JPH06224677A - Frequency adjusting method for piezoelectric resonator - Google Patents

Abstract

PURPOSE:To improve the working precision for frequency adjustment to prevent the occurrence of defective articles and the degradation of characteristics by laminating a vapor-deposited film on the surface of an oscillation electrode to adjust the frequency. CONSTITUTION:Mask members 12 which are provided with holes 13 so that parts of oscillation electrodes 4 are exposed are put on upper and lower faces of a piezoelectric mother substrate 9, and the film thickness which corresponds to the measured value of a frequency and should be added is calculated, and a metallic film is laminated again on parts of oscillation electrodes 4 by vapor-deposition or sputtering based on this film thickness. Metallic plates or heat-resisting tapes are used as these mask members 12, and dimensions of holes 13 may be equal to or larger than those of oscillation electrodes 4. The frequency is measured, and the metallic film is laminated furthermore in the same manner in accordance with the measured value if necessary, and it is adjusted to a required frequency fo. Sealing plates which are provided with recessed parts so that cavities are formed in parts of oscillation electrodes 4 are laminated and adhered on upper and lower faces of the piezoelectric mother substrate 9, and they are unified and cut and are provided with an external electrode, thus forming a piezoelectric resonator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency adjusting method for adjusting a frequency by forming a film on a vibrating electrode portion of a piezoelectric resonator, and for example, a piezoelectric resonance utilizing an energy trap type thickness longitudinal vibration. The present invention relates to a frequency adjusting method for a piezoelectric resonator in which a metal film is formed on the electrode portion of the child by redeposition to adjust the frequency.

[0002]

2. Description of the Related Art Conventionally, as an example of a chip-type piezoelectric resonator, there is one utilizing energy trap type thickness longitudinal vibration having a structure shown in FIGS. This piezoelectric resonator 1
Is laminated on and bonded to the upper and lower surfaces of the piezoelectric element 2 formed by providing the vibrating electrode 4 and the extraction electrode 5 on the piezoelectric substrate 3 and adhering the insulating sealing member 6 such as alumina to the extraction electrode 5. The external electrodes 7 are provided so as to extend from both sides of the outside to the ends. The above-mentioned piezoelectric element 2 has a substantially rectangular piezoelectric substrate 3 made of piezoelectric ceramics, and has both upper and lower main surfaces facing each other with the vibrating electrodes 4 facing each other with the piezoelectric substrate 3 interposed therebetween, and the vibrating electrodes 4 facing each other. The extraction electrode 5 is provided along the end portion on the side. When the sealing member 6 is laminated and adhered to the piezoelectric element 2, the vibrating space is formed by the recess 8 formed in the portion of the sealing member 6 facing the vibrating electrode 4. Then, by applying a voltage to the external electrode 7 of the piezoelectric resonator 1, the vibrating electrode 4 of the piezoelectric element 2
Resonance vibration or anti-resonance vibration is generated in the part and is taken out to the outside. The frequency fo (H
The relationship between z) and the thickness t (mm) of the piezoelectric substrate is expressed by the following equation. fo = K / t, where K = v / 2 (v is the speed of sound in the object (m / sec))

In the conventional method of manufacturing the piezoelectric resonator 1 by adjusting its frequency, first, as shown in FIG.
A mother substrate of piezoelectric ceramics is processed to have a thickness obtained by calculation so as to oscillate at a predetermined frequency, metal films 10 are formed on both sides of the substrate by metal deposition, and a voltage of 3 to 5 KV / mm is applied to polarize the film. Then, the piezoelectric mother substrate 9 is formed. Then, the resonance frequency, the anti-resonance frequency, and the oscillation frequency are measured, and if the required frequency is insufficient for the film thickness, vapor deposition is repeated until the frequency is reached. Next, as shown in FIG. 7B, the etching resist ink 11 is applied to a desired electrode shape,
The unnecessary portion of the metal film is removed by etching, the resist ink is removed thereafter, and as shown in FIG. 7C, the vibrating electrode 4 and the extraction electrode 5 having a required shape are formed. Here, the oscillation frequency is measured again, and ink for frequency adjustment is applied to the surface of the vibrating electrode 4 according to the measured value to obtain the required frequency (f
Adjust to o).

