JP2000357935A - Electrode film pattern structure of piezoelectric vibrator and forming method of electrode film pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve monconformities that cause a case where the foreign matters attached on the element plate surfaces other than the exciting electrodes move these electrodes and deteriorate the vibrator characteristic by placing the auxiliary electrodes for intensive excitation on both main surfaces of the vibrator with distances secured to the exposed areas of the element plate surfaces prepared along the outer circumference edges of the exciting and lead electrodes. SOLUTION: A piezoelectric vibrator 1 includes a rectangular thin (of paper strap shape) piezoelectric element plate 2, the exciting electrodes 3 and 4 which are formed on both main sides of the plate 2 and the lead electrodes 3a and 4a which are drawn to the edge of the plate 2 from the electrodes 3 and 4 respectively. Then an auxiliary electrode (exclusively used for intensive excitation) 11 is formed on the entire remaining areas of both sides of the plate 2 with a distance secured to the exposed areas 10 prepared along the outer circumference edges of the electrodes 3, 4, 3a and 4a respectively. In such a constitution, the foreign matters attached to the electrode 11 can also be eliminated via the intensive excitation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a piezoelectric vibrating element, and more particularly to a piezoelectric vibrating element generated when a surface of a substrate other than an excitation electrode and a lead electrode formed on a main surface of a piezoelectric substrate is exposed. The present invention relates to a piezoelectric vibrating element having an electrode film pattern structure that can solve various problems that have occurred. Further, the present invention relates to a method for forming an electrode film pattern of a piezoelectric vibrating element, which can accurately form an electrode film pattern of the piezoelectric vibrating element by a simple method.

[0002]

2. Description of the Related Art Piezoelectric devices such as a piezoelectric vibrator and a piezoelectric oscillator using a piezoelectric vibrating element represented by quartz are used as indispensable main parts in various electronic devices, especially communication devices. (First Conventional Example) FIGS. 10 (a) and 10 (b) are explanatory diagrams of the front and back surfaces of a conventional piezoelectric vibrating element using a rectangular thin plate-shaped piezoelectric element. The element 1 includes excitation electrodes 3 and 4 on both front and back main surfaces of a piezoelectric element 2 made of a piezoelectric material such as quartz, and lead electrodes 3a and 4a extending from each excitation electrode to the edge of the element. ing. The excitation electrodes 3, 4 and the lead electrodes 3 a, 4 a are electrode film patterns formed by vapor deposition with a metal mask of a required shape arranged on the piezoelectric element plate 2. When the piezoelectric vibrating element 1 is incorporated in the package 6 of the piezoelectric device 5 shown in FIG. 10C, the lead electrodes 3a, 4a
Is fixed to the electrode pad 7 on the support pedestal 6a in the package with the conductive adhesive 8 so that the cantilever is supported. Reference numeral 9 denotes a metal lid that closes an upper opening of the package 6.
By the way, conventionally, a technique called strong excitation has been implemented for the purpose of improving the oscillation level of a manufactured piezoelectric vibration element. This is because a current for vibrating at a high level far exceeding the drive level intended for use of the piezoelectric vibration element is supplied to the excitation electrode via the lead electrode, so that the excitation electrode is vibrated strongly and the excitation electrode is vibrated. This is a method for removing adhered foreign matter. By performing the strong excitation in a state where the piezoelectric vibrating element is adhered to the piezoelectric device package 6 in a cantilever manner, it is possible to remove adhering foreign matter which is a factor that hinders good vibration of the excitation electrode. The characteristics of the piezoelectric device incorporating the piezoelectric vibration element can be stabilized, and the reliability can be improved. But,
The strong vibration that occurs when the strong excitation is performed is the excitation electrode 3,
Because the concentration is at 4, the foreign matter removing effect near the excitation electrode is exhibited, but the foreign matter removing effect around the excitation electrode is small. For this reason, a situation in which the foreign matter adhering to the surface of the base plate other than the excitation electrode moves to and adheres to the surface of the excitation electrode occurs with the passage of time, which is a factor of deteriorating the characteristics of the piezoelectric vibration element.

