Piezoelectric oscillator with constant temperature chamber

Abstract

This invention provides a piezoelectric oscillator with a constant temperature chamber that suppresses changes in output frequency due to changes in ambient temperature, thereby achieving superior frequency stability. [Solution] The piezoelectric oscillator 1 with a constant temperature bath comprises a flat first resin substrate 2, a second resin substrate 3 having a rectangular parallelepiped through hole in the center, fixing pins 6 that fix the second resin substrate above the first resin substrate at predetermined intervals, a ceramic package 41 mounted on the upper surface of the second resin substrate covering the through hole, an IC chip 42 mounted on the mounting surface of the ceramic package and containing a heater for heating the piezoelectric vibrator, a lid 43 that seals the IC chip inside the ceramic package, a piezoelectric vibrator 70 mounted on the lower surface of the ceramic package and located in the space surrounded by the side of the through hole and the ceramic package, and a cover 5 that cooperates with the first resin substrate to surround the second resin substrate, ceramic package, piezoelectric vibrator and IC chip.

Description

[Technical Field]

[0001] The present disclosure relates to a piezoelectric oscillator with a thermostatic chamber in which an oscillation circuit is housed in a thermostatic chamber. [Background Art]

[0002] In various electronic devices such as mobile phones and personal computers, a crystal oscillator combining a crystal resonator and an integrated circuit (IC: Integrated Circuit) chip is known, for easily obtaining a stable frequency required for information processing, communication processing or the like. Types of the crystal oscillator include temperature compensated crystal oscillators (TCXO: Temperature Compensated Crystal Oscillator), voltage controlled crystal oscillators (VCXO: Voltage Controlled Crystal Oscillator), and oven controlled crystal oscillators (OCXO: Oven Controlled Crystal Oscillator).

[0003] Among these crystal oscillators, the one having particularly excellent frequency stability is the oven controlled crystal oscillator. The oven controlled crystal oscillator houses the crystal resonator or the crystal oscillator in a thermostatic chamber to keep the temperature of the crystal resonator or the crystal oscillator constant, thereby suppressing changes in output frequency caused by changes in ambient temperature. The oven controlled crystal oscillator is required, for example, as a reference for frequency, time and hour to achieve synchronization in communication base stations of smartphones or wired networks.

[0004] For example, Patent Document 1 discloses a high-stability piezoelectric oscillator as an example of such an oven controlled crystal oscillator. In particular, in the high-stability piezoelectric oscillator disclosed in Patent Document 1, the piezoelectric resonator is heated by a heater, and the heater temperature is controlled by a temperature control circuit. Furthermore, in the high-stability piezoelectric oscillator disclosed in Patent Document 1, a metal oven is not used, the thermostatic chamber is constituted by a printed circuit board such as glass epoxy, and the piezoelectric resonator is fitted into an opening of the printed circuit board. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2005-175703 [Overview of the project] [Problems that the invention aims to solve]

[0006] In recent years, with the development of electronic devices that require more precise operation, the applications of temperature-controlled crystal oscillators have expanded, and the demand for superior stability in temperature-controlled crystal oscillators has increased. Furthermore, with the advancement of communication technology, the demand for superior stability has also increased in applications such as communication base stations. However, simply housing a crystal resonator or crystal oscillator in a temperature-controlled bath to maintain a constant temperature has not been sufficient to adequately meet the requirements of various applications.

[0007] This disclosure has been made in view of the above issues, and its purpose is to provide a piezoelectric oscillator with a constant temperature chamber that can suppress changes in output frequency due to changes in ambient temperature and achieve better frequency stability. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, a piezoelectric oscillator with a constant temperature bath is provided, comprising: a flat first resin substrate; a second resin substrate having through holes; fixing pins for fixing the second resin substrate at predetermined intervals above the first resin substrate; a ceramic package mounted on the upper surface of the second resin substrate, covering the through holes; an IC chip mounted on the mounting surface of the ceramic package; a lid for sealing the IC chip within the ceramic package; a piezoelectric vibrator mounted on the lower surface of the ceramic package and located in the space surrounded by the side of the through holes and the ceramic package; a heater unit for heating the piezoelectric vibrator; and a cover that cooperates with the first resin substrate to surround the second resin substrate, the ceramic package, the piezoelectric vibrator, and the heater unit. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a piezoelectric oscillator with a constant temperature chamber that can suppress changes in output frequency due to changes in ambient temperature and achieve better frequency stability.

