JPH04287412A - Manufacture of piezoelectric resonance element - Google Patents

Abstract

PURPOSE:To enhance the degree off concentration of frequencies onto plural piezoelectric resonance elements by forming a thin electrode to a piezoelectric substrate with a large thickness and forming a thick electrode to the piezoelectric substrate with a small thickness. CONSTITUTION:An electrode 2 is formed to the entire face of both major faces of the piezoelectric substrate 1 by the method such as vapor-deposition. A mask 5 for pattern partial vapor deposition to expose a part 1a with small thickness of the piezoelectric substrate 1 is applied to a unit 4 and the part 1a with small thickness of the electrode material unit 4 is vapor-deposited, an electrode 2a is laminated further on the electrode 2 to uniformize the thickness of the unit 4 entirely. Then the processing such as etching is implemented to form a prescribed electrode pattern and the piezoelectric resonance element in the thickness longitudinal vibration mode is cut out by cutting the unit 4. Thus, the electrode is formed thin to the thick piezoelectric substrate 1 and the thick electrode is formed to the piezoelectric substrate with the smaller thickness, then the thickness of the unit is entirely uniformized.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a method for manufacturing a piezoelectric resonant element, and more particularly, to a method for manufacturing a piezoelectric resonant element, in which a plurality of piezoelectric resonant elements are cut out from a single unit by cutting a unit formed by forming electrodes on a piezoelectric substrate. Regarding the manufacturing method.

0002

2. Description of the Related Art For example, as shown in FIG. 10, a thickness longitudinal vibration mode piezoelectric resonant element 53 in which electrodes (vibrating electrodes) 52 are formed on both sides of a piezoelectric substrate 51 is as shown in FIG.
It is manufactured by cutting out a plurality of piezoelectric resonant elements 53 by cutting a unit 54 in which a predetermined pattern of electrodes 52a are formed on a piezoelectric substrate 51a in the width direction and length direction. Further, as shown in FIG. 12, a thickness shear vibration mode piezoelectric resonant element 63 in which electrodes 62 are formed on both sides of an elongated piezoelectric substrate 61, some of which are opposed to each other through the piezoelectric substrate 61, is shown in FIG. As shown, a unit 6 has electrodes 62a formed in a predetermined pattern on both sides of a piezoelectric substrate 61a.
It is manufactured by cutting 4 in the width direction.

0003

[Problems to be Solved by the Invention] However, in the conventional manufacturing method described above, the piezoelectric substrate 51 constituting the unit usually
The thicknesses of a and 61a are not necessarily uniform, and the unit 5 for the piezoelectric resonant element 53 in the thickness longitudinal vibration mode shown in FIG.
4 is thin at one end and thick at the other end, and in the unit 64 for a piezoelectric resonant element in thickness-shear vibration mode shown in FIG. 13, the center is thick and the thickness increases toward the ends. It's getting smaller.

By the way, there is a relationship between the frequency and the thickness of (the vibrating part of) the piezoelectric resonant element: f×t=C (constant) (where f: frequency, t: thickness of the element,
C: Frequency constant). Therefore, if there are variations in the thickness of the units 54, 64, there is a problem that the frequencies of the piezoelectric resonance elements 53, 63 obtained vary depending on the position of the units 54, 64 from which the piezoelectric resonance elements 53, 63 are cut out.

The present invention solves the above-mentioned problems, and provides a piezoelectric device that can improve the frequency concentration of a plurality of piezoelectric resonant elements cut out from one unit by making the thickness of the unit uniform. An object of the present invention is to provide a method for manufacturing a resonant element.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, a method for manufacturing a piezoelectric resonant element according to the present invention involves cutting a unit formed by forming electrodes on the surface of a piezoelectric substrate to produce a plurality of piezoelectric resonators. In a method of manufacturing a piezoelectric resonant element by cutting out an element, the thickness of the unit is made uniform as a whole by forming thin electrodes on thicker parts of the piezoelectric substrate and thicker electrodes on thinner parts, It is characterized by increasing the frequency concentration of a plurality of piezoelectric resonant elements cut out from one unit.

[0007] Further, by applying a mask with a pattern that exposes the thinner portion of the unit and laminating electrodes on the thinner portion of the unit, the thickness of the unit can be made uniform as a whole.

Furthermore, the piezoelectric substrate is provided with a screen that has a dense mesh in the parts corresponding to the thicker parts and a coarser mesh in the parts corresponding to the thinner parts, and the electrode material is passed through the screen. By vapor deposition, the thickness of the unit can be made uniform as a whole by forming thin electrodes on the thicker parts of the piezoelectric substrate and thicker electrodes on the thinner parts of the piezoelectric substrate.

[0009]

[Operation] In the method of manufacturing a piezoelectric resonant element of the present invention, the electrodes are thinly formed in the thicker parts of the piezoelectric substrate, and the electrodes are thicker in the thinner parts, so that the overall thickness of the unit is reduced. The frequency is made uniform, preventing variations in frequency depending on the cutout position, and improving frequency concentration.