(Second Conventional Example) Next, as shown in FIGS. 10 (a) and 10 (b), a conventional piezoelectric vibrating element is an electrode film for exciting piezoelectric vibration on both front and back surfaces of a strip-shaped piezoelectric element plate 2. In order to form a pattern (excitation electrodes 3, 4 and lead electrodes 3a, 4a), the front and back surfaces of the piezoelectric element 2 are masked using a metal mask or the like, and then an electrode film is formed by vapor deposition or sputtering. A desired electrode film pattern was obtained by film formation. The electrode area of the excitation electrodes 3 and 4 is determined according to a desired equivalent constant (for example, equivalent inductance, equivalent capacitance, parallel capacitance, equivalent resistance represented by an electric equivalent circuit). Heretofore, it has been general that no film is formed on the base plate surface other than the excitation electrodes 3 and 4 for deriving these equivalent constants and the lead electrodes 3a and 4a by masking. However, the recent demand for miniaturization of piezoelectric devices has spread to the piezoelectric vibrating elements to be used, and in order to control the equivalent constant of the main vibration and the parasitic auxiliary vibration with high accuracy, the electrode film pattern has As for the accuracy, there is a demand for higher accuracy than ever before in proportion to miniaturization. When these electrode film patterns are formed by a conventional vapor deposition method using a metal mask, a shadow formed at the time of film formation due to the thickness of the mask and a shadow between the mask and the piezoelectric element plate are formed. There are drawbacks such as the reproducibility of the desired electrode film pattern being reduced due to the wraparound of the film-forming material into the contact gap, and the variation of the electrical equivalent constant and parasitic auxiliary vibration being increased. In particular, in the case of a piezoelectric vibrating element that uses the thickness-shear vibration mode, the thickness of the piezoelectric element becomes thinner as the target frequency increases, and the vibration energy of the piezoelectric element is confined to a very small area of the piezoelectric element. Therefore, the required electrode film pattern such as the excitation electrode also has an extremely small area. As a result, the above-mentioned disadvantages of the vapor deposition method using a metal mask are further amplified.

On the other hand, a photolithography method has been conventionally known as a technique for forming an electrode film pattern with high precision.
Resist coating, photomask exposure, etching,
Since a plurality of steps such as resist stripping and cleaning are performed, a large amount of time is required, thereby reducing productivity and increasing costs. In addition, these metal masks and photomasks require a large number of types for each target frequency, and have a disadvantage that a large amount of management cost is required for maintaining and managing them with high accuracy. Conventionally, a method of trimming an electrode film by irradiating a laser beam is also known.However, when processing an electrode film formed on a crystal material such as quartz, the laser beam passes through the inside of a solid. For this reason, there is a problem that the electrode film formed on the back surface of the piezoelectric element is also trimmed, which makes it difficult to form a desired pattern.

[0005]

The problem to be solved by the present invention is, for example, the case where strong excitation is performed in a piezoelectric vibrating element in which excitation electrodes and lead electrodes are formed on both front and back surfaces of a piezoelectric element plate, respectively. In addition, as a result of significantly reducing the foreign matter removing effect on the surface of the base plate other than the excitation electrode, foreign matter attached to the surface of the base plate other than the excitation electrode is transferred onto the excitation electrode and deteriorates the characteristics of the piezoelectric vibration element. The problem is to solve the problem that causes it. Another object of the present invention is to provide a method for forming an electrode film pattern of a piezoelectric vibrating element, which significantly reduces the number of manufacturing steps when forming an electrode film pattern with high accuracy and facilitates the formation of an electrode film pattern with high accuracy. Is to provide.

[0006]