[0010] The effects described above are merely illustrative for the sake of explanation, and the effects relating to this disclosure are not limited to those described above. In addition to the effects described above, any other effects described herein may be achieved. [Brief explanation of the drawing]

[0011] [Figure 1] This is a perspective view of a crystal oscillator with a constant temperature bath according to the first embodiment. [Figure 2] This is an exploded perspective view of a crystal oscillator with a constant temperature bath according to the first embodiment. [Figure 3] This is a rear view of a crystal oscillator with a constant temperature bath according to the first embodiment. [Figure 4] Figure 4(a) is a perspective view of the oscillator components constituting the constant-temperature bath crystal oscillator according to the first embodiment, and Figure 4(b) is an exploded side view of the oscillator components constituting the constant-temperature bath crystal oscillator according to the first embodiment. [Figure 5]Figure 1 shows a cross-sectional view of a crystal oscillator with a constant temperature bath along the dashed line AA. [Figure 6] This is an enlarged cross-sectional view of a crystal oscillator with a constant temperature bath according to the second embodiment, similar to Figure 5. [Modes for carrying out the invention]

[0012] The following description will detail a constant-temperature oven-equipped crystal oscillator, which is an example of a constant-temperature oven-equipped piezoelectric oscillator according to this disclosure, with reference to the drawings. Note that this disclosure is not limited to the content described below, and can be modified and implemented as such without altering its essence. Furthermore, the drawings used in each embodiment are schematic representations of the constant-temperature oven-equipped crystal oscillator according to this disclosure, and have been partially emphasized, enlarged, reduced, or omitted to enhance understanding, and may not accurately represent the scale or shape of each component. Additionally, some numerical values ​​used in each embodiment are examples only and can be changed as needed. Common components in the drawings are denoted by the same reference numerals.

[0013] (First Embodiment) First, the basic structure of the constant-temperature bath crystal oscillator according to this disclosure will be described with reference to Figures 1 to 5. Figure 1 is a perspective view of the constant-temperature bath crystal oscillator 1 according to this embodiment. Figure 2 is an exploded perspective view of the constant-temperature bath crystal oscillator 1 according to this embodiment. Figure 3 is a rear view of the constant-temperature bath crystal oscillator 1 according to this embodiment. Figure 4(a) is a perspective view of the oscillation component 4 constituting the constant-temperature bath crystal oscillator 1 according to this embodiment, and Figure 4(b) is an exploded side view of the oscillation circuit section 40 constituting the constant-temperature bath crystal oscillator 1 according to this embodiment. Figure 5 is a cross-sectional view of the constant-temperature bath crystal oscillator 1 along the dashed line AA in Figure 1.

[0014] As can be seen from Figures 1 and 2, the constant-temperature bath-type crystal oscillator 1, an example of a piezoelectric device, has a first resin substrate 2, a second resin substrate 3, an oscillator component 4, a cover 5, and fixing pins 6. The constant-temperature bath-type crystal oscillator 1 has a structure in which the first resin substrate 2 and the second resin substrate 3 are separated by the fixing pins 6, and these components are covered by the cover 5 when the oscillator component 4 is mounted on the second resin substrate 3. The constant-temperature bath-type crystal oscillator 1 can generate a very stable frequency and can produce a regular reference signal.

[0015] In the following, the mounting direction of the second resin substrate 3 on the first resin substrate 2 is defined as the vertical direction, and the direction perpendicular to the vertical direction is defined as the horizontal direction. Furthermore, in the vertical direction, the side where the first resin substrate 2 is located is defined as the lower side, and the side where the second resin substrate 3 and the oscillator component 4 are located is defined as the upper side. Therefore, the cover 5 covers the first resin substrate 2, the second resin substrate 3, the oscillator component 4, and the fixing pins 6 from above.