[0010] Furthermore, by masking the thick part of the unit and exposing only the thin part,
The overall thickness of the unit can be made uniform by forming (laminating) an electrode on top of the electrode in the thinner part of the unit using a method such as vapor deposition.

[0011]Furthermore, the portions of the piezoelectric substrate corresponding to the thicker portions are screened with a denser mesh, and the portions corresponding to the smaller thickness are screened with a coarser mesh. By vapor depositing the material, a large amount of electrode material (metal) vapor reaches the piezoelectric substrate from the coarse mesh areas of the screen, and a small amount from the dense mesh areas, and the vapor reaches the thicker areas of the piezoelectric substrate. The electrodes are formed thinly, and the electrodes are formed thickly in the thinner parts of the piezoelectric substrate, so that the thickness of the unit is made uniform throughout.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a unit 4 according to an embodiment of the present invention. This unit 4 is a unit for manufacturing a piezoelectric resonant element 3 in a thickness longitudinal vibration mode as shown in FIG. Electrode 2 is formed by the method described below. Next, a mask 5 for partial vapor deposition with a pattern that exposes the thin portion 1a of the piezoelectric substrate 1 (unit 4) (that is, does not cover the thin portion 1a) is applied on the unit 4, and the electrode material is applied. The thinner portion 1a of the unit 4 is evaporated (partial evaporation), and the electrode 2a is further laminated on the electrode 2 to make the thickness of the unit 4 uniform throughout. Then, after processing such as etching to form a predetermined electrode pattern, the unit 4 is cut to cut out the piezoelectric resonant element 3 in the thickness longitudinal vibration mode as shown in FIG.

According to the manufacturing method of the above embodiment, the thickness of the unit 4 is made uniform as a whole by stacking the electrode 2a on the thinner part of the unit 4. The resulting piezoelectric resonant elements 3 have small variations in frequency depending on the cutting position, and a plurality of piezoelectric resonant elements 3 with high frequency concentration can be obtained from one unit 4. Note that the pattern of the mask is not limited to one that exposes a part of the unit 4 in a rectangular shape as shown in the above embodiment (FIG. 2), but it is also possible to stack the electrode 2a on a thinner part of the unit 4. Various patterns of masks can be used. therefore,
For example, as shown in FIG. 3, it is also possible to stack the electrodes 2a using a mask 6 having a pattern that exposes a portion of the unit 4 in a triangular shape. Furthermore, there is no particular restriction on the number of times the partial vapor deposition is performed, and it can be performed in multiple steps as necessary. That is, after performing partial deposition using a mask 5 as shown in FIG. 2, a second partial deposition is performed using a mask 6 as shown in FIG. 3 to uniformize the thickness of the unit 4 with higher precision. It is also possible to do something like this.

FIGS. 4 and 5 are diagrams showing other embodiments of the present invention, and are diagrams showing an embodiment of a method of manufacturing a piezoelectric resonant element 13 in a thickness shear vibration mode as shown in FIG. 12. In this embodiment, the electrodes 12 are formed by vapor deposition on the entire surface of both main surfaces of the piezoelectric substrate 11, and a mask 15 is applied to expose the thinner end sides of the unit 14 (FIG. 4). Electrodes 12a are partially deposited only on both small ends.

[0015] In the above embodiment, the case where the electrodes were formed by vapor deposition was explained, but the method of forming the electrodes is not limited to the vapor deposition method, and methods such as sputtering and plating can also be used. be.

Further, other embodiments of the present invention are shown in FIGS. 6 to 9. In the manufacturing method of the piezoelectric resonant element of this embodiment, the mesh is dense in the portion corresponding to the thicker portion of the piezoelectric substrate 21, and the mesh is coarser in the portion corresponding to the thinner portion. Screen (vapor deposition pattern mask) 2 with mesh roughness changed at predetermined gradations as shown in FIG.
5 covers the piezoelectric substrate 21, and an electrode material is deposited thereon to form the electrode 22 on the piezoelectric substrate 21. According to this method, a large amount of metal (electrode material) vapor 26 passes through the coarse mesh portion of the screen 25, and a small amount of metal vapor 26 passes through the dense mesh portion. The electrode 22 is formed thickly in the thinner portion of the piezoelectric substrate 21, and the electrode 22 is thinner formed in the thicker portion of the piezoelectric substrate 21, so that the thickness of the unit 24 is made uniform as a whole. According to this method, it is possible to form the electrode 22 whose thickness changes at a predetermined gradation at each position by one vapor deposition without repeating the vapor deposition process multiple times, simplifying the manufacturing process. Manufacturing costs can be reduced. In the above embodiments, FIGS. 6 and 7 show a method for manufacturing a piezoelectric resonant element for thickness longitudinal vibration mode, and FIGS. 8 and 9 show a method for manufacturing a piezoelectric resonant element for thickness shear vibration mode. It shows. It should be noted that as a method for forming electrodes in the above embodiments using this vapor deposition pattern mask 25, a plating method is inappropriate, and it is preferable to use a vapor deposition method.