According to a first aspect of the present invention, there is provided a piezoelectric element, at least one excitation electrode formed on at least one main surface of the piezoelectric element, and the excitation electrode. And a lead electrode drawn out of the piezoelectric vibrating element, the main surface of the piezoelectric vibrating element is separated from a raw plate surface exposed region arranged along the outer peripheral edges of the excitation electrode and the lead electrode, It is characterized in that auxiliary electrodes for excitation are arranged. The invention according to claim 2 is characterized in that the auxiliary electrode is formed on the entire surface of the remaining raw plate separated from the raw plate surface exposed region arranged along the outer peripheral edges of the excitation electrode and the lead electrode. The invention according to claim 3 is a piezoelectric element plate, comprising: an excitation electrode, a lead electrode drawn out from the excitation electrode, and a substrate surface exposed region arranged along the outer peripheral edge of the excitation electrode and the lead electrode on the front side main surface of the piezoelectric element plate. And an auxiliary electrode for strong excitation, which is disposed at a distance from the piezoelectric element, and an electrode film pattern serving also as the excitation electrode and the auxiliary electrode on the back side over the entire or wide area of the back side main surface of the piezoelectric element plate. Is formed. According to a fourth aspect of the present invention, after forming an electrode film on the entire front and back main surfaces of the piezoelectric element plate, the electrode film is selectively removed by electric discharge machining to form the element plate surface exposed region. Thus, a desired electrode film pattern is formed. According to a fifth aspect of the present invention, the piezoelectric plate having an electrode film formed entirely on the main surface is placed on an XY table controlled by a CPU, and a plurality of discharge electrodes are disposed to face the piezoelectric plate surface. Thus, a plurality of electrode film patterns are simultaneously formed on the surface of the piezoelectric element. The invention according to claim 6 is characterized in that a thickness-sliding piezoelectric material is used as the piezoelectric element plate. The invention according to claim 7 is characterized in that the piezoelectric vibration element is a multi-electrode type piezoelectric vibration element.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. (Embodiment Corresponding to First Conventional Example) FIG.
(b) is a diagram showing a front main surface and a back main surface of a piezoelectric vibrating element according to one embodiment of the present invention. The piezoelectric vibrating element 1 has a rectangular thin plate (strip) made of a piezoelectric material such as quartz. ), Excitation electrodes 3 and 4 respectively formed on the front and back main surfaces of the piezoelectric element 2, and lead electrodes 3 a drawn out from the excitation electrodes 3 and 4 to the edges of the piezoelectric element, respectively. 4a, and each of the excitation electrodes 3, 4 and the lead electrodes 3a,
Auxiliary electrodes (electrodes dedicated to strong excitation) 11 are separated from the piezoelectric element 2 by an element exposed surface 10 arranged along the outer peripheral edge of the element 4a.
Is characterized in that it is arranged over the entire remaining area on both sides. In this embodiment, the bare plate surface exposed region 10
Is a slit having a substantially uniform width, but this is merely an example, and the width and shape of the slit can be variously modified. Also, a lead electrode 3 extending from the excitation electrode
Various modifications are also possible for the shapes of a and 4a, the drawing direction, and the like. Exciting electrodes 3 and 4, lead electrodes 3a and 4a
The exposed surface 10 of the base plate is a conductive film pattern. As a method of forming the conductive film pattern, for example, a conductive film is uniformly formed on both front and back main surfaces of the piezoelectric plate 2 by vapor deposition or the like. After the film formation, the base plate surface exposed region 10 is formed by the method described in each embodiment described later, or the base plate surface is formed by performing vapor deposition in a state where a metal mask is fixed to the piezoelectric base plate surface in advance. A conductive film is formed on the entire surface of the base plate excluding the exposed region 10. Alternatively, each excitation electrode, lead electrode and auxiliary electrode 11 may be selectively formed on the piezoelectric element plate by photoetching. If the auxiliary electrode is located on the opposite side of one of the lead electrodes, when the lead electrode is fixed in the package with the conductive adhesive, the conductive adhesive is attached to the auxiliary electrode on the opposite side. Since there is a risk of short-circuiting the lead electrode and the lead electrode, a part of the auxiliary electrode 11 (a part near the edge 2a) is formed by forming the bare plate surface exposed region 10A as shown by a dashed line as necessary. You may make it electrically separate from another part. This configuration for preventing short circuit can be applied commonly to all the following embodiments.

