JPH09326668A - Piezoelectric element and production of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an insulation film, which has thickness for securing enough electric insulation property, can suppress the discharge and adsorption of gas and further improves flexibility and tight adhesion not to damage vibration characteristics, on the surface of a piezoelectric body where electrodes are formed. SOLUTION: After a piezoelectric vibrator 2 forming electrodes 5 and 6 on the surface of the piezoelectric body is mounted at a plug 3 and before it is completed by being airtightly sealed into a case, gas discharge is generated in prescribed gas for discharge under atmospheric pressure or nearby pressure, the excited active element of organic compound of liquid or gas is generated at ordinary temperature during gas discharge 36, and the plug and the surface of the piezoelectric vibrator are exposed on this element. On the surface of them, the organic material is polymerized, and a resin film 9 is formed so as to cover all the electrodes, its dividing line 18 and the mount connecting part of the plug or the like. In the case of a tuning fork piezoelectric vibrator, the surface of the resin film is irradiated with laser beams from the upside so that frequency control is performed. Besides, near a tuning fork shaped part, the resin film is made thinner than the other area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator formed of a piezoelectric crystal such as quartz or a piezoelectric ceramic material, and SAW (Surface Acoustic Wave).
The present invention relates to a piezoelectric element such as a device, and more particularly to a piezoelectric element manufactured by utilizing a surface treatment technology using excited active species generated in plasma under atmospheric pressure or a pressure in the vicinity thereof and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a piezoelectric element utilizing a resonance action based on a piezoelectric effect is well known and is used for a vibrator, a filter, an oscillator and the like. Piezoelectric elements include piezoelectric vibrators such as tuning fork type oscillators having a frequency band of about 20 kHz to 1 MHz, AT cut oscillators of about 4 to 125 MHz, and SAW devices using surface acoustic waves. Generally, a piezoelectric vibrator includes a vibrating piece made of a piezoelectric body such as a crystal plate having an electrode formed on the surface thereof, and a plug for mounting the vibrating piece and electrically connecting it to the outside. The resonator element is hermetically sealed in the case using a hermetic terminal.

SAW devices can stably obtain high frequencies in the 100 MHz to gigahertz band, and are used as SAW resonators for constructing oscillation circuits and SAW filters for high frequencies. Generally, a SAW device has a SAW piece made of a piezoelectric material such as a crystal plate having a fine comb-shaped electrode formed on the surface thereof. The SAW piece is usually entirely bonded on a support and vacuum-sealed in a case,
Recently, the applicant of the present application has developed a SAW device having a structure in which a SAW piece is mounted in a cantilever manner on a plug having a hermetic terminal similar to that of a piezoelectric vibrator and is vacuum-sealed in a case.

However, in these piezoelectric elements, before the element piece such as the piezoelectric vibrating piece or the SAW piece is hermetically sealed inside the case, foreign matter is mixed into the case during the manufacturing process, or the plug or the surface of the case is sealed. The plating may come off and generate dust. In the case of a tuning fork type piezoelectric vibrator or a SAW device, if such dust adheres to the surface of the piezoelectric body and short-circuits between adjacent electrodes, there is a risk that problems such as oscillation stoppage and changes in electrical impedance will occur. In particular, since miniaturization of electronic parts has been recently demanded, the gap between the electrodes is narrowed to about 20 to 30 μm in order to miniaturize the piezoelectric element, and a short circuit between the electrodes is likely to occur. Also,
The electrode deteriorates due to the adsorption of oxygen mixed in the case during sealing and the gas released from the plug and case after sealing,
There is a possibility that the oscillation frequency shifts or the CI (crystal impedance) value increases, which deteriorates the characteristics of the piezoelectric element and reduces the reliability.

Therefore, conventionally, a piezoelectric element having an insulating film formed on the surface of a piezoelectric body having electrodes formed thereon has been developed. For example, in Japanese Examined Patent Publication No. 22564/1990, the electrode portion formed on the piezoelectric substrate is covered with an insulating film of tantalum pentoxide formed by sputter deposition to suppress deterioration of characteristics due to short circuit between the electrodes. A SAW element having such a structure has been proposed. In addition, Japanese Patent Application No.
No. 2916660 discloses that an insulating film made of an oxide or fluoride such as SiO 2 is formed on at least the surface of a flat electrode of a tuning fork type piezoelectric vibrator by vacuum vapor deposition, sputtering, vacuum plasma CVD, or the like, and a gas from the outside or It describes a configuration that prevents changes in the oscillation frequency and deterioration of characteristics such as CI due to the adsorption of dust. Furthermore, JP-A-60-134
In Japanese Patent No. 617, a piezoelectric resin is applied on a metal layer deposited on the surface of a piezoelectric vibration plate and patterned by a photolithography technique to form an excitation electrode and an extraction electrode,
Further, a piezoelectric vibrator in which a polyimide resin film is left on the electrode to prevent deterioration due to oxidation or the like and a method for manufacturing the same are disclosed.

[0006]

However, in the conventional piezoelectric element in which the insulating film of the electrode portion is formed of a hard and rigid oxide such as SiO2 as described above, if the insulating film is made too thick, the element is not formed. The vibration of the piece is obstructed, the CI value deteriorates, and the efficiency decreases. Therefore, the film thickness of the insulating film is usually around 1000 Å, but this may not be able to ensure sufficient electrical insulation. Moreover, the allowable range of film thickness is ±
There is a problem that it is difficult to control the film thickness in the manufacturing process because it is necessary to set the film thickness to a high accuracy of about 200Å and to eliminate the unevenness of the film thickness.

Further, particularly in the case of a tuning fork type piezoelectric vibrator,
Conventionally, frequency adjustment is generally performed by removing the metal electrode film of the frequency adjustment weight using laser light. However, the laser beam cannot be removed because it passes through a conventional insulating film made of an oxide such as SiO2. Therefore, when the conventional frequency adjusting method using laser light is adopted, the insulating film must be formed by using a mask or the like except for the electrode film in the weighted portion, and there is a problem that the work is troublesome.

Further, when the insulating film is formed before mounting the element piece on the plug, it is necessary to mask the land for electrically connecting the electrode to the plug, so that the film forming process is troublesome. Furthermore, after sealing in the case, metal parts such as lands and inner leads, which are not covered with the insulating film and are exposed inside the case, remain on the surface of the element piece and the plug. There is a risk of short-circuiting between the electrodes that operate.

