Piezoelectric devices

Abstract

To provide piezoelectric devices that are versatile, suitable for various applications, and highly stable, while meeting the demands for miniaturization and improved reliability. [Solution] The package comprises a rectangular base plate in plan view, a wall portion provided along the edge of the base plate and whose height gradually increases toward the outer edge of the base plate, a first mounting terminal located on the upper surface of the base plate, and second and third mounting terminals located on the upper surface of the wall portion at different heights; a thermistor mounted on the first mounting terminal; a first piezoelectric vibrator mounted on the second mounting terminal and rectangular in plan view; and a second piezoelectric vibrator mounted on the third mounting terminal, rectangular in plan view and having a greater thickness than the first piezoelectric vibrator.

Description

Technical Field

[0005] , ,

[0001] The present disclosure relates to a piezoelectric device which is a passive element utilizing the piezoelectric effect.

Background Art

[0002] Piezoelectric devices are widely used in various electronic devices such as mobile phones and personal computers, mainly for frequency selection and control. Piezoelectric devices can be classified into piezoelectric vibrators, piezoelectric oscillators, SAW devices, optical devices, etc. according to their functions. Among them, crystal devices such as crystal oscillators and crystal oscillators using crystals as piezoelectric elements which are passive elements utilizing the piezoelectric effect are widely known and commonly used.

[0003] With the miniaturization and densification accompanying the miniaturization of recent electronic devices, the demand for miniaturization and reliability improvement of crystal devices has been increasing more and more. In order to meet such demands, it is known to use a so-called crystal oscillator with built-in thermistor in which a crystal vibrating piece and a thermistor are housed in one package. For example, Patent Document 1 discloses a vibration device (crystal oscillator) in which a crystal vibrating piece and a thermistor are housed in a package, and the frequency variation of the crystal vibrating piece is corrected based on the detection of the ambient temperature of the crystal vibrating piece by the thermistor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the aforementioned quartz oscillator, the change in the thermistor's resistance due to changes in the ambient temperature of the quartz crystal is converted into a change in voltage, which is then output to the temperature compensation circuit. The temperature compensation circuit then outputs a correction signal to the oscillation circuit based on this change in voltage, and the oscillation circuit applies a corrected drive signal to the quartz crystal based on this correction signal. As a result, in the aforementioned quartz oscillator, fluctuations in the resonant frequency of the quartz crystal due to changes in ambient temperature are corrected, and excellent frequency-temperature characteristics are obtained.

[0006] However, in the aforementioned quartz oscillator, one thermistor functions for each quartz crystal. Therefore, if an electronic device is to obtain multiple frequencies, it is necessary to implement multiple quartz oscillators. For example, if two frequencies are to be obtained, two quartz oscillators must be implemented. As a result, the number of components (number of quartz oscillators and thermistors) in the electronic device increases, making it difficult to adequately meet the demand for miniaturization.

[0007] This disclosure has been made in view of these challenges, and its purpose is to provide a piezoelectric device that is suitable for a variety of applications and has excellent stability, while also meeting the demands for miniaturization and improved reliability. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, a piezoelectric device is provided, comprising: a package having a rectangular base plate in plan view, a wall portion provided along the edge of the base plate and having a height that increases in stages toward the outer edge of the base plate, a first mounting terminal disposed on the upper surface of the base plate, and second and third mounting terminals disposed on the upper surface of the wall portion at different heights; a thermistor mounted on the first mounting terminal; a first piezoelectric vibrator mounted on the second mounting terminal and having a rectangular shape in plan view; and a second piezoelectric vibrator mounted on the third mounting terminal and having a rectangular shape in plan view and a greater thickness than the first piezoelectric vibrator. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide piezoelectric devices that are suitable for a variety of applications and have excellent stability, while also meeting the demands for miniaturization and improved reliability.

