JP2006033354A5 - - Google Patents

Description

Method for adjusting frequency of piezoelectric vibrator, piezoelectric vibrator and electronic device

  The present invention relates to a frequency adjustment method of a piezoelectric vibrator in which a tuning fork arm performs flexural vibration, a piezoelectric vibrator, and an electronic apparatus.

  In recent years, with the widespread use of portable electronic devices and the like, there is a demand for miniaturization and high accuracy of electronic components constituting them. A piezoelectric vibrator used as a reference signal source of a portable electronic device is also required to be downsized and highly accurate, and various proposals have been made conventionally. For example, as shown in Patent Document 1, it has been proposed that a groove is provided in the tuning fork arm of a piezoelectric vibrator to reduce a series resistance that causes a loss in a vibration equivalent circuit and to reduce the size of the piezoelectric vibrator. ing.

  In addition, as a frequency adjusting method of the piezoelectric vibrator in which the groove portion is formed in the tuning fork arm, as disclosed in Patent Document 1, a metal film provided at the tip of the tuning fork arm of the piezoelectric vibrator is irradiated with laser light, Frequency adjustment is performed by a general method of removing a part of the metal film.

JP-A-56-65517

  Generally, in frequency adjustment of a piezoelectric vibrator, mass adjustment is performed by adding mass to the tip of the tuning fork arm or removing mass, but the frequency change with respect to mass change increases as the piezoelectric vibrator becomes smaller. Become. For this reason, in order to adjust the frequency of the miniaturized piezoelectric vibrator to a desired value, when adding mass by vapor deposition or the like, it is necessary to control a very small amount of vapor deposition, and also irradiate laser light or the like. In order to remove the mass, it is necessary to reduce the spot diameter of the laser beam. However, there is a limit to controlling a very small amount of vapor deposition and reducing the spot diameter of the laser beam, and there has been a problem that in a miniaturized piezoelectric vibrator, the frequency cannot be accurately adjusted to a desired value.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a frequency adjustment method for a piezoelectric vibrator that can precisely match the frequency of a miniaturized piezoelectric vibrator with high accuracy. . Another object is to provide a piezoelectric vibrator frequency-adjusted by the piezoelectric vibrator frequency adjusting method of the present invention and an electronic device including the piezoelectric vibrator.

In order to solve the above problems, a method of manufacturing a piezoelectric vibrator of the present invention includes a tuning fork arm and a tuning fork base that connects one end of the tuning fork arm, and the tuning fork arm performs flexural vibration. A method of manufacturing a piezoelectric vibrator, the step of forming grooves on the upper and lower surfaces facing the thickness direction of the tuning fork arm, the step of forming excitation electrodes on each of the side surface of the tuning fork arm and the groove, And a step of removing a part of the excitation electrode formed in the groove .

In the piezoelectric vibrator manufacturing method of the present invention, the groove includes a bottom and a side, and the excitation electrode includes a bottom electrode formed on the bottom and a groove formed on a side of the groove. And a step of removing a part of the bottom electrode .

  The method for manufacturing a piezoelectric vibrator according to the present invention is characterized in that the step of removing a part of the excitation electrode formed in the groove is performed by laser light irradiation.

Further, the method for manufacturing a piezoelectric vibrator of the present invention includes a step of removing a part of the excitation electrode of the groove by sequentially irradiating laser light in a direction from the open tip of the tuning fork arm toward the tuning fork base. It is characterized by having .

The manufacturing method of a piezoelectric vibrator of the present invention, the tuning fork arms comprises two tuning fork arms, the mass removal of the portion of the excitation electrodes formed in the grooves of one of said tuning fork arm and the other of the tuning fork arms The two tuning fork arms have substantially the same amount .

In the method for manufacturing a piezoelectric vibrator according to the present invention, a pitch for sequentially irradiating the excitation electrodes formed in the groove with laser light is smaller than a spot diameter of the laser light .

  In the piezoelectric vibrator manufacturing method of the present invention, a part of the weight formed at the tip of the tuning fork arm is irradiated by laser light irradiation before the step of removing a part of the excitation electrode formed in the groove. And a step of removing, and a step of removing a part of the excitation electrode routed around the surface of the tuning fork arm by laser light irradiation.