On the other hand, when the insulating film is formed after the element piece is mounted on the plug, if the insulating film is formed even in the sealing portion of the plug, the airtightness inside the case cannot be ensured. Therefore, it is necessary to mask the plug when forming the insulating film, but complete masking is practically difficult. In addition, such masking becomes a large scale, resulting in poor workability and reduced production efficiency.

Further, since the film forming process by sputtering or vapor deposition requires expensive vacuum equipment, it takes time and cost in manufacturing, and it is difficult to continuously process the piezoelectric element with other manufacturing processes. Manufacturing automation and productivity cannot be improved. In addition, since batch processing is generally performed under vacuum or reduced pressure, it is not possible to simultaneously measure the frequency of the element pieces while forming the insulating film, so it is very difficult to control the film thickness. Especially in the case of sputtering, the adhesion of the coating may differ depending on the surface condition of the piezoelectric body and electrodes to be formed, which may affect the frequency aging characteristics of the piezoelectric element. is necessary.

Similarly, in the piezoelectric vibrator disclosed in Japanese Patent Laid-Open No. 60-134617, it is not possible to simultaneously form the insulating film and measure the frequency because the manufacturing process is batch processing. Further, since the resin film is formed before mounting on the plug, it is necessary to remove the resin film from the extraction electrode when connecting to the plug, which is a troublesome manufacturing process. Moreover, since the connection part with the plug and the surface of the plug cannot be covered, there is a possibility that these parts exposed inside the case may be deteriorated due to oxidation or dust may be generated to short-circuit the extraction electrodes.

Therefore, the piezoelectric element of the present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a surface of the piezoelectric body on which an electrode is formed with a sufficient electrical insulation property. (EN) Provided is a piezoelectric element having an insulating film having a film thickness for ensuring the above, suppressing the release and adsorption of gas, and having excellent flexibility and adhesiveness without impairing its vibration characteristics. .

Further, an object of the present invention is to manage such a film thickness and film quality in order to form such an insulating film relatively easily in a short time and at a low cost, and to secure insulation and adhesion. It is an object of the present invention to provide a method for manufacturing a piezoelectric element, which is easy to control, has excellent workability, and can improve productivity by automation and in-line processing. In addition to this, it is an object of the present invention to provide a manufacturing method capable of easily and accurately adjusting the frequency of a tuning fork type piezoelectric vibrator.

[0014]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and its contents will be described below with reference to the embodiments shown in the drawings. The piezoelectric element of the present invention is
An element piece having an electrode formed on the surface of the piezoelectric body, a plug for mounting the element piece, and a case for hermetically housing the element piece, the surface of the element piece is at or near atmospheric pressure. It is characterized in that a predetermined discharge gas is coated with a resin film formed by using excited active species of an organic compound generated by gas discharge.

Since the resin film formed on the surface of the element piece by utilizing the plasma generated by the gas discharge under the atmospheric pressure has sufficient flexibility, it is substantially formed even if it is formed relatively thick. There is no risk of disturbing the vibration of the element piece. Therefore, while maintaining the characteristics of the piezoelectric element, it is possible to significantly improve the electrical insulation and effectively prevent the deterioration of the electrodes and the like due to the release of gas and the mixing of oxygen. In addition, the allowable range of film thickness can be set to a large value of ± 1000Å, and even if there is some unevenness in the film thickness, the effect on the insulating property and the characteristics of the piezoelectric element is extremely small. It's easy.

According to the present invention, the resin coating can be formed of a polymerized film of an organic material. For example, when the resin coating is formed of a silicone resin film, water repellency can be obtained in the resin coating, which is more convenient. At this time, if the lower layer portion of the resin film is formed of an inorganic element or its oxide contained in the organic compound, the adhesion is improved and excellent frequency aging characteristics are obtained.

As such a piezoelectric element, as the element piece, a tuning fork type piezoelectric vibrator having a piezoelectric vibrating piece vibrating in a bending vibration mode or a torsional vibration mode, and a bar type having a crystal vibrating piece vibrating in a thickness shear mode are used. AT-cut crystal unit, SAW resonator using surface acoustic wave, S
There are SAW devices that have SAW pieces such as AW filters. In particular, in the case of a tuning fork type piezoelectric vibrator in which electrodes with different polarities are adjacent to each other on the piezoelectric surface, a short circuit between the electrodes is completely prevented, so the dividing line between the electrodes can be set narrower, and the product It is possible to reduce the size and excite more efficiently.

Further, in the case of a tuning fork type piezoelectric vibrator, according to the present invention, a tuning fork-shaped element piece having two arm portions extending in the longitudinal direction from the base end portion connected to the plug is made of resin. The film thickness of the coating film is formed thinner in the region near the fork portion where the arm portion joins to the base end portion along the longitudinal direction thereof than in other regions. As a result, the vibration of the piezoelectric vibrating piece is not substantially suppressed by the resin coating, particularly in the region near the fork of the tuning fork where the distortion amount of the flexural vibration is maximum, so the influence on the CI value is ensured. It can be prevented. In particular, if the film thickness of the resin coating near the fork part is about 1/2 of the film thickness of other regions, preferably 500 to 1000 Å, the desired insulation effect can be obtained without affecting the characteristics of the piezoelectric vibrator. It is convenient because it can be obtained.

Further, in the method for manufacturing a piezoelectric element of the present invention, after mounting the element piece having the electrode formed on the surface of the piezoelectric body on the plug and before air-tightly sealing the inside of the case to complete the atmosphere, A gas discharge is generated in a predetermined discharge gas under a pressure in the vicinity thereof, and an excited active species of an organic compound that is a liquid or a gas at room temperature is generated by the gas discharge, and the surface of the element piece mounted on the plug is The method is characterized by including a step of exposing to an excited active species to form a resin coating film of an organic material on the surface.

As described above, plasma is generated by gas discharge under atmospheric pressure, and excited active species of organic substances generated thereby cause binding and dissociation one after another, thereby polymerizing the resin coating directly from the gas phase, Since an insulating film with a sufficient film thickness can be formed on the entire surface of the element exposed to the excited active species and the surface of the plug, all electrodes and their dividing lines, and the mount connection part of the plug are completely insulated. can do. Moreover, since the resin coating has flexibility, even if it is formed on the sealing surface of the plug, there is no risk of impairing the airtightness between the case and the plug. Therefore, masking of the plug is not required during film formation, and the work is easy. Further, since a vacuum device and equipment are not required, the manufacturing device can be configured easily and inexpensively, and can be inlined and automated. Furthermore, since the resin film is formed with the element piece mounted on the plug, the frequency can be measured during the film formation, and it is easy to accurately control and manage the film thickness suitable for the desired frequency. .

