JP4003290B2 - Support structure of piezoelectric vibrator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a piezoelectric device, and more particularly, to a support structure of a piezoelectric vibrator in a piezoelectric device of a type in which a circular piezoelectric vibrator is horizontally sealed on a metal base and hermetically sealed by a metal case. . More specifically, the present invention relates to a support structure for a piezoelectric vibrator that is excellent in impact resistance and vibration resistance and that can operate stably even in adverse environments.
[0002]
[Prior art]
Along with the rapid growth of the mobile communication market in recent years, communication devices are required to have strict specifications suitable for installation in a harsher environment. In addition, as the demand for miniaturization of measuring instruments increases, miniaturization and portability are progressing, and therefore, they are often used in harsh environments. Therefore, the piezoelectric device such as an oscillator or a vibrator as a reference frequency generation source used in these devices is required to have a performance capable of obtaining a stable frequency output even under an impact or vibration environment. Yes.
3A, 3B, and 3C are a perspective view, an essential configuration diagram, and a support configuration diagram of an example of a conventional piezoelectric device. The piezoelectric device is in an insulated state in the disk-shaped metal base 1. FIG. The three lead members 2 (input side), 3 (output side), 4 (dummy) that penetrate airtightly at the top, and the crank shape that extends upward with the lower ends fixed by the upper portions of the lead members 2, 3, 4 respectively. The three conductive supports 5, 6, 7 and the receiving surfaces 5 a, 6 a, 7 a of the supports 5, 6, 7 support the crystal base plate 8 at three points and the crystal base plate 8 (piezoelectric base plate) A circular piezoelectric vibrator (circular crystal vibrator) 11 having lead electrodes 9a and 10a respectively extending from the excitation electrodes 9 and 10 to the end edges, respectively, formed on both main surfaces, and the circular crystal vibrator 11. It comprises a metal case (not shown) that hermetically seals the space on the metal base 1.
Two of the three lead members 2, 3, 4, for example, reference numerals 2 and 3 are the input side and the output side, and the other one lead member 4 is a means (dummy) for supporting the support. . The supports 5, 6, and 7 are formed by forming a thin metal plate into a crank shape as shown in FIGS. 3 (b) and 3 (c).
[0003]
Each of the supports 5, 6, and 7 is formed by forming a thin metal plate into a crank shape as shown in FIGS. 3 (b) and 3 (c), and the main surface of the crystal base plate 8 on the receiving surfaces 5 a, 6 a, and 7 a. In a state where the side end surfaces (outer peripheral surfaces) of the quartz base plate 8 are closely supported by the front surfaces of the back plates 5b, 6b, 7b, and solder or along the side edges of the back plates 5b, 6b, 7b. It is fixed to the crystal unit 11 by applying a binder 15 such as a conductive adhesive. Specifically, each of the supports 5 and 6 connected to the electrically functioning lead members 2 and 3 is soldered or conductive with respect to each end portion of both lead electrodes 9a and 10a of the crystal resonator. While being electrically connected by a binder 15 such as an adhesive, it is also mechanically fixed to the quartz base plate 8 at the same time. Further, the support 7 connected to the lead member 4 that is not electrically functioning is mechanically connected and fixed to the end face of the crystal base plate by a binder 15.
The quartz crystal support structure in this type of piezoelectric device employs a three-point support structure, so even when impact forces or vibrations are added as external environmental factors compared to the two-point support structure, the frequency There is little distortion in the output, a stable frequency output can be obtained, and impact resistance and vibration resistance can be improved.
[0004]
By the way, when supporting the crystal resonator in the above-described type of piezoelectric device, a binder 15 is applied along both side edges of the support back plates 5b, 6b, 7b (shown in mesh pattern in FIG. 3 (c)). The reason is that applying a binder along only one side edge does not provide sufficient contact length between the side edge of the quartz base plate and the side edge of the back plate of the support. It is because it is difficult to obtain. The supports 5, 6, and 7 are formed by bending a thin metal plate into two cranks at 90 degrees, so that a certain amount of width and thickness are required to ensure the necessary rigidity. On the other hand, the wide width contributes to increasing the support stability of the quartz base plate. By using three such supports and supporting the crystal resonator at three points, the crystal resonator is supported on the base 1 in a stable state and outputs a stable frequency against external impact. Is possible. In order to secure a more stable frequency against external impact, the number of supports may be increased.
