JPH0456508A - Piezoelectric vibrator and its frequency adjustment method - Google Patents

Abstract

PURPOSE:To adjust the frequency with high accuracy and good productivity by radiating a laser beam to a frequency adjustment material provided to an air-tight package inner face from the outside and allowing the scattered frequency adjustment material to be deposited onto an electrode of a diaphragm. CONSTITUTION:A crystal resonator 6 is sealed air-tight with a sealing agent 8 by using a case 2 and a glass cover 1 and a metallic coat film 9 as a frequency adjustment material is vapor-deposited to an inner face of the transparent glass cover 1. When a laser beam 12 is radiated from the outside onto the metallic coat film 9 while being moved horizontally, the scattered metal is deposited onto an electrode 7 arranged to a crystal resonator 6 in a consecutive meandering way as the frequency adjustment material 10 thereby decreasing the resonance frequency of the crystal resonator 6. Since the frequency is adjusted efficiently after the resonator chip is sealed air-tight in the air-tight package in this way, the frequency deviation of the product is decreased.

Description

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

BACKGROUND OF THE INVENTION Piezoelectric vibrators using crystals or the like have various vibration modes depending on the purpose of use, but the thickness shear mode is generally used at present.

In this thickness shear mode, the resonant frequency of the piezoelectric vibrator changes in inverse proportion to the thickness of the diaphragm. Furthermore, it is known that the resonance frequency decreases due to the mass addition effect of the electrode, and this mass addition effect is used to adjust the resonance frequency.

A conventional piezoelectric vibrator and its frequency adjustment method will be described below.

FIG. 7 shows an internal structure diagram of a crystal resonator commonly used in conventional piezoelectric resonators, and FIG. 8 is a schematic diagram showing a method for adjusting the frequency of the crystal resonator.

In FIG. 7, electrodes 16 are formed by depositing metals such as silver or aluminum to a thickness of several thousand on both sides of a crystal plate 13 whose frequency has been adjusted by precisely polishing both sides (sometimes polishing).
and attach it to the base 14 of the retainer with the supporter 18.
It is attached to. Although this supporter 18 is plate-shaped in the figure, it may also be linear depending on the type V conditions.

In addition, this supporter 18 not only supports the crystal plate 13 but also functions as an electrical conductor.Whether in the form of a plate or a wire, the contact point with the crystal plate 13 is to prevent the crystal plate 13 from falling off. , and fixed with a conductive adhesive 19.

The input/output terminals 16 pass through the base 14, and a metal cover 20 is bonded to the outer periphery of the base 14 for sealing. Furthermore, a frequency adjusting body 17 for final frequency adjustment is uniformly attached on the electrode 16 of the crystal plate 13 in a slightly smaller shape than the electrode 16 of the crystal plate 13.

FIG. 8 shows a method of adjusting the frequency of the crystal resonator before hermetically sealing it. That is, in the vacuum chamber 22, the one shown in FIG. 7 before being covered with the metal cover 20 is placed. After creating a high vacuum atmosphere in the vacuum chamber 22, the evaporation source 24 is electrically heated, and the metal 2, such as silver or aluminum, for frequency adjustment is melted by heating.
3 is evaporated, and the electrode 1 of the crystal plate 13 is exposed through the mask 21.
6, uniformly evaporate a thousand electrodes 16 in a slightly smaller shape. At the same time, while reading the oscillation frequency of the crystal oscillator during silver deposition using the counter 28, when the oscillation frequency drops to a certain set value, the shutter 26 is closed by the comparator 2, stopping the evaporation and adjusting the oscillation frequency. was.

Problems to be Solved by the Invention However, in the conventional frequency adjustment method using the general vacuum evaporation method, a high vacuum of 1 O-storr or more is required, and a high cost is incurred for vacuum equipment including the vacuum chamber 22 etc. In addition, adjusting the frequency required extra time for vacuuming, etc., which worsened productivity. In addition, frequency adjustment must be performed before hermetic sealing, and as the resonant frequency of the crystal oscillator changes due to hermetic sealing such as resistance welding or cold welding, the resonant frequency of the finished product can be adjusted with high precision. It was extremely difficult to adjust. Furthermore, as the frequency band becomes higher, the crystal resonator becomes smaller and the electrode 16 of the crystal plate 13 also becomes smaller.
Not only is it extremely difficult to adjust the frequency, as a portion of the electrode 16 sometimes protrudes outside the electrode 16 of No. 3, but the reliability is also affected, such as by increasing the equivalent resistance.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a device that allows resonance frequency adjustment to be performed with high precision and with good productivity.

