JP2007180996A - Piezoelectric resonator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric resonator wherein the rigidity of glass packages can be strengthened by containing insulating whisker to the glass packages and no adverse effect is given onto a resonation characteristic of a piezoelectric resonator element without distorting the piezoelectric resonator element plate sandwiched between the packages even when stress is externally applied to the packages. <P>SOLUTION: The piezoelectric resonator 1 is provided, wherein the first package and the second package are combined in a form of sandwiching the piezoelectric resonator element between the packages and the first package, and the second package, and the piezoelectric resonator element are coupled with each other so that an internal space formed by first and second recessed parts is hermetically sealed, insulating whisker is contained in glass structures configuring the first and second packages 18, 20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In recent years, along with the remarkable miniaturization of devices such as mobile communication devices, further miniaturization of electronic components such as piezoelectric vibrators used in these devices is required. At present, piezoelectric vibrators having an outer size of 2.5 mm × 2.0 mm have become mainstream, and various piezoelectric vibrators having a size smaller than that have been developed. The piezoelectric vibration element mounted in the piezoelectric vibrator is provided on the front and back main surfaces of the piezoelectric element plate with an excitation electrode for exciting the piezoelectric element plate in a desired vibration mode and an insulating container for housing the piezoelectric element. An extraction electrode for connecting to various electrode pads to be formed is formed. As a piezoelectric vibration element shape, a square or rectangular flat plate shape which is advantageous for downsizing has become mainstream.

  As an example of the prior art, FIG. 3 shows the width of a piezoelectric vibrator that hermetically seals the vibration region of the piezoelectric vibration element in a form in which the outer peripheral portion of the piezoelectric vibration element on which various electrodes are formed is sandwiched and fixed by a glass insulating container body. It is sectional drawing of a direction. That is, the piezoelectric vibrator 30 has container bodies 32 and 33 bonded to the upper and lower sides of the piezoelectric vibration element 31, respectively, and two containers on the side surfaces in the thickness direction of the bonded container bodies 32 and 33 and the piezoelectric vibration element. External connection electrode terminals 34 extending to the main body surface are formed. Excitation electrodes 35 are formed on both the front and back main surfaces of the piezoelectric vibration element 31. The container body has recesses 36 and 37 on the surface facing the piezoelectric vibration element so as not to disturb the resonance vibration of the piezoelectric vibration element. Is formed.

The piezoelectric vibrator as described above is disclosed in the following prior art documents.
JP 2003-142748 A JP 2001-244775 A

  In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

  However, in the piezoelectric vibrator having the above-described form, glass made of hard and brittle material is used for the container body that sandwiches the piezoelectric vibration element. Therefore, when stress is applied from the outside, even if the stress is very small, The piezoelectric vibration element sandwiched between the container bodies may be distorted, which may adversely affect the vibration characteristics of the piezoelectric vibration element. In addition, when momentary external stress such as drop impact is applied to the container body, the container body formed of only a hard and brittle material such as glass tends to cause chipping or cracks in the container body. The airtightness may be destroyed, and the vibration characteristics of the piezoelectric vibration element may be deteriorated.

The present invention has been made in order to solve the above-mentioned problems. An excitation electrode is provided at the approximate center of the front and back main surfaces of a flat plate-shaped piezoelectric element plate, and the piezoelectric element plate is formed from each excitation electrode. To one corner of the two opposing edges, an extraction electrode drawn on the same main surface as each excitation electrode and one corner of the two opposing edges of the piezoelectric element plate A piezoelectric vibration element having a container connection electrode that is electrically connected to the extraction electrode;
A first recess having a shape in which the excitation electrode is located in the opening is formed on a main surface facing the piezoelectric vibration element, and the first contour is glass having the same contour shape as the piezoelectric vibration element. A container body;
An external connection electrode terminal having a second concave portion in which the excitation electrode is located in the opening on one main surface facing the piezoelectric vibration element and including a ground electrode terminal on the other main surface And a predetermined terminal of the external connection electrode terminals is electrically connected to the container body connection electrode formed on the piezoelectric vibration element. And the second container body,
The first container body and the second container body are combined with the piezoelectric vibration element sandwiched therebetween, and the first space is formed so that the internal space formed by the first recess and the second recess is airtight. In the piezoelectric vibrator formed by mutually bonding the container body, the second container body, and the piezoelectric vibration element,
The piezoelectric vibrator is characterized in that an insulating whisker is contained in a glass structure constituting the first container body and the second container body.

  The piezoelectric vibrator according to the preceding paragraph, wherein the insulating whisker is an aluminum borate whisker.

