JP2019165358A - Dual tuning fork type piezoelectric vibration chip - Google Patents

Abstract

To provide a dual tuning fork type piezoelectric vibration chip capable of reducing a CI value and ensuring intensity.SOLUTION: A dual tuning fork type piezoelectric vibration chip 10 has a form that an opening end side of a vibration arm part in the dual tuning fork type piezoelectric vibration chip is connected, and is formed by a piezoelectric vibration chip such as a crystal. The dual tuning fork type piezoelectric vibration chip 10 forms middle bank parts 45 and 55 between outer bank parts 43 and 53 on an outer surface side and inner bank parts 44 and 54 on an inner surface side by providing outer grooves 41 and 51 and inner grooves 42 and 52 on both main surfaces to each of a pair of vibration arm parts 40 and 50. According to an embodiment, as mentioned above, an electric field is distributed in a depth in a thickness direction by forming each groove, and a CI value can be reduced, and by forming outer grooves and inner grooves as the grooves and the middle bank parts between both grooves, an intensity of the dual tuning fork type piezoelectric vibration chip 10 can be secured.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a double tuning fork type piezoelectric vibrating piece, and more particularly to a double tuning fork type piezoelectric vibrating piece having a groove formed in a longitudinal direction.

The double tuning fork type piezoelectric vibrating piece is used in various devices such as a diaphragm as an element capable of detecting a deformation caused by an external force by a change in frequency.
In this double tuning fork type piezoelectric vibrating piece, a pair of parallel vibrating arm portions are disposed between two opposing base portions, and two different excitation electrodes are respectively provided in three vibrating regions on the vibrating arm portion. It is formed (Patent Document 1).

FIG. 6 shows a cross section of both vibrating arm portions of the double tuning fork type piezoelectric vibrating piece proposed in Patent Document 1. As shown in FIG.
In the technique described in Patent Document 1, as shown in FIG. 6, longitudinal grooves 410 and 510 are provided on both main surfaces of the vibrating arm portions 400 and 500 to form an H-shaped cross section.
As described above, the cross-sectional shape is H-shaped, and the excitation electrode on the main surface side is formed inside the groove, whereby the electric field is distributed deeply, thereby improving the electric field efficiency and reducing the CI value (crystal impedance). It is suitable for downsizing.

However, since the double tuning fork type piezoelectric vibrating piece detects a change in frequency with respect to a tensile or compressive stress, not only the original vibration but also an external stress is applied to the vibrating arm portion.
For this reason, in the technique described in Patent Document 1 in which the cross-sectional shape of the vibrating arm portion is H-shaped, the strength of the vibrating arm portion may be reduced and may be broken due to vibration or external stress.

JP 2014-42242 A

  An object of the present invention is to provide a double tuning fork type piezoelectric vibrating piece capable of reducing CI value and ensuring strength.

(1) In the invention described in claim 1, a pair of base portions and a pair of vibration regions extending between the base portions and having three vibration regions between one base portion and the other base portion. A pair of vibrating arms, a longitudinal groove formed on both opposing principal surfaces in each of the three vibrating regions of the pair of vibrating arms, and the pair of vibrating arms from the pair of bases The first electrode integrally formed over the portion and the first electrode are electrically separated from each other and formed integrally from the pair of base portions to the pair of vibrating arm portions, A second electrode that vibrates the three vibration regions together with one electrode, and at least one of the grooves formed at the three positions includes two parallel grooves. A double tuning fork type piezoelectric vibrating piece is provided.
(2) In the invention according to claim 2, the two parallel grooves are formed to have the same width, and the center line in the longitudinal direction of the middle bank portion formed between the two grooves is the vibrating arm. The double tuning fork type piezoelectric vibrating piece according to claim 1, wherein the double tuning fork type piezoelectric vibrating piece coincides with a longitudinal center line of the portion.
(3) In the invention according to claim 3, when the width of the inner bank portion is L3, the width of the groove is L2, and the width of the outer bank portion between the outer side surface of the vibrating arm portion and the groove is L1 Furthermore, the double tuning fork type piezoelectric vibrating piece according to claim 1 or 2, wherein L1>L2> L3 is provided.
(4) In the invention according to claim 4, when the width of the inner bank portion is L3, the width of the groove is L2, and the width of the outer bank portion between the outer side surface of the vibrating arm portion and the groove is L1 Further, the double tuning fork type piezoelectric vibrating piece according to claim 1 or 2, wherein L3> L1 is provided.
(5) In the invention described in claim 5, the two parallel grooves are formed in each of the three vibration regions, and any one of claims 1 to 4 A double tuning fork type piezoelectric vibrating piece according to claim 1 is provided.
(6) In the invention described in claim 6, among the three vibration regions, one groove is formed in the two vibration regions on the pair of base portions, and in the central vibration region, 5. The double tuning fork type piezoelectric vibrating piece according to any one of claims 1 to 4, wherein two grooves are formed.
(7) In the invention according to claim 7, two grooves are formed in at least one vibration region of the two vibration regions on the pair of base portions of the three vibration regions. The double tuning fork type piezoelectric vibrating piece according to any one of claims 1 to 4, wherein the double tuning fork type piezoelectric vibrating piece is formed, wherein one groove is formed in another vibration region. provide.