Means for Solving the Problems and In order to achieve the above object, the present invention provides an airtight container, at least a portion of which is translucent, a diaphragm provided in the airtight container, and a front and back surface of the diaphragm. an electrically conductive means introduced into the inside of the airtight container from the outside and connected to the electrodes on the front and back surfaces; a frequency adjustment object provided on a portion, a frequency adjustment object scattered from the frequency adjustment object is provided on the electrode portion corresponding to the frequency adjustment object, and this frequency adjustment object:
It has a shape in which a plurality of continuous or discontinuous straight portions are arranged in parallel.

The manufacturing method includes irradiating a laser beam from the outside of the airtight container through the light-transmitting part to the frequency adjustment object provided on the inner surface of the airtight container, scattering the frequency adjustment object by this irradiation, and scattering the frequency adjustment object. The frequency of the diaphragm is adjusted by attaching the frequency adjustment material on the electrodes of the diaphragm in the arrangement shape described above.

Effects of the present invention With the above configuration, it is possible to adjust the frequency in the atmosphere by using a finished product in which the vibrating piece is hermetically sealed in an airtight container, and vacuum equipment such as a vacuum container is not required, resulting in a simple equipment configuration. Since the frequency can be adjusted continuously in a short period of time, production efficiency can be significantly improved. However, there is no need to consider frequency variations in post-processing since the frequency is adjusted after hermetically sealing each unit, and the frequency deviation in the finished product can be reduced.

Embodiment FIG. 1 is a partially cutaway perspective view showing an embodiment of the present invention. A rectangular crystal resonator 6 with electrodes arranged on its front and back surfaces is supported and electrically connected to the holding part 4 of the lead terminal 3, which is used as an example of an electrically conductive means, by means of a conductive adhesive 6. . A metal coating film 9 as an example of a frequency adjustment material is applied to the inner surface of the transparent glass cover 1 by vacuum deposition. The inner surface of the glass cover 1 is roughened by sandblasting, polishing, etc., and the metal coating film 9 is provided on this roughened portion. Furthermore, in this embodiment, the material of the metal coating film 9 is the material of the crystal resonator 6.
The same silver as the electrode 7 formed in is used. The crystal resonator 6 is hermetically sealed to the case 2 and the glass cover 1 using a sealant 8. In other words, the glass cover 1 and the case 2 form an airtight container.

FIG. 2 shows an embodiment of the frequency adjustment method of the present invention, and is a conceptual diagram of frequency adjustment using a laser beam after vacuum sealing. 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. Although not shown, the lead terminal 3 is connected to an oscillator, and the oscillation frequency can be checked with a counter. Here, continuous wave light was pulsed from the outside through the glass cover 1 using a Q switch! The 5G laser beam 12 is focused near the metal coating film 9 by a focusing lens 11. Then, the laser beam 12 is irradiated onto the metal coat film 9 while moving in the left-right direction using a galvanometer method in which the laser beam 12 is scanned using two galvanometers. Here, the galvanometer type described above is used to move the laser beam 12, but the two Miranes can also be used with an XY table method in which the prism is fixed to an XY table, or a fiber method in which the output optical part of the optical fiber is moved freely by a robot. be. The XAG laser beam 12 can be transmitted through the Galanuka permeate 1, and only the metal coated film 9 can be selected and instantaneously scattered. As shown in FIG. 3, the scattered metal is deposited on the electrode 7 disposed on the crystal oscillator 6 as a frequency adjustment body 10 in a continuous meandering shape with a plurality of straight sections arranged in parallel, resulting in a mass addition effect. As a result, the oscillation frequency of the crystal resonator 6 decreases. Furthermore, the YAG laser beam 12 is swept and repeated until a predetermined set frequency is reached.

In this embodiment, a YAG laser beam is used as the laser beam 12, but any laser beam that can be transmitted through the glass cover 1 can be used. Further, although silver was used for the electrode 7 and the metal coating film 9 and was applied by vacuum evaporation, it is sufficient that it is stable on the electrode 7.
It is also possible to apply by a method such as printing.

In this example, the inner surface of the glass cover 1 was roughened for the following reasons.

In other words, since the portion of the metal coat film 9 irradiated with the laser beam 12 immediately scatters, the energy of the remaining laser beam 12 irradiated thereon will attack the electrode 7 in the future. Therefore, the above-mentioned surface roughening was performed in order to prevent the adverse effects caused by such residual energy.If the surface is roughened, the remaining energy will be dispersed in the roughened portion and then directed toward the electrode 7. Therefore, the electrode 7 will not be locally attacked.

