JPS5937719A - Manufacture of longitudianl oscillation type piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To improve shape precision and to reduce variance in characteristics by forming a main oscillation part which performs longitudinal oscillation and a supporting part in one body by photoetching. CONSTITUTION:A piezoelectric wafer is etched into the outward shape of a piezoelectric oscillator. Then, a thin conductive film 37 is formed over the nearly entire surface of an oscillator part 31 in a process (E), and photoresists 38 and 38' are formed in electrode shapes in a process (F); and thin conductive films 32, 32', and 38' are etched by using the photoresists 38 and 38' as corrosion resistant films in a process (G), and the photoresists 38 and 38' are separated in a process (H). Thus, the electrodes are formed in the photoetching process, so the shape precision is high and the variance in characteristics is less.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a longitudinally vibrating piezoelectric vibrator in which a main vibrating part that vibrates longitudinally and a support part of the main vibrating part are integrally formed by photoetching.

An object of the present invention is to facilitate electrode formation of a longitudinal vibration type piezoelectric vibrator and to reduce manufacturing costs.

Conventionally, a longitudinal vibration type piezoelectric vibrator as shown in FIG. 1 has been used as a piezoelectric vibrator for a frequency band around several 100 KHz to IMHz. FIG. 1 is a perspective view showing the oscillating piece 1 with electrodes 2.3 formed on the front and back surfaces and thin hanging wires 4, 4'.
2 shows a structure in which the center of gravity of the oscillating piece 1 is fixedly supported by soldering. The vertical vibration type piezoelectric vibrator has the following characteristics: 1. Due to variations in the positional accuracy of fixing and supporting the oscillating piece to the hanging wire and the amount of solder, there are large variations in CI value, vibration leakage, etc. 2. Connection strength between the hanging wire and the oscillating piece 4. The shape of the suspension wire makes the container larger, etc. ing.

Another conventional example of a longitudinal vibration type piezoelectric vibrator is shown in a perspective view in FIG. In the figure, the IIt vibration type piezoelectric vibrator of this example includes a main vibrating part 5 that vibrates longitudinally, a connecting part 6, 6', and a supporting part 7.
．． 7' are integrally formed by photo-etching, and are further supported by a fixing portion 8, which is a separate member in the shape of a tuning fork.

Furthermore, a perspective view of another conventional example of a vertically vibrating piezoelectric vibrator produced by photoetching is shown in No. 31N(A).

In the figure, the longitudinal vibration type piezoelectric vibrator of this example includes a main vibrating part 9, a double frame 10.11 surrounding the main vibrating part 9, and connecting parts 12, 12', 13. 15' is integrally formed by photoetching.

All of the three conventional devices described above have been devised in various ways to suppress the leakage of main vibration energy, but the effects are not sufficient, and they also have drawbacks in terms of manufacturing cost and dimensions. There is.

The present applicant has previously filed an application for a longitudinal vibration type piezoelectric vibrator having a structure that eliminates the conventional drawbacks described above, suppresses leakage of main vibration energy, and is suitable for downsizing and cost reduction.

The first embodiment is shown in a perspective view in FIG. 4(A). In the same figure, the present invention includes a main vibrating part 14 that vibrates longitudinally, a connecting part 15.15' provided in the IJ force direction of the main vibrating part 14 at a position where the vibration displacement of the main vibrating part 14 is the smallest, Connecting portion 15. Support parts 16 and 16' extend from both ends of the main vibration part 14 in parallel with one of the main vibration parts 14, and the support parts of the support parts 16 and 16' except for the main vibration part 14 form a tuning fork shape. A base 17 is provided in this manner, and the length L of the base 17 is set to be at least twice the width W of the support portions 16 and 16' corresponding to the tuning fork arms. This is a longitudinal vibration type piezoelectric vibrator having the above configuration. In this example, the longitudinal vibration type piezoelectric vibrator responds to the vibration in the short side direction caused by the longitudinal vibration of the main vibration part.
The supporting portion and the connecting portion, which are equivalent to the tuning fork arms, perform bending vibration. The longitudinal vibration type piezoelectric vibrator has a tuning fork shape in the part that supports the main vibrating part, so it has a structure suitable for downsizing and cost reduction, and has the advantage of effectively suppressing leakage of vibration energy. . By the way, the second
The conventional longitudinal vibration type piezoelectric vibrator shown in FIGS. The so-called NT rotated by an angle of 15° to +5° around the X' axis (not shown)
It is formed by photo-etching a cut crystal wafer. Excitation of longitudinal vibration is achieved by two 'electrodes 1B and 19 formed on the front and back sides of the main vibrating section 9, that is, on the 2' plane.
An electric field E is generated, and the X component f4x of the electric field E becomes an effective component for excitation, and is directed in the Y-axis direction, that is, in the length direction of the main vibration section 9. therefore.