According to the present invention, the resin film can be formed by mixing the discharge gas with an organic compound. Silicone or a hydrocarbon compound can be used as the organic compound.

Further, according to the present invention, while the element piece mounted on the plug is relatively moved from the downstream side to the upstream side with respect to the flow of the discharge gas supplied to the gas discharge region, The surface of the element piece is exposed to the excited active species of the discharge gas. In such a case, generally, on the downstream side of the discharge gas containing the excited active species, a hydrophilic film having a high degree of polymerization and adhesion and a small number of methyl groups is formed, whereas on the upstream side, the degree of polymerization is high. Also, a water-repellent film having low adhesion and a large number of methyl groups is formed. Therefore, the properties of the resin coating formed on the surface of the piezoelectric body can be controlled in the thickness direction so that the lower layer portion has high adhesion and the surface layer portion has high water repellency. Therefore, it is possible to obtain an insulating film having excellent frequency aging characteristics and capable of suppressing gas release and adsorption. In an actual production line, while discharging the element mounted on the plug so as to pass through the gas discharge area, a discharge gas is supplied so that the element flows from the exit side to the entrance side. It is convenient to supply.

Further, according to the present invention, in the case where the element piece is a piezoelectric vibrating piece having a tuning fork shape, the frequency of the piezoelectric vibrating piece is formed by irradiating a laser beam on the resin coating after forming the resin coating. Can be adjusted. As a result, the resin film and the metal film on the surface of the resonator element can be removed at the same time, so that the frequency can be adjusted more accurately and easily, and the resin film can be formed on the entire surface of the resonator element without masking. Good and complete insulation treatment is possible.

When the element piece is a tuning-fork-shaped piezoelectric vibrating piece, two arms extend the time for exposing the surface of the element piece to the excited active species in the longitudinal direction from the base end portion connected to the plug. In the region near the fork portion where the portion is joined to the base end portion, the film thickness of the resin coating is set in the region near the fork portion as described above by making the exposure time shorter in other regions along the longitudinal direction. In, it is possible to manufacture a piezoelectric element that is thinner than other regions.

In this case, a gas is generated by applying a predetermined voltage while supplying a discharge gas between a pair of power supply electrodes and a ground electrode which are arranged opposite to each other, and a piezoelectric vibrating reed mounted on a plug. To move in the gas discharge region between the two electrodes by moving along its longitudinal direction,
At this time, if the speed at which the region near the fork passes through the gas discharge region is made higher than the passing speed of the other region, the exposure time to the region near the fork is shortened, and the film of the resin film is formed. The thickness can be easily adjusted.

[0026]

1 shows a tuning-fork type piezoelectric vibrator 1 to which the present invention is applied. As in the conventional case, a piezoelectric vibrating piece 2 and a plug 3 for supporting the piezoelectric vibrating piece 2 in a cantilever manner. And a bottomed cylindrical metal case 4. As shown in FIG. 2, the piezoelectric vibrating piece 2 is made of a thin crystal piece that is formed into a desired tuning fork shape and has two left and right arm portions extending in the longitudinal direction from the base end. Flat electrodes 5 and 6 formed on the side surface and side electrodes 7 formed in the plate thickness direction,
8 is provided. As shown in FIG. 3, the side surface electrodes 7 and 8 of this embodiment are formed so as to slightly wrap around from the respective side surfaces of the crystal piece to the front and back surfaces thereof. In addition, an electrically insulating resin coating 9 is formed on almost the entire surface of the piezoelectric vibrating piece 2. Piezoelectric resonator element 2 mounted on plug 3
Is hermetically sealed in the case 4, and the inside of the case 4 is
Normally maintained in a vacuum atmosphere.

The tuning fork type piezoelectric vibrator 1 of this embodiment can be manufactured according to the steps shown in the flow chart of FIG. First, similarly to the conventional process, the raw quartz stone is cut into blocks having a predetermined size and shape, and the blocks are cut into wafers having a predetermined plate thickness and polished. On both front and back surfaces, for example, a Cr film and an Au film are formed as a corrosion resistant film by sputtering or vapor deposition, and the resist applied thereon is patterned into a tuning fork shape with a photomask to remove the exposed corrosion resistant film. A large number of tuning fork-shaped outer shapes are etched on a quartz wafer using hydrofluoric acid or the like.

Next, a Cr underlayer having a film thickness of 100 to 500 Å is formed on the surface of the crystal piece by a conventional technique, for example, by vapor deposition or sputtering, and a film having a film thickness of 2000 to 2000 is formed thereon. An Au electrode film of about 3000Å
It is formed by patterning using a photolithography technique. In another embodiment, the electrodes can be formed by vapor deposition or sputtering of Cr and Au films with the surface of the quartz piece masked.

The gap between the adjacent planar electrode and side electrode, called a dividing line, is about 20 to 30 μm in the narrowest place in order to efficiently oscillate a small piezoelectric vibrating piece in response to the demand for miniaturization of parts. Is. The electrode film is Ag
It can also be formed by. At the lower end of the base end portion of the piezoelectric vibrating piece 2, connection lands 10 and 1 drawn out from the electrodes are formed.
1 are provided on the left and right. Further, weights 12 and 13 for frequency adjustment are provided at the tips of the arms of the piezoelectric vibrating piece 2. The weight portions 12 and 13 are formed to have a thickness of about 2 to 3 μm by depositing an Au film thicker than other electrode portions.

Next, the individual piezoelectric vibrating pieces 2 are cut from the crystal wafer and mounted on the plugs 3, respectively.
The plug 3 is a so-called hermetic terminal, and has two lead wires 16 penetrating an insulator 15 made of glass in which a metal ring 14 is fitted on the outer periphery thereof. Short pin-shaped inner leads 17 protruding from the insulator of the plug 3 to the inside of the case 4 are connected to the respective lands of the piezoelectric vibrating piece 2 by brazing using solder or bonding using Ag paste or the like. As a result, the plug 3 can support the piezoelectric vibrating piece 2 in a cantilever manner, and at the same time, the electrode can be electrically connected to the external circuit through the lead wire 16.