[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 quartz crystal oscillator according to the first embodiment. [Figure 2] Figure 2(a) is a top view showing the internal structure of the quartz crystal oscillator according to the first embodiment, and Figure 2(b) is a top view of the package of the quartz crystal oscillator according to the first embodiment. [Figure 3] Figure 3(a) is a bottom view of the crystal oscillator package according to the first embodiment, and Figure 3(b) is an end view along the dashed line AA in Figure 2(a). [Figure 4] Figure 4(a) is a top view of the crystal oscillator package according to the second embodiment, and Figure 4(b) is a bottom view of the crystal oscillator package according to the second embodiment. [Figure 5] This is an end view of a quartz crystal oscillator according to the second embodiment, similar to Figure 3(b). [Figure 6] Figure 6(a) is a top view of the crystal oscillator package according to a modified example of the second embodiment, and Figure 6(b) is a bottom view of the crystal oscillator package according to a modified example of the second embodiment. [Figure 7] This is an end view of a modified crystal oscillator according to the second embodiment, similar to Figure 3(b). [Modes for carrying out the invention]

[0012] The following describes in detail a quartz oscillator and its crystal oscillating element, which are examples of piezoelectric devices of this disclosure, with reference to the drawings. This disclosure is not limited to the content described below, and can be modified and implemented as long as the gist of the disclosure is not altered. Furthermore, the drawings used in each embodiment and modification schematically represent the quartz oscillator and crystal oscillating element of this disclosure, and may 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 and modification are examples only and can be changed as needed. Common components in the drawings are denoted by the same reference numerals.

[0013] The structure of the quartz crystal oscillator and quartz crystal oscillator according to this disclosure will be described with reference to Figures 1 to 3. Figure 1 is a perspective view of the quartz crystal oscillator according to this embodiment. Figure 2(a) is a top view showing the internal structure of the quartz crystal oscillator according to this embodiment, and Figure 2(b) is a top view of the package of the quartz crystal oscillator according to this embodiment. In particular, Figure 2(a) shows the quartz crystal oscillator with the cover removed, and Figure 2(b) shows the quartz crystal oscillator with both the cover and the quartz crystal oscillator removed. Furthermore, Figure 3(a) is a bottom view of the package of the quartz crystal oscillator according to this embodiment, and Figure 3(b) is an end view along the dashed line AA in Figure 2(a).

[0014] As can be seen from Figures 1 and 3(b), the crystal oscillator 1, an example of a piezoelectric device, comprises a crystal oscillator package 2 (hereinafter simply referred to as package 2), a first crystal oscillator 3, a second crystal oscillator 4, and a thermistor 5 mounted in the concave mounting space 2a of package 2, and a metal cover (lid) 6 for sealing the mounting space 2a. The crystal oscillator 1 is a piezoelectric element that can generate two constant frequencies due to the piezoelectric phenomenon by applying a voltage to the first crystal oscillator 3 and the second crystal oscillator 4, which are examples of piezoelectric oscillators.

[0015] Package 2 is a ceramic package formed by laminating multiple ceramics on which a desired metal pattern is formed on the surface. Specifically, Package 2 has a laminated structure in which a first wall 11, a second wall 12, and a third wall 13, which are embankment-shaped wall portions with openings of predetermined dimensions, and a rectangular bottom plate 14 in plan view are laminated. Specifically, the first wall 11 is provided along the edge of the bottom plate 14, the second wall 12 is provided along the edge of the first wall 11, and the third wall 13 is provided along the edge of the second wall 12. Furthermore, the opening of the second wall 12 is formed to be larger than the opening of the first wall 11, and the opening of the third wall 13 is formed to be larger than the opening of the second wall 12. In other words, Package 2 has wall portions formed by the first wall 11, the second wall 12, and the third wall 13, whose height increases in stages toward the outer edge of the bottom plate 14. Furthermore, this layered structure provides package 2 with a concave mounting space 2a for mounting the first quartz crystal 3, the second quartz crystal 4, and thermistor 5.