In the piezoelectric vibrating element 1 of this embodiment, since the auxiliary electrode 11 is formed over a wide area on the surface of the base plate other than the excitation electrodes 3 and 4, the work of removing foreign matter by strong excitation can be performed by the auxiliary electrode 1.
1 can be implemented. That is, by applying a current having a higher frequency than the current applied to the excitation electrodes 3 and 4 to the excitation electrodes 3 and 4 and the auxiliary electrode 11 simultaneously at the time of actual use, these are strongly excited, and these are applied to each conductive film pattern. Foreign matter adhering to the can be removed. Therefore, when this piezoelectric vibrating element is incorporated into a piezoelectric device 5 as shown in FIG. 10 (c) and actually used, the frequency stability is reduced due to foreign matter adhering to the conductive film patterns 3, 4, and 11. Can be effectively prevented. As a modification of FIG. 1, for example, a configuration in which only the back main surface of the piezoelectric element plate is entirely covered with an electrode film pattern may be employed. In this case, a part of the entire surface electrode on the back side main surface functions as an excitation electrode, while foreign matter is removed from the electrode film pattern on the entire back surface during strong excitation.

As another configuration example of the conductor film pattern of the piezoelectric vibration element exhibiting such excellent effects, for example,
Examples shown in FIGS. 2, 3 and 4 can be exemplified. First, FIGS. 2 (a) and 2 (b) are diagrams showing a front main surface and a back main surface of a piezoelectric vibrating element according to a modification of the embodiment shown in FIG. The conductor film patterns 3, 4, 3a, 4a,
11 is different from the above-described embodiment in the shape of the auxiliary electrode 11. Further, the conductor film patterns 3, 4, 3a, 4a, 11 of this embodiment are formed so as to be substantially symmetrical on the front and back of the piezoelectric element plate. In this embodiment, as shown in the figure, the bare plate surface exposed region 10 is a narrow exposed region formed in a slit shape along the entire outer periphery of the excitation electrodes 3 and 4 and the base ends of the lead electrodes 3a and 4a. 10a, a wide exposed region 10 extends from the middle part of each of the lead electrodes 3a, 4a to the tip end (the side of the raw plate edge 2a).
b. Further, the auxiliary electrode 11 is a lead electrode 3
A portion near the raw plate edge 2a from which a and 4a are drawn out is removed in a required shape, and this portion is a second raw plate surface exposed region 12. The narrow portion of the auxiliary electrode 11 adjacent to the second bare plate surface exposed region 12 is the auxiliary electrode lead portion 11a.
And serves as a current supply unit when the auxiliary electrode 11 is strongly excited. The wide exposed region 10b and the second bare plate surface exposed region 12 are preset so that their widths w are substantially the same. The base plate edge 2a from which the lead electrode is drawn out is used to support the quartz resonator element 1 cantilever in the package 6 of the piezoelectric device 5 shown in FIG.
An electrode film pattern is a portion which is bonded and fixed to the electrode pad 7 on the support pedestal 6a in the package, and has a wide exposed region 10b and a second exposed surface 12 of the raw plate arranged along the raw plate edge 2a. Are not present, but these areas 10
Since b and 12 are close to the auxiliary electrode 11, when the auxiliary electrode is vibrated strongly, the foreign substances adhering to these regions 10b and 12 are removed. This type of piezoelectric vibrating element 1
Is incorporated in the package 6 of the piezoelectric device 5 as shown in FIG. 10 (c), each end of the lead electrodes 3a, 4a is connected to two pads 6a on a support base 6a in the package 6, not shown. And the ends of the auxiliary electrode lead portions 11a provided on the front and back surfaces are also fixed to the other pads 6a on the support pedestal in the package using the conductive adhesive 8. In this state, a current for vibrating the piezoelectric vibrating element 1 at a high level far exceeding the drive level for which the piezoelectric vibrating element 1 is used is passed from each pad to each lead electrode 3a, 4a and the auxiliary electrode lead portion 11a, and the excitation electrode By energizing the excitation electrodes 3, 4 and the auxiliary electrode 11, the excitation electrodes 3, 4 and the auxiliary electrode 11 are vibrated strongly to remove foreign substances adhering to the excitation electrode and the auxiliary electrode, respectively.