With the piezoelectric vibrating reed 2 mounted on the plug 3 in this way, as will be described later with reference to FIG. 5, the resin coating 9 is formed by using plasma generated by discharge under atmospheric pressure.
Is formed. The resin coating 9 of the present embodiment is made of a silicone resin film, and not only the surfaces of the planar electrodes 5 and 6 and the side electrodes 7 and 8, but also the quartz ground surface exposed to the dividing line 18, the above-mentioned respective lands, inner leads and them. The film is formed so as to completely cover the connection part of.

As a result, in the piezoelectric vibrating piece 2, the electrodes and lands adjacent to each other are short-circuited due to dust produced in the manufacturing process, the plug, the case, or the like, or the gas released from the plug, the case, or the Ag paste is discharged. It is possible to completely prevent adsorption to the electrode film. Furthermore, since the resin film 9 has flexibility, even if it is formed to have a sufficient thickness to exhibit electric insulation, there is no possibility of substantially disturbing the vibration of the piezoelectric vibrating piece during use. In addition to the above silicone, various resin materials made of organic compounds such as hydrocarbon compounds can be used for the resin coating 9.

The resin coating film 9 is generally formed by using a surface treatment apparatus having the structure shown in FIG. The surface treatment device 19 is
It has a plate-shaped power supply electrode 21 connected to the AC power supply 20, a stage 22 as a ground electrode facing the electrode with a narrow gap, and a gas supply device 23 for supplying a discharge gas to the gap. The lower surface of the power supply electrode 21 is covered with a dielectric 24 such as flat plate quartz in order to eliminate abnormal discharge. The gas supply device 23 has a nozzle 25 that opens so as to eject a discharge gas into the space between the dielectric and the stage.

By discharging the discharge gas from the nozzle 25,
The atmosphere between the dielectric and the stage and in the vicinity thereof is replaced with the discharge gas. According to the present invention, the piezoelectric vibrating reed 2 mounted on the plug 3 is continuously conveyed in the direction of the arrow A by, for example, a conveyor means, and is horizontally opposed between the dielectric 24 and the stage 22 with respect to the nozzle 25. Side to the nozzle side. Therefore, the piezoelectric vibrating reed 2 is conveyed from the downstream side to the upstream side with respect to the flow of the discharge gas. As the discharge gas, a gas is used in which a rare gas such as helium is used as a carrier gas and vaporized silicone is mixed in order to easily generate a gas discharge under atmospheric pressure. Silicone can be easily mixed with the discharge gas by heating a liquid that is liquid at room temperature to an appropriate temperature to vaporize it.

The discharge gas mixed with vaporized silicone can be easily obtained by using the gas supply device 23 having the structure shown in FIG. 6, for example. A bypass 28 is provided in a pipe line 27 leading from the gas supply source 26 to the nozzle 25, and a part of carrier gas such as helium sent from the gas supply source is sent into the tank 29. Liquid silicone 30 is stored in the tank at room temperature and is easily vaporized by a heater 31. The carrier gas introduced into the tank 29 is returned to the conduit 27 containing the vaporized silicone. The proportion of silicone contained in the discharge gas supplied to the gap of the surface treatment apparatus is controlled by the control valves 32, 3
From the gas supply source 26 via the conduit 27 and the bypass 2
The flow rate of the carrier gas sent to the control unit 8 is appropriately adjusted by controlling the flow rate control devices 34 and 35, respectively.

FIG. 7 shows another embodiment of the gas supply device for supplying the discharge gas in which the vaporized silicone is mixed in the same manner. In this embodiment, instead of omitting the heater of FIG. 6 from the tank 29 provided in the bypass 28, the carrier gas introduced from the gas supply source 26 is jetted into the liquid silicone 30 of the tank 29. As a result, a carrier gas containing vaporized silicone is generated in the space above the tank, which can be similarly returned to the pipe line 27 and supplied from the nozzle 25 to the surface treatment apparatus.

At the same time, a predetermined voltage is applied from the AC power supply to the power supply electrode 21 to generate a gas discharge between the stage 22 and the stage 22 under the atmospheric pressure or a pressure near the atmospheric pressure.
In the discharge region 36, plasma is generated by the gas discharge, and the discharge gas causes reactions such as dissociation, ionization, and excitation, thereby generating active species of silicone. As the silicone active species sequentially bond and dissociate, the silicone resin is polymerized directly from the gas phase on the surface of the piezoelectric vibrating reed 2 passing through the discharge region, and the resin coating 9 shown in FIG. It is easily formed in a relatively short time. The film thickness and the film formation rate of the resin coating film 9 are controlled by adjusting the discharge conditions such as the amount of silicone mixed with the discharge gas, the exposure time to the gas discharge, and the voltage used.

In another embodiment, in addition to silicone, an organic compound which is liquid or gas at room temperature, for example, an organic substance such as a hydrocarbon compound can be used as the discharge gas, and a resin polymer film corresponding to the material used can be used. It is formed. When the organic compound used is a liquid at room temperature, it can be vaporized by heating and mixed with a carrier gas as described above for silicone, or when it is a gas at room temperature, it can be used as it is by mixing with a carrier gas. To do.

As the carrier gas, in addition to the above helium, a rare gas such as argon, nitrogen, CF4 or the like can be used. In particular, when a gas containing nitrogen, fluorohydrocarbon, or fluorocarbons such as CF4 is used, the film formation rate of the resin film can be increased.

Generally, in the film forming method using plasma, which is formed under atmospheric pressure or a pressure in the vicinity thereof as in the present invention, FIG.
In the discharge area 36, the organic film formed in the area on the right side close to the nozzle 25 opening has a low degree of polymerization and adhesion, high water repellency, and contains a large amount of methyl groups. It is known that the organic film formed in the far left region has a high degree of polymerization and adhesion, exhibits hydrophilicity, and tends to have few methyl groups.
Therefore, as shown in FIG. 5, the piezoelectric vibrating reed 2 is discharged while supplying the discharge gas so that the conveyed piezoelectric vibrating reed 2 flows from the outgoing side to the incoming side. The resin coating 9 on the second surface can change its film quality in the thickness direction from a lower layer portion having high adhesion to an upper layer portion of a desired organic polymer film. Further, productivity can be improved by continuously transporting a large number of piezoelectric vibrating reeds 2 by the conveyor means and sequentially performing film formation processing.