[0016] <First resin substrate> First, as can be seen from Figures 2 and 3, the first resin substrate 2 is a flat substrate with a rectangular shape in plan view. The first resin substrate 2 is a substrate made of resin. This resin is, for example, glass epoxy used in general rigid-type circuit boards. That is, the first resin substrate 2 may be, for example, a glass epoxy substrate or a glass composite substrate.

[0017] Furthermore, as can be seen from Figures 2, 3, and 5, the first resin substrate 2 has six cylindrical through holes 21 formed therein. Specifically, three through holes 21 are formed on each of the short sides of the first resin substrate 2. Fixing pins 6 are fitted into the through holes 21. That is, three fixing pins 6 are erected along each of the short sides of the first resin substrate 2. The fixing pins 6 are joined to the first resin substrate 2 by a bonding material such as solder.

[0018] Furthermore, as shown in FIG. 3, six external connection terminals 22 are formed on the back surface of the first resin substrate 2. In particular, three external connection terminals 22 are formed on each of the long sides of the first resin substrate 2. As shown in FIG. 5, a circuit pattern (first circuit pattern) 23 is formed on the surface of the first resin substrate 2 (the surface opposite to the surface on which the external connection terminals 22 are formed). Although not shown in the drawings, the circuit pattern 23 is also formed on the side surface of the first resin substrate 2, and electrically connects the external connection terminals 22 and the fixing pins 6, or electrically connects the electronic component 82 (shown in FIG. 5) mounted on the surface of the first resin substrate 2 and the external connection terminals 22.

[0019] <Second Resin Substrate> Next, as can be seen from FIG. 2 and FIG. 5, the second resin substrate 3 has a shape in which a rectangular parallelepiped through-hole 31 is formed in the central portion of a rectangular flat plate-shaped substrate. That is, the outer shape of the second resin substrate 3 is frame-shaped. In addition, six cylindrical through-holes 32 are formed in the second resin substrate 3. Specifically, three through-holes 32 are formed on each of the short sides of the second resin substrate 3.

[0020] Similarly to the first resin substrate 2, the second resin substrate 3 is a substrate made of resin. The resin is, for example, glass epoxy used for general rigid circuit boards. That is, the second resin substrate 3 may also be, for example, a glass epoxy substrate or a glass composite substrate.

[0021] Furthermore, as can be seen from FIG. 2 and FIG. 5, when the oven-controlled crystal oscillator 1 is assembled, the through-holes 32 of the second resin substrate 3 are positioned to face the through-holes 21 formed in the first resin substrate 2. Therefore, as shown in FIG. 5, in the manufactured oven-controlled crystal oscillator 1, the fixing pins 6 are inserted through the through-holes 32 of the second resin substrate 3. Then, the second resin substrate 3 is fixed at a predetermined distance from the first resin substrate 2 by the annular locking portions 61 of the fixing pins 6.

[0022] As shown in Figure 5, the upper surface (the surface located vertically upward) of the second resin substrate 3 has multiple circuit patterns (second circuit patterns) 33 formed thereon, each consisting of connection terminals for mounting the oscillator component 4 and wiring sections extending from the connection terminals to the through holes 32. For example, there are six connection terminals, corresponding to the number of connection terminals in the IC package described later. The wiring sections may also be formed around and on the inner surface of the through holes 32 so as to provide electrical connections with the fixed pins 6. Furthermore, a portion of the circuit patterns 33 is electrically connected to a circuit pattern 23 formed on the first resin substrate 2 via the fixed pins 6.

[0023] The second resin substrate 3 will have a smaller external shape than the first resin substrate 2, but from the viewpoint of suppressing the dissipation of heat generated by the heater part of the IC chip, which will be described later, it is preferable to make it as small and thin as possible. In other words, it is preferable to adjust the external dimensions and thickness to be as small as possible so that the temperature control for the crystal oscillator 70, which will be described later, can be performed efficiently and accurately.

[0024] <Oscillating components> Next, as can be seen from Figures 2 and 4, the oscillation component 4 consists of an oscillation circuit section 40 that incorporates an IC chip (described later) and a quartz crystal oscillator 70, which is a piezoelectric resonator mounted on the back surface of the oscillation circuit section 40. In other words, the oscillation component 4 is an example of a quartz oscillator consisting of a quartz crystal oscillator 70 and an oscillation circuit section 40 that includes a circuit for oscillating it.