FIGS. 3 (a) and 3 (b) are diagrams showing the front and back surfaces of a piezoelectric vibrating element according to another embodiment of the present invention. Figure 3 (a)
On the other hand, as shown in FIG. 3B, a full-surface electrode as an auxiliary electrode 15 is formed on the back surface of the piezoelectric element plate 2. The configuration of the electrode film pattern formed on the surface of the element plate of the piezoelectric vibration element 1 is different from that of FIG. 1 in that the edge of the lead electrode 3a and the edge of the auxiliary electrode 11 In this configuration, the terminal ends before reaching the edge 2a. In other words, the bare plate surface exposed region 10 is formed to have a predetermined width w1 from the entire outer periphery of the excitation electrode 3, a slit-like narrow width exposed region 10 a surrounding the middle of each lead electrode 3 a, and the bare plate edge 2 a. Wide exposed area 1 exposed in a rectangular shape over
0c. On the back surface of the piezoelectric element 2, a full-surface electrode 15 serving as an excitation electrode and an electrode dedicated to strong excitation is formed over the entire surface. When the piezoelectric vibrating element 1 having such a configuration is cantilevered in a package 6 as shown in FIG. 10 (c), it is fixed along the edge 2a as a fixed portion for cantilevering support in the package. While the part 16 is selected and fixed on the electrode pad 7 in the package by the conductive adhesive 8,
A current is supplied to the lead electrode 3a using a bonding wire 17, and a current is supplied to the auxiliary electrode 11 on the front surface using a bonding wire 18. A current can be supplied to the whole surface electrode 15 on the back surface by conducting the electrode pad 7 in the package and the whole surface electrode 15 via the conductive adhesive 8. Excitation electrode 3, auxiliary electrode 1
1. The effect of completely removing foreign matter by strong excitation of the entire surface electrode 15 is the same as in the above-described embodiment. Also,
Foreign matter adhering to the wide exposed region 10c can be removed by strong excitation of the auxiliary electrode 11 on the front side and the full-surface electrode 15 on the back side.

4 (a) and 4 (b) are front and back side views of a piezoelectric vibrating element according to another embodiment of the present invention. Electrode film patterns 3, 4, 3a, 4a, 11 formed on the front side of the plate 2.
Is similar to that of the embodiment shown in FIG. 2A, except that the shape of the electrode film pattern formed on the back side of the base plate is different. That is, the base plate surface side is the base plate surface exposed area 10.
Correspond to the entire outer periphery of the excitation electrodes 3 and 4 and the respective lead electrodes 3a and 4
While each of the lead electrodes 3a, 4a has a narrow width exposed region 10a formed in a slit shape along the base end of the lead electrode 3a, 4a.
A wide exposed region 10b extends from the intermediate portion to the tip portion (the raw plate edge 2a side). Further, the auxiliary electrode 11
A portion near the base plate edge 2a from which the lead electrodes 3a and 4a are drawn out is removed in a required shape, and this portion is a second base plate surface exposed region 12. The narrow portion of the auxiliary electrode 11 adjacent to the second bare plate surface exposed region 12 is an auxiliary electrode lead portion 11a, and serves as a current supply portion when the auxiliary electrode 11 is strongly excited. Also, the wide exposed area 10b
And the second bare plate surface exposed region 12 are set in advance so that their widths w are substantially the same.

On the other hand, on the back surface side of the piezoelectric element plate 2, an exposed area 20 is formed over a range of width w from the edge 2a of the element plate. 21a
Is divided by Further, the area excluding the raw plate surface exposed area 20 and the lead electrode 21a is the entire excitation / auxiliary electrode 21. When the piezoelectric vibrating element 1 according to this embodiment is fixed in a package 6 as shown in FIG. 10C by cantilever support, each lead electrode 3a, auxiliary electrode lead portion 11a, and lead electrode 21a are respectively Each of the three electrode pads provided in the package 6 is connected and fixed using a conductive adhesive. Excitation electrode 3, auxiliary electrode 1
1. The effect of completely removing foreign matter by strong excitation of the excitation / auxiliary electrode 21 is the same as in the above embodiments. In addition, foreign substances adhering to the exposed surface 20 of the base plate are treated with the auxiliary electrode 11 on the front side and the excitation / auxiliary electrode 2 on the rear side.
1 can be removed by strong excitation. In each of the piezoelectric vibrating elements according to the above-described embodiments, a single excitation electrode is formed on each of the front and back surfaces of the piezoelectric element. It goes without saying that the present invention can be applied to a multi-electrode type piezoelectric vibrating element such as an MCF (monolithic crystal filter) in which electrodes are separately arranged.