However, the wide support and wider contact area with the crystal unit, and the increased number of supports and wider contact area with the crystal unit, have the disadvantage of hindering free vibration of the crystal unit. This causes a problem that the required excitation amplitude cannot be obtained due to an increase in the amount of excitation energy leaked from the contact portion with the support. In addition, the presence of a total of 6 binders with 2 binders for each support leads to an increase in stress on the quartz base plate due to thermal changes, and this increase in stress increases over time, resulting in frequency fluctuations. Bring.
In addition, since the number of bent portions in the processing of the support increases, the support price increases, and the support is difficult to elastically deform, so that it is difficult to absorb and relax the stress applied to the crystal resonator, and the frequency stability against vibration and the like is reduced. . Further, there are a total of six fixing portions due to the conductive adhesive, which causes a problem of poor workability.
[0005]
Next, FIGS. 4A, 4B, and 4C are an overall perspective view, a main configuration diagram, and a configuration diagram of a support showing a support structure of a crystal resonator in another conventional piezoelectric device.
The difference between the conventional support structure and the type shown in FIG. 3 is that a substantially T-shaped thin metal plate is used as a support. The supports 20, 21, and 22 have bases 20 a, 21 a, and 22 a that are fixed to the upper ends of the lead members 2, 3, and 4, and curved inner surfaces that are in close contact with the side end surfaces (outer peripheral surfaces) of the crystal base plate 8. And wide connecting pieces 20b, 21b, and 22b. On the side end surfaces of the quartz base plate to which each of the connection pieces 20b, 21b, 22b is in contact, a metallized portion as an extended end of the lead electrodes 9a, 10a or a specially provided metallized portion is provided. Each metallized portion, the Au-Ge chip 23 and each of the connection pieces 20b, 21b, and 22b are bonded to each other by metal eutectic bonding by heating with a thin Au-Ge chip 23 interposed between 21b and 22b. It was stuck. However, since the surfaces of the supports 20, 21, and 22 are smooth, when an external impact is applied to the crystal resonator, peeling is likely to occur at the eutectic bonding surface with the Au—Ge chip. For this reason, the fixing strength is increased by increasing the area of each of the connection pieces 20b, 21b, 22b of the support to ensure a large fixing area with the crystal element side edge.
However, if the fixing area between the support and the edge of the crystal base plate is widened, the stress on the crystal unit that occurs with thermal and secular changes will increase, reducing the stability of the output frequency of the crystal unit. The problem occurs. Furthermore, when the number of supports is increased in order to improve the frequency stability against external shock, the fixing area of the entire support is increased, and similarly the stability of the output frequency of the crystal unit is lowered. Get up.
[0006]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to use a lightweight and simple structure support in a piezoelectric device having a support structure in which three outer peripheral edges of a circular crystal resonator are supported by three supports erected on a metal base. Accordingly, it is an object of the present invention to provide a support structure for a piezoelectric vibrator that can reduce the fixing area between the quartz vibrator and the quartz vibrator. More specifically, if the contact area with the crystal unit is increased by widening the support or increasing the number of supports, this will cause a problem that obstructs the free vibration of the crystal unit and leak from the contact part with the support. Although an increase in the amount of excitation energy causes a problem that a necessary excitation amplitude cannot be obtained, the present invention does not increase the contact area and the number of supports, so the above-described problem does not occur.
In addition, when the metallized portion on the outer periphery of the quartz crystal resonator and the supporter are bonded using an Au—Ge chip, there is a problem that the bonding strength is reduced and peeling is likely to occur. It also solves such problems.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, three lead members that penetrate the metal base in an airtight state in an insulated state, a support that is fixed to the upper part of each lead member and extends upward, and each support has an outer peripheral portion 3 A circular piezoelectric vibrator having a lead electrode that is point-supported and extends from excitation electrodes formed on both main surfaces of the piezoelectric element plate to the edge of the piezoelectric vibrator, and a metal base including the piezoelectric vibrator. A piezoelectric device comprising a metal case for hermetically sealing a space, wherein two of the supports are electrically connected at their upper ends to the ends of both lead electrodes of the piezoelectric vibrator. The support has a plate-like configuration in which a support piece obtained by cutting two parallel downwards from the center of the upper edge of the support is bent 90 degrees, and a crystal resonator is formed on the upper surface of the support piece. Lord of The back plate on the upper part of the support is brought into contact with the outer peripheral surface of the crystal unit while the support is supported, and a binder is injected into the void formed by bending the support piece to fix the back plate and the outer peripheral surface of the crystal unit. It is characterized by that.