  From the piezoelectric vibrator of the present invention to which the above means is applied, the glass container constituting the piezoelectric vibrator contains insulating whiskers, particularly aluminum borate whiskers. It can be strengthened compared to the configuration, and even when stress is applied from the outside, the piezoelectric vibration element sandwiched between these container bodies is significantly less distorted, adversely affecting the vibration characteristics of the piezoelectric vibration element. Will not affect. In addition, even when instantaneous external stress such as a drop impact is applied to the container body, it is possible to prevent the container body from being broken or cracked, and the vibration characteristics of the piezoelectric vibration element can be maintained as good. .

  With such an action, the present invention has an effect of providing a piezoelectric vibrator having excellent stress resistance and impact resistance and excellent frequency characteristics.

Embodiments of a piezoelectric vibrator according to the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic exploded perspective view illustrating an embodiment of a piezoelectric vibrator according to the present invention by using a quartz crystal vibrator which is one form of the piezoelectric vibrator. FIG. 2 is a schematic cross-sectional view when the crystal resonator shown in FIG. 1 is assembled and then cut along a virtual cutting line A1-A2 shown in FIG. In addition, the same code | symbol in each figure shall show the same object. In each of the drawings, a part of the structure is not shown, and some dimensions are exaggerated for clarity. In particular, the thickness dimension of each part is exaggerated.

  That is, in FIGS. 1 and 2, on both main surfaces of the rectangular thin plate-shaped crystal base plate 11, the substantially rectangular excitation electrode 12 is opposed to the main surface at the substantially center of the crystal base plate 11. In addition, an extraction electrode 13 is formed by extending from the excitation electrode 12 on each of the main surfaces of the front and back surfaces to the short side direction of a different quartz base plate for each main surface, Further, a quartz crystal vibration in which a container body connection electrode 14 electrically connected to each extraction electrode 13 is formed at one corner of the short side of the quartz base plate 11 in which each extraction electrode 13 extends. An element 10 is prepared.

  Each container body connection electrode 14 electrically connected to each extraction electrode 13 formed on both main surfaces is at least on the main surface on the side facing the second container body to be described later in the crystal resonator element 10. The excitation electrode 12 and the extraction electrode 13 formed on the side facing the first container body, which will be described later, are electrically connected by a conduction means such as a conduction through hole 15 penetrating the quartz base plate 11. Is secured. Further, the crystal element plate 11 constituting the crystal resonator element 10 is cut out from the artificial crystal at a desired cut angle and processed to have an outer shape, for example, a so-called AT cut angle crystal element plate and a thickness-shearing fundamental wave vibration mode. When a vibration in the vicinity of 300 MHz is obtained, the thickness of the quartz base plate 11 constituting the quartz resonator element 10 is processed to about 5.5 μm.

  In addition, a first concave portion 17 having a configuration in which the excitation electrode 12 is positioned in the opening when combined with the crystal resonator element 10 is formed on the main surface facing the crystal resonator element 10. A first container body 18 having a glass with the same contour shape as a main formation is prepared. The glass structure constituting the first container body 18 contains insulating aluminum borate whiskers. Thus, by including the aluminum borate whisker in the glass structure constituting the first container body 18, it is possible to reinforce its rigidity as compared with a single glass container body.

  Further, a second recess 20 having a shape in which the excitation electrode 12 is positioned in the opening when combined with the crystal resonator element 10 is formed on one main surface facing the crystal resonator element 10, and the other main surface. An external connection electrode terminal 21 including a ground electrode terminal is formed on the surface, and a predetermined terminal of the external connection electrode terminal 21 is electrically connected to the container body connection electrode 14 formed on the crystal resonator element 10. A second container body 22 is prepared which is mainly connected to glass having the same contour shape as that of the crystal resonator element 10 to be connected. Insulating aluminum borate whiskers are also contained in the glass structure constituting the second container body 22 in the same manner as the first container body 18. Thus, by including the aluminum borate whisker in the glass structure constituting the second container body, it is possible to reinforce its rigidity as compared with a single glass container body. The electrical connection between the external connection electrode terminal 21 and the container body connection electrode 14 of the crystal resonator element 10 is made by a conductive through hole 23 formed in the second container body 22. .

  The quartz resonator element 10, the first container body 18, and the second container body 22 having such a configuration are the first concave portion 17 opening of the first container body 18 and the second container body 22. The conductive through-hole 23 formed in the second container body 22 has a configuration in which the opening of the recess 20 faces the crystal vibration element 10 and sandwiches the crystal vibration element 10 therebetween, and the container body of the piezoelectric vibration element The side wall portion top surface that is combined at a position where it is electrically connected to the connection electrode 14 and surrounds the first recess 17 in the first container body 18, and the side wall that surrounds the second recess 20 in the second container body 22. The top surface of the part and the front and back main surfaces of the crystal resonator element 10 are directly bonded to form the crystal unit 1.