  According to the present invention, at least one of the longitudinal grooves formed in each of the three vibration regions of the vibrating arm portion includes two parallel grooves, and the inner bank portion is formed between the grooves. Therefore, the CI value can be reduced and the strength can be secured.

It is a figure showing the appearance perspective state and section of a double tuning fork type piezoelectric vibrating piece. It is explanatory drawing showing the electrode arrangement | positioning formed in the double tuning fork type piezoelectric vibrating piece. It is sectional drawing in each vibration area | region in a double tuning fork type piezoelectric vibrating piece. It is explanatory drawing about the modification of a double tuning fork type piezoelectric vibrating piece. It is explanatory drawing about the other modification of a double tuning fork type piezoelectric vibrating piece. It is sectional drawing of the vibration area | region in the conventional double tuning fork type piezoelectric vibrating piece.

Hereinafter, preferred embodiments of the double tuning fork type piezoelectric vibrating piece of the present invention will be described in detail with reference to FIGS. 1 to 5.
(1) Outline of Embodiment The double tuning fork type piezoelectric vibrating piece 10 of this embodiment has a shape in which the open ends of the vibrating arm portions of two tuning fork type piezoelectric vibrating pieces are connected, and piezoelectric vibration such as quartz crystal. It is formed with a piece.
The double tuning fork type piezoelectric vibrating piece 10 is provided with outer grooves 41, 51 and inner grooves 42, 52 on both main surfaces for each of the pair of vibrating arm portions 40, 50, so that the outer bank on the outer surface side is provided. Middle bank portions 45 and 55 are formed between the portions 43 and 53 and the inner bank portions 44 and 54 on the inner surface side.
Thus, according to the present embodiment, the electric field is deeply distributed in the thickness direction due to the formation of the groove, and the CI value can be reduced.
And in this embodiment, the strength of the double tuning fork type piezoelectric vibrating piece 10 can be ensured by forming the outer groove and the inner groove as the grooves and forming the inner bank portion between the grooves. .

(2) Details of Embodiment FIG. 1 is a perspective view (a) showing an external shape of a double tuning fork type piezoelectric vibrating piece 10 and an AA sectional view (b). In FIG. 1, electrodes formed on the surface will be described later, and are omitted in order to avoid complication of the drawing.
As shown in FIG. 1, the double tuning fork type piezoelectric vibrating piece 10 of the present embodiment is made of quartz, and has two base portions 20, 30 facing each other and a pair of vibrating arm portions connected to both the base portions 20, 30. 40 and 50 are provided.
The vibrating arm portions 40 and 50 are formed with three vibration regions including a vibration region 60a, a vibration region 60b, and a vibration region 60c in the direction from the base 20 toward the base 30.
In the following description, when one of the three vibration regions is specified and described, a description will be given by adding a to c as a vibration region 60a, a vibration region 60b, and a vibration region 60c. The contents common to each vibration region will be described by omitting the symbols a to c, such as each vibration region 60. Similarly, each part formed in the vibration region 60 is, for example, outer grooves 41a to 41c in the case of representing each corresponding to the vibration regions 60a to 60c, and the outer groove 41 for common contents. Let's represent.

