JP2000040931A - Piezoelectric resonator, method of manufacturing piezoelectric resonator, and method of adjusting frequency of piezoelectric resonator - Google Patents

Abstract

[PROBLEMS] To manufacture a high-frequency piezoelectric resonator, the thickness of a ceramic substrate is reduced (several hundred μm or less in the MHz band). , Cracks and chips occur, and the thickness accuracy of 0.1% is the limit. SOLUTION: A resist forming step (FIGS. 1 (d) and (e)) for forming a resist 13 in a desired pattern on electrodes 12 formed on both main surfaces of a ceramic substrate 11, and after the resist forming step A vibration electrode forming step of etching the electrode 12 to form a vibration electrode 14 having a desired pattern (FIG. 1F); A frequency adjusting step (FIG. 1 (g)) of adjusting the frequency of the piezoelectric resonator by removing all or a part of the piezoelectric resonator 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a piezoelectric resonator used for a piezoelectric ceramic oscillator or a piezoelectric ceramic filter using an energy confining type in a thickness-longitudinal or thickness-shear mode, a method for manufacturing a piezoelectric resonator, and a piezoelectric resonator. The present invention relates to a method for adjusting the frequency of a resonator.

[0002]

2. Description of the Related Art A conventional method of manufacturing a piezoelectric resonator will be described using an energy trap type piezoelectric resonator. An energy confined resonator using thickness longitudinal or thickness shear vibration has a relationship of thickness × frequency = K (frequency constant). Therefore, even in the conventional manufacturing method, first, in order to improve the thickness accuracy, first, a step of preparing a ceramic substrate, and then, in order to finish the thickness of the ceramic substrate to a desired thickness, that is, a desired frequency, A step of polishing, a step of forming electrode films on both main surfaces of the ceramic substrate by vapor deposition, a step of applying a high voltage to the electrode films in insulating oil, and a step of polarizing the electrodes used for the polarization. Is generally followed by a step of removing a vibrating electrode by vapor deposition, sputtering or the like.

As disclosed in JP-A-7-58569 and JP-A-6-224677, in order to adjust the frequency more precisely, a manufacturing method of lap polishing after a polarization step, a vibration electrode, Is formed, a mass load film such as a vapor-deposited film is formed on the surface of the vibrating electrode.

[0004]

However, in the conventional manufacturing method, when a high-frequency piezoelectric resonator is manufactured, the thickness of the ceramic substrate is reduced (in the MHz band, several hundred μm or less), so that lap polishing is performed. In the mechanical adjustment method using the method, there is a problem that a crack or a chip is generated and a problem that a thickness accuracy of 0.1% is a limit. Also, in the method of forming a mass load film by vapor deposition, it is not possible to individually change the vapor deposition amount of a large number of resonators having different frequency adjustment amounts, and the adjustment is limited to a unit of 0.1%. There is.

The present invention has been made in consideration of the above-described problems of the conventional method of manufacturing a piezoelectric resonator, and has been made in consideration of the above-described problems. It is an object of the present invention to provide a method for manufacturing a resonator and a method for adjusting the frequency of a piezoelectric resonator. It is another object of the present invention to provide a piezoelectric resonator which has no defect and whose frequency is accurately adjusted.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, a first present invention (corresponding to the first aspect of the present invention).
A resist forming step of forming a resist in a desired pattern on electrodes formed on both main surfaces of the piezoelectric substrate; and after the resist forming step, the electrodes are etched to form the desired pattern of vibrations. A vibrating electrode forming step of forming an electrode, and a frequency adjusting step of adjusting the frequency of the piezoelectric resonator by removing all or a part of the resist on the vibrating electrode after the vibrating electrode forming step A method for manufacturing a piezoelectric resonator, characterized in that:

A second aspect of the present invention (corresponding to the second aspect of the present invention) includes a polarizing step of polarizing the piezoelectric substrate by applying a voltage to the electrode, wherein the polarizing step includes:
A first method of manufacturing a piezoelectric resonator according to the present invention, which is performed before the resist forming step or after the vibration electrode forming step and before the frequency adjusting step.

A third aspect of the present invention (corresponding to the third aspect of the present invention) is characterized in that the resist is a resin having a thermosetting property and / or a photosetting property. This is a method for manufacturing the piezoelectric resonator of the present invention.

In a fourth aspect of the present invention (corresponding to the fourth aspect of the present invention), the resist is removed by a laser beam in the frequency adjusting step.
The method for manufacturing a piezoelectric resonator according to any one of the above (1) to (3).