(Embodiment Corresponding to Second Conventional Example) Next, FIG. 5 is a diagram showing the principle of a method of forming an electrode film pattern using an electric discharge machining method, and FIG.
(b) is a perspective view and AA sectional view of a piezoelectric vibration element formed by the processing method of FIG. According to the method of the present invention, the electrode films 30, 31 are previously deposited on the entire front and back surfaces of the piezoelectric element plate 2 made of a thickness-sliding piezoelectric material such as quartz by vapor deposition or sputtering.
Are formed, and the electrode film surface is selectively etched by electric discharge machining to form the exposed surface 10 of the base plate surface of an arbitrary shape, thereby forming an electrode film pattern of a desired shape. It was made. In the present embodiment, as means for implementing the electric discharge machining method, two machining terminals 35 and 36 and each machining terminal 3 are provided.
DC power supply 3 connected to lead wires 5 and 36 via lead wire 37
8 is used. As shown in FIG. 5, a machining method using this electric discharge machining means connects one machining terminal 35 connected to one electrode of a DC power supply 38 to an appropriate position on one electrode film pattern 30 to be machined. In this state, when the tip of the other processing terminal 36 connected to the other electrode of the DC power supply is brought into contact with a desired position of the electrode film 30, discharge occurs between the electrode film 30 and the processing terminal 36. I do. Due to this discharge phenomenon, the electrode film 30 in contact with the tip of the processing terminal 36 is partially peeled off and etching is performed, exposing the raw plate surface. Utilizing this etching principle, the contact position of the processing terminal 36 can be changed to a desired path 4.
By moving along the zero, the etching line 41 can be continuously formed on the electrode film pattern. The piezoelectric element plate surface is exposed in the etching line 41, and the etching line 41 becomes the element plate surface exposed region 10.

FIGS. 6 (a) and 6 (b) show a structure of the piezoelectric vibrating element 1 obtained by the processing method shown in FIG. 5, and this structure is similar to the piezoelectric vibrating element shown in FIG. The electrodes 3 and 4 are inside the exposed area 10 of the base plate, and the electrode films outside the exposed areas are the auxiliary electrodes 11 for strong excitation. Further, a separation electrode film pattern 42 having a predetermined area is formed by a part of the auxiliary electrode 11, that is, a position near the raw plate edge 2 a by the raw plate exposed region 10 d. This is because when the edge 2a of the piezoelectric vibration element 1 is cantilevered in the piezoelectric device package with a conductive adhesive, the end of the lead electrode 3a on the front side and the auxiliary electrode 11 on the back side are short-circuited. Lead electrode 4a on the back side
This is to prevent a short circuit between the electrode and the auxiliary electrode 11 on the front side. The electric discharge machining method according to the present embodiment can be used for machining the electrode film patterns of all types of piezoelectric vibration elements shown in the above embodiment. The processing method as described above can be performed by forming an etching line with a processing terminal while step-feeding the table while a piezoelectric element, which is a workpiece, is placed on a high-precision XY table. High accuracy. Further, by performing this control by the CPU, the shape and type of the bare plate exposed region (etching line) can be selected innumerably, and it is not necessary to prepare a metal mask or a photomask for each design frequency. In addition, it is a processing method suitable for batch processing such as simultaneous drawing of a plurality of electrode film patterns on a large-sized piezoelectric element and completion of required processing, followed by division into individual pieces. It becomes possible to reduce to. Note that this embodiment is
It goes without saying that the present invention can be applied to a multi-electrode type piezoelectric vibration element.

Next, an embodiment in which a piezoelectric vibration element is formed by batch processing using the above-mentioned electric discharge machining method will be described with reference to FIG. FIG. 7 is a view for explaining a procedure for forming a piezoelectric vibration element by batch processing using the electric discharge machining method shown in FIG.
The electrode films 51 and 52 are formed on the entire front and back surfaces of the piezoelectric element plate 5 by the electric discharge machining method shown in FIG.
Etching line in each section on 0 (exposed area of raw plate surface)
After simultaneously forming 53, the individual piezoelectric vibration elements (pieces) shown in FIG. 8 are obtained by dividing and cutting along the vertical and horizontal lines A and B. The XY table mainly controlled by the CPU and the electric discharge machining apparatus shown in FIG. 5 are used for this batch processing. The processing terminals 36 for the number of piezoelectric vibrating elements to be formed are arranged facing the large-area piezoelectric element plate 50 fixed on the XY table, and the XY table is moved. It can be formed efficiently and collectively with high precision. The width dimension of the etching line 53 can be arbitrarily formed by selecting the tip size of the processing terminal 36.