  The piezoelectric vibrator of the present invention includes a tuning fork arm, a tuning fork base connecting one end of the tuning fork arm, a groove formed on the upper and lower surfaces facing the thickness direction of the tuning fork arm, and the tuning fork arm. A piezoelectric vibrator in which the tuning fork arm performs flexural vibration, and a part of the excitation electrode formed in the groove is removed. Features.

In addition, the piezoelectric vibrator of the present invention has a weight with a part removed at the tip of the tuning fork arm, and the excitation electrode is routed around the surface of the tuning fork arm. The portion is removed.

The packaged piezoelectric vibrator of the present invention includes a tuning fork arm, a tuning fork base connecting one end of the tuning fork arm, a groove formed on the upper and lower surfaces facing the thickness direction of the tuning fork arm, A piezoelectric vibrator having a tuning fork arm side surface and excitation electrodes respectively formed on the groove portion, wherein the tuning fork arm performs flexural vibration, wherein the piezoelectric vibrator is adhesively fixed in a receiving container, A part of the excitation electrode formed in the groove is removed, and the inside of the container is maintained in a vacuum atmosphere.

In addition, the piezoelectric vibrator of the present invention has a weight with a part removed at the tip of the tuning fork arm, and the excitation electrode is routed around the surface of the tuning fork arm. The portion is removed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1A is a plan view showing a configuration of a piezoelectric vibrator according to the present invention, and FIG. 1B is a cross-sectional view taken along the line AA in FIG. A piezoelectric vibrator 1 made of a piezoelectric material such as quartz has two tuning fork arms 2 and 3. One end of the tuning fork arms 2 and 3 is connected to the tuning fork base 4, and the other end is open. Grooves 5 and 6 are formed at the center of the tuning fork arms 2 and 3 across the center line in the width direction, and the grooves 5 and 6 are provided on the upper and lower surfaces of the tuning fork arms 2 and 3 facing in the thickness direction. Yes. The piezoelectric vibrator 1 is provided with excitation electrodes 7 and 8 so that the tuning fork arms 2 and 3 can be flexibly vibrated. Further, a weight 9 is provided at the open ends of the tuning fork arms 2 and 3. The excitation electrodes 7 and 8 are made of a metal film such as Au, and the weight 9 is made of a metal film such as Ag or Au.

  2 (a) and 2 (b) are schematic cross-sectional views taken along the line BB of the tuning fork arm 2 shown in FIG. 1 (a), illustrating the vibration principle of the piezoelectric vibrator according to the present invention. FIG. A groove side electrode 8a is provided on the side surface of the groove 5 of the tuning fork arm 2, and a bottom electrode 8b is provided on the bottom of the groove. These groove side electrode 8a and bottom electrode 8b are included in the excitation electrode 8 shown in FIG. 1, and are configured to be the same as the excitation electrode 8. A side electrode 7 a is provided on the side surface of the tuning fork arm 2. The side electrode 7 a is included in the excitation electrode 7 shown in FIG. 1 and is configured to be the same electrode as the excitation electrode 7. The excitation electrodes 7 and 8 are configured to be different from each other.

  Next, the operation of the tuning fork arm 2 in the configuration of the excitation electrodes 7 and 8 of the tuning fork arm 2 will be described. As shown in FIG. 2A, when a positive voltage is applied to the side electrode 7a and a negative voltage is applied to the groove side electrode 8a and the groove bottom electrode 8b, the direction from the side electrode 7a to the groove side electrode 8a (in the direction of the arrow) Electric field works in the direction shown). As shown in FIG. 2B, when a negative voltage is applied to the side electrode 7a and a positive voltage is applied to the groove side electrode 8a and the groove bottom electrode 8b, the direction from the groove side electrode 8a to the side electrode 7a ( An electric field works in the direction indicated by the arrow).

