JPH0414309A - Piezoelectric vibrator and its frequency regulation - Google Patents

Abstract

PURPOSE:To easily regulate a resonance frequency with high accuracy by allowing a laser beam to irradiate a vapor-deposition body in a package via a light transmission section from the outside of the air-tight package to evaporate the vapor-deposition body and vapor-depositing the evaporated vapor- deposition body onto the electrode of a vibration chip. CONSTITUTION:A glass cover 1 is adhered to a case 2 with a sealing agent 8 air-tightly, a YAG laser beam 11A obtained by making continuous stimulated light into a pulse form irradiates through the glass cover 1 externally while focusing the vicinity of a chromium coat film 9A and a silver coat film 9B. Then the laser 11A transmits through the glass cover 1 and the films 9A, 9B only are selected and momentarily evaporated. Since the evaporated metal 10 is deposited to the one side of an electrode 7 arranged to a vibration chip 6, the oscillating frequency of the chip 6 due to the mass addition effect is deceased, and the operation is repeated till the oscillating frequency reaches a prescribed setting frequency by sweeping the laser beam 11A. Thus, the resonance frequency is regulated continuously and efficiently in air, the frequency deviation of the completed product is decreased and a multi-layer vapor- deposition body is adopted to prevent careless chipping.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a piezoelectric vibrator used as a reference clock of various gravity devices and a method for adjusting its frequency.

Conventional technology Piezoelectric resonators using single crystals such as quartz have extremely large Q(iiiI) and can provide highly stable performance. However, for this reason, advanced technology is required to adjust the resonant frequency. There are various vibration modes, but currently it is common to use the thickness shear mode. In this thickness shear mode, the resonant frequency of the piezoelectric vibrator changes in inverse proportion to the thickness of the vibrating piece. It is known that the resonant frequency decreases due to the effect of adding mass to the electrodes, and conventionally, this effect of adding mass has been used to adjust the resonant frequency.

A conventional piezoelectric vibrator and its frequency adjustment method will be described below with reference to the drawings.

FIG. 4 shows the structure of a crystal resonator that is common among conventional piezoelectric resonators, and FIG. 6 shows a method for adjusting the frequency of the crystal resonator.

As shown in FIG. 4, electrodes 16 are arranged on the front and back surfaces of the vibrating piece 120. Further, the electrodes 16 on the front and back surfaces are supported by the holding portion 1 of the lead terminal 13 by a conductive adhesive 18 and are electrically connected to each other. The lead terminal 13 is connected to the case 1 through a hermetically sealed connector 14.
9. Further, a mass body 16 for adjusting the frequency is added to the center of the electrode 16.

FIG. 6 shows a situation in which frequency adjustment is performed before the case 19 is hermetically sealed.
are connected, but their oscillation frequencies still vary. The crystal resonator 12 is placed in a vacuum container 21, and silver 22 for frequency adjustment is evaporated from an evaporation source 23 through a mask 2o.

At the same time, the oscillation frequency of the crystal resonator 12 is read by a counter 26 while the silver 22 is being deposited. When the oscillation frequency drops to a certain set value due to the mass addition effect, the shutter 24 is closed by the comparator 27 and vapor deposition is stopped, thereby adjusting the oscillation frequency. The above general crystal oscillator 12
Recently, studies have been conducted to increase the oscillation frequency by removing a portion of the pole 15 using laser light.

Problems to be Solved by the Invention As mentioned above, the frequency adjustment method in the conventional general vapor deposition method requires a high vacuum of about 10 Torr, and a lot of cost is incurred for vacuum equipment such as the vacuum container 21. . In addition, conventionally, frequency adjustment had to be performed in the pre-process of hermetic sealing, but since the resonant frequency changes during the hermetic sealing process using the case 19, the resonant frequency of the finished product can be adjusted with high precision. It was very graceful to adjust. In addition, the silver particles that were attached to the frequency adjustment equipment caused the crystal resonator 1 to be damaged.
2, etc., and may be carried into the finished product.
It affected its reliability.

On the other hand, in the frequency adjustment method in which part of the stain pole is removed using a laser beam, the electrode 15 that applies the electric field to the vibrating element is partially removed, but the more the frequency is adjusted, the more area is removed. As a result, the electric field applied to the vibrating element becomes weaker, leading to an increase in equivalent resistance.

In addition, it is virtually impossible to adjust the frequency by using a frequency adjustment amount within a range that does not affect the equivalent resistance because the adjustment range is narrow and frequency variations after vapor deposition cannot be absorbed.