In the piezoelectric vibrating reed 2 whose entire surface is covered with the resin coating film 9 in this manner, the frequency is adjusted by shaving the weights 12 and 13 at the ends of the arms with a laser. As in the conventional case, a laser beam 37 having an output of about 20 W is irradiated on the resin coating film 9 from a spot having a diameter of 20 to 40 μm as shown in FIG. The resin coating 9 which is an organic substance has a weight portion 12,
It is sublimated and removed by the laser beam 37 together with the electrode film composed of the Cr underlayer 38 and the Au film 39 that form the element 13.
According to the present embodiment, it is not necessary to mask the weight portion to provide the insulating film as in the above-mentioned conventional technique, and the frequency is adjusted by forming the resin coating after mounting on the plug, which improves workability. The productivity can be improved and a more complete insulation effect can be obtained.

Next, before mounting the case 4, the piezoelectric vibrating reed and the plug are heated in a vacuum to be outgassed, thereby forcing gas and moisture which may be released from their surfaces over time. To be released. Then, by pressing the metal ring 14 of the plug 3 into the opening of the case 4 in a vacuum or nitrogen atmosphere, the piezoelectric vibrating piece 2 is sealed in the case, and the tuning fork type piezoelectric vibrator 1 shown in FIG. Is completed. The surface of the metal ring 14 and the inner surface of the case 4 are preliminarily solder-plated, and this solder fills the gap between the metal ring and the case at the time of press fitting, so that the airtightness inside the case 4 is maintained. .

Further, in the present embodiment, when the resin coating 9 is formed, the conventional masking for the plug 3 on which the piezoelectric vibrating reed 2 is mounted is not used, so that the piezoelectric vibrating reed and the plug as a whole are gas-discharged. Be exposed to. Therefore, the resin film 9 is also formed on unnecessary portions other than the electrodes 5 to 8 and the dividing line 18 of the piezoelectric vibrating piece. However, for example, the resin coating formed on the surface of the metal ring 14 is easily removed when the plug is press-fitted into the case, or even if the plug remains, the resin coating has flexibility as described above, thus impairing airtightness. There is no fear.

FIG. 9 shows a modification of the piezoelectric vibrating reed having an electrode having a shape different from that of the above embodiment. This piezoelectric vibrating piece 40 has flat electrodes 41, 4 having the same shape as in FIG.
2, the side electrodes 43 and 44 are formed only on the side surfaces of the quartz plate. Also in this case, the resin coating 45 is
The piezoelectric vibrating piece 4 is formed by the film forming method described above with reference to FIG.
It is formed so as to completely cover the surfaces of the electrodes and the dividing line 46 over the entire surface of 0.

As is generally well known, the tuning fork type piezoelectric vibrator, as shown in FIGS. 10A and 10B, flexurally vibrates when the inside and outside of each arm 47 are alternately repeatedly expanded and contracted. The range is generally limited to the region of the excitation electrode 48, and the strain amount becomes maximum near the fork portion 50 where the both arm portions 47 are joined to the base end portion 49, as shown in FIG. 10C. Therefore, in another embodiment of the present invention shown in FIG. 11, the film thickness of the resin coating 53 in the region near the fork 52 along the longitudinal direction of the piezoelectric vibrating piece 51 is formed thinner than the other regions. As a result, the flexural vibration of the piezoelectric vibrator does not have to be suppressed by the resin coating 53, so that the CI value can be kept good.

It is convenient that the film thickness of the resin coating 53 is set to about 1/2 of the film thickness in other regions in the region near the fork. In order not to suppress the vibration and at the same time to ensure the minimum necessary insulating property of the resin coating, it is preferable to set the film thickness in the vicinity of the fork portion to about 500 to 1000 Å, and in that case, the film in other regions. Thickness is about 1000-200
It is 0Å. According to the inventor of the present application, the resin coating formed according to the present invention has the same degree of insulating property, although there is some difference in flexibility depending on the material.

When the CI value of the tuning fork type piezoelectric vibrator manufactured according to this example was measured, the results shown in FIG. 12 were obtained. The tuning fork type piezoelectric vibrator used for the test has a frequency of 32k.
Hz, φ2 × 6 mm size, the film thickness of the resin coating near the fork is 500 Å, and the film thickness of other regions is 2000
As Å, 28 samples were manufactured. The measurement results of the CI value of these samples are shown in FIG. 12A. As a comparative example, 28 samples of the same tuning-fork type piezoelectric vibrator in which the film thickness of the resin film was uniformly formed to 2000 Å were manufactured. The measurement result of the CI value of the comparative sample is shown in FIG. 12B.
Shown in

As can be seen by comparing FIGS. 12A and 12B, the CI value of the piezoelectric vibrator according to the present embodiment has a peak of 2.
In the case of the comparative example, the peak is 30 kΩ, which is as high as 2 kΩ, and the variation is large, whereas the variation is small at 8 kΩ. In fact, the piezoelectric vibrator has been downsized in response to the demand for downsizing of electronic components, but its CI value slightly rises with downsizing. Therefore, it is not preferable that the CI value is further increased due to the surface treatment for forming the insulating film. According to this embodiment, the tuning fork type piezoelectric vibrator can be downsized, and at the same time, a good CI value can be maintained.

The tuning fork type piezoelectric vibrator shown in FIG. 11 can simultaneously form a resin coating on both surfaces of the vibrating piece by using the surface treatment apparatus shown in FIG. This surface treatment device is a so-called line type for linear surface treatment,
It has a pair of a power supply electrode 54 and a ground electrode 55 facing each other in the vertical direction. The two electrodes have the same structure in which the electrodes are vertically arranged in a flat plate shape, and the outer surfaces thereof are covered with dielectrics 56 and 57 such as glass and alumina, and are vertically symmetrically arranged. Nozzles 60 and 61, which open toward a narrow gap defined between the electrodes by wall portions 58 and 59 of an insulating material, are arranged on one side of both electrodes to supply a common discharge gas. It is connected to the source 62.

The tuning fork type piezoelectric vibrating piece 64 mounted on the plug 63 is held by holding the outer leads 66 from above and below by a suitable holding means 65 made of an insulating material so that both the front and back surfaces thereof are horizontal. Holding means 65
Can move the piezoelectric vibrating piece 64 back and forth along its longitudinal direction (arrow B) while adjusting its speed.