[0025] As can be seen from Figures 2, 4, and 5, the oscillator circuit section 40 includes an IC package 41 (hereinafter simply referred to as package 41), an IC chip 42 mounted in the recessed mounting space 40a of the package 41, and a metal lid (cover) 43 for sealing the mounting space 40a. In other words, the oscillator circuit section 40 functions as a component that controls the crystal oscillator 70 using the IC chip 42.

[0026] Package 41 is a ceramic package formed by stacking multiple ceramics on which a desired metal pattern is formed on the surface. Therefore, package 41 has a higher thermal conductivity compared to the first resin substrate 2 and the second resin substrate 3. Specifically, package 41 has a laminated structure in which a rectangular bottom plate 41a, a first frame wall 41b with an opening of a predetermined size, and a second frame wall 41c with an opening larger than the opening of the first frame wall 41b are sequentially stacked in plan view. In particular, the first frame wall 41b is provided along the edge of the bottom plate 41a, and the second frame wall 41c is provided along the edge of the first frame wall 41b. With this laminated structure, package 41 has a mounting space 40a with a concave shape for mounting the IC chip 42.

[0027] As can be seen from Figures 2 and 4, the shape of the package 41 is a rectangular parallelepiped, and in plan view it is rectangular. In the following, the horizontal direction mentioned above may be distinguished as the long side direction (long side direction) and the short side direction (short side direction) of the package 41. Furthermore, in the package 41, the surface located on the upper side in the vertical direction may be called the top surface or front surface, and the surface located on the lower side may be called the bottom surface or back surface.

[0028] The exposed surface (the upper surface in the vertical direction) of the bottom plate 41a of the package 41 has a mounting area (mounting surface) for the IC chip 42. In contrast, as can be seen from Figures 4 and 5, the back surface (the lower surface in the vertical direction) of the bottom plate 41a of the package 41 has six connection terminals 44 that are connected to the circuit pattern 33 of the second resin substrate 3 via a conductive bonding member 81 such as solder. Specifically, three connection terminals 44 are formed on each of the short sides of the bottom plate 41a.

[0029] Furthermore, as can be seen from Figures 4 and 5, four crystal mounting terminals 45 are formed on the back surface of the bottom plate 41a of the package 41, on which a crystal oscillator 70 is mounted via a conductive bonding member 81 such as solder. Specifically, the crystal mounting terminals 45 are located in the center of the bottom plate 41a. In addition, electronic component terminals (not shown) are also formed on the back surface of the bottom plate 41a of the package 41, on which other electronic components 82 are mounted via a conductive bonding member such as solder.

[0030] As shown in Figure 5, an IC chip terminal 48 is formed on the exposed surface (the upper surface in the vertical direction) of the first frame wall 41b of the package 41, which is electrically connected to the IC chip 42 via a wire 47. In other words, the IC chip terminal 48 functions as a terminal for wire bonding.

[0031] As can be seen from Figures 2, 4(b), and 5, a sealing conductor pattern 49 is formed on the exposed surface (the upper surface in the vertical direction) of the second frame wall 41c of the package 41. The planar shape of the conductor pattern 49 is frame-shaped, similar to the second frame wall 41c. A lid 43 is then joined to the conductor pattern 49 by a known metal joint. This seals the mounting space 40a of the package, and the mounting space 40a is sealed using a vacuum or a gas such as nitrogen. In other words, the IC chip 42 is housed in a sealed state within the package 41.

[0032] The IC chip 42 includes not only a crystal control unit for controlling the crystal oscillator 70, but also a heater unit for heating the crystal oscillator 70, and a heater control unit for controlling the heater unit. For example, the heater unit is composed of a heater element and is built into the IC chip 42. The crystal control unit and the heater control unit are various electronic circuits that constitute the IC chip 42. Note that the heater unit may not be built into the IC chip 42, but may be provided, for example, in the mounting space 40a or on the back surface of the bottom plate 41a of the package 41.