  In this way, when viewed from the center of the tuning fork arm 2, the direction of the electric field is opposite on the right and left sides of the tuning fork arm 2, so if one of the left and right produces an elongation distortion, the other one has a shrinkage distortion. As a result, the tuning fork arm 2 bends. When an alternating voltage is applied to the side electrode 7a, the groove side electrode 8a, and the groove bottom electrode 8b (excitation electrode 7 and excitation electrode 8), the tuning fork arm 2 bends and vibrates. The electric field acting on the tuning fork arm 2 has only a component perpendicular to the opposing side electrode 7a and groove side electrode 8a. For this reason, if it is set as the above structures, the tuning fork arm 2 can be excited efficiently and the piezoelectric vibrator can be miniaturized. In the above description, the groove bottom electrode 8b is provided. However, if the opposite side electrode 7a and the groove side electrode 8a are configured as different electrodes, the groove bottom electrode 8b is caused by bending vibration of the tuning fork arm 2. Is not directly involved, and the groove bottom electrode 8b may not be provided.

  Next, a method for adjusting the frequency of the piezoelectric vibrator of this embodiment will be described. FIG. 3 is a flowchart for explaining the frequency adjustment process of the piezoelectric vibrator. In step S1, as shown in FIG. 1, a weight 9 is formed by vapor deposition or sputtering of Au or Ag on the tips of the tuning fork arms 2 and 3 of the piezoelectric vibrator 1.

  Next, it progresses to the mounting process which fixes the piezoelectric vibrator 1 to a storage container (step S2). FIG. 6A is a plan view showing a state in which the piezoelectric vibrator is mounted on the storage container. The storage container 21 formed of ceramics or the like is open on one side and is provided with a recess. A pedestal 22 is formed in the recess, and the piezoelectric vibrator 1 is bonded and fixed to the pedestal 22 with a conductive adhesive 23. Although not shown, the excitation electrode of the piezoelectric vibrator 1 and the circuit wiring arranged in the housing container 21 are electrically connected via the conductive adhesive 23.

  Next, it progresses to step S3 and becomes a sealing process. FIG.6 (b) is a schematic sectional drawing which shows the state after a sealing process. A lid 24 formed of a transparent glass material is disposed from the upper portion of the storage container 21, and the storage container 21 is sealed in a vacuum atmosphere so that the piezoelectric vibrator 1 is packaged.

  Thereafter, frequency adjustment of the piezoelectric vibrator is performed in steps S4 to S6. These frequency adjustments are performed by irradiating the transparent lid 24 of the packaged piezoelectric vibrator 1 shown in FIG. 6B with laser light and removing the weights and electrodes formed on the tuning fork arm. The frequency of the piezoelectric vibrator 1 before the frequency adjustment is set lower than a desired frequency by adding the weight 9, and the frequency adjustment is performed in the direction of increasing the frequency by removing the weight and the electrode. FIG. 4 is a plan view for explaining a method of adjusting the frequency of the piezoelectric vibrator. FIG. 4 (a) is a frequency adjustment 1, FIG. 4 (b) is a frequency adjustment 2, and FIG. 4 (c) is a frequency adjustment 3 process. It is a top view corresponding to.

  In the step of frequency adjustment 1 in step S4, as shown in FIG. 4A, the weight 9 formed at the tip of the tuning fork arm 2 and 3 of the piezoelectric vibrator 1 is irradiated with the laser beam spot 10a, and the weight 9 Remove some. In this step, the weight 9 of the tuning fork arms 2 and 3 is irradiated with the laser light spot 10a several times until the frequency of the piezoelectric vibrator 1 reaches a predetermined value determined as the frequency adjustment 1, and Remove the part. Further, the removal of part of the weight 9 is set so that the tuning fork arms 2 and 3 have substantially the same amount in consideration of the balance of vibration. In the adjustment in the frequency adjustment 1 step, due to the mass effect of the removed weight 9, the frequency change of the piezoelectric vibrator 1 is large and the frequency is adjusted roughly.