Therefore, an object of the present invention is to enable adjustment of the resonance frequency to be performed with high precision and easily.

Means for Solving the Problems In order to achieve this object, the present invention provides an airtight container, at least a portion of which is translucent, a vibrating piece provided in the airtight container, and a surface of the vibrating piece. an electrode provided on each of the back surfaces; an electrical communication means introduced from the outside of the airtight container into the inside thereof and connected to the electrodes on the front and back surfaces; The structure includes a multilayer vapor deposited body.

In the above configuration, a laser beam is irradiated from outside the airtight container through the light-transmitting part to the vapor deposited body provided in the airtight container, the vapor deposited body is evaporated by this irradiation, and the vaporized body is evaporated. By depositing KW on the vibrating element, the frequency of the vibrating element is adjusted.

In this case, since the vibrating element is hermetically sealed in an airtight container, it is possible to adjust the frequency in the atmosphere.Therefore, a conventional vacuum device such as a vacuum container is not required, and the frequency can be adjusted continuously with a simple configuration. You will be able to do this. In addition, since the frequency is adjusted one by one after hermetically sealing, there is no need to consider frequency variations in subsequent processes, and the frequency deviation in the finished product can be reduced. Further, in the present invention, a laser beam is used for frequency adjustment, but there is no need to remove a part of the electrode as in the conventional method, and there is little deterioration in equivalent resistance.

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

FIG. 1 is a partially cutaway perspective view showing an embodiment of the present invention. FIG. 2 is a sectional view showing a two-layer metal coating film according to an embodiment of the present invention. In FIGS. 1 and 2, reference numeral 1 is a light-transmitting cover glass whose one side has been roughened, and a chromium coat film 9 & 9 and then a silver coat film 9B are deposited on the rough surface of the glass in a multi-layered state by vapor deposition. It is set up in Further, a rectangular vibrating piece 6 having electrodes 7 arranged on the front and back sides is supported and electrically connected to the holding part 4 of the lead terminal 3 used as an example of an electrically conducting means by means of a conductive adhesive 5. The glass cover 1 is arranged with its rough surface side as the inner surface side.

Further, the vibrating piece 6 is connected to the case 2 and the glass cover 1.
It is hermetically sealed using a sealing agent 8. In other words, the glass cover 1 and the case 2 form an airtight container.

FIG. 3 is a conceptual diagram showing an embodiment of the frequency adjustment method of the present invention. Frequency adjustment is performed after the glass cover 1 is hermetically sealed to the case 2 by adhering it to the case 2 with an adhesive 8. The lead terminal 3 is connected to an oscillator, and the oscillation frequency can be checked with a counter. Here, YAG laser light 11A, which is a continuous wave light pulsed by a Q switch, is irradiated from the outside through the glass cover 1 while focusing on the chromium code film 9m and the silver coat film 9B. YAG laser 11 people (1,o
eμm) can be transmitted through the glass cover 1, and only the chromium coat film 9M and silver coat film 9B can be selectively evaporated instantly. Since the evaporated metal 10 adheres to one side of the electrode 7 disposed on the vibrating element 6, the oscillation frequency of the vibrating element 6 decreases due to the mass addition effect.

This is repeated until the YAG laser beam 11 is swept and reaches a predetermined set frequency.

In this embodiment, a YA laser was used as the laser beam 11, but any laser can be used as long as it can pass through the glass cover 1.

Further, in this embodiment, the inner surface of the glass cover 1 is roughened for the following reasons. Cutting laser beam 1
Chrome coated film 9B irradiated with 1mm, silver coated 9B
Since the portion evaporates immediately, the energy of the remaining laser beam 11A irradiated thereon will in turn attack the electrode 7. Therefore, the above-mentioned surface roughening was performed in order to prevent such harmful effects caused by the remaining energy.If the surface is roughened, the remaining energy will be dispersed in the roughened portion and directed toward the electrode 7. As a result, there is no chance that it will locally attack the electrode element. Moreover, the reason why the metal coating film is made into two layers is as follows. In other words, the adhesion strength of the silver coat film 9B to the Galanu cover 1 is weak with a general vapor deposition force.
The surrounding area evaporated by the laser beam 11A may peel off and adhere to the vibrating piece 6, degrading the characteristics of the piezoelectric vibrator. Therefore, the first layer of the metal coating film is coated with chromium [
By using 9A, the bonding strength between the glass cover 1 and the chromium coated film 9 is strong, thereby improving the adhesion strength of the silver coated film 9B. Since the further pressure laser beam 11m is absorbed by the chromium coat film 9m, the power of the laser can be effectively utilized.