[0033] As can be seen from Figures 4 and 5, the quartz crystal resonator 70, which is an example of a piezoelectric resonator, has a quartz crystal resonator package 71 (hereinafter simply referred to as package 71), a quartz crystal vibrator 72 mounted in a concave mounting space 70a of the package 71, and a metal lid (cover) 73 for sealing the mounting space 70a. The quartz crystal resonator 70 is an element that can generate a constant frequency due to the piezoelectric effect when a voltage is applied to the quartz crystal vibrator 72, which is an example of a piezoelectric vibrator. The type of cut from the quartz crystal rough is not limited to AT cut, but may also be a Z cut or a two-turn cut such as SC cut, etc.

[0034] The package 71 is a ceramic package formed by stacking multiple ceramics on which a desired metal pattern is formed on the surface. Specifically, the package 71 has a laminated structure in which a rectangular base plate 71a and a frame wall 71b, which is a ridge portion with an opening of a predetermined size, are stacked in plan view. In particular, the frame wall 71b is provided along the edge of the base plate 71a. With this laminated structure, the package 71 has a mounting space 70a with a concave shape for mounting the quartz crystal oscillator 72.

[0035] Here, the package 71 is rectangular in shape, and in plan view, it is rectangular. In the following, the horizontal direction mentioned above may be distinguished as the long side direction (long side direction) and the short side direction (short side direction) of the quartz oscillator 70 and package 71. Furthermore, in the quartz oscillator 70, the surface located on the lower side in the vertical direction may be called the top surface or front surface, and the surface located on the upper side may be called the bottom surface or back surface.

[0036] Two adhesive pads, which are terminals 74 for mounting a crystal diaphragm, are formed on the exposed surface (the surface located on the lower side in the vertical direction) of the bottom plate 71a of the package 71. In particular, the terminals 74 for mounting a crystal diaphragm are provided on one end in the long-side direction within the inner region enclosed by the frame wall 71b. Here, a crystal diaphragm 72 is mounted on the terminals 74 for mounting a crystal diaphragm via a conductive adhesive 75.

[0037] On the other hand, a resonator-side mounting pattern 76 for supplying power to the crystal oscillator 72 is formed on the lower surface (the upper surface in the vertical direction) of the bottom plate 71a of the package 71. The resonator-side mounting pattern 76 is electrically connected to the crystal mounting terminal 45 of the package 41 via a connecting member 81. For example, the resonator-side mounting pattern 76 includes resonator-side signal terminals provided at two corners on the lower surface of the bottom plate 71a of the package 71. In particular, these resonator-side signal terminals may be provided at two diagonally opposite corners on the lower surface of the bottom plate 71a of the package 71. The shape of these resonator-side signal terminals may also be rectangular in plan view.

[0038] A sealing conductor pattern 77 is formed on the exposed surface (the surface located on the lower side in the vertical direction) of the frame wall 71b of the package 71. The planar shape of the conductor pattern 77 is frame-like, similar to the frame wall 71b. A lid 73 is then joined to the conductor pattern 77 by a known metal joint. This seals the mounting space 70a of the package, and the mounting space 70a is sealed using a vacuum or a gas such as nitrogen.

[0039] When the oscillator component 4 having the structure described above is mounted on the second resin substrate 3, the following structure and arrangement are formed. Specifically, as shown in Figure 5, the through-hole 31 of the second resin substrate 3 is covered from above by the package 41. The crystal oscillator 70 mounted on the bottom surface of the package 41 is located in the space 3a surrounded by the through-hole 31 of the second resin substrate 3 and the package 41. Furthermore, the electronic component 82 mounted on the bottom surface of the package 41 is also located in space 3a. For example, considering contact between the crystal oscillator 70 and the electronic component 82 and the side surface of the through-hole 31, it is preferable to have a gap of approximately 0.3 mm from the side surface of the crystal oscillator 70 or the electronic component 82 to the side surface of the through-hole 31. However, this gap can be adjusted as appropriate depending on the dimensions of the constant-temperature bath crystal oscillator 1 and the oscillator component 4.