[0016] Here, the shape of package 2 is a rectangular parallelepiped, and in top view (Figure 2(a)), it is rectangular. In the following, the thickness direction of the crystal oscillator 1 and package 2 is defined as the vertical direction, and the direction perpendicular to this vertical direction is defined as the horizontal direction. Furthermore, the horizontal direction may be distinguished as the long side direction (long side direction) and the short side direction (short side direction) of the crystal oscillator 1 and package 2. In addition, for each component, 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.

[0017] A sealing conductor pattern 15 is formed on the upper surface of the third wall 13 of package 2. The planar shape of the conductor pattern 15 is frame-like, similar to the walls (first wall 11, second wall 12, and third wall 13). A cover 6 is then joined to the conductor pattern 15 by known metal bonding. This seals the mounting space 2a of the package, and the mounting space 2a is sealed using a vacuum or a gas such as nitrogen.

[0018] As can be seen from FIGS. 2(a), 2(b), 3(a) and 3(b), two second mounting terminals 16 and 17 for mounting the first crystal oscillator 3 are formed on the upper surface of the first wall 11 of the package 2. The first crystal oscillator 3 is mounted on the second mounting terminals 16 and 17 via conductive adhesives 23 and 24. Further, the second mounting terminals 16 and 17 are electrically connected to external connection terminals 29a and 30a provided on the lower surface of the bottom plate 14 via two connection wirings (custrations) provided on the side surfaces of the first wall 11 and the bottom plate 14. Here, only the connection wiring 30b is shown in FIG. 3(b). Note that the connection wiring may be provided inside the first wall 11 and the bottom plate 14.

[0019] As can be seen from FIGS. 2(a), 2(b), 3(a) and 3(b), two third mounting terminals 18 and 19 for mounting the second crystal oscillator 4 are formed on the upper surface of the second wall 12 of the package 2. The second crystal oscillator 4 is mounted on the third mounting terminals 18 and 19 via conductive adhesives 21 and 22. Further, the third mounting terminals 18 and 19 are electrically connected to external connection terminals 27a and 28a provided on the lower surface of the bottom plate 14 via connection wirings (custrations) 27b and 28b (see FIG. 1) provided on the side surfaces of the second wall 12, the first wall 11 and the bottom plate 14. Note that the connection wiring may be provided inside the second wall 12, the first wall 11 and the bottom plate 14.

[0020] Here, the second mounting terminals 16 and 17 and the third mounting terminals 18 and 19 are formed so as to be located at different heights in the vertical direction. Specifically, since the third mounting terminals 18 and 19 are formed on the upper surface of the second wall 12 and the second mounting terminals 16 and 17 are formed on the upper surface of the first wall 11, the third mounting terminals 18 and 19 are located at a higher position than the second mounting terminals 16 and 17. Thereby, it becomes possible to mount the first crystal oscillator 3 and the second crystal oscillator 4 so as to overlap each other, and space saving of the package 2 can be achieved.

[0021] Furthermore, the second mounting terminals 16 and 17 and the third mounting terminals 18 and 19 are formed to be located at different ends in the long-side direction of package 2. This allows for relatively simple connection to the external connection terminals 27a, 28a, 29a, and 30a.

[0022] As can be seen from Figures 2(a) and 3(b), the first quartz crystal vibrator 3 and the second quartz crystal vibrator 4 are formed in a rectangular shape when viewed from above. Furthermore, the first quartz crystal vibrator 3 and the second quartz crystal vibrator 4 are mounted so that their long and short sides are aligned with the long and short sides of the quartz crystal oscillator 1. In other words, the long sides of the first quartz crystal vibrator 3 and the second quartz crystal vibrator 4 coincide with the long sides of the quartz crystal oscillator 1, and the short sides of the first quartz crystal vibrator 3 and the second quartz crystal vibrator 4 also coincide with the short sides of the quartz crystal oscillator 1. Note that the type of cut from the quartz crystal rough for the first quartz crystal vibrator 3 and the second quartz crystal vibrator 4 is not limited to the AT cut, but may also be made by other cuts such as the Z cut or SC cut (two-turn cut).