Outer grooves 41 and 51 and inner grooves 42 and 52 having the same width and the same length are formed in each vibration region 60 on both opposing main surfaces of the vibrating arm portions 40 and 50.
Thereby, as shown in FIG. 1B, outer bank portions 43 and 53 are formed between the outer side surfaces of the vibrating arm portions 40 and 50 and the outer grooves 41 and 51, and the inner side surfaces and the inner grooves 42 and 52 are Inner bank portions 44 and 54 are formed between them.
Further, middle bank portions 45 and 55 are formed between the outer grooves 41 and 51 and the inner grooves 42 and 52.
The outer grooves 41, 51 and the inner grooves 42, 52 are formed at equal intervals from the center line in a direction orthogonal to the axial center line of the vibrating arm portions 40, 50. It is formed on the center line.

Here, the width of each bank and the groove will be described. As shown in FIG. 1B, the cross-sectional shapes of the vibrating arm portion 40 and the vibrating arm portion 50 are the same, the width of the outer bank portion 43 and the inner bank portion 44, and the width of the outer groove 41 and the inner groove 42. Are the same.
Now, as shown in FIG. 1B, the width of the outer bank portion 43 is L1, the width of the outer groove 41 is L2, and the width of the middle bank portion 45 is L3.
In this embodiment, it is formed so that L1>L2> L3.
On the other hand, the strength can be further increased by setting L3> L1. In this case, L3>L1> L2 may be satisfied by narrowing the groove width L2 as compared to the embodiment, and L3>L2> L1 may be satisfied by narrowing the outer bank portion and the inner bank portion. It is good also as L3>L2> = L1 by narrowing both groove width L2, an outer bank part, and an inner bank part.
However, as described later, the minimum width of the outer bank portions 43 and 53 and the inner bank portions 44 and 54 is required to be larger than the minimum width that divides the main electrode by leaving the excitation electrode 91 and the excitation electrode 92. It is.
Further, the minimum groove width of the groove width L3 is a width that can be processed, and a width that is larger than a width that can form the excitation electrodes 91 and 92 in the groove is required. For the first electrode 91 and the second electrode 92, electrode films are formed by, for example, electrode sputtering. The entire groove may be filled with electrodes.

  In this embodiment, the upper surfaces of the middle bank portions 45 and 55 are formed on the same plane (main surface) as the upper surfaces of the outer bank portions 43 and 53 and the inner bank portions 44 and 54. 55 may be formed lower than the main surface.

Next, the electrodes formed on the double tuning fork type piezoelectric vibrating piece 10 will be described.
FIG. 2 is a perspective view of the double tuning fork type piezoelectric vibrating piece 10 showing the arrangement state of the first electrode 91 and the second electrode 92. In FIG. 2, the outer grooves 41 and 51 and the inner grooves 42 and 52 are not shown in order to clarify the wiring state.
3A and 3B are cross-sectional views in a plane orthogonal to the longitudinal direction of the double tuning fork type piezoelectric vibrating piece 10, where FIG. 3A shows the AA cross section in FIG. 2 and FIG. 3B shows the BB cross section. The CC cross section in FIG. 2 is omitted because it is the same as the AA cross section.

As shown in FIG. 2, on the outer surfaces (outer peripheral surfaces) of the base portions 20 and 30 and the vibrating arm portions 40 and 50 of the double tuning fork type piezoelectric vibrating piece 10, a pair (two systems) of first electrodes 91 and A second electrode 92 is formed.
The first electrode 91 and the second electrode 92 vibrate at a predetermined frequency in the direction of approaching or separating the vibrating arm portions 40 and 50 for each of the vibration region 60a, the vibration region 60b, and the vibration region 60c by applying a voltage. It is an electrode for making it.
Each of the first electrode 91 and the second electrode 92 is integrally (electrically) connected as a whole, and the first electrode 91 and the second electrode 92 are electrically disconnected from each other. 40 and 50 are formed by patterning.