A fifth aspect of the present invention (corresponding to the fifth aspect of the present invention) comprises a piezoelectric substrate, a vibrating electrode opposed to the piezoelectric substrate, and a mass load film formed on the vibrating electrode. Wherein the mass load film has a mass necessary to give a desired frequency to the piezoelectric resonator, and is made of a material that can be a resist when the vibrating electrode is formed by etching. It is a piezoelectric resonator.

A sixth aspect of the present invention (corresponding to the sixth aspect of the present invention) comprises a piezoelectric substrate, a vibrating electrode opposed to the piezoelectric substrate, and a mass load film formed on the vibrating electrode. A method of adjusting the frequency of the piezoelectric resonator, which is a material that can be a resist when the mass load film is formed by etching the vibrating electrode, wherein all or a part of the mass load film, A frequency adjustment method of the piezoelectric resonator, wherein the frequency of the piezoelectric resonator is adjusted by removing with a laser beam or other means.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, the first embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. FIG. 1 is a cross-sectional view of each step illustrating a method for manufacturing a piezoelectric resonator having a thickness longitudinal vibration according to the present embodiment. In FIG. 1, 11 is a ceramic substrate, 12 is an electrode, 13 is a resist, 14
Is a vibration electrode, and 15 is a laser beam.

First, as shown in FIG. 1A, a ceramic substrate mainly containing a piezoelectric ceramic such as lead zirconate titanate is prepared.

Next, as shown in FIG. 1B, electrodes are formed on both main surfaces. Methods for forming electrodes include vapor deposition,
Any of a dry method such as sputtering, a wet method such as electroless plating, and a method of printing a conductive paste is possible.

Next, as shown in FIG. 1C, polarization is performed (corresponding to the polarization step of the present invention). For the polarization, for example, a voltage of 2 to 5 KV / mm is applied in insulating oil. However, since the thickness of the ceramic substrate is thin, when the applied voltage is 500 V or less, it is possible even in the air.

Next, as shown in FIG. 1D, a resist layer is formed on the electrodes.

Next, as shown in FIG. 1E, a resist is formed in a desired pattern (together with FIG. 1D corresponds to the resist forming step of the present invention).

Next, as shown in FIG. 1 (f), the electrodes are etched in a pattern to form a vibrating electrode and a lead electrode (corresponding to the vibrating electrode forming step of the present invention).

Next, after measuring the frequency, as shown in FIG. 1 (g), the resist on the vibrating electrode is partially removed by laser light to reduce the mass load, thereby adjusting the frequency. Thus, the piezoelectric resonator of the present invention is obtained (corresponding to the frequency adjusting step of the present invention).

In the above description, the resist is desirably resin or metal. In the case of a resin, a photocurable resin or a thermosetting resin is desirable. In addition, a resin having both photocurable and thermosetting properties is particularly desirable. When a photocurable resin is used, first, as shown in FIG. 1D, a resin is formed on the entire surface of the electrode, and then exposed and developed in a desired pattern, and the pattern is formed as shown in FIG. Although a patterned resist is formed, there is a merit that a vibration electrode and a lead electrode after etching can be obtained with high accuracy. In the case of a thermosetting resin, the step of FIG. 1D is unnecessary, and as shown in FIG. 1E, after patterning directly by a screen printing method or the like,
Heating and curing to form a resist . In the case of a resin having both photocurable and thermosetting properties, there is an effect that both good points can be obtained. When a metal is used as a resist, it is necessary to selectively etch the electrode at the time of etching, so that the metal must have higher corrosion resistance to an etchant than the electrode. For example, when the electrode is copper and the etching solution is an aqueous ferrous chloride solution, it is desirable to use nickel or tin as the resist.

In the above, when the resist is a resin, the laser beam is desirably an excimer laser beam or a harmonic YAG laser beam having a wavelength of 400 nm or less, for example. The resin used at that time preferably has an absorptance of 40% or more at a wavelength of 400 nm or less. The reason is,
This is because the resist can be finely removed, that is,
This is because the frequency can be adjusted with high accuracy. When the resist is metal, a fundamental wave YAG laser is desirable.