  Next, the process proceeds to the step of frequency adjustment 2 in step S5. In the step of frequency adjustment 2, as shown in FIG. 4 (b), a laser beam spot 10b is irradiated to a portion slightly closer to the tuning fork base 4 from the tips of the tuning fork arms 2 and 3. In this portion, a part of the excitation electrodes 7 and 8 routed on the surface of the piezoelectric vibrator 1 is disposed, and a part of the excitation electrodes 7 and 8 is removed by irradiating the laser beam spot 10b. To do. In this process, the excitation electrodes 7 and 8 of the tuning fork arms 2 and 3 are irradiated with the laser beam spot 10b several times until the frequency of the piezoelectric vibrator 1 reaches a predetermined value determined as the frequency adjustment 2, and excitation is performed. A part of the electrodes 7 and 8 is removed. The removal of a part of the excitation electrodes 7 and 8 is set so that the tuning fork arms 2 and 3 have substantially the same amount in consideration of the balance of vibration.

  In the adjustment in the step of frequency adjustment 2, the frequency of the piezoelectric vibrator 1 can be adjusted by the mass effect of the excitation electrodes 7 and 8 removed. The thicknesses of the excitation electrodes 7 and 8 are formed sufficiently thinner than the thickness of the weight 9, and the frequency change in one laser beam spot irradiation is smaller than that in the frequency adjustment 1. As described above, the frequency adjustment 2 can be adjusted with higher accuracy than the frequency adjustment 1. Next, when a more precise frequency adjustment is required, such as a miniaturized piezoelectric vibrator, the frequency adjustment 3 in step S6 which is the gist of the present invention is performed.

  In the step of frequency adjustment 3 in step S6, as shown in FIG. 4C, the groove portions 5 and 6 provided in the tuning fork arms 2 and 3 are irradiated with the laser beam spot 10c. In this portion, groove bottom electrodes 7b and 8b, which are part of the excitation electrodes 7 and 8 routed around the surface of the piezoelectric vibrator 1, are disposed. By irradiating the laser beam spot 10c, the groove bottom portion is provided. A part of the electrodes 7b and 8b is removed. In this step, the laser beam spot 10c is applied to the groove bottom electrodes 7b and 8b of the tuning fork arms 2 and 3 until the frequency of the piezoelectric vibrator 1 reaches a predetermined value (desired final frequency) determined as the frequency adjustment 3. Then, a part of the groove bottom electrodes 7b and 8b is removed. At this time, when it is necessary to irradiate the laser beam spot 10c a plurality of times, the laser beam spot 10c is sequentially irradiated in the direction from the tips of the tuning fork arms 2 and 3 toward the tuning fork base 4. Further, it is desirable that the removal of a part of the groove bottom electrodes 7b and 8b is almost the same amount in the tuning fork arms 2 and 3 in consideration of the balance of vibration.

  In the adjustment in the frequency adjustment 3 step, the frequency of the piezoelectric vibrator 1 can be adjusted by the mass effect of the removed groove bottom electrodes 7b and 8b. The thicknesses of the groove bottom electrodes 7b and 8b are the same as those of the excitation electrodes 7 and 8 to be removed by the frequency adjustment 2, but the position to be removed by the frequency adjustment 3 is close to the tuning fork base 4, so that the laser beam spot is irradiated once. The frequency change at is small. As described above, the frequency adjustment 3 can be adjusted with higher accuracy than the frequency adjustment 2. In the frequency adjustment 3, the irradiation position of the laser light spot 10 c approaches the tuning fork base 4 as the laser light spot 10 c is sequentially irradiated in the direction from the tip of the tuning fork arms 2 and 3 toward the tuning fork base 4. Although this is a very small amount, the change in frequency in one irradiation with a laser beam spot becomes smaller. This also makes it possible to adjust the frequency with high accuracy. Further, since the groove bottom electrodes 7b and 8b do not directly affect the bending vibration of the tuning fork arms 2 and 3, even if the groove bottom electrodes 7b and 8b are removed, the characteristics of the piezoelectric vibrator 1 are not affected. The frequency can be adjusted.