[0040] Here, it is preferable that the crystal oscillator 70 does not protrude from the space 3a, taking into consideration heating by the heater portion of the IC chip 42 and contact with the first resin substrate 2 and the electronic components 82 mounted thereon. In other words, it is preferable that the crystal oscillator 70 has a thickness smaller than the thickness of the second resin substrate 3. To put it another way, it is preferable that the crystal oscillator 70 is mounted with the side opposite to the mounting surface to the package 41 (the back surface of the bottom plate 71a of the package 71) (the lid 73) located in the space 3a.

[0041] In addition, the crystal oscillator 70 may be replaced with, for example, a surface acoustic wave (SAW) resonator, other piezoelectric oscillators, or micro-electro-mechanical systems (MEMS) oscillators. In other words, the piezoelectric oscillator is not limited to the crystal oscillator 70 as in this embodiment, but may be an oscillator equipped with other members having resonant characteristics (piezoelectric vibrating pieces such as ceramics or silicon), or a MEMS oscillator, etc.

[0042] <Cover> Next, as can be seen from Figures 1, 2, and 5, the cover 5 is a component that works in cooperation with the first resin substrate 2 to surround the second resin substrate 3, the oscillator component 4, and the fixing pins 6. For this reason, the cover 5 has a rectangular parallelepiped shape with an opening formed inside, and works in cooperation with the first resin substrate 2 to form an internal space 5a. The cover 5 is made of a metal material such as brass, but it may also be made of resin or the like.

[0043] Furthermore, the cover 5 may be fixed to the first resin substrate 2 with an adhesive or the like, or it may be mechanically fixed with screws or the like. Moreover, the cover 5 is fixed in such a way that a gap is formed between it and the first resin substrate 2. As a result, the internal space 5a formed by the cooperation of the cover 5 and the first resin substrate 2 is not airtight.

[0044] <Fixing pin> The fixing pin 6 is a cylindrical member and has an annular locking portion 61 for fixing the second resin substrate 3. Preferably, the fixing pin 6 is made of a metal member with low thermal conductivity. For example, the fixing pin 6 may be made of cobalt, stainless steel, or titanium, or an alloy thereof. More specifically, the fixing pin 6 may be made of Kovar.

[0045] The number of fixed pins 6 is not limited to 6. It can be appropriately changed depending on the number of connection terminals 44 of the oscillator component 4 and the number of electronic components 82 mounted on the first resin substrate 2 and the second resin substrate 3. For example, one fixed pin 6 may be placed on each short side. Furthermore, the fixed pins 6 may be arranged along the long side of the first resin substrate 2, and the number of pins placed on each side may also be different.

[0046] As described above, in this embodiment, a two-tiered structure is formed in which a first resin substrate 2 and a second resin substrate 3, both with low thermal conductivity, are connected spaced apart by fixing pins 6, both with low thermal conductivity. Furthermore, an oscillator component 4, made of a ceramic package with high thermal conductivity, is mounted on the second resin substrate 3. As a result, the oscillator component 4 is mounted thermally spaced apart from the first resin substrate 2, which suppresses the dissipation of heat generated in the oscillator component 4 to the outside, allowing the oscillator component 4 to be heated efficiently. In addition, since the exterior of the oscillator component 4 is made of a ceramic package, it is possible to heat the crystal oscillator 70 that constitutes the oscillator component 4 efficiently and accurately. As a result, power consumption associated with heating the oscillator component 4 is suppressed.

[0047] On the other hand, if the oscillator component is mounted directly onto an external mounting substrate (corresponding to the first resin substrate 2) without adopting the aforementioned two-tiered structure, most of the heat generated by the oscillator component is absorbed by the substrate. As a result, the oscillator component does not heat up easily, and the power consumption associated with heating the oscillator component 4 increases.

[0048] (Second Embodiment) In the first embodiment, only the crystal oscillator 70 of the oscillation component 4 was located within the through-hole 31 of the second resin substrate 3. However, the oscillation component 4 may be arranged to be entirely housed within the through-hole of the second resin substrate 3. Such an embodiment will be described as the second embodiment with reference to Figure 6. Here, Figure 6 is an enlarged cross-sectional view of the constant-temperature bath crystal oscillator 101 according to the second embodiment, shown in the same way as Figure 5. In particular, Figure 6 is an enlarged cross-sectional view so as to focus on the second resin substrate 103 and the oscillation component 4. Note that only the parts that differ from the first embodiment will be described in detail, and the same content will be omitted from the description, and the same reference numerals will be used in the drawings in principle.