As can be seen from the above description, according to the method of manufacturing a piezoelectric resonator having a thickness-longitudinal vibration in the present embodiment, mechanical adjustment such as lap polishing is not required for a thin ceramic substrate. In addition, the electrode used for polarization can be shared with the vibration electrode and the extraction electrode, and the resist for forming the vibration electrode and the like can be shared as the mass load film used for frequency adjustment, so that the number of steps can be reduced.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An embodiment will be described with reference to the drawings. FIG. 2 is a cross-sectional view of each step showing a method of manufacturing a piezoelectric resonator having a thickness longitudinal vibration according to the present embodiment. 2, 21 is a ceramic substrate, 22 is an electrode, 23 is a resist, 24
Is a vibration electrode, and 25 is a laser beam.

First, as shown in FIG. 2A, a ceramic substrate mainly containing a piezoelectric ceramic such as lead zirconate titanate is prepared.

Next, as shown in FIG. 2B, electrodes are formed on both main surfaces. Methods for forming electrodes include vapor deposition,
Any of a dry method such as sputtering, a wet method such as electroless plating, and a method of printing a conductive paste is possible.

Next, as shown in FIG. 2C, a resist layer is formed on the electrodes.

Next, as shown in FIG. 2D, a resist is formed in a desired pattern (together with FIG. 2C corresponds to the resist forming step of the present invention).

Next, as shown in FIG. 2E, the electrodes are etched in a pattern to form a vibrating electrode and a lead electrode (corresponding to the vibrating electrode forming step of the present invention).

Next, as shown in FIG. 2F, partial polarization is performed (corresponding to the polarization step of the present invention). For the polarization, for example, a voltage of 2 to 5 KV / mm is applied in insulating oil.
However, since the thickness of the ceramic substrate is thin, the applied voltage is 5
When the voltage is lower than 00 V, it is possible even in the atmosphere.

Next, after measuring the frequency, as shown in FIG. 2 (g), the resist on the vibrating electrode is partially removed by laser light to reduce the mass load, thereby adjusting the frequency. Thus, the piezoelectric resonator of the present invention is obtained (corresponding to the frequency adjusting step of the present invention).

In the above description, the resist is desirably resin or metal. In the case of a resin, a photocurable resin or a thermosetting resin is desirable. In addition, a resin having both photocurable and thermosetting properties is particularly desirable. When a photocurable resin is used, first, as shown in FIG. 2D, a resin is formed on the entire surface of the electrode, and then exposed and developed in a desired pattern, and the pattern is formed as shown in FIG. Although a patterned resist is formed, there is a merit that a vibration electrode and a lead electrode after etching can be obtained with high accuracy. In the case of a thermosetting resin, the step of FIG. 2D is unnecessary, and as shown in FIG. 2E, after patterning directly by a screen printing method or the like,
Heats and cures to form a resist. Compared to photo-curable resin, it has high adhesion to ceramic substrate and electrodes, and has high hardness after curing, so it has good points that hardly cause vibration inhibition. . In the case of a resin having both photocurable and thermosetting properties, there is an effect that both good points can be obtained. When a metal is used as a resist, it is necessary to selectively etch the electrode at the time of etching, so that the metal must have higher corrosion resistance to an etching solution than the electrode. For example, when the electrode is copper and the etchant is an aqueous ferrous chloride solution, it is desirable to use nickel or tin as the resist.

Also, when the resist is resin,
For example, an excimer laser beam or a harmonic YAG laser beam having a wavelength of 400 nm or less is desirable. The resin used at that time has an absorptance of 40% at a wavelength of 400 nm or less.
The above is desirable. The reason is that the resist can be finely removed, that is, the frequency can be adjusted with high precision. When the resist is metal, a fundamental wave YAG laser is desirable.

As can be seen from the above description, according to the method of manufacturing a piezoelectric resonator having a thickness-longitudinal vibration according to the present embodiment, mechanical adjustment such as lap polishing is not required for a thin ceramic substrate. In addition, the electrode used for polarization can be shared with the vibration electrode and the extraction electrode, and the resist for forming the vibration electrode and the like can be shared as the mass load film used for frequency adjustment, so that the number of steps can be reduced.

In the first and second embodiments described above, the polarization step of the present invention may be performed before the resist forming step of the present invention or the vibrating electrode forming step and the frequency adjusting step of the present invention. However, the present invention is not limited to this, and it suffices that polarization as a piezoelectric resonator is finally performed. Also, it has been described that before the resist forming step of the present invention, a piezoelectric substrate is prepared and a step of forming an electrode is performed thereon. However, the present invention is not limited to this. May be prepared. In short, a resist forming step of forming a resist in a desired pattern on the electrodes formed on both main surfaces of the piezoelectric substrate, and after the resist forming step, the electrodes are etched to form the desired pattern of vibrations. A vibrating electrode forming step of forming an electrode, and a frequency adjusting step of adjusting the frequency of the piezoelectric resonator by removing all or a part of the resist on the vibrating electrode after the vibrating electrode forming step. What is necessary is just a manufacturing method of a piezoelectric resonator.