Similar to the surface treatment apparatus shown in FIG. 5, a gas mixed with vaporized silicone is supplied from a gas supply source 62 and jetted from the nozzles 60 and 61 into the gap between the electrodes, while an AC power source 67 is supplied. From the above, a predetermined voltage is applied to the power supply electrode 54 to generate a gas discharge between both electrodes under an atmospheric pressure or a pressure near the atmospheric pressure. The discharge region 68 is formed in a straight line in the vertical direction with respect to the drawing, in which the excited active species of silicone are generated as in the above-described embodiment.

The tuning fork type piezoelectric vibrating piece 64 is moved horizontally by the holding means 65 along the longitudinal direction in a direction orthogonal to the linear discharge region. Piezoelectric vibrating piece 64
Both the front and back surfaces of the arm 69 are exposed to the discharge region linearly in the longitudinal direction from the tip of the arm 69 to the base 70, and the silicone resin is directly polymerized from the gas phase to form a resin. A coating is formed at the same time. The moving speed of the piezoelectric vibrating piece 64 is set to a slow and constant speed from the tip of the arm 69 to the vicinity of the fork 71, and a region r near the fork is fast, and is set to a slow and constant speed behind the region. . As a result, the exposure time to the discharge region in the region r near the fork can be shortened and the exposure time to the other regions can be lengthened, whereby the resin film of the piezoelectric vibrator can be formed with the film thickness as shown in FIG. Can be formed into a distribution.

Further, if the holding means 65 holds a large number of piezoelectric vibrating reeds in the vertical direction with respect to the drawing, it is convenient because they can be simultaneously passed through the linear discharge region for processing. The moving speed of the piezoelectric vibrating piece can be appropriately set depending on the size of the electrode, discharge conditions such as applied voltage, required film thickness, and the like. Further, in the above-described embodiment, the piezoelectric vibrating reed is processed only in the direction of feeding the piezoelectric vibrating reed from the arm tip toward the base end to the discharge area, but the same processing can be performed when pulling back from the discharge area. In still another embodiment, it is possible to fix the holding position of the piezoelectric vibrating piece and move the electrode side for processing. In addition, it is of course possible to process each of the front and back surfaces of the piezoelectric vibrating piece.

The present invention can be applied not only to the tuning fork type piezoelectric vibrator described above, but also to other types of piezoelectric elements such as a bar type AT cut crystal resonator and a SAW device. FIG. 14A shows an example of a bar-type AT-cut crystal unit to which the present invention is applied. The crystal resonator 72 includes a crystal vibrating piece 73, a plug 74 that supports the crystal vibrating piece 73, and a bottomed cylindrical metal case 75. In the crystal vibrating piece 73, the rectangular excitation electrodes 76 having the same pattern are formed on the front and back surfaces of the thin rectangular crystal plate by Cr.
The underlying layer is formed by vapor-depositing or sputtering a thin film of Ag or Au on the underlying layer, and the connecting lands 77 and 78 drawn out from the electrode are provided at the lower end of the underlying layer.

The plug 74 is a so-called hermetic terminal having two lead wires 81 penetrating a glass insulator 80 fitted with a metal ring 79, and an inner lead 82 projecting inside the case 75 is formed in each of the above. The crystal vibrating piece 73 is supported in a cantilever manner by soldering to the land. The crystal vibrating piece 73 is hermetically housed in the case 75, which is normally maintained in a vacuum or nitrogen atmosphere, by press-fitting the metal ring 79 of the plug into the opening of the case.

As shown in FIG. 14B, a resin coating 83 is formed on the entire surface of the crystal vibrating piece 73. The resin coating 83 can be formed by using the surface treatment device 19 of FIG. 5, similarly to the tuning fork type piezoelectric vibrator of FIG. A discharge gas in which an organic compound such as silicone is mixed with a carrier gas such as helium is used, and a gas discharge is generated under atmospheric pressure or a pressure in the vicinity thereof to generate an excited active species of the organic compound. The crystal vibrating piece 73 mounted on the plug 74 is exposed to form a polymer film so as to cover the entire surface thereof. This resin coating short-circuits between adjacent lands 77 and 78,
It is possible to eliminate the possibility that the gas emitted from the plug 74 or the case 75 is adsorbed to the excitation electrode 76 of the crystal vibrating piece and causes characteristic deterioration such as shift of oscillation frequency or increase of CI value.
Further, since the resin coating 83 has flexibility, the vibration of the crystal vibrating piece 73 is not hindered and there is no risk of degrading the performance of the crystal resonator. In addition, the resin coating formed on the surface of the metal ring of the plug 74 does not impair the airtightness when the plug is press-fitted into the case 75.

FIG. 15A shows an embodiment of a SAW device to which the present invention is applied. The SAW device 84 has substantially the same structure as the piezoelectric vibrator described above, and has a SAW piece 85.
Is cantileverly mounted on a plug 86 which is a hermetic terminal, and is hermetically housed in a cylindrical metal case 87 having a bottom. The SAW piece 85 has an interdigital finger electrode (IDT) formed by combining a pair of comb-shaped electrodes 88 and 89 in the approximate center of the main surface of a rectangular quartz plate, and has grid-shaped reflectors on both sides in the longitudinal direction. 90 is provided, and at the lower end, a connection land 91 drawn out from each of the comb-shaped electrodes,
92 are provided on the left and right. These electrodes, reflectors and lands are formed by depositing an Al thin film on the surface of the quartz plate by vapor deposition or sputtering and patterning it using a photolithography technique. A conductive material such as an Al-Cu alloy can be used. For the base of the SAW piece 85, a piezoelectric material such as lithium tantalate or lithium niobate can be used instead of quartz.

Similar to the piezoelectric vibrator of FIGS. 1 and 14, in the plug 86, each inner lead 95 of the two lead wires 94 penetrating the insulator 93 made of glass has the lands 91 and 92 of the SAW piece. The SAW pieces are vacuum-sealed by press-fitting the metal rings 96, which are respectively soldered to the above, and which fit the insulator to the outside, into the openings of the case 87. SA of this embodiment
By supporting the SAW piece 85 so that it floats above the case 87, the W device secures a sufficient gap between the W device and the case 87, so that oscillations due to their contact and instability in the case occur. Prevents the generation of dust,
It is possible to reduce adverse effects such as deformation of the SAW piece and a change in frequency due to the stress that acts from the outside, and a very stable resonance frequency and excellent aging characteristics can be obtained. In addition to the cylindrical shape, the case 87 has an elliptic cylindrical shape,
It can be formed into various shapes such as a round can shape and a box shape, and can also be formed of ceramics.