The etching line 53 is not only formed with high precision by moving the XY table controlled by the CPU, but also an arbitrary etching line is obtained by inputting the shape of the etching line to be formed. be able to. As shown in FIGS. 5A and 5B, the piezoelectric vibrating element obtained by the batch processing is
The excitation electrodes 3, 4 and the lead electrodes 3a,
4a and a configuration in which an auxiliary electrode 11 for strong excitation is provided outside the etching line (exposed area of the raw plate surface) 53. FIGS. 9A and 9B are configuration diagrams of individual pieces of a monolithic type piezoelectric vibrating element obtained by batch processing, and two excitation electrodes 55, 55 are provided on one surface of the piezoelectric element plate 2. The electrodes are opposed to each other with an etching line 53 interposed therebetween, and a common electrode 56 is formed on the back surface thereof.
After the electrode film pattern 56 is formed on the back surface of the piezoelectric element plate 2, the electrode film 57 remaining on the outer periphery of the electrode film pattern 56 may be left as an equivalently floating electrode having no potential. . In each of the above embodiments, the method of forming an electrode film pattern is mainly described by taking a thickness-slip piezoelectric vibration element as an example. However, the present invention relates to a method of forming an electrode film pattern of a piezoelectric vibration element using a piezoelectric material other than the thickness-slip. Can also be applied.

[0017]

According to the present invention, strong excitation is performed by leaving an electrode film pattern for strong excitation as an auxiliary electrode on the surface of the base plate other than the excitation electrodes and lead electrodes formed on the piezoelectric element plate. In this case, the effect of removing foreign substances on the surface of the base plate other than the excitation electrode can be improved, and the foreign substances adhering to the surface of the base plate other than the excitation electrode are transferred to the excitation electrode and the characteristics of the piezoelectric vibration element are reduced. It is possible to solve a problem that causes deterioration. In addition, since an electric discharge machining method is used as a method of forming the exposed surface of the raw plate surrounding the excitation electrode and the lead electrode, it is possible to realize an electrode film pattern formation that solves all the drawbacks of the conventional machining method. Was completed. That is, in the method of forming a desired electrode film pattern by a vapor deposition method after masking the surface of the piezoelectric element using a conventional metal mask, many types of metal masks are prepared and held according to the type of the electrode pattern. And the shape of the metal mask is transferred directly to the piezoelectric plate,
Degradation of the accuracy of the electrode film pattern was easily caused by the influence of the dimensional accuracy of the mask and the thickness dimension of the mask. However, in the method of the present invention, the desired width was obtained by moving the processing electrode along the contour of the electrode film pattern. Can be directly formed along a desired route, so that a highly accurate electrode film pattern can be formed with high productivity. In addition, the method of the present invention can greatly reduce equipment and man-hours as compared with the photolithography technology, and eliminates the need for photomask production and management. Therefore, productivity is high and cost can be reduced. In addition, by performing the method of forming an electrode film pattern using the above-described electric discharge machining method in a batch process, a highly accurate piezoelectric vibrating element can be efficiently manufactured in a short time. In particular, when manufacturing using a microcomputer including a CPU, the electrode film pattern to be formed can be arbitrarily selected, so that the overall manufacturing time can be reduced.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing a front surface side and a back surface side of a piezoelectric vibration element according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing a front surface side and a back surface side of a piezoelectric vibration element according to a modification of the embodiment shown in FIG.

FIGS. 3A and 3B are configuration diagrams of a front surface and a back surface of a piezoelectric vibration element according to another embodiment of the present invention.

FIGS. 4A and 4B are configuration diagrams of a front surface and a back surface of a piezoelectric vibrating element according to another embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating the principle of an electric discharge machining method used in the present invention.

6 (a) and (b) are a perspective view and a cross-sectional view taken along the line AA of the piezoelectric vibration element obtained by the processing method of FIG.

FIG. 7 is a diagram illustrating a procedure of a batch process performed using the processing method of the present invention.