In addition, three lead members that penetrate the metal base in an airtight state in an insulated state, a support that is fixed to the upper portion of each lead member and extends upward, and each support supports the outer periphery at three points. A circular piezoelectric vibrator having a lead electrode extending from an excitation electrode formed on each of the main surfaces to an edge of the piezoelectric vibrator, and a metal case for hermetically sealing a space on a metal base including the piezoelectric vibrator; Two of the supports are electrically connected to the ends of both lead electrodes of the piezoelectric vibrator, and each support is formed on the outer peripheral surface of the crystal vibrator. The support is fixed to the metallized part via Au-Ge metal, and the support has at least one through hole in a region in contact with the metallized part on the outer peripheral surface of the crystal resonator. Some of the metal is solidified intrudes into the through hole during the melting of Ge metal. In addition, three lead members that penetrate the metal base in an airtight state in an insulated state, a support that is fixed to the upper portion of each lead member and extends upward, and each support supports the outer periphery at three points. A circular piezoelectric vibrator having a lead electrode extending from an excitation electrode formed on each of the main surfaces to an edge of the piezoelectric vibrator, and a metal case for hermetically sealing a space on a metal base including the piezoelectric vibrator; Two of the supports are electrically connected to the ends of both lead electrodes of the piezoelectric vibrator, and each support is formed on the outer peripheral surface of the crystal vibrator. In the case where the support is fixed to the metallized portion via a binder, the support has at least one through hole in a region in contact with the metallized portion on the outer peripheral surface of the crystal unit. Some of the binder is solidified by entering into the through hole Toruji.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
1 (a), (b), (c), and (d) are a perspective view, a side view of a main part, and a support showing an internal configuration of a piezoelectric device including a crystal resonator having a three-point support structure according to an embodiment of the present invention. FIG. 2 is a perspective view of an example, and a front view of a joint portion, and this piezoelectric device includes three lead members 2 (input side) and 3 (output side) penetrating through a disk-shaped metal base 1 in an insulated state. 4 (dummy), three crank-shaped conductive supports 30, 31, 32 that are fixed at the lower ends by the upper portions of the lead members 2, 3, 4 and extend upward, and the supports 30, 31. , 32 support the crystal base plate 8 at three points, and lead electrodes 9a, 10a extending from the excitation electrodes 9, 10 respectively formed on both main surfaces of the crystal base plate 8 (piezoelectric base plate) to the edges. A vertical circular piezoelectric vibrator (circular crystal vibrator) 11 provided, and the circular crystal vibrator 1 1 and a metal case (not shown) that hermetically seals the space on the metal base 1 including the metal base 1.
Two of the three lead members 2, 3, 4, for example, reference numerals 2 and 3 are the input side and the output side, and the other one lead member 4 is a means (dummy) for supporting the support. .
The supports 30, 31, and 32 are configured by forming a thin metal plate as shown in FIGS. 1 (b) and 1 (c). A rectangular cut piece 36 having a predetermined width is provided by forming parallel cuts 35, and the rectangular piece 36 is bent 90 degrees to one side. The rectangular piece after bending becomes a supporting piece 36. While the lower end portion of each support is fixed to the upper end portion of each lead member 2, 3, 4, the main surface of the crystal unit 11 is closely supported and supported by the upper surface of the support piece 36 of each support upper end portion. The side end face (outer peripheral face) of the crystal unit 11 is contact-supported by the front face 37a of the back plate 37 located on both sides of the small piece 36. Further, as shown in FIG. 1 (d), the binder 38 is dropped once (injected) into the space between the two back plates 37, thereby fixing the crystal oscillator side end face and the support upper part. Yes.
Compared with the support of the conventional example shown in FIG. 3, the support of this embodiment has an apparently smaller area in contact with the crystal unit, so that the factors that obstruct the free vibration of the crystal unit are reduced. Since the amount of excitation energy leaking from the contact portion is reduced, a crystal resonator that outputs a necessary excitation level can be easily realized.
In addition, the binder is not dripped in two places along both sides of the conventional one support, but the joining is performed only by dropping once in the space located at the center of each support. As a result, the number of fixing points is halved and the joining work is facilitated.
In addition, since the support of this embodiment has few bending points, it is easy to process, the support price can be reduced, and the external shock can be absorbed and relaxed by elastic deformation of the support.