[0023] The first crystal vibrator 3 and the second crystal vibrator 4 have different thicknesses in the vertical direction. Specifically, the thickness of the second crystal vibrator 4 is greater than that of the first crystal vibrator 3. That is, the second crystal vibrator 4 has a lower oscillation frequency than the first crystal vibrator 3. For example, the oscillation frequencies of the first crystal vibrator 3 and the second crystal vibrator 4 are 48 MHz for the first crystal vibrator 3 and 20 MHz for the second crystal vibrator 4. By mounting two rectangular crystal vibrators with different oscillation frequencies on a single crystal oscillator, it is possible to operate two electronic components or electronic circuits with different frequencies required by a single crystal oscillator, leading to an improvement in mounting density. Furthermore, by placing the thicker second crystal vibrator 4 above the first crystal vibrator 3, the mounting space 2a is not blocked, and heat accumulation (generation of temperature differences) in the mounting space 2a can be suppressed.

[0024] As can be seen from Figures 2(b), 3(a), and 3(b), two first mounting terminals 41 and 42 for mounting the thermistor 5 are formed on the upper surface of the bottom plate 14 of package 2. The thermistor 5 is mounted on the first mounting terminals 41 and 42 via conductive adhesives 43 and 44. The thermistor 5 is a temperature sensor that detects the temperature in the mounting space 2a of package 2 and performs temperature compensation by transmitting the detection signal to an IC chip (not shown). The first mounting terminals 41 and 42 are electrically connected to external connection terminals 31 and 32 provided on the lower surface of the bottom plate 14 via connection wiring 45 provided inside the bottom plate 14.

[0025] In the quartz oscillator 1, two quartz crystals, the first quartz crystal 3 and the second quartz crystal 4, are mounted in the package 2. Here, the thermistor 5 is provided in the mounting space 2a of the package, making it possible to detect the temperature more accurately. As a result, temperature compensation can be accurately performed in the quartz oscillator 1, leading to improved stability and reliability of the quartz oscillator 1.

[0026] As described above, in this embodiment, two rectangular crystal oscillators (first crystal oscillator 3 and second crystal oscillator 4) having different oscillation frequencies are mounted in a single package 2, and a configuration is adopted to suppress the occurrence of temperature differences between the first crystal oscillator 3 and the second crystal oscillator 4. This makes it possible to reduce the space and manufacturing cost of the crystal oscillator 1, while ensuring the stability and reliability of the crystal oscillator 1. Furthermore, by mounting a thermistor in the package 2, the stability and reliability of the crystal oscillator 1 can also be ensured from the standpoint of temperature compensation.

[0027] (Modification of the first embodiment) In the above embodiment, the thickness of the second crystal oscillator 4 was greater than that of the first crystal oscillator 3, and the oscillation frequency of the second crystal oscillator 4 was lower than that of the first crystal oscillator 3. However, the embodiment is not limited to this. Specifically, the thickness of the second crystal oscillator 4 may be smaller than that of the first crystal oscillator 3, and the oscillation frequency of the second crystal oscillator 4 may be higher than that of the first crystal oscillator 3. For example, the oscillation frequency of the second crystal oscillator 4 may be 48 MHz, and the oscillation frequency of the first crystal oscillator 3 may be 40 MHz. In other words, as long as the size and thickness of the first crystal oscillator 3 and the second crystal oscillator 4 do not cause heat buildup in the mounting space 2a of the package 2, the crystal oscillator 1 can function while ensuring stability and reliability.

[0028] In the above embodiment, the oscillation frequencies of the first crystal oscillator 3 and the second crystal oscillator 4 were different, but the first crystal oscillator 3 and the second crystal oscillator 4 may have the same oscillation frequency. In this case, even if the oscillation frequencies are the same, it is possible to implement two crystal oscillators with different temperature characteristics and electrical characteristics to match the required specifications of the electronic circuit by changing the type of crystal cut (cutting angle), etc., which leads to space saving and improved mounting density for the crystal oscillator 1.