[0004]

However, as described above, the frequency of the piezoelectric resonator is measured, and ink for frequency adjustment is applied to the electrode surface according to the measured value to adjust it to the required frequency (fo). With this method, there is a problem that it is difficult to apply the frequency adjustment ink with high accuracy, the occurrence rate of defective products is high, and the characteristics of the ink are deteriorated, resulting in poor durability.

The present invention has been made in order to solve the above-mentioned conventional problems, and improves the processing accuracy of frequency adjustment, prevents the generation of defective products, and prevents the deterioration of characteristics of the piezoelectric resonator. The purpose is to provide a method of adjustment.

[0006]

A method of adjusting a frequency of a piezoelectric resonator according to the present invention comprises forming metal films on both upper and lower main surfaces of a piezoelectric ceramic substrate and then polarizing the piezoelectric substrate to form a piezoelectric substrate. In the frequency adjusting method of the piezoelectric resonator, in which the unnecessary portion of the metal film is removed to form an electrode having a desired shape, and the frequency of the opposing vibrating electrode is measured to adjust the frequency, the vibration is generated according to the measured frequency. It is characterized in that the frequency is adjusted by forming a vapor deposition film on the electrode surface.

[0007]

According to the method of adjusting the frequency of the piezoelectric resonator according to the present invention, metal films are formed on both upper and lower main surfaces of the piezoelectric ceramic substrate, a voltage is applied to form the piezoelectric substrate, and it is unnecessary by etching. Remove the metal film from the part to form the vibrating electrode and the extraction electrode in the required shape, measure the frequency of the vibrating electrode, mask the part other than the vibrating electrode part, and vapor-deposit it to a thickness corresponding to the frequency of the vibrating electrode. Form a film to adjust the frequency. According to the present invention which adjusts the frequency in this way, since the metal film is directly formed on the vibrating electrode surface by vapor deposition and the frequency is adjusted, compared to the conventional frequency adjusting method such as masking and applying ink. The number of steps and the forming time can be reduced, the productivity can be improved in this respect, and the manufacturing cost can be reduced. Further, there is no variation in the film thickness due to the application of ink, it is possible to prevent variation in quality due to processing, and the defective product rate can be reduced accordingly. Further, it is possible to prevent changes in electrical characteristics due to ink deterioration and improve durability, which also improves reliability in quality.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views for explaining a method of adjusting the frequency of a piezoelectric resonator according to an embodiment of the present invention. In the present embodiment, a piezoelectric resonator that uses thickness longitudinal vibration in which a piezoelectric element is laminated on the above-described sealing substrate will be described as an example. The same reference numerals are attached to the portions corresponding to the above-mentioned conventional example. The piezoelectric resonator 1 of the present embodiment has a structure similar to that shown in FIGS. 5 and 6, in which a vibration space is formed on the surface portion of the vibration electrode 4 of the piezoelectric element 2, and the upper and lower surfaces of the piezoelectric substrate 3 are formed. , Sealing member 6
Are laminated and adhered to each other so as to be electrically connected to the extraction electrode 5 and extended from both side surfaces of the outside to the end portion to provide the external electrode 7. However, a metal film for frequency adjustment is attached to the surface of the vibrating electrode 4 of this embodiment.

Hereinafter, a method of adjusting the frequency of the piezoelectric resonator will be described in detail. First, required electrodes are formed as in the conventional case. As shown in FIG. 7, the substrate is processed to have a thickness calculated to oscillate a predetermined frequency, and metal films 10 are formed on both surfaces of the substrate by vapor deposition (FIG. 7 (a)), and a voltage of 3 to 5 KV / mm is applied. By applying, the piezoelectric mother substrate 9 is formed. Then, the resonance frequency, the anti-resonance frequency, and the oscillation frequency are measured, and if the required frequency is insufficient for the film thickness, vapor deposition is repeated until the frequency is reached. Next, the etching resist ink 11 is applied to the required electrode shape (FIG. 7B), and the unnecessary portion of the metal film is removed by etching, and the resist ink is removed to form the electrodes 4 and 5 having the required shape. (FIG. 7C), and the frequency is measured.