As shown in FIG. 15B, a resin film 97 is formed on the entire surface of the SAW piece 85. The resin film 97 can be formed by using the surface treatment apparatus 19 of FIG. 5, similarly to the piezoelectric vibrators of FIGS. 1 and 14. A discharge gas in which a carrier gas such as helium is mixed with an organic compound is used, and a gas discharge is generated under atmospheric pressure or a pressure in the vicinity thereof to generate an excited active species of the organic compound, and a plug 86 is added thereto. The SAW piece 85 mounted on is exposed to form a polymer film so as to cover the entire surface. In the SAW piece 85, the resin coating completely covers not only the electrodes and the reflector, but also the exposed crystal ground surface, so that the manufacturing process and the plug,
The dust generated from the case or the like short-circuits between the adjacent electrodes and the electrodes or reflectors, or between the adjacent lands, and the gas released from the plug, the case, or the adhesive is adsorbed on the metal film of the electrodes or the like. Can be completely prevented. Furthermore, since the resin coating 97 has flexibility, even if it is formed to have a sufficient thickness to exhibit electric insulation, there is no risk of substantially impairing the performance of the SAW piece during use. Further, there is no fear that the airtightness between the case 87 and the plug will be impaired by the resin coating formed on the surface of the metal ring of the plug 86.

Although the present invention has been described in detail with reference to its preferred embodiments, it will be apparent to those skilled in the art that the present invention may be modified or changed in various ways within the technical scope thereof. Can be carried out.

[0061]

Since the present invention is configured as described above, it has the following effects. According to the piezoelectric element of the present invention, the element piece, since the resin coating covering the surface thereof has flexibility, vibration is not hindered even if the film thickness is increased, while maintaining the characteristics of the piezoelectric element, It is possible to greatly improve the electrical insulation and prevent the deterioration of the electrodes and the like due to the release and adsorption of gas and the mixing of oxygen. In particular, in the case of a tuning fork type piezoelectric vibrating piece, the resin coating in the vicinity of the fork where the arm portion of the tuning fork branches along the lengthwise direction is made thinner than other regions, so that the resin coating may suppress vibration. Since the CI value is eliminated and the CI value is maintained, it is not necessary to change the shape of the resonator element unnecessarily even when the size is reduced, and it is easy to save the power consumption.

Further, according to the method of manufacturing a piezoelectric element of the present invention, the element is prepared by directly polymerizing the organic matter from the gas phase by utilizing the excited active species of the organic matter generated by the plasma produced under the atmospheric pressure. Since the resin coating is formed on the surfaces of the piece and the plug, all the electrodes and the dividing lines thereof, and the mount connection portion of the plug can be completely electrically insulated. Since this resin coating is flexible, even if it is formed on the sealing surface of the plug, there is no risk of impairing the airtightness of the case and the plug, and therefore masking is not required during film formation, so the film formation process is easy. Is. Further, since a vacuum device and equipment are not required, the manufacturing device is simple and inexpensive, and in-line and automation can be performed, so that productivity improvement and cost reduction can be easily realized.

Furthermore, since the frequency can be measured at the same time when the resin film is formed, the film thickness suitable for the desired frequency can be accurately controlled and managed, and the performance of the piezoelectric element can be improved. To be In particular, in the case of a tuning fork type piezoelectric vibrating piece, even if a resin coating is formed on the entire surface including the frequency adjusting weight portion, the resin coating and the metal film can be simultaneously removed by irradiating the laser on the resin coating. Since the frequency can be easily adjusted, not only a high-quality and high-performance tuning-fork type piezoelectric vibrator can be obtained by achieving both accurate frequency adjustment and the insulation effect, but the workability is improved and the product is produced. It is possible to improve the sex.

Furthermore, the element piece mounted on the plug is
For example, by carrying it in a gas discharge by mounting it on a conveyor means, the surface of the discharge gas is moved relative to the flow of the discharge gas supplied to the region of the gas discharge from the downstream side to the upstream side. By forming a resin film by exposing it to excited active species, the film quality can be controlled in the thickness direction so that the lower layer part has high adhesion and the surface part has high water repellency. An insulating film having excellent aging characteristics and capable of effectively protecting the electrode by suppressing gas release and adsorption can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a tuning fork type piezoelectric vibrator according to the present invention.

FIG. 2 is an enlarged plan view showing the piezoelectric vibrating piece of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

4 is a flow chart showing a manufacturing process of the tuning fork type piezoelectric vibrator of FIG. 1. FIG.

FIG. 5 is a diagram schematically showing the configuration of a surface treatment apparatus for forming a resin coating on the surface of a piezoelectric vibrating piece by atmospheric pressure plasma according to the present invention.

FIG. 6 is a block diagram showing a configuration of an embodiment of a gas supply device that supplies a discharge gas containing vaporized silicone.

FIG. 7 is a block diagram showing an embodiment of a gas supply device having a configuration different from that of FIG.

FIG. 8 is a partially enlarged cross-sectional view of a tip of an arm portion of a piezoelectric vibrating piece showing a weight portion whose frequency is adjusted by laser light.

9 is a cross-sectional view of a piezoelectric vibrating reed having an electrode shape different from that in FIG.

10A and 10B are plan views showing bending vibration of a tuning fork type piezoelectric vibrator, and FIG. 10C is a view showing the amount of strain along the longitudinal direction of the piezoelectric vibrator.

FIG. 11 is a side view of a tuning fork type piezoelectric vibrating piece according to another embodiment of the present invention.

12 is a bar graph showing CI values measured for the tuning fork type piezoelectric vibrator according to the example of FIG. 11, and FIG. 12 is a comparative example thereof.

FIG. 13 is a diagram schematically showing a configuration of a surface treatment apparatus for forming the resin film of FIG.

14A is a vertical sectional view of a bar-type AT-cut crystal unit according to the present invention, and FIG. 14B is a crystal vibrating piece XIV-XIV thereof.
It is sectional drawing in a line.