[0049] As shown in Figure 6, the second resin substrate 103 has a through hole 131. The through hole 131 consists of a first opening 131a that houses the oscillation circuit section 40 and a second opening 131b that houses the crystal oscillator 70. Furthermore, the through hole 131 has a structure in which the first opening 131a and the second opening 131b communicate with each other. That is, in the through direction of the through hole 131, the second resin substrate 103 has a first opening 131a formed on its upper surface, which is a recess that communicates with the second opening 131b, which is part of the through hole 131. For example, the first opening 131a may be formed by counterboring, and then the second opening 131b, which penetrates the second resin substrate 103 from the bottom surface of the first opening 131a, may be formed thereafter.

[0050] A circuit pattern 33 for mounting the oscillation circuit section 40 is formed on the bottom surface of the first opening 131a. When the oscillation component 4 is mounted on the circuit pattern 33 via a connecting member 81, the oscillation circuit section 40 is positioned so as to be surrounded by the first opening 131a, and the crystal oscillator 70 is positioned so as to be surrounded by the second opening 131b. Thus, the first opening 131a forms a space 103a for housing the oscillation circuit section 40, and the second opening 131b forms a space 103b for housing the crystal oscillator 70.

[0051] In this second embodiment, as in the first embodiment, the heat generated in the oscillating component 4 is suppressed from being dissipated to the outside, and the oscillating component 4 can be heated efficiently. In particular, in the second embodiment, the oscillation circuit section 40, which includes the heater section, is also surrounded by the second resin substrate 103, which has low thermal conductivity. As a result, the heat from the heater section is less likely to be dissipated to the outside, and the power consumption associated with heating the oscillating component 4 is further suppressed.

[0052] (Embodiments of this disclosure) A first embodiment of the present disclosure is a piezoelectric oscillator with a constant temperature bath, characterized by comprising: a flat first resin substrate; a second resin substrate having through holes; fixing pins for fixing the second resin substrate at predetermined intervals above the first resin substrate; a ceramic package mounted on the upper surface of the second resin substrate, covering the through holes; an IC chip mounted on the mounting surface of the ceramic package; a lid for sealing the IC chip within the ceramic package; a piezoelectric vibrator mounted on the lower surface of the ceramic package and located in the space surrounded by the side of the through holes and the ceramic package; a heater unit for heating the piezoelectric vibrator; and a cover that cooperates with the first resin substrate to surround the second resin substrate, the ceramic package, the piezoelectric vibrator, and the heater unit.

[0053] In this configuration, the first and second resin substrates, which have low thermal conductivity, are connected separated by fixing pins, and the ceramic package containing the IC chip, which has high thermal conductivity, is mounted on the second resin substrate. As a result, the ceramic package is mounted thermally separated from the first resin substrate, which suppresses the dissipation of heat generated by the heater to the outside, allowing the piezoelectric vibrator to be heated efficiently. Therefore, changes in output frequency due to changes in ambient temperature are suppressed, and better frequency stability can be achieved.

[0054] A second embodiment of the present disclosure is that, in the first embodiment, the piezoelectric vibrator has a thickness less than the thickness of the second resin substrate. This causes the piezoelectric vibrator to be surrounded by the second resin substrate, allowing the piezoelectric vibrator to be heated more efficiently.

[0055] A third embodiment of the present disclosure is that, in the first or second embodiment, the piezoelectric vibrator is mounted with the side opposite to the mounting surface on the ceramic package located in the space. This surrounds the piezoelectric vibrator with the second resin substrate, allowing the piezoelectric vibrator to be heated more efficiently.

[0056] A fourth embodiment of this disclosure is that, in any of the first to third embodiments, the IC chip incorporates the heater unit. This allows for effective use of space within the ceramic package, enabling miniaturization of the ceramic package. Furthermore, the heater unit can be brought closer to the piezoelectric vibrator, allowing the piezoelectric vibrator to be heated more efficiently.