The structure is such that only the conductive thin films formed on the front and back surfaces of the piezoelectric wafer can serve as a corrosion-resistant film and an electrode film during etching of the external shape. On the other hand, the vertical vibration type piezoelectric vibrator shown in FIG. It is formed by photo-etching so that the width direction of the main vibrating part is the X-axis and the length direction is the Y-axis.

FIG. 4 CB) is a cross-sectional view taken along Q-Q′ in FIG. The main electrodes 20 and 21 are formed perpendicular to the X-axis, that is, on the side surface of the main vibrating section 14. Therefore, compared to other conventional longitudinal vibration type piezoelectric vibrators shown in Figs. 2 and 3, it has the advantage of high electric field excitation efficiency. This method has the drawback that it is necessary to form electrodes at the same time. A so-called masking method is generally used to form electrodes on the side surfaces. FIG. 5 is an explanatory diagram of the masking method. In the figure, 22 is a longitudinal vibration type piezoelectric vibrator, and a main vibration part 23. Connecting part 24゜24', supporting part 25.25
', and a base 26, and electrodes 27 and 28 are formed on the surfaces thereof using conductive thin films. Reference numeral 29 denotes a frame for connecting a plurality of vertically vibrating piezoelectric vibrators 22 on the same universal bar, and the frame 29 and the vertical piezoelectric vibrators 22 are coupled by a coupling portion 30 . The electrodes are formed on the side surface of the main vibrating section 23 through the opening 1 for forming a conductive thin film.
A planar electrode 27 is formed in advance by snogging a conductive thin film through the mask 106 with a mask 103 having a 01, 102 in close contact with the longitudinal vibration type piezoelectric vibrator 22. A side electrode can be formed to electrically connect to the .28. Furthermore, the sectional view of FIG. 6 is explained in detail in section 2) regarding electrode formation. (A) to () () in Figure 1 indicate the order of processing steps, and (
A) is a conductive thin film 32 that is resistant to corrosion against the etching solution of the piezoelectric wafer on the front and back surfaces of the piezoelectric wafer.
．． The process of forming 32' (CB) in the same figure is the process of forming photoresist 33 and 33' (CB) of the external shape of the vertical vibration type piezoelectric vibrator on the conductive thin film 32, 327 (CB) in the same figure.
) is photoresist! The process of etching the conductive thin film 32゜32/ into the external shape of a vertical vibrator using r3e55' as a corrosion-resistant film. Figure (D) shows the process of longitudinally vibrating the piezoelectric Unino-31 using the conductive thin film 32.32' as a corrosion-resistant film. (E) is a process of forming photoresists (33, 33') in the shape of planar electrodes (Y) (Y) is a process of etching the photoresist (33, 33') into the external shape of a piezoelectric vibrator. The photoresist film 321 (CO) in the same figure is the process of peeling off the photoresist 33, 33', and CH) in the same figure is the mask 36.
．． In this step, side electrodes 35° and 35' are formed by the above-described masking method according to No. 56. In addition, in the order of the processing steps described above, the step of forming the 7-hole resist 35.33' having the electrode shape shown in FIG. 6(I) is performed as shown in FIG.
It is also possible to do it after. The method of forming a side surface using the conventional masking method described above has the following drawbacks.