15A is a longitudinal sectional view of a SAW device according to the present invention, and FIG. 15B is a sectional view of the SAW piece taken along line XV-XV.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tuning fork type piezoelectric vibrator 2 Piezoelectric vibrating piece 3 Plug 4 Metal case 5,6 Planar electrode 7,8 Side electrode 9 Resin coating 10, 11 Land 12, 13 Weight part 14 Metal ring 15 Insulator 16 Lead wire 17 Inner lead 18 Split Line 19 Surface Treatment Device 20 AC Power Supply 21 Power Supply Electrode 22 Stage 23 Gas Supply Device 24 Dielectric 25 Nozzle 26 Gas Supply Source 27 Pipeline 28 Bypass 29 Tank 30 Liquid Silicone 31 Heater 32, 33 Control Valves 34, 35 Flow Control Device 36 Discharge region 37 Laser light 38 Cr Underlayer 39 Au film 40 Piezoelectric vibrating piece 41, 42 Planar electrode 43, 44 Side electrode 45 Resin coating 46 Dividing line 47 Arm 48 Excitation electrode 49 Base end 50 Fork 51 Piezoelectric vibration One piece 52 Fork portion 53 Resin coating 54 Power electrode 55 Ground electrode 56, 57 dielectric 58, 59 wall 60, 61 nozzle 62 gas supply source 63 plug 64 piezoelectric vibrating piece 65 holding means 66 outer lead 67 AC power supply 68 discharge region 69 arm 70 base end 71 fork 72 AT-cut crystal oscillator 73 Crystal vibrating piece 74 Plug 75 Metal case 76 Excitation electrode 77, 78 Land 79 Metal ring 80 Insulator 81 Lead wire 82 Inner lead 83 Resin coating 84 SAW device 85 SAW piece 86 Plug 87 Metal case 88, 89 Comb type electrode 90 Reflector 91, 92 Land 93 Insulator 94 Lead wire 95 Inner lead 96 Metal ring 97 Resin coating

Claims (19)

[Claims] 1. A device comprising an element piece having an electrode formed on the surface of a piezoelectric body, a plug for mounting the element piece, and a case for hermetically housing the element piece, the surface of the element piece comprising:
A piezoelectric element, which is covered with a resin film formed by using excited active species of an organic compound generated by gas discharge in a predetermined discharge gas under atmospheric pressure or a pressure in the vicinity thereof. 2. The piezoelectric element according to claim 1, wherein the resin film is a polymer film of an organic material. 3. The piezoelectric element according to claim 1, wherein the resin coating film is a silicone resin film. 4. The piezoelectric element according to claim 1, wherein the resin coating film has a lower layer portion made of an inorganic element contained in the organic compound or an oxide thereof. 5. The piezoelectric element according to claim 1, wherein the element piece is a piezoelectric vibrating piece vibrating in a bending vibration mode. 6. The piezoelectric element according to claim 1, wherein the element piece is a piezoelectric vibrating piece that vibrates in a thickness shear mode. 7. The piezoelectric element according to claim 1, wherein the element piece is a piezoelectric vibrating piece that vibrates in a torsional vibration mode. 8. The SA in which the element piece utilizes a surface acoustic wave.
The piezoelectric element according to claim 1, wherein the piezoelectric element is a W piece. 9. The film of the resin film, wherein the piezoelectric vibrating piece has a tuning fork shape having a base end portion connected to the plug and two arm portions extending in the longitudinal direction from the base end portion. The piezoelectric element according to claim 5, wherein a thickness of the piezoelectric element is smaller in a region near a fork portion where the arm portion is coupled to the base end portion along the longitudinal direction than in other regions. 10. The piezoelectric element according to claim 9, wherein the film thickness of the resin coating in the vicinity of the fork portion is about ½ of the film thickness of other regions. 11. The film thickness of the resin coating in the vicinity of the fork is 500 to 1000Å.
The piezoelectric element as described in the above. 12. A method of manufacturing a piezoelectric element, comprising: an element piece having an electrode formed on the surface of a piezoelectric body; a plug for mounting the element piece; and a case for hermetically housing the element piece. After mounting the element piece on the plug and before sealing it in the case, a gas discharge is generated in a predetermined discharge gas under atmospheric pressure or a pressure in the vicinity thereof, and the liquid discharge is performed at room temperature by the gas discharge. A method of manufacturing a piezoelectric element, which comprises a step of generating an excited active species of a gaseous organic compound, exposing the surface of the element piece to the excited active species, and forming a resin coating film covering the surface. . 13. A method of manufacturing a piezoelectric element according to claim 12, wherein the organic compound is mixed with the predetermined discharge gas. 14. The method for manufacturing a piezoelectric element according to claim 12, wherein the organic compound is silicone or a hydrocarbon compound. 15. With respect to the flow of the predetermined discharge gas supplied to the gas discharge region, while relatively moving the element piece mounted on the plug from the downstream side toward the upstream side, 15. The method for manufacturing a piezoelectric element according to claim 12, wherein the surface is exposed to the excited active species. 16. While transporting the element piece mounted on the plug so as to pass through the gas discharge region,
16. The method of manufacturing a piezoelectric element according to claim 15, wherein the predetermined discharge gas is supplied so that the element piece flows from the exit side of the gas discharge area toward the entrance side. 17. The element piece is a piezoelectric vibrating piece having a tuning fork shape, and the frequency of the piezoelectric vibrating piece is adjusted by irradiating a laser beam on the resin coating after forming the resin coating. 13. The method for manufacturing a piezoelectric element according to claim 12, wherein. 18. The tuning fork-shaped piezoelectric vibrating piece, wherein the element piece has two arm portions extending in a longitudinal direction from a base end portion connected to the plug, and the surface of the piezoelectric vibrating piece is excited by the excitation. 13. The exposure time to the active species is set to be shorter in a region near the fork portion where the arm portion is bonded to the base end portion along the longitudinal direction than in other regions. Manufacturing method of piezoelectric element. 19. The gas discharge is generated by applying a predetermined voltage while supplying the discharge gas between a pair of power supply electrodes and a ground electrode that are arranged opposite to each other, and the gas discharge is generated, and the plugs are connected to the both electrodes. By moving the mounted piezoelectric vibrating piece along the longitudinal direction, the piezoelectric vibrating reed is passed through the gas discharge region, and the speed at which the region near the fork passes through the gas discharge region is passed through the other region. 19. The method of manufacturing a piezoelectric element according to claim 18, wherein the method is faster than the speed.