According to the frequency adjustment method described above, the piezoelectric vibrator itself consisting of the airtight container and the vibrating piece 6 can be placed in the atmosphere, which eliminates the need for a high vacuum device such as the conventional vacuum container 21, resulting in a simple configuration. Frequency adjustment becomes possible with equipment. Furthermore, the speed of frequency adjustment can be increased compared to conventional systems, allowing continuous and efficient frequency adjustment.

Next, in the conventional process, the vibrating element 12 is hermetically sealed inside the case 19 after frequency adjustment, but there was a problem that the frequency changed due to distortion of the lead terminal 13 during the hermetic sealing process. Since the frequency adjustment according to the present invention can be performed after the vibrating element 6 is hermetically sealed in the airtight container, the frequency deviation of the finished product can be reduced. Furthermore, since the electrode is not directly scraped off unlike conventional methods using laser light, the pressure W
The equivalent resistance of the vibrator hardly deteriorated.

In addition, in FIG. 3, after passing through the condenser lens 11, -+I
Even if the focal point of the light 11A is set before it enters the glass cover 1, the metal coating film can be evaporated by the laser beam 11A. In this case, the glass cover 1 will not be damaged due to the energy of the laser beam 11 being too strong.

Note that the chromium coat film 9 used as the first layer in the above embodiments may be an aluminum coat film or a nickel coat film. ′! ! The silver coat film 9B used as the second layer is preferably formed of the same material as the electrode 7. Further, from the viewpoint of preventing deterioration of the electrode 7, it is preferable that the first layer is thinner than the second layer as shown in FIG. 2 so that as little of the material as possible adheres to the electrode 7.

Effects of the Invention As is clear from the above description, the piezoelectric vibrator and its frequency adjustment method of the present invention have the advantage that the frequency of the piezoelectric vibrator can be continuously and efficiently adjusted in the atmosphere. Further, since the frequency can be adjusted after the vibrating element is hermetically sealed in the airtight container, it is possible to reduce the frequency deviation of the finished product. Furthermore, since the vapor deposited body is made of multiple layers, it is possible to prevent accidental peeling off.

[Brief Description of the Drawings] Fig. 1 is a partially cutaway perspective view showing an embodiment of a piezoelectric vibrator of the present invention, Fig. 2 is a sectional view showing a metal coated film portion of an embodiment of the present invention, FIG. 3 is a cross-sectional view showing an embodiment of the piezoelectric vibrator frequency adjustment method of the present invention, FIG. 4 is a half-sectional front view showing a conventional piezoelectric vibrator, and FIG. 6 is a conventional frequency adjustment method using a vapor deposition method. FIG. 1...Glass cover, 2...Case,
3... Lead terminal, 4... Holding part, 6
... Conductive adhesive, 6 ... Vibration piece, 7
...Electrode, 8...Sealing agent, 9m...
...Chrome coat film, 9B...Silver coat film,
10... Evaporated metal, 11... Condensing lens, 11m... Laser light. Name of agent: Patent attorney Shigetaka Awano and 1 other person No. 4
Figure 5 Figure 3 IO vaporized 4 belonging to

Claims (4)

[Claims] (1) An airtight container, at least a portion of which is translucent, a vibrating piece provided within the airtight container, electrodes provided on the front and back surfaces of the vibrating piece, and an airtight container from the outside of the airtight container. A piezoelectric vibrator comprising: electrical conduction means introduced into the interior thereof and connected to the electrodes on the front and back surfaces; and a multilayer vapor deposited body provided on the inner surface of the light-transmitting part of the airtight container. (2) Roughening the inner surface of the transparent part of the airtight container,
The piezoelectric vibrator according to claim 1, wherein a vapor deposited body is provided on the roughened portion. (3) Claim (1) wherein the vapor deposited body is formed of a metal coated film.
), or the piezoelectric vibrator according to (2). (4) An airtight container, at least a portion of which is translucent, a vibrating piece provided within the airtight container, electrodes provided on the front and back surfaces of the vibrating piece, and an airtight container from the outside of the airtight container. electrically conductive means introduced into the interior and connected to the electrodes on the front and back surfaces, and a multilayer vapor deposited body provided on the inner surface side of the light-transmitting part of the airtight container, from the outside of the airtight container, By irradiating the vapor deposited body provided on the inner surface side of the airtight container with laser light through the light-transmitting part, vaporizing the vapor deposited body by this irradiation, and depositing this vaporized vapor deposit on the electrode of the vibrating piece. , a piezoelectric vibrator frequency adjustment method for adjusting the frequency of this vibrating piece.