[0029] In the above embodiment, the first crystal oscillator 3 and the second crystal oscillator 4 were mounted at different ends in the long-side direction of the package 2, but they may be mounted at the same end. In this case, the position of the connection wiring for connecting to the external connection terminal can be changed as appropriate.

[0030] (Second Embodiment) In the first embodiment, two quartz crystals, a first quartz crystal and a second quartz crystal, were used. However, the number of quartz crystals is not limited to this, and three or more quartz crystals may be used. Such a case will be described as the second embodiment with reference to Figures 4 and 5. Figure 4(a) is a top view of the package of the quartz crystal resonator 101 according to this embodiment, and Figure 4(b) is a bottom view of the package of the quartz crystal resonator 101 according to this embodiment. Figure 5 is an end view of the quartz crystal resonator 101 according to the second embodiment, shown in the same way as Figure 3(b). In this embodiment, the parts that differ from the first embodiment will be described in principle, and the description of the same parts will be omitted, and the same reference numerals will be used in the drawings.

[0031] As can be seen from Figures 4(a), 4(b), and 5, two fourth mounting terminals 161 and 162 for mounting the third crystal oscillator 107 are formed on the upper surface of the bottom plate 14 of the package 102. The third crystal oscillator 107 is mounted on the fourth mounting terminals 161 and 162 via conductive adhesives 147 and 148. The fourth mounting terminals 161 and 162 are also electrically connected to external connection terminals 151 and 152 provided on the lower surface of the bottom plate 14 via connection wiring 146 provided inside the bottom plate 14.

[0032] As can be seen from Figure 5, the third crystal oscillator 107 is formed in a rectangular shape in plan view. Furthermore, the third crystal oscillator 107 is mounted so that its long and short sides are aligned with the long and short sides of the crystal oscillator 101. In other words, the long side of the third crystal oscillator 107 coincides with the long side of the crystal oscillator 101, and the short side of the third crystal oscillator 107 also coincides with the short side of the crystal oscillator 101. Note that the mounting orientation of the third crystal oscillator 107 is not limited to the above, and the third crystal oscillator 107 may be mounted so that its long side coincides with the short side of the crystal oscillator 101, and its short side coincides with the long side of the crystal oscillator 101. In this case, the external connection terminals 151 and 152 may be positioned biased toward one of the long sides of the crystal oscillator 101.

[0033] The first crystal vibrator 3, the second crystal vibrator 4, and the third crystal vibrator 107 have different thicknesses in the vertical direction. Furthermore, the thickness of the second crystal vibrator 4 is formed to be greater than that of the first crystal vibrator 3. In other words, the second crystal vibrator 4 has a lower oscillation frequency than the first crystal vibrator 3. Examples of the oscillation frequencies of the first crystal vibrator 3, the second crystal vibrator 4, and the third crystal vibrator 107 are 40 MHz for the first crystal vibrator 3, 16 MHz for the second crystal vibrator 4, and 76.8 MHz for the third crystal vibrator 107. In this way, by mounting three rectangular crystal vibrators with different oscillation frequencies on a single crystal oscillator, it is possible to operate three electronic components or electronic circuits with different frequencies required by a single crystal oscillator, leading to an improvement in mounting density. Furthermore, by positioning the thicker second quartz crystal oscillating element 4 above the first quartz crystal oscillating element 3, the mounting space 2a is not blocked, and heat accumulation (generation of temperature differences) in the mounting space 2a can be suppressed.