In each of the above embodiments, a method for manufacturing a piezoelectric resonant element in a thickness longitudinal vibration mode and a thickness shear vibration mode has been described, but the present invention is not limited to the above embodiments, and can be applied to other vibration modes. The present invention can also be applied to a method of manufacturing a piezoelectric resonant element.

[0018]

Effects of the Invention As described above, the method for manufacturing a piezoelectric resonant element of the present invention is such that the electrodes are formed thinly in the thicker portions of the piezoelectric substrate, and the electrodes are thickly formed in the thinner portions of the piezoelectric substrate. Since the thickness of the unit is made uniform throughout, the thickness of the unit can be made uniform without using any particular frequency adjustment ink, and the concentration of frequencies of the multiple piezoelectric resonant elements cut out from the unit can be adjusted. can be improved.

Furthermore, the thickness of the unit can be easily made uniform by applying a mask with a predetermined pattern to a unit formed by forming electrodes on the surface of a piezoelectric substrate, and further laminating electrodes in the thinner parts. .

Furthermore, the coarseness of the mesh is varied at a predetermined gradation so that the mesh is dense in the part corresponding to the thicker part of the piezoelectric substrate and coarser in the part corresponding to the thinner part. By using a screen that has been evaporated and depositing electrode material from above, an electrode whose thickness changes in a predetermined gradation can be formed in a single evaporation process without repeating multiple evaporation processes, and the thickness of the unit can be increased. This makes it possible to make the electrodes uniform throughout, simplifying the electrode formation process and reducing manufacturing costs.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a unit for a piezoelectric resonant element according to an embodiment of the present invention.

FIG. 2 is a diagram showing one step in an embodiment of the present invention, and is a plan view showing a state in which a mask for partial evaporation is applied to the unit.

FIG. 3 is a diagram illustrating one step in an embodiment of the present invention, and is a plan view illustrating a state in which a mask for another partial vapor deposition is applied to the unit.

FIG. 4 is a plan view showing one step of a method for manufacturing a piezoelectric resonant element according to another embodiment of the present invention.

FIG. 5 is a side view showing a unit for a piezoelectric resonant element according to another embodiment of the invention.

FIG. 6 is a plan view showing a screen (vapor deposition pattern mask) according to still another embodiment of the present invention.

FIG. 7 is a side cross-sectional view showing one step of still another embodiment of the present invention.

FIG. 8 is a plan view showing a screen (vapor deposition pattern mask) according to still another embodiment of the present invention.

FIG. 9 is a side sectional view showing one step of still another embodiment of the present invention.

FIG. 10 is a perspective view showing a piezoelectric resonant element of a conventional example and an example.

FIG. 11 is a perspective view showing a conventional method of manufacturing a piezoelectric resonant element.

FIG. 12 is a perspective view showing a piezoelectric resonant element of another conventional example and another example.

FIG. 13 is a perspective view showing another conventional method of manufacturing a piezoelectric resonant element.

[Explanation of symbols]

1, 11, 21 piezoelectric substrate 2, 12, 2
2 Electrodes 2a, 12a Electrodes (laminated electrodes) 3
, 13 piezoelectric resonant element 4,
14, 24 Unit 5, 6
mask 25
Screen (vapor deposition pattern mask)

Claims (3)

[Claims] 1. A method for manufacturing a piezoelectric resonant element in which a plurality of piezoelectric resonant elements are cut out by cutting a unit in which electrodes are formed on the surface of a piezoelectric substrate, the electrodes being thinly formed in the thicker portions of the piezoelectric substrate. Piezoelectric resonance is characterized in that the thickness of the unit is made uniform as a whole by forming thick electrodes in the parts where the thickness is small, and the frequency concentration of multiple piezoelectric resonance elements cut out from one unit is increased. Method of manufacturing elements. 2. The thickness of the unit is reduced by applying a mask with a pattern that exposes the thinner portion of the unit formed by forming electrodes on the surface of the piezoelectric substrate, and laminating the electrodes on the thinner portion of the unit. 2. The method of manufacturing a piezoelectric resonant element according to claim 1, wherein the piezoelectric resonant element is made uniform throughout. 3. The piezoelectric substrate is provided with a screen that has a dense mesh in the portion corresponding to the thicker portion and a coarse mesh in the portion corresponding to the thinner thickness portion, and the electrode material is passed through the screen. By vapor deposition, the electrodes are formed thinly in the thicker parts of the piezoelectric substrate, and the electrodes are thicker in the thinner parts of the piezoelectric substrate, thereby making the thickness of the unit uniform throughout. The method of manufacturing a piezoelectric resonant element according to claim 1.