In the first and second embodiments, the method of manufacturing the piezoelectric resonator of the present invention has been mainly described. However, the piezoelectric resonator of the present invention comprises a piezoelectric substrate and the piezoelectric substrate. Comprising a vibrating electrode and a mass load film formed on the vibrating electrode, the mass load film having a mass necessary to give a desired frequency to the piezoelectric resonator,
The vibration electrode is made of a material that can be a resist when the vibration electrode is formed by etching. Further, the frequency adjustment method of the piezoelectric resonator of the present invention, a piezoelectric substrate, a vibrating electrode opposed to sandwich the piezoelectric substrate,
A mass load film formed on the vibration electrode, wherein the mass load film adjusts the frequency of a piezoelectric resonator that is made of a material that can be a resist when the vibration electrode is formed by etching. The frequency of the piezoelectric resonator is adjusted by removing all or a part of the mass load film using a laser beam or other means. The method for adjusting the frequency of the piezoelectric resonator of the present invention is used, for example, when changing the frequency of the piezoelectric resonator of the present invention to another frequency.

[0037]

As is apparent from the above description, the present invention according to claims 1 to 4 provides a piezoelectric resonator capable of accurately adjusting the frequency without causing defects such as cracks and chips. A manufacturing method can be provided.
That is, a thin ceramic substrate does not require mechanical adjustment such as lapping. In addition, the electrode used for polarization can be shared with the vibration electrode and the extraction electrode, and the resist for forming the vibration electrode and the like can be shared as the mass load film used for frequency adjustment, so that the number of steps can be reduced.

The present invention according to claim 5 has no defects,
A piezoelectric resonator whose frequency is adjusted with high accuracy can be provided.

The present invention according to claim 6 can provide a method of adjusting the frequency of a piezoelectric resonator that can adjust the frequency with high accuracy.

[Brief description of the drawings]

FIGS. 1A to 1C are cross-sectional views illustrating a method of manufacturing a piezoelectric resonator having a thickness-longitudinal vibration according to a first embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views illustrating a method of manufacturing a piezoelectric resonator having a thickness-longitudinal vibration according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Ceramic substrate 12 Electrode 13 Resist 14 Vibration electrode 15 Laser light 21 Ceramic substrate 22 Electrode 23 Resist 24 Vibration electrode 25 Laser light

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Hase 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5J033 AA02 BB04 CC13 DD02 KK02 KK06 5J041 AA12 AA15 CB05

Claims (6)

[Claims] A resist forming step of forming a resist in a desired pattern on electrodes formed on both main surfaces of the piezoelectric substrate; and after the resist forming step, the electrode is etched to form the desired pattern. A vibrating electrode forming step of forming a vibrating electrode having a shape, and a frequency adjusting step of adjusting the frequency of the piezoelectric resonator by removing all or a part of the resist on the vibrating electrode after the vibrating electrode forming step And a method for manufacturing a piezoelectric resonator. 2. A polarizing step of polarizing the piezoelectric substrate by applying a voltage to the electrode, wherein the polarizing step is performed before the resist forming step or after the vibrating electrode forming step and The method according to claim 1, wherein the method is performed before the frequency adjusting step. 3. The method according to claim 1, wherein the resist is a thermosetting resin and / or a photosetting resin. 4. The method according to claim 1, wherein the resist is removed by a laser beam in the frequency adjusting step. 5. A piezoelectric substrate, a vibrating electrode opposed to the piezoelectric substrate with the piezoelectric substrate interposed therebetween, and a mass load film formed on the vibrating electrode, wherein the mass load film provides a desired frequency to the piezoelectric resonator. A piezo-resonator having a mass required to provide the material and a material that can be used as a resist when the vibrating electrode is formed by etching. 6. A piezoelectric device comprising: a piezoelectric substrate; a vibrating electrode opposed to the piezoelectric substrate with the piezoelectric substrate interposed therebetween; and a mass load film formed on the vibrating electrode, wherein the mass load film forms the vibrating electrode by etching. A method of adjusting the frequency of a piezoelectric resonator made of a material that can become a resist, wherein the whole or a part of the mass load film is removed by using a laser beam or other means, whereby the piezoelectric resonance is removed. A method for adjusting the frequency of a piezoelectric resonator, comprising adjusting the frequency of a resonator.