[0034] Furthermore, other examples of the oscillation frequencies of the first crystal oscillator 3, the second crystal oscillator 4, and the third crystal oscillator 107 include 32 MHz for the first crystal oscillator 3, 16 MHz for the second crystal oscillator 4, and 48 MHz for the third crystal oscillator 107. By using three crystal oscillators in such a way that their oscillation frequencies are related to frequency multiplication and division, frequency multiplication and division circuits become unnecessary, thereby reducing the manufacturing cost of the electronic component.

[0035] Two first mounting terminals 141 and 142 for mounting the thermistor 5 are formed on the upper surface of the bottom plate 14 of the package 102. The thermistor 5 is mounted on the first mounting terminals 141 and 142 via conductive adhesives 43 and 44. The first mounting terminals 141 and 142 are also electrically connected to external connection terminals 131 and 132 provided on the lower surface of the bottom plate 14 via connection wiring 45 provided inside the bottom plate 14.

[0036] The thermistor 5 is mounted so that its short and long sides are aligned with the long and short sides of the crystal oscillator 101. In other words, the long side of the thermistor 5 coincides with the short side of the crystal oscillator 101, and the short side of the thermistor 5 also coincides with the long side of the crystal oscillator 101. However, the mounting orientation of the thermistor 5 is not limited to the above; the thermistor 5 may be mounted so that its long side coincides with the long side of the crystal oscillator 101, and its short side coincides with the short side of the crystal oscillator 101. In this case, the external connection terminals 131 and 132 may be positioned biased towards one of the long sides of the crystal oscillator 101.

[0037] As described above, in this embodiment, three rectangular quartz crystal oscillators (first quartz crystal oscillator 3, second quartz crystal oscillator 4, and third quartz crystal oscillator 107) having different oscillation frequencies are mounted in a single package 102, and a configuration is adopted to suppress the occurrence of temperature differences between the first quartz crystal oscillator 3 and the second and third quartz crystal oscillators 4 and 107. This makes it possible to further reduce the space and manufacturing cost of the quartz crystal oscillator 101, while ensuring the stability and reliability of the quartz crystal oscillator 101. In addition, by mounting the thermistor 5 in the package 102, the stability and reliability of the quartz crystal oscillator 101 can also be ensured from the standpoint of temperature compensation.

[0038] In this embodiment, three quartz crystals are used, but the number of quartz crystals mounted in the package 102 may be four or more. In this case, the number of mounting terminals for the quartz crystals, the number of external connection terminals, and the shape of the package wall will be adjusted as appropriate.

[0039] (Modified version of the second embodiment) In the second embodiment, a quartz oscillator having both three or more quartz crystals and a thermistor in the mounting space was described. However, the quartz oscillator may not have a thermistor and may simply have three or more quartz crystals in the mounting space. Such a case will be described as a modification of the second embodiment with reference to Figures 6 and 7. Figure 6(a) is a top view of the package 202 of the quartz oscillator 201 according to the modification of this embodiment, and Figure 6(b) is a bottom view of the package 202 of the quartz oscillator 201 according to the modification of this embodiment. Figure 7 is an end view of the quartz oscillator 201 according to the modification of this embodiment, shown in the same way as Figure 3(b). In this modification, the parts that differ from the first and second embodiments will be described in principle, and the description of the same parts will be omitted, and the same reference numerals will be used in the drawings.

[0040] As can be seen from Figures 6(a), 6(b), and 7, two fourth mounting terminals 261 and 262 for mounting the third crystal oscillator 207 are formed on the upper surface of the bottom plate 14 of the package 202. The third crystal oscillator 207 is mounted on the fourth mounting terminals 261 and 262 via conductive adhesives 247 and 248. The fourth mounting terminals 261 and 262 are also electrically connected to external connection terminals 251 and 252 provided on the lower surface of the bottom plate 14 via connection wiring 246 provided inside the bottom plate 14.