The first electrode 91 and the second electrode 92 are formed by mounting electrodes 91m and 92m formed on the base 20 and excitation electrodes 91 and 92 formed in the three regions of the vibrating arm portions 40 and 50, respectively. The connection electrodes 91 and 92 are connected.
The mount electrode 91m and the mount electrode 92m are electrodes connected to each of the two external electrodes when the double tuning fork type piezoelectric vibrating piece 10 is installed, and are formed on one main surface of the base portion 20.

One of the excitation electrode 91 and the excitation electrode 92 is disposed opposite to both main surfaces with respect to the vibration arm portion 40, and the other is disposed opposite to both side surfaces (outer surface and inner surface), so that the vibration arm portion 40. The vibrating arm portion 50 is vibrated by arranging one of the vibrating arm portions 50 to face both side surfaces and the other of the vibrating arm portions 50 to face both main surfaces.
The excitation electrodes 91 and 92 are formed such that the length in the longitudinal direction is at least longer than the entire length of the outer grooves 41 and 51 and the inner grooves 42 and 52.
As shown in FIG. 3, the excitation electrode 91 and the excitation electrode 92 formed on both main surfaces of the vibrating arm portions 40 and 50 are also formed in the grooves of the outer groove 41 and the inner groove 42 (the groove side surface and the groove bottom surface). Has been.
On the other hand, the excitation electrodes 91 formed on both side surfaces of the vibrating arm portion 50 are also formed on the main surfaces of the outer bank portions 43 and 53 in addition to the side surfaces of the vibrating arm portion 50. This is because the electrode area contributing to the electric field distribution is increased by dividing the excitation electrode 91 and the excitation electrode 92 on the main surface.

The specific arrangement in each vibration region is as follows.
That is, as shown in FIG. 2, the first electrode 91 includes a mount electrode 91m, a connection electrode 91ma, an excitation electrode 91a, a connection electrode 91ab, an excitation electrode 91b, a connection electrode 91bc, an excitation electrode 91c, and a connection electrode 91cc. .
The second electrode 92 includes a mount electrode 92m, a connection electrode 92ma, an excitation electrode 92a, a connection electrode 92ab, an excitation electrode 92b, a connection electrode 92bc, an excitation electrode 92c, and a connection electrode 92cc.

In the vibration region 60a, as shown in FIG. 2 and FIG. 3A, the excitation electrodes 91a and the excitation electrodes 92a are opposed to each other on both main surfaces of the vibration arm 40, respectively. Excitation electrodes 92a are arranged on both main surfaces, and excitation electrodes 91a are arranged on both sides.
In the vibration region 60b, as shown in FIG. 2 and FIG. 3B, the excitation electrodes 92b and the excitation electrodes 91b are opposed to each other on both main surfaces of the vibration arm portion 40, respectively. Exciting electrodes 91b are arranged on the surface, and exciting electrodes 92b are arranged opposite to each other on both sides.
In the excitation region 60 c, as shown in FIG. 2, excitation electrodes 91 c are disposed opposite to both main surfaces of the vibrating arm portion 40, and excitation electrodes 92 c are opposed to both side surfaces, and excitation electrodes 92 c are disposed on both main surfaces of the vibrating arm portion 50. The excitation electrodes 91c are arranged opposite to each other on both sides.

On the other hand, as shown in FIG. 2, in the base parts 20 and 30 and the vibrating arm parts 40 and 50, the connection electrodes 91 and 92 are connected as follows.
That is, the connection electrode 91ma connects the mount electrode 91m and the excitation electrode 91a, and the connection electrode 92ma connects the mount electrode 92m and the excitation electrode 92a. The connection electrode 91ab connects the excitation electrode 91a and the excitation electrode 91b, and the connection electrode 92ab connects the excitation electrode 92a and the excitation electrode 92b. The connection electrode 91bc connects the excitation electrode 91b and the excitation electrode 91c, and the connection electrode 92bc connects the excitation electrode 92b and the excitation electrode 92c.
The connection electrode 91cc connects the excitation electrode 91c of the vibrating arm unit 40 and the excitation electrode 91c of the vibrating arm unit 50, and the connection electrode 92cc connects the excitation electrode 92c of the vibrating arm unit 40 and the excitation electrode 92c of the vibrating arm unit 50. Is connected.