[0057] A fifth embodiment of this disclosure is that, in any of the first to fourth embodiments, the fixing pin electrically connects the first circuit pattern formed on the first resin substrate and the second circuit pattern formed on the second resin substrate. This eliminates the need for a dedicated component to electrically connect the first circuit pattern and the second circuit pattern, thereby reducing the cost and miniaturizing the piezoelectric oscillator with a constant temperature bath.

[0058] A sixth embodiment of the present disclosure is that, in any of the first to fifth embodiments, the fixing pin includes at least one of cobalt, stainless steel, and titanium. This prevents heat from being conducted from the second resin substrate to the first resin substrate via the fixing pin, and allows the piezoelectric vibrator to be heated more efficiently.

[0059] A seventh embodiment of the present disclosure is that, in any of the first to sixth embodiments, the second resin substrate has a recess on its upper surface that communicates with the through hole in the direction of the through hole. As a result, the ceramic package containing the IC chip is also surrounded by the second resin substrate, which has low thermal conductivity, making it more difficult for heat from the heater to be dissipated to the outside, and further reducing the power consumption associated with heating the IC chip.

[0060] An eighth embodiment of this disclosure is that, in any of the first to seventh embodiments, the ceramic package is mounted in the recess. As a result, the ceramic package containing the IC chip is also surrounded by a second resin substrate with low thermal conductivity, making it more difficult for heat from the heater to be dissipated to the outside, and further reducing the power consumption associated with heating the IC chip. [Explanation of Symbols]

[0061] 1. Crystal oscillator with constant temperature bath (piezoelectric oscillator with constant temperature bath) 2. First resin substrate 3. Second resin substrate 4. Oscillator 5 Cover 6 Fixing pins 21 Through hole 22 External connection terminals 23 Circuit Pattern (First Circuit Pattern) 31 Through hole 32 Through holes 33 Circuit Pattern (Second Circuit Pattern) 41 IC packages (ceramic packages) 42 IC chips 43 Cover (Lid) 61 Locking part 70. Crystal oscillator (piezoelectric oscillator) 131 Through hole 131a First opening (recess) 131b 2nd opening

Claims

1. A flat first resin substrate, A second resin substrate having through holes, Above the first resin substrate, fixing pins are provided at predetermined intervals to secure the second resin substrate, On the upper surface of the second resin substrate, a ceramic package is mounted covering the through hole, An IC chip mounted on the mounting surface of the aforementioned ceramic package, A lid that seals the IC chip inside the ceramic package, A piezoelectric vibrator is mounted on the lower surface of the ceramic package and is located on the side of the through hole and in the space surrounded by the ceramic package, A heater section for heating the piezoelectric vibrator, A piezoelectric oscillator with a constant temperature bath, characterized by comprising a second resin substrate, a ceramic package, a piezoelectric vibrator, and a cover that cooperates with the first resin substrate to surround the heater portion.

2. The piezoelectric oscillator with a constant temperature bath according to claim 1, characterized in that the piezoelectric vibrator has a thickness smaller than the thickness of the second resin substrate.

3. The piezoelectric oscillator with a constant temperature bath according to claim 2, characterized in that the piezoelectric vibrator is mounted with the side opposite to the mounting surface of the ceramic package located in the space.

4. The piezoelectric oscillator with a constant temperature bath according to claim 1 or 2, characterized in that the IC chip incorporates the heater section.

5. The piezoelectric oscillator with a constant temperature bath according to claim 1 or 2, characterized in that the fixing pin electrically connects the first circuit pattern formed on the first resin substrate and the second circuit pattern formed on the second resin substrate.

6. The piezoelectric oscillator with a constant temperature bath according to claim 5, characterized in that the fixing pin includes at least one of cobalt, stainless steel, and titanium.

7. The piezoelectric oscillator with a constant temperature bath according to claim 1, characterized in that the second resin substrate has a recess on its upper surface that communicates with the through hole in the direction of the through hole.

8. The piezoelectric oscillator with a constant temperature bath according to claim 7, characterized in that the ceramic package is mounted in the recess.

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