8A and 8B are a configuration diagram and a cross-sectional view of a piezoelectric vibrating element obtained by a batch process.

9A and 9B are a configuration diagram and a sectional view of a piezoelectric vibrating element obtained by a batch process.

10 (a) and 10 (b) are explanatory diagrams of the front and back surfaces of a conventional piezoelectric vibrating element using a rectangular thin plate-shaped piezoelectric element, and FIG. FIG.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 piezoelectric vibrating element, 2 piezoelectric element plate, 2a element plate edge (adhesive support end), 3, 4 excitation electrode, 3a, 4a lead electrode, 5 piezoelectric device, 6 package, 6a support pedestal, 7 electrode pad, 8 Conductive adhesive, 10, 10A
Base plate exposed area, 10a, 10b Narrow exposed area, 1
DESCRIPTION OF SYMBOLS 1 Auxiliary electrode (electrode dedicated to strong excitation), 11a Auxiliary electrode lead portion, 12 Second bare plate surface exposed region, 15 Full surface electrode, 20 Raw plate surface exposed region, 21 Excitation and auxiliary electrode
1a Lead electrode, 35, 36 Processing terminal, 37 Lead power, 38 DC power supply, 40 Base plate surface exposed area, 41
Etching line, 42 separation electrode film pattern, 50
Large area piezoelectric element, 51, 52 Electrode film, 53 Etching line (element plate exposed area).

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuichiro Kawaguchi 2-1-1 Kotani, Samukawa-cho, Koza-gun, Kanagawa Prefecture Inside Toyo Communication Equipment Co., Ltd. (72) Inventor Hiroyasu Saida 2-1-1 Kotani, Samukawa-cho, Koza-gun, Kanagawa No. 1 Toyo Tsushinki Co., Ltd. F term (reference) 5J108 AA01 BB02 CC04 DD02 EE03 EE04 EE07 EE18 FF02 KK02 MM14

Claims (7)

[Claims] 1. A piezoelectric vibrating element comprising: a piezoelectric element plate; at least one excitation electrode formed on at least one main surface of the piezoelectric element plate; and a lead electrode drawn out of the excitation electrode. An electrode for a piezoelectric vibrating element, wherein an auxiliary electrode for strong excitation is arranged on the main surface of the element, with a bare plate exposed area arranged along the outer peripheral edges of the excitation electrode and the lead electrode. Film pattern structure. 2. The device according to claim 1, wherein the auxiliary electrode is formed on the entire surface of the remaining raw plate separated from the exposed surface of the raw plate disposed along the outer peripheral edges of the excitation electrode and the lead electrode. The electrode film pattern structure of the piezoelectric vibrating element. 3. An excitation electrode, a lead electrode drawn out from the excitation electrode, and a bare plate surface exposed area arranged along the outer peripheral edges of the excitation electrode and the lead electrode, on the front side main surface of the piezoelectric element plate. A piezoelectric vibrating element formed with a strong excitation auxiliary electrode disposed in a manner to form an electrode film pattern serving also as a back excitation electrode and an auxiliary electrode on the whole or wide area of the back main surface of the piezoelectric element plate. An electrode film pattern structure of a piezoelectric vibrating element, characterized in that: 4. After forming an electrode film on the entire front and back main surfaces of the piezoelectric element plate, the electrode film is selectively removed by electric discharge machining etching to form the element plate surface exposed region. 4. The method for forming an electrode film pattern of a piezoelectric vibrating element according to claim 1, wherein a desired electrode film pattern is formed. 5. The piezoelectric element having an electrode film formed entirely on both front and rear main surfaces is placed on an XY table controlled by a CPU, and a plurality of discharge electrodes are disposed opposite to the piezoelectric element surface. 5. The method according to claim 4, wherein a plurality of electrode film patterns are simultaneously formed on the surface of the piezoelectric plate. 6. An electrode film pattern structure and a method for forming an electrode film pattern of a piezoelectric vibration element according to claim 1, wherein a thickness-sliding piezoelectric material is used as said piezoelectric element plate. 7. An electrode film pattern structure and a method for forming an electrode film pattern of a piezoelectric vibration element according to claim 1, wherein said piezoelectric vibration element is a multi-electrode type piezoelectric vibration element.