[0041] As can be seen from Figure 7, the third crystal oscillator 207 is formed in a rectangular shape in plan view. Furthermore, the third crystal oscillator 207 is mounted so that its long and short sides are aligned with the long and short sides of the crystal oscillator 201. In other words, the long side of the third crystal oscillator 207 coincides with the long side of the crystal oscillator 201, and the short side of the third crystal oscillator 207 also coincides with the short side of the crystal oscillator 201. Note that the mounting orientation of the third crystal oscillator 207 is not limited to the above, and the third crystal oscillator 207 may be mounted so that its long side coincides with the short side of the crystal oscillator 201, and its short side coincides with the long side of the crystal oscillator 201. In this case, the external connection terminals 251 and 252 may be positioned biased toward one of the long sides of the crystal oscillator 201.

[0042] Similar to the second embodiment, in this modified example, the first crystal diaphragm 3, the second crystal diaphragm 4, and the third crystal diaphragm 207 have different thicknesses in the vertical direction. Furthermore, the thickness of the second crystal diaphragm 4 is formed to be greater than that of the first crystal diaphragm 3. That is, the second crystal diaphragm 4 has a lower oscillation frequency than the first crystal diaphragm 3. Examples of the oscillation frequencies of the first crystal diaphragm 3, the second crystal diaphragm 4, and the third crystal diaphragm 207 are 40 MHz for the first crystal diaphragm 3, 16 MHz for the second crystal diaphragm 4, and 76.8 MHz for the third crystal diaphragm 207. In this way, by mounting three rectangular crystal diaphragms with different oscillation frequencies on a single crystal oscillator, it is possible to operate three electronic components or electronic circuits with different frequencies required by a single crystal oscillator, leading to an improvement in mounting density. Furthermore, by positioning the thicker second quartz crystal oscillating element 4 above the first quartz crystal oscillating element 3, the mounting space 2a is not blocked, and heat accumulation (generation of temperature differences) in the mounting space 2a can be suppressed.

[0043] Furthermore, other examples of the oscillation frequencies of the first crystal oscillator 3, the second crystal oscillator 4, and the third crystal oscillator 207 include 32 MHz for the first crystal oscillator 3, 16 MHz for the second crystal oscillator 4, and 48 MHz for the third crystal oscillator 107. By using three crystal oscillators in such a way that the three oscillation frequencies are related to frequency multiplication and division, frequency multiplication and division circuits become unnecessary, thereby reducing the manufacturing cost of the electronic component.

[0044] As described above, in this modified example, three rectangular crystal oscillators (first crystal oscillator 3, second crystal oscillator 4, and third crystal oscillator 207) having different oscillation frequencies are mounted in a single package 202, and a configuration is adopted to suppress the occurrence of temperature differences between the first crystal oscillator 3 and the second and third crystal oscillators 207. This makes it possible to further reduce the space required for the crystal oscillator 201 and the manufacturing cost, while also ensuring the stability and reliability of the crystal oscillator 201.

[0045] In this modified example, three quartz crystals are used, but the number of quartz crystals mounted in package 202 may be four or more. In this case, the number of mounting terminals for the quartz crystals, the number of external connection terminals, and the shape of the package wall will be adjusted as appropriate.

[0046] (Embodiments of this disclosure) A first embodiment of the present disclosure is a piezoelectric device characterized by comprising: a package having a rectangular base plate in plan view, a wall portion provided along the edge of the base plate and having a height that increases in stages toward the outer edge of the base plate, a first mounting terminal disposed on the upper surface of the base plate, and second and third mounting terminals disposed on the upper surface of the wall portion at different heights; a thermistor mounted on the first mounting terminal; a first piezoelectric vibrator mounted on the second mounting terminal and having a rectangular shape in plan view; and a second piezoelectric vibrator mounted on the third mounting terminal and having a rectangular shape in plan view and a greater thickness than the first piezoelectric vibrator. This allows for the mounting of two piezoelectric vibrators with different oscillation frequencies in a single package, thereby reducing the space required for the piezoelectric device and lowering manufacturing costs. Furthermore, it is possible to ensure the stability and reliability of the piezoelectric device from the viewpoint of temperature compensation.