Next, as shown in FIGS. 1 and 2, a mask member 12 having a hole 13 so that the vibrating electrode 4 is exposed.
The one on top surface of the piezoelectric mother substrate 9, the film thickness should be added in accordance with the measured value of the frequency is calculated, and the thickness of the prospect, deposition, or again metal portion of the vibrating electrode 4 performs sputtering Stack the membranes. The mask member 12 is
The size of the hole 13 may be the same as or larger than that of the vibrating electrode 4, using a metal plate or a heat-resistant tape. Further, one mask member 12 may not be provided with a hole so that the metal film is stacked only on the one vibrating electrode 4. Then, the frequency is measured, and if necessary, metal films are stacked in the same manner according to the measured value, and the frequency is adjusted to the required frequency (fo).

Subsequently, as shown in FIG. 3, the piezoelectric mother substrate 9
The sealing plate 14 provided with the concave portion 15 so as to form a cavity in the vibrating electrode 4 is laminated and adhered to the upper and lower surfaces of
As shown in FIG. 3, after being integrated, the line AA, B in FIG.
By cutting along the line -B, the external electrode 7 is provided to form a piezoelectric resonator as shown in FIGS. As a method of forming the cavity for the vibration space, a sealing member 6 is formed by applying a thick adhesive to form a gap.
May be laminated and adhered.

As in the above-described embodiment, since the metal film of the same material is again deposited on the vibrating electrode 4 by vapor deposition or sputtering to adjust the frequency, the electric characteristics of this piezoelectric resonator are ink. It does not deteriorate like the conventional example adjusted in. Further, since thickness control can be easily controlled like ink coating, thickness adjustment is easy and frequency adjustment can be performed accurately. Although the thickness longitudinal vibration has been described as an example in the above embodiment, the scope of application of the present invention is not limited to this, and can be applied to piezoelectric resonators of other modes, particularly on the surface of the vibration electrode of the piezoelectric element. This is effective when a film is formed and frequency adjustment is performed.

[0013]

As described above, according to the method for adjusting the frequency of the piezoelectric resonator of the present invention, since the frequency is adjusted by laminating the vapor deposition film on the surface of the vibrating electrode, the thickness can be easily adjusted and the quality can be improved by processing. Can be prevented from varying, and the defective product rate can be reduced and the quality can be improved. Further, by using a metal film, there is an effect that deterioration of the film can be surely prevented, durability of the piezoelectric resonator can be improved, and reliability of quality can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which masks are laminated to explain a method of adjusting a frequency of a piezoelectric resonator according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a state in which the masks of the above-described embodiment are stacked and vapor deposited.

FIG. 3 is a perspective view showing a state in which a sealing substrate is laminated on a piezoelectric mother substrate whose frequency is adjusted according to the above embodiment.

FIG. 4 is a perspective view showing an integrated state of the above embodiment.

FIG. 5 is an exploded perspective view showing a piezoelectric resonator.

FIG. 6 is a perspective view showing the piezoelectric resonator.

FIG. 7 is a perspective view illustrating a step of forming a frequency-adjusted vibrating electrode.

[Explanation of symbols]

 1 Piezoelectric Resonator 2 Piezoelectric Element 3 Piezoelectric Substrate 4 Vibrating Electrode 5 Extraction Electrode 9 Piezoelectric Mother Substrate 12 Mask Member 13 Hole

Claims (1)

[Claims] 1. A piezoelectric substrate is formed by forming metal films on both upper and lower main surfaces of a piezoelectric ceramic substrate, and forming a piezoelectric substrate by polarization.
In the frequency adjusting method of the piezoelectric resonator, in which the unnecessary portion of the metal film is removed to form an electrode having a desired shape, and the frequency of the opposing vibrating electrode is measured to adjust the frequency, the vibration is generated according to the measured frequency. A frequency adjusting method for a piezoelectric resonator, characterized in that a frequency is adjusted by forming a vapor deposition film on an electrode surface.