1. The piezoelectric vibrator and the mask must have alignment accuracy with a misalignment of 10 microns or less, and furthermore, both must be placed in close contact with each other in the thin film forming apparatus, which requires a lot of manufacturing man-hours.

2. If alignment accuracy is not ensured, there will be a short between the two electrodes or insufficient thin film adhesion to the side surfaces, resulting in a decrease in processing yield. Also, characteristics tend to vary.

The present invention solves the above-mentioned conventional drawbacks, and the present invention solves the seventh problem.
The figure shows an example in cross section. The processing steps in FIGS. 6(A) to 6(D) showing the conventional example described above, that is, the step of etching a piezoelectric wafer into the external shape of a piezoelectric vibrator, are omitted because they are the same, and are omitted in the following text. Processing steps related to the invention are shown as (E) to (H). The same figure (I
n) is a conductive thin film 67 on almost the entire surface of the vibrator part (indicated by the main vibrating part 31 in the figure) which has been etched into the external shape.
The same diagram shows the process of forming (l is photoresist in the shape of an electrode)
38.38', the same figure (G) shows a conductive thin film 52.32 using photoresist 38.38' as an anti-corrosion film.
', 37 is etched, and (H) in the same figure is a process of peeling off the photoresist 38, 68'. Incidentally, in the order of the processing steps described above, the step of forming the conductive thin film 37 shown in FIG.
The same step may be carried out after the film is peeled off in advance.

According to the above processing steps, the following advantages can be obtained.

1. Manufacturing costs can be reduced because there is no need for complicated mask alignment, and only a photo-etching process is required.

2. Since 11 poles are formed through a photo-etching process, the shape accuracy is good and there is little variation in characteristics.

Furthermore, in the manufacturing method of the present invention, as shown in FIG.
This can be easily accomplished by immersion in a resist solution, spraying with a spray gun, or coating. In the embodiments of the present invention, a vertically vibrating piezoelectric vibrator using two quartz crystal plates has been described, but in other longitudinally vibrating piezoelectric vibrators using quartz plates, the supporting portion is shaped like a tuning fork. The present invention can be applied to any vertically vibrating piezoelectric vibrator having a main electrode on its side surface. In addition, conductive thin films 52° 32', 57
Although a single layer is shown in the drawings, it is also possible to apply multilayer films such as two or three layers.

[Brief explanation of the drawing]

FIGS. 1 to 3 show a conventional example of a longitudinal vibration type piezoelectric vibrator. FIG. 4 shows an example of a longitudinal vibration type piezoelectric vibrator that was filed in the applicant's earlier application. FIG. 5 is an explanatory diagram of a masking method for forming side electrodes on the longitudinal vibration type piezoelectric vibrator shown in FIG. 4. FIG. 6 is a diagram 8A showing a more detailed explanation of FIG. 5. FIG. 7 shows an embodiment of the present invention. 14... Main vibration part 15... Connection part 16... Support part 17... Base 20.21... Electrode 22... ...Longitudinal vibration type piezoelectric vibrator 23... Main vibration part 24... Connection part 25... Support part 26... Base part 27, 28. ... Electrode 29 ... Frame 30 ... Bonding part 31 ... Piezoelectric wafer 32 ... Conductive thin film 33 ... Photo Resist 35...Side electrode 36...Mask 37...Conductive thin film 38...Photoresist 101.102...Opening 103.・・・・・・Mask and above Applicant Matsushima Kogyo Co., Ltd. Agent Patent attorney Mogami Muzai 1st grade 2nd grade (B) 5th grade

Claims (1)

[Claims] In a method for manufacturing a longitudinally vibrating piezoelectric vibrator in which a main vibrating part that vibrates longitudinally and a supporting part of the main vibrating part are integrally formed by photoetching, a piezoelectric wafer is attached to the longitudinally vibrating piezoelectric vibrator. A vertical process consisting of a process of etching the external shape, a process of forming a conductive thin film on almost the entire surface of the vertical vibration type piezoelectric vibrator, and a process of etching a part of the conductive thin film to form an electrode. A method for manufacturing a vibrating piezoelectric vibrator.