  Laser light such as YAG laser, YVO4 laser, and YLF laser can be used as the laser light described in the above embodiment. Also, a laser beam spot diameter of about φ15 μm to φ5 μm is used. In the above embodiment, the frequency of the piezoelectric vibrator 1 before the frequency adjustment is set lower than the desired frequency, and the frequency adjustment is performed in the direction of increasing the frequency by removing masses such as weights and electrodes. Although performed, the frequency of the piezoelectric vibrator 1 before frequency adjustment is set higher than the desired frequency, the mass is added to the same position as the position where the mass is removed, and the frequency is adjusted in the direction of decreasing the frequency. You can also

  As described above, by adjusting the mass of the groove portions 5 and 6 formed in the tuning fork arms 2 and 3, the change in frequency with respect to the mass change is small compared to the mass adjustment of the tip portions of the tuning fork arms 2 and 3, It is possible to adjust the frequency of the piezoelectric vibrator with high accuracy. For this reason, particularly in a small piezoelectric vibrator, if this method is used in the final adjustment process of frequency adjustment, the frequency can be adjusted with high accuracy.

(Modification)
FIG. 5 is an explanatory diagram showing a modification of the embodiment of the present invention. In FIG. 5A, in the step of frequency adjustment 3, the bottom electrode 8b of the tuning fork arm 2 is irradiated with two laser beam spots 10c, and the bottom electrode 7b of the tuning fork arm 3 is irradiated with one laser beam spot 10c. The frequency adjustment is finished. That is, the tuning fork arms 2 and 3 adjust the frequency of the piezoelectric vibrator 1 with different masses. Although the masses of the two tuning fork arms 2 and 3 are slightly different, the frequency adjustment amount is almost half that when the two tuning fork arms are adjusted with the same mass, and the frequency adjustment accuracy can be improved. Particularly in the final frequency adjustment, the mass difference between the tuning fork arms is very small and does not affect the characteristics of the vibration of the piezoelectric vibrator 1.

  In FIG. 5B, in the step of frequency adjustment 3, the pitch for sequentially irradiating the bottom electrodes 7b and 8b of the tuning fork arms 2 and 3 with the laser beam spot 10c is set smaller than the spot diameter of the laser beam. In this way, the laser beam spots 10c overlap, and the area where the bottom electrodes 7b and 8b are removed after the second laser beam spot 10c irradiation can be reduced. Accordingly, the mass to be removed is reduced, the frequency change of the piezoelectric vibrator 1 can be reduced, and the frequency can be adjusted with high accuracy.

  In FIG. 5 (c), in the step of frequency adjustment 3, the pitch at which the bottom electrodes 7b and 8b of the tuning fork arms 2 and 3 are irradiated with the laser beam spot 10c is set to gradually increase toward the tuning fork base 4. In this way, as the tuning fork base 4 is approached, the frequency change in one irradiation with the laser beam spot 10c becomes smaller, so that the frequency can be adjusted with high accuracy.

(Second Embodiment)
Next, an embodiment of a piezoelectric vibrator according to the present invention will be described. FIG. 6B is a schematic cross-sectional view showing the configuration of the packaged piezoelectric vibrator. The piezoelectric vibrator 1 is bonded and fixed in the housing container 21, the inside of the housing container 21 is held in a vacuum atmosphere, and sealed with a lid 24 to form a packaged piezoelectric vibrator 20. The frequency of the packaged piezoelectric vibrator 20 is accurately adjusted using the frequency adjusting method described in the first embodiment. As described above, the piezoelectric vibrator 20 in which the frequency is adjusted with high accuracy can be provided by using the piezoelectric vibrator frequency adjusting method of the first embodiment.

(Third embodiment)
Next, an embodiment of an electronic device according to the present invention will be described.

  FIG. 7 is a schematic configuration diagram showing the configuration of the electronic device. The electronic device 30 includes the piezoelectric vibrator 20 described in the second embodiment. Examples of the electronic device 30 using the piezoelectric vibrator 20 of the above embodiment include portable electronic devices such as a mobile phone, a digital camera, and a video camera. In these electronic devices 30, the piezoelectric vibrator 20 is used as a reference signal source. By providing the piezoelectric vibrator 20 with a small size and high accuracy, an electronic device with a small size, excellent portability, and good characteristics can be provided.

