JPH0583064A - Manufacture of crystal vibrator - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for manufacturing a crystal unit, which is stable in quality and has little change in characteristics over time. According to a method of manufacturing a crystal resonator, a heat treatment for removing a deformed layer of a crystal substrate is performed, and then an electrode is formed on the crystal substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a crystal unit used in electronic equipment and the like.

[0002]

2. Description of the Related Art A conventional method of manufacturing a crystal unit is to wrap a crystal substrate to a predetermined thickness, etch it with hydrofluoric acid or the like to remove a work-affected layer, and then use silver, nickel, aluminum, etc. as electrodes. Was formed on a quartz substrate by a vacuum thin film forming method such as vacuum deposition or sputtering.

[0003]

However, according to the conventional technique, the work-affected layer on the outermost surface of the quartz substrate can be removed by etching, but the deformed layer of quartz of several tens of microns on the surface of the quartz substrate cannot be removed. When electrodes are formed on such a crystal substrate to form a crystal oscillator, the vibration frequency is increased due to the loss when the crystal oscillator vibrates, that is, the CI value increases or the deformation layer of the crystal changes with time. Since it changes, it is not possible to obtain a highly accurate crystal unit. In addition, since the way the deformable layer enters the crystal is not always constant, it is not possible to obtain a crystal oscillator with stable quality in the manufacturing process.

The present invention solves the above problems and provides a method of manufacturing a crystal unit, which can prevent the characteristics of the crystal unit from changing over time and ensure stable quality.

[0005]

According to a method of manufacturing a crystal unit of the present invention, a crystal substrate is subjected to heat treatment at a temperature not lower than 300 degrees Celsius and not higher than an inflection point of the crystal, and then electrodes are formed on the crystal substrate. Characterize.

If the heat treatment temperature is less than 300 degrees Celsius, the deformed layers of the quartz substrate cannot be rearranged by the heat treatment to restore the normal state. Further, if the inflection point of the crystal is exceeded, the piezoelectricity of the crystal is lost and it cannot be used as a vibrator, which is not suitable.

[0007]

The present invention will be described in detail by taking a method of manufacturing a bar AT oscillator as an example.

A raw quartz crystal is cut into a quartz wafer having a thickness of 50 microns in the AT-cut direction by using a band saw.
Next, the quartz wafer is polished to a thickness of 44 microns by double-sided lapping, and the size of the bar AT oscillator is 2 mm x 4 mm.
Cut by dicing. Further, in order to remove the work-affected layer on the outermost surface of the crystal wafer, etching is performed with hydrofluoric acid to form a crystal chip having a thickness of 40 μm.

Next, after heat treatment was performed under the conditions shown in Table 1 in an argon atmosphere, silver was deposited as an electrode by vacuum evaporation.
The thickness of 000A is 1.5mm × 3.
It is formed with a size of 5 mm. As comparative examples, a sample outside the temperature range of the heat treatment of the present invention and a sample not subjected to the heat treatment were prepared.

Next, a lead wire was soldered to the above sample and press-fitted into a case in a vacuum atmosphere to form a bar AT oscillator.

The characteristics of the bar AT oscillator thus obtained were measured by the oscillation method at each of the vibration frequency f and the CI value at 100 levels, and then the aging characteristics were left for 1000 hours at 130 degrees Celsius. Then, f and CI values were measured again. The results are shown in Table 2.

As can be seen from Table 2, bar A according to the invention
The T-oscillator has excellent aging characteristics and, at the same time, has a small variation in characteristics, and is a highly accurate and stable bar A.
A T oscillator can be obtained.

In the present invention, the electrodes are formed after heat-treating the quartz substrate. However, when the heat treatment is performed after forming the electrodes, the electrodes are oxidized, the adhesion of the electrodes is deteriorated, and the quartz substrate of the electrode material is used. Is not suitable because it will diffuse into

Although the bar AT oscillator is described in the embodiment, it is needless to say that the same effect can be obtained also in the oscillator using a crystal substrate.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

As described above, according to the present invention, it is possible to obtain a highly accurate crystal oscillator which is stable in quality and has little change over time. In particular, the effect of the present invention is more remarkable as the vibration frequency is higher and the thickness of the crystal substrate is smaller as in the AT vibrator.

Further, not only the crystal oscillator but also the filter using the crystal substrate can be obtained by removing the deformed layer of the crystal substrate, so that a product with stable quality and less change with time can be obtained.

Claims (1)

[Claims] 1. A method for manufacturing a crystal resonator, comprising: subjecting the crystal substrate to heat treatment at a temperature of 300 ° C. or higher and at an inflection point of the crystal or lower, and then forming electrodes on the crystal substrate. Production method.