  By this bonding, an internal space formed by the first concave portion 17 and the second concave portion 20 and the crystal resonator element 10 and including a part of the excitation electrode 12 and the extraction electrode 13 is formed in an airtight manner. The When the second container body 22 is joined to the crystal resonator element 10, the excitation electrode 11 of the crystal resonator element 10 and a predetermined electrode terminal among the external connection electrode terminals 21 of the second container body 22 Are electrically connected by a conduction through hole 23 formed inside the second container body 22.

  Forming the piezoelectric resonator element 10 between the first container body 18 and the second container body 22 whose rigidity is enhanced by forming the crystal resonator 1 having the above-described form and containing insulating whiskers. For this reason, even when stress is applied from the outside of the crystal resonator, the crystal resonator element 10 sandwiched between the container bodies is significantly distorted, and the vibration characteristics of the crystal resonator element 10 are adversely affected. Absent. In addition, even when instantaneous external stress such as a drop impact is applied to the container body, it is possible to prevent the container body from being broken or cracked, and the vibration characteristics of the crystal resonator element 10 can be maintained as good. is there.

  In addition, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention. For example, in the above embodiment, a quartz crystal resonator using quartz as the material of the piezoelectric element plate is illustrated, but the present invention is not limited to the material disclosed in the embodiment, and other than that, lithium tantalate, lithium niobate Alternatively, the present invention is effective even when piezoelectric ceramics are used. In addition, when crystal is used as the material of the piezoelectric element plate, the method for forming the crystal element plate is not only the grinding and polishing process described above, but also a crystal element plate formed by CVD (Chemical Vapor Deposition). good. Further, the insulating whisker is not limited to the above-described aluminum borate whisker, and any other insulating whisker may be used as long as the same effect as that of the present invention is achieved.

  Furthermore, in the above-described example, the main material of the container body constituting the crystal unit is disclosed as glass. However, a form equivalent to the above-described embodiment (including insulating whiskers) is possible, and an external The glass is not limited to the above-described glass as long as it is a substance that relieves stress from and does not disturb the vibration characteristics of the internal vibration element. For example, by using the same crystal material as the material for forming the crystal resonator element 10 (further formed with the same cut angle), it is possible to fix the bonded portion at the time of heating due to the difference in coefficient of thermal expansion between the crystal resonator element 10 and the container body. Generation of the generated thermal stress can be suppressed, and deterioration of various characteristics of the crystal resonator due to the stress can be prevented.

FIG. 1 is a schematic exploded perspective view illustrating an embodiment of a piezoelectric vibrator according to the present invention, which is exemplified by a quartz crystal vibrator that is one form of a piezoelectric vibrator. FIG. 2 is a schematic cross-sectional view when the crystal resonator shown in FIG. 1 is assembled and cut along a virtual cutting line A1-A2 shown in FIG. FIG. 3 is a cross-sectional view showing an embodiment of a conventional piezoelectric vibrator.

Explanation of symbols

1 ... Piezoelectric vibrator (quartz crystal vibrator)
10 ... Piezoelectric vibration element (crystal vibration element)
11 ... Piezoelectric element (crystal element)
DESCRIPTION OF SYMBOLS 12 ... Electrode for excitation 13 ... Extraction electrode 14 ... Electrode for container body connection 15, 23 ... Conduction through hole 17 ... 1st recessed part 18 ... 1st container body 20. ..Second recess 21 ... External connection electrode terminal 22 ... Second container

Claims (2)

An excitation electrode at the approximate center of the front and back main surfaces of the flat plate-shaped piezoelectric element plate, and from each of the excitation electrodes toward one corner of the two opposite edges of the piezoelectric element plate, Each of the excitation electrodes has an extraction electrode drawn out on the same main surface, and a container body connection electrode electrically connected to the extraction electrode at one corner of two opposing edge portions of the piezoelectric element plate A piezoelectric vibration element;
A first recess having a shape in which the excitation electrode is located in the opening is formed on a main surface facing the piezoelectric vibration element, and the first contour is glass having the same contour shape as the piezoelectric vibration element. A container body,
An external connection electrode terminal having a second concave portion in which the excitation electrode is positioned in the opening is formed on one main surface facing the piezoelectric vibration element, and includes a ground electrode terminal on the other main surface. A glass having the same contour shape as that of the piezoelectric vibration element, wherein a predetermined terminal of the external connection electrode terminals is electrically connected to the container body connection electrode formed on the piezoelectric vibration element. A second container body as a main formation,
The first container body and the second container body are combined in a form sandwiching the piezoelectric vibration element, and the internal space formed by the first recess and the second recess is airtight. In the piezoelectric vibrator formed by joining the first container body, the second container body and the piezoelectric vibration element to each other,
An insulating whisker is contained in a glass structure constituting the first container body and the second container body.   2. The piezoelectric vibrator according to claim 1, wherein the insulating whiskers are aluminum borate whiskers.

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