(A) is a top view of the piezoelectric vibrator of 1st Embodiment, (b) is sectional drawing which follows the AA disconnection of the same figure (a). FIG. 3 is a schematic cross-sectional view illustrating the operating principle of a piezoelectric vibrator. The flowchart explaining a frequency adjustment process. It is a top view explaining the adjustment method of the frequency adjustment of a piezoelectric vibrator, (a) is frequency adjustment 1, (b) is frequency adjustment 2, (c) is a top view corresponding to frequency adjustment 3. (A), (b), (c) is a top view which shows the modification of 1st Embodiment. FIG. 4A is a plan view in which a piezoelectric vibrator is disposed in a container, and FIG. 4B is a schematic cross-sectional view of a packaged piezoelectric vibrator. The block diagram which shows the structure of an electronic device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Piezoelectric vibrator, 2, 3 ... Tuning fork arm, 4 ... Tuning fork base, 5, 6 ... Groove, 7, 8 ... Excitation electrode, 7a ... Side electrode, 7b ... Groove bottom electrode, 8a ... Groove side electrode, 8b ... Groove bottom electrode, 9 ... weight, 10a, 10b, 10c ... laser beam spot, 20 ... packaged piezoelectric vibrator, 30 ... electronic device.

Claims (11)

A tuning fork arm and a tuning fork base that connects one end of the tuning fork arm, and a method of manufacturing a piezoelectric vibrator in which the tuning fork arm performs flexural vibration,
Forming a groove on the upper and lower surfaces facing the thickness direction of the tuning fork arm;
Forming excitation electrodes on each of the side surface of the tuning fork arm and the groove, and
And a step of removing a part of the excitation electrode formed in the groove . The groove part has a bottom part and a side part, and the excitation electrode has a bottom electrode formed on the bottom part and a groove side electrode formed on a side face of the groove part ,
The method for manufacturing a piezoelectric vibrator according to claim 1, further comprising a step of removing a part of the bottom electrode . 3. The method of manufacturing a piezoelectric vibrator according to claim 1, wherein the step of removing a part of the excitation electrode formed in the groove is performed by laser beam irradiation. 4. The piezoelectric vibration according to claim 3, further comprising the step of irradiating a laser beam sequentially in a direction from the open tip of the tuning fork arm toward the tuning fork base to remove a part of the excitation electrode of the groove. Child manufacturing method. The tuning fork arm is composed of two tuning fork arms, and the mass obtained by removing a part of the excitation electrode formed in the groove portion of one tuning fork arm and the other tuning fork arm is substantially equal in both tuning fork arms. A method for manufacturing a piezoelectric vibrator according to any one of claims 1 to 4 . 5. The method of manufacturing a piezoelectric vibrator according to claim 4, wherein a pitch for sequentially irradiating the excitation electrodes formed in the groove with laser light is smaller than a spot diameter of the laser light . Before the step of removing a part of the excitation electrode formed in the groove,
Removing a part of the weight formed at the tip of the tuning fork arm by laser light irradiation; and
And a step of removing a part of the excitation electrode routed to the surface of the tuning fork arm by laser light irradiation. A tuning fork arm, a tuning fork base for connecting one end of the tuning fork arm, a groove formed on the upper and lower surfaces facing in the thickness direction of the tuning fork arm, and a side surface of the tuning fork arm and the groove. An excitation electrode, and the tuning fork arm is a piezoelectric vibrator for bending vibration,
A part of the excitation electrode formed in the groove is removed, and the piezoelectric vibrator is characterized in that At the tip of the tuning fork arm, the weight is partially removed,
The piezoelectric vibrator according to claim 8, wherein the excitation electrode is routed around a surface of the tuning fork arm, and a part of the excitation electrode is removed on the surface. A tuning fork arm, a tuning fork base for connecting one end of the tuning fork arm, a groove formed on the upper and lower surfaces facing in the thickness direction of the tuning fork arm, and a side surface of the tuning fork arm and the groove. An excitation electrode, and the tuning fork arm is a piezoelectric vibrator for bending vibration,
The piezoelectric vibrator is adhesively fixed in the container,
A part of the excitation electrode formed in the groove is removed,
A packaged piezoelectric vibrator characterized in that the inside of the container is maintained in a vacuum atmosphere. At the tip of the tuning fork arm, the weight is partially removed,
The packaged piezoelectric vibrator according to claim 10, wherein the excitation electrode is routed around a surface of the tuning fork arm, and a part of the excitation electrode is removed on the surface.