranged. Unlike the recess 2a, the recess 2e where the chip capacitor 4d is arranged does not require a cover for sealing.

[0111] Here, the chip capacitor 4d can be arranged in the same space (within the recess 2a) as the core portion 5, however, by means of... Figure 13 By arranging the circuit components and the core 5 in different spaces (within the recess 2e) as shown, the heat capacity within the space housing the core 5 can be reduced, enabling low-energy-consumption temperature control and improving the temperature tracking performance of the core 5. Furthermore, the atmosphere inside the hermetically sealed recess 2a prevents the subsequent generation of gas due to solder, flux, etc. Therefore, the adverse effects of gas on the core 5 can be eliminated, thereby further stabilizing the electrical characteristics.

[0112] This application is based on priority of Japanese Patent Application No. 2020-149902, filed in Japan on September 7, 2020. Therefore, all contents of that application are combined into this application.

[0113] <Industry availability>

[0114] This invention can be used in a thermostatic tank type piezoelectric oscillator having a core comprising a piezoelectric vibrator, an oscillator IC, and a heater IC.

Claims

1. A thermostatic bath type piezoelectric oscillator, comprising at least an oscillator IC, a piezoelectric vibrator, and a heater IC, the core of which is sealed in a heat-insulating package in a hermetically sealed state, characterized in that: The core component is supported in the package by a core substrate. Viewed from above, the core substrate is connected to the package body at a location further outward than the area where the core portion is located. The piezoelectric vibrator and the heater IC are stacked in a stacked structure, and on the surface where the piezoelectric vibrator and the heater IC are joined, the area of ​​the heater IC is larger than the area of ​​the piezoelectric vibrator.

2. The thermostatic bath type piezoelectric oscillator according to claim 1, characterized in that: The core substrate and the package are connected by a mechanical connection.

3. The thermostatic bath type piezoelectric oscillator according to claim 1 or 2, characterized in that: A gap is provided between the core substrate and the inner bottom surface of the package.

4. The thermostatic bath type piezoelectric oscillator according to claim 3, characterized in that: The core substrate is bonded to the package body by an adhesive. The gap is formed by the adhesive sandwiched between the core substrate and the package.

5. The thermostatic bath type piezoelectric oscillator according to claim 3, characterized in that: A pair of opposing stepped portions are formed inside the package, and the gap is formed by a recess formed between the pair of stepped portions.

6. The thermostatic bath type piezoelectric oscillator according to claim 5, characterized in that: The recess is formed at a position corresponding to the core portion when viewed from above.

7. The thermostatic bath type piezoelectric oscillator according to claim 1 or 2, characterized in that: The piezoelectric vibrator includes a first sealing component and a second sealing component made of glass or crystal, and a piezoelectric vibrating plate made of crystal. The piezoelectric vibrating plate has a vibrating portion with excitation electrodes formed on two main surfaces. The first sealing component and the second sealing component are stacked and joined across the piezoelectric vibrating plate, and the vibrating portion of the piezoelectric vibrating plate disposed inside is hermetically sealed.

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