The first electrode 91 and the second electrode 92 of the present embodiment are formed of two metal layers, a chromium layer formed on the surface of crystal and a gold layer formed thereon.
The first electrode 91 and the second electrode 92 are formed by forming a chromium layer and a metal layer by metal sputtering on the surface of the crystal formed by processing the quartz plate to form the outer shape and outer and inner grooves of the double tuning fork type piezoelectric vibrating piece. Then, by dividing the first electrode 91 and the second electrode 92 by a photolithography process using the mask pattern for exposure (resist film coating, exposure / development with the mask pattern, metal etching, and resist film peeling). A circuit pattern is formed.

  In addition, as a constituent material of the 1st electrode 91 and the 2nd electrode 92, if it has electroconductivity substantially, it will not specifically limit, For example, gold | metal | money, silver, copper, chromium, aluminum, or an alloy containing these Various conductive materials such as metal materials such as carbon black, carbon-based materials such as carbon black, electron conductive polymer materials, ion conductive polymer materials, conductive oxide materials, etc., one or two of these A combination of more than one species can be used.

As described above, according to the double tuning fork type piezoelectric vibrating piece 10 of the present embodiment, one longitudinal groove is formed in the three vibration regions 60a, 60b, and 60c in the vibration arm portions 40 and 50. Instead of a book, two outer grooves 41a-c, 51a-c and two inner grooves 42a-c, 52a-c are formed, and intermediate bank portions 45a-c, 55a-c are formed between both grooves. ing.
And the intensity | strength of a vibrating arm part can be improved by forming middle bank part 45a-c and 55a-c in a longitudinal direction.
Further, as will be described later, the excitation electrodes are also formed on the inner surfaces of the outer grooves 41a to 51c and 51a to 42c and the inner grooves 42a to 42c, 52a to 52c, thereby improving the electric field efficiency (reducing the CI value). be able to.

Next, a modification of this embodiment will be described.
In the described embodiment, the case where the two grooves and the middle bank portion are formed at the three positions of the vibration regions 60a to 60c has been described. However, in the modification described below, the grooves are formed at two or less positions. .
FIG. 4 is a perspective view showing the external shape of a double tuning fork type piezoelectric vibrating piece in a modified example.
In the first modification shown in FIG. 4A, two grooves are formed in the vibration region 60a on the base 20 side and the vibration region 60b on the vibration arm portions 40 and 50, and the vibration region 60c on the base 30 side. One groove is formed on the surface.
In this first modified example, the base 20 side on which the mount electrodes 91m and 92m (see FIG. 2) are formed is fixed and the base 30 side is opened, for example, when the double tuning fork type piezoelectric vibrating piece 10 is used for a diaphragm. It is particularly effective when That is, since the stress on the open end side is smaller than that on the fixed end side, there is one groove in the vibration region 60c on the open end side.

In the second modification shown in FIG. 4B, the vibration arm portions 40 and 50 have two grooves only in the vibration region 60a closest to the base portion 20, and vibrations in the central vibration region 60b and the base portion 30 side. The region 60c is a single groove.
Similar to the first modification, the second modification is an example in which the vibration region 60a to which the stress is most applied is a double groove when the base 20 side is a fixed end and the base 30 side is an open end.

FIG. 5 is a perspective view showing the appearance of a double tuning fork type piezoelectric vibrating piece according to another modification.
In the third modification shown in FIG. 5C, two grooves are formed in the vibration region 60a on the base 20 side and the vibration region 60c on the base 30 side with respect to the vibrating arm portions 40 and 50, and the vibration at the center is formed. One groove is formed in the region 60b.
This third modification is particularly effective when both the base 20 and the base 30 are fixed. That is, when both end sides of the base portions 20 and 30 are fixed, the largest stress is often applied to the central portion, and therefore, there is one groove in the vibration region 60b in the central portion.

In the fourth modified example shown in FIG. 5D, the vibration region 60 a and the base part on the base 20 side with respect to the vibrating arm parts 40 and 50 are opposite to the vibrating arm parts 40 and 50, as opposed to the third modified example. One groove is formed in the vibration region 60c on the 30 side, and two grooves are formed in the central vibration region 60b.
In the fourth modification, when one or both of the double tuning fork type piezoelectric vibrating piece 10 and the base 20 and the base 30 are fixed, the vibration region 60a on the base 20 and 30 side is caused by the fixing method and the arrangement state. This is effective when stress is applied to the vibration region 60c.