[0009]
2 (a), 2 (b) and 2 (c) are a perspective view showing an internal configuration of a piezoelectric device including a quartz resonator having a three-point support structure according to another embodiment of the present invention, a side view of an essential part, and an example of a support. The support 40 used in this embodiment is a rectangular metal plate having an inner surface shape that can be brought into close contact with the side end surface of the crystal unit 11, and each lead member 2, 3, 4 is fixed to the upper end of 4 and one or a plurality of through holes 41 are formed in the upper part. The through hole 41 is formed in a range in contact with the lead electrodes 9a, 10a or the metallized portion located on the side end surface of the crystal resonator 11, and the support upper portion where the through hole 41 is formed and the side end surface of the metallized crystal resonator. The Au-Ge chip 42 is heated in a state where the Au-Ge chip 42 is sandwiched between the two, so that the Au-Ge chip 42 is melted to join the two. Most of the molten Au—Ge chip 42 contributes to the bonding between the side end surface of the crystal resonator and the inner surface of the support, while a part of the molten Au—Ge metal is solidified while entering the through hole 41. Therefore, the eutectic bond between the Au—Ge metal and the support interface is not peeled off by the rivet effect of the Au—Ge metal.
According to this embodiment, since the bonding force using the Au-Ge metal is enhanced using the through hole, it becomes possible to reduce the bonding area of the support in contact with the crystal oscillator side end surface, It is possible to realize a piezoelectric device with high frequency stability against aging.
Even if the support stability is increased by increasing the number of supports, the bonding area between the crystal unit and the support is extremely small compared to the conventional example, so the stress applied to the crystal unit is minimized. It can be.
Moreover, since the support structure does not have a bent portion, elastic deformation is easy, and external shock can be absorbed and relaxed to improve the frequency stability of the crystal unit.
In the second embodiment, the support and the metallized portion may be joined using the binder (conductive adhesive, solder, etc.) used in the first embodiment instead of the Au—Ge metal. . Also in this case, a part of the binder is melted and enters the through hole, so that the joining is ensured.
[0010]
【The invention's effect】
As described above, according to the present invention, in a piezoelectric device having a support structure that supports three outer peripheral edges of a circular crystal resonator by three supports erected on a metal base, a lightweight and simple support is used. As a result, it is possible to reduce the fixed area between the quartz resonator and the quartz resonator.
More specifically, if the contact area with the crystal unit is increased by widening the support or increasing the number of supports, this will cause a problem that obstructs the free vibration of the crystal unit and leak from the contact part with the support. Although an increase in the amount of excitation energy causes a problem that a necessary excitation amplitude cannot be obtained, the present invention does not increase the contact area and the number of supports, and thus the above-described problem does not occur.
In addition, when the metallized portion on the outer periphery of the quartz crystal resonator and the supporter are bonded using an Au—Ge chip, there is a problem that the bonding strength is reduced and peeling is likely to occur. Such problems can be solved.
[Brief description of the drawings]
FIGS. 1 (a), (b), (c) and (d) are a perspective view and a side view of an essential part showing an internal configuration of a piezoelectric device including a crystal resonator having a three-point support structure according to an embodiment of the present invention. The perspective view of an example of a support, and the front view of a junction part.
FIGS. 2A, 2B and 2C are a perspective view showing an internal configuration of a piezoelectric device including a quartz resonator having a three-point support structure according to another embodiment of the present invention, a side view of a main part, and a support; FIG.
FIGS. 3A, 3B and 3C are a perspective view, a main part configuration diagram, and a support configuration diagram of an example of a conventional piezoelectric device.
FIGS. 4A, 4B, and 4C are an overall perspective view, a main configuration diagram, and a configuration diagram of a support showing a support structure of a crystal resonator in another conventional piezoelectric device.
[Explanation of symbols]
1 Metal base, 2, 3, 4 Lead member, 8 Crystal base plate, 9, 10 Excitation electrode, 9a, 10a Lead electrode, 11 Crystal resonator, 30, 31, 32 Support, 35 Notch, 36 Rectangular small piece, 37 Back Plate, 37a Front, 38 Binder, 40 Support, 41 Through hole.

Claims (1)

  Three lead members that penetrate the metal base in an airtight state in an insulated state, a support that is fixed to the top of each lead member and extends upward, and each support supports the outer peripheral portion at three points. A circular piezoelectric vibrator having a lead electrode extending from an excitation electrode formed on each surface to an edge of the piezoelectric vibrator, and a metal case for hermetically sealing a space on a metal base including the piezoelectric vibrator. A piezoelectric device, wherein two of the supports are electrically connected at their upper ends to the ends of both lead electrodes of the piezoelectric vibrator, and the support has a central portion at its upper edge. The support piece obtained by cutting two parallel downwards is formed into a plate-like structure bent 90 degrees, and the upper surface of the support is supported with the main surface of the crystal unit supported on the upper surface of the support piece. Back Of the piezoelectric vibrator characterized in that the back plate and the quartz crystal outer peripheral surface are fixed by injecting a binder into the space formed by bending the support piece and bending the support piece. Support structure.

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