[0047] A second embodiment of the present disclosure is that, in the first embodiment, the wall portion comprises a frame-shaped first wall provided along the edge of the bottom plate, a frame-shaped second wall provided along the edge of the first wall and having an opening larger than the opening of the first wall, exposing a portion of the upper surface of the first wall, and a frame-shaped third wall provided along the edge of the second wall and having an opening larger than the opening of the second wall, exposing a portion of the upper surface of the second wall. This makes it possible to mount two piezoelectric vibrators with different oscillation frequencies in a single package, thereby saving space and reducing manufacturing costs for the piezoelectric device.

[0048] A third embodiment of this disclosure is that, in the first or second embodiment, the second mounting terminal is located on the upper surface of the first wall, and the third mounting terminal is located on the upper surface of the second wall. This allows two piezoelectric vibrators with different oscillation frequencies to be mounted in a single package, thereby reducing the space required for the piezoelectric device and lowering manufacturing costs.

[0049] A fourth embodiment of this disclosure is that, in any of the first to third embodiments, the second mounting terminal and the third mounting terminal are provided at different ends in the long-side direction of the package. This allows for relatively simple connection to external connection terminals, which contributes to ensuring durability and reliability as a piezoelectric device.

[0050] A fifth embodiment of the present disclosure is, in any of the first to fourth embodiments, the package further comprises a fourth mounting terminal located on the upper surface of the bottom plate, wherein a third piezoelectric vibrator, which is rectangular in plan view, is mounted on the fourth mounting terminal. This allows three piezoelectric vibrators with different oscillation frequencies to be mounted in a single package, further reducing the space required for the piezoelectric device and further reducing manufacturing costs. [Explanation of Symbols]

[0051] 1. Crystal oscillator (piezoelectric device) 2. Package for crystal oscillator (package) 3. First crystal vibrator (first piezoelectric vibrator) 4. Second quartz crystal vibrator (second piezoelectric vibrator) 5 Thermistor 11 1st wall 12 Second wall 13 Third wall 14 Bottom plate 16,17 Second mounting terminal 18,19 Third mounting terminal 41,42 First mounting terminal 101 Crystal oscillator (piezoelectric device) 107 Third Quartz Crystal Vibrator (Third Piezoelectric Vibrator) 161,162 Fourth mounting terminal

Claims

1. A package comprising a rectangular base plate in plan view, a wall portion provided along the edge of the base plate and whose height gradually increases toward the outer edge of the base plate, a first mounting terminal located on the upper surface of the base plate, and second and third mounting terminals located on the upper surface of the wall portion at different heights, The thermistor mounted on the first mounting terminal, Mounted on the second mounting terminal is a first piezoelectric vibrator which is rectangular in shape when viewed from above, A piezoelectric device characterized by having a second piezoelectric vibrating piece mounted on the third mounting terminal, having a rectangular shape in plan view and having a greater thickness than the first piezoelectric vibrating piece.

2. The aforementioned wall portion is A frame-shaped first wall provided along the edge of the bottom plate, A frame-shaped second wall is provided along the edge of the first wall, has an opening larger than the opening of the first wall, and exposes a portion of the upper surface of the first wall. The piezoelectric device according to claim 1, characterized in that it comprises a frame-shaped third wall provided along the edge of the second wall, having an opening larger than the opening of the second wall, and exposing a portion of the upper surface of the second wall.

3. The second mounting terminal is located on the upper surface of the first wall, The piezoelectric device according to claim 2, characterized in that the third mounting terminal is located on the upper surface of the second wall.

4. The piezoelectric device according to claim 3, characterized in that the second mounting terminal and the third mounting terminal are provided at different ends of the package in the direction of the long side.

5. The package further comprises a fourth mounting terminal located on the upper surface of the bottom plate, The piezoelectric device according to claim 1, characterized in that a third piezoelectric vibrator, which is rectangular in shape when viewed from above, is mounted on the fourth mounting terminal.

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