  In the first to fourth modifications described above, two grooves are formed in the vibration region 60 to which stress is applied more than others. Therefore, in the case of each modification, the vibration region 60 where the stress is applied may be L1 ≦ L3 with respect to the width L1 of the outer bank portion and the width L3 of the middle bank portion described in FIG. preferable.

In the embodiment and each modification described above, the case where the mount electrodes 91m and 92m are provided only on the base 20 has been described. However, the mount electrodes 91m and 92m may be provided on both the base 20 and the base 30. .
By disposing the mount electrodes 91m and 92m on both the base portions 20 and 30 in this way, there is no restriction on confirming the disposition direction (longitudinal direction) when mounting the double tuning fork type piezoelectric vibrating piece 10.
Further, even when the fixing is performed on one side of both the bases 20 and 30 and the other side is an open end, there is no restriction on the direction, so that it is easy to mount. In particular, in the case of the fourth modified example described with reference to FIG. 5 (d), since the two grooves are formed in the vibration regions 60a and 60c on the base 20 and 30 side, it may be mounted in any direction. However, resistance can be obtained even against strong stress on the fixed part side.

10 Double tuning fork type piezoelectric vibrating piece 20, 30 Base 40, 50 Vibrating arm portion 41a, 41b, 41c, 51a, 51b, 51c Outer groove 42a, 42b, 42c, 52a, 52b, 52c Inner groove 43a, 43b, 43c, 53a 53b, 53c Outer bank portion 44a, 44b, 44c, 54a, 54b, 54c Middle bank portion 45a, 45b, 45c, 55a, 55b, 55c Middle bank portion 60a, 60b, 60c Vibration region 60a
91 First electrode 91m Mount electrode 91a, 91b, 91c Excitation electrode 91ma, 91ab, 91bc, 91cc Connection electrode 92 Second electrode 92m Mount electrode 92a, 92b, 92c Excitation electrode 92ma, 92ab, 92bc, 92cc Connection electrode

Claims (7)

A pair of bases;
A pair of vibrating arm portions extending between the two base portions and having three vibration regions between one base portion and the other base portion;
Longitudinal grooves formed on both opposing main surfaces in each of the three vibration regions of the pair of vibrating arms,
A first electrode integrally formed from the pair of bases to the pair of vibrating arms;
The first electrode is integrally formed from the pair of base portions to the pair of vibrating arms in a state of being electrically disconnected from the first electrode, and vibrates the three vibration regions together with the first electrode. Two electrodes,
At least one of the grooves formed in the three places includes two parallel grooves,
This is a double tuning fork type piezoelectric vibrating piece. The two parallel grooves are formed to have the same width, and the center line in the longitudinal direction of the middle bank portion formed between the two grooves coincides with the center line in the longitudinal direction of the vibrating arm portion.
The double tuning fork type piezoelectric vibrating piece according to claim 1. When the width of the middle bank portion is L3, the width of the groove is L2, and the width of the outer bank portion between the outer side surface of the vibrating arm portion and the groove is L1,
3. The double tuning fork type piezoelectric vibrating piece according to claim 1, wherein L1>L2> L3. When the width of the middle bank portion is L3, the width of the groove is L2, and the width of the outer bank portion between the outer side surface of the vibrating arm portion and the groove is L1,
3. The double tuning fork type piezoelectric vibrating piece according to claim 1, wherein L3> L1. The two parallel grooves are formed in each of the three vibration regions,
The double tuning fork type piezoelectric vibrating piece according to any one of claims 1 to 4, wherein: Of the three vibration regions, one groove is formed in the two vibration regions on the pair of base portions, and two grooves are formed in the central vibration region.
The double tuning fork type piezoelectric vibrating piece according to any one of claims 1 to 4, wherein: Of the three vibration regions, two grooves are formed in at least one vibration region of the two vibration regions on the pair of base portions, and one vibration region is formed in the other vibration region. A groove is formed,
The double tuning fork type piezoelectric vibrating piece according to any one of claims 1 to 4, wherein:

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