According to the frequency adjustment method described above, since the airtight container and the piezoelectric vibrator itself such as the crystal resonator 6 can be placed in the atmosphere, high vacuum equipment such as a conventional vacuum container is not required. Frequency adjustment becomes possible with the configuration equipment. Furthermore, the frequency adjustment speed can be increased compared to the conventional method, and frequency adjustment can be performed continuously and efficiently. Next, in the conventional process, after frequency adjustment, the crystal oscillator 6
is housed in a case and hermetically sealed by resistance welding or cold welding, but there was a problem that the frequency changed after hermetically sealing, but the frequency adjustment of the crystal oscillator 6 according to this embodiment Since this was done after hermetic sealing, the frequency deviation of the finished product could be reduced.

Further, since the electrode 7 is not directly removed unlike the conventional example using the laser beam 12, the equivalent resistance of the crystal resonator 6 hardly deteriorates. In addition, in FIG. 2, even if the focal point of the laser beam 12 after passing through the focusing lens 11 is placed before it enters the glass cover 1, the laser beam will still cause the metal coating film 9.
can be dispersed. In addition, in this case, the glass cover 1 will not be damaged due to the energy of the laser beam 12 being too strong.

4 to 6 show the frequency adjustment body 1 provided on the electrode 9.
Fig. 4 shows another embodiment of o.

In FIG. 5, a plurality of continuous or discontinuous straight lines are arranged in parallel. In addition, the one shown in FIG. 6 is a discontinuous meandering frequency adjustment body 1 instead of the one shown in FIG. 3.
0 is set.

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. However, since the frequency can be adjusted after the vibrating piece is hermetically sealed in the airtight container, it is possible to reduce the frequency deviation of the finished product.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing an embodiment of the piezoelectric vibrator of the present invention, FIG. 2 is a cross-sectional view showing an embodiment of the frequency adjustment method for a piezoelectric vibrator of the present invention, FIG. 3, and FIG. 1 is a perspective view of another embodiment of the frequency adjustment body, FIG. 7 is a half-sectional front view showing the structure of a conventional piezoelectric vibrator, and FIG. 8 is a configuration diagram showing a conventional frequency adjustment method using a vacuum evaporation method. It is. 1... Galanu cover, 2... Case,
3... Lead terminal, 4... Holding part, 6
... Conductive adhesive, 6 ... Crystal resonator, 7 ... Electrode, 8 ... Sealing agent, 9 ...
...Metal coat film, 1o...Frequency adjustment body, 11...Focal lens, 12...Laser light.

Claims (6)

[Claims] (1) An airtight container, at least a portion of which is translucent, a diaphragm provided within the airtight container, electrodes provided on the front and back surfaces of the diaphragm, and an airtight container from the outside of the airtight container. an electrically conductive means introduced into the interior thereof and connected to the electrodes on the front and back surfaces; and a frequency adjustment member provided in a portion inside the airtight container corresponding to a light-transmitting portion of the airtight container; A frequency adjustment body scattered from the frequency adjustment object is provided on the electrode portion corresponding to the object, and this frequency adjustment body has a plurality of continuous or discontinuous straight portions arranged in parallel. A piezoelectric vibrator with a shaped frequency adjustment body. (2) In claim (1), the frequency adjustment object is a piezoelectric vibrator formed of a metal coated film provided on the inner surface of the light-transmitting part of the airtight container. (3) A piezoelectric vibrator according to claim (2), in which the electrode and the frequency adjuster are made of the same metal material. (4) An airtight container, at least a portion of which is translucent, a diaphragm provided within the airtight container, electrodes provided on the front and back surfaces of the diaphragm, and from the outside of the airtight container, an electrically conductive means introduced into the interior thereof and connected to the electromagnetic waves on the front and back surfaces; and a frequency adjustment member provided in the interior portion of the airtight container corresponding to the light-transmitting portion of the airtight container; In a light-transmitting part of the container, a laser beam is irradiated from the outside of the airtight container through the light-transmitting part to a frequency adjustment object provided in the airtight container, and the frequency adjustment object is scattered by this irradiation, By attaching this scattered frequency adjustment material to the electrode of the diaphragm in a shape in which a plurality of continuous or discontinuous linear parts are arranged in parallel, a piezoelectric material that adjusts the frequency of the diaphragm is applied. How to adjust the frequency of a vibrator. (5) A method for adjusting the frequency of a piezoelectric vibrator according to claim (4), wherein the frequency adjusting object is a metal coated film provided on the inner surface of a light-transmitting part of an airtight container. (6) A method for adjusting the frequency of a piezoelectric vibrator according to claim (5), wherein the metal coating film is provided on a roughened inner surface of an airtight container.