JPS5847316A - Thickness slip piezoelectric oscillator and its production - Google Patents

Abstract

PURPOSE:To obtain an oscillator having a reduced amount of leakage of vibrating energy with an easy way of production, by forming a driving electrode on the main surface opposite to a thickness slip piezoelectric oscillator with the center part of the main surface formed into a convex surface and the outer circumference part formed into a level difference surface, respectively and holding the oscillator at the outer circumference edge part of the level difference surface. CONSTITUTION:Photoresists 2 and 2A are coated on the entire surfaces of main surfaces 1a and 1b of an AT-cut quartz bar 1 of a thickness slip piezoelectric element. Then the circumferences of the surfaces 1a and 1b are covered with a mask, and only the center part of each surface is exposed to light and developed to cake the photoresist. Thus resist films 3 and 4 are formed at the center parts of the main surfaces. Then the bar 1 is soaked into an etching solution, and the bare part containing no resist film is corroded to form level difference surfaces 5 and 6. Then the driving electrodes 7 and 8 plus the lead-out electrodes 7a and 8a extending to the outer circumference are formed by the vacuum vapor deposition after the exfoliation of films 3 and 4. These electrodes 7a and 8a on the surfaces 5 and 6 of the bar 1 are held with conduction by holding springs 10 and 11. The springs 10 and 11 are stuck to an airtight terminal 12. Thus a crystal oscillator 9 is obtained. The bar 1 is approximate to a biconvex type to reduce the leakage of energy for the oscillator 9.

Description

[Detailed Description of the Invention] The present invention is a book related to a peri-piezoelectric vibrator and its manufacturing method.
The crystal piece is held on the outer periphery by a holding spring, etc., and in order to reduce the leakage of vibration energy from this holding part, the crystal piece is beveled, convexed, etc.
The outer periphery is made thinner to concentrate daytime energy in the center of the main surface.

These processes are extremely complicated as they are performed using polishing equipment, and in particular, in the case of convex processing, the main surface of the crystal piece is polished, which directly affects the oscillation frequency, and the polishing condition and thickness must be carefully checked. The present invention eliminates the above drawbacks, and provides a thickness-slip piezoelectric vibrator that is easy to manufacture, suitable for mass production, and has little leakage of vibration energy from the outer periphery holding part, and a method for manufacturing the same. Embodiments of the present invention will now be described with reference to the drawings. First, an embodiment of the piezoelectric agitator manufacturing method of the present invention will be described in detail with reference to FIG.

In the case, 1 is a thickness-slip piezoelectric element, for example, it is an AT-cut crystal piece, and the oscillation frequency of the main vibration is 4M.
It has a disc shape with a thickness of around 0.40 in the Hz band and a diameter of 6 to 8 degrees. 03 on the entire main surface 1a and Ib of this crystal blank 1.
) Photoresists 2 and 2A, which are acid-resistant films, are applied. Next, the photoresist is exposed and developed according to a normal photo process to solidify the photoresist (resist films 5 and 4 are formed at the center of the main surfaces 1a and Ib of the crystal piece 1 as shown in Q).

When solidifying the resist films 3 and 4, the main surface 1a of the crystal piece 1 should be covered with a mask and only the central part exposed.
, Ib. Note that it is sufficient that one resist film is formed at least in the center of one main surface.
When formed on the entire surface, the resist films 3 and 4, which will be described later, are solidified acid-resistant films that are not corroded by etching solutions such as hydrofluoric acid and ammonium fluoride that corrode the crystal piece 1.

Then, the crystal blank 1 on which the resist films 3 and 4 were formed was placed in the above-mentioned 7
When immersed in an etching solution such as tonic acid, the bare portions on which no resist film is formed, as shown in FIG. 0, are corroded and step surfaces 5 and 6 are formed. In this example, the corrosion depth of this stepped surface is 0.1~
Approximately 0.2 mm is appropriate.Then, after peeling off the resist p145.4 as in (g), drive electrodes 7 and 8 are formed by vacuum evaporation or the like as in (g). Drive electrode 7
, 8 are extraction electrodes 7a, 8 extending to the outer peripheral edge as shown in the figure.
m may be formed at the same time, or may be a ring-shaped electrode (not shown) having a through hole in the center. Furthermore, the drive electrode may reach the stepped surface. This crystal piece 1 has a convex central part on both main surfaces, and stepped surfaces 5 and 6 on the outer periphery, and is a crystal similar to a piezo-type crystal piece polished into a biconvex lens shape. Next, a crystal piece that is approximated as a plano-compex type crystal piece polished into a plano-convex lens shape will be explained in Figure 1 (C'/- (F5). i is a crystal similar to crystal piece 1. Resist films 3A and 4A are formed on one side.The resist film 5A is formed on the center of one main surface, and the resist film 4A is formed on the entire surface of the other main surface. In this example, the resist films 3A and 4A are formed by printing or the like. When one of these crystal pieces is immersed in an etching solution such as chloric acid, the bare part where the resist film is not formed is corroded ( )' as shown in step N and surface S.
Aη・formed. In this case, the other main surface is completely covered with the resist film 4A and is therefore not corroded. Next, the resist film is peeled off as shown in d, and the drive electrode 7 is removed as shown in C1'.
A, form 8A. If these drive voltages do not have a drawer or polarization, such as a kettle, an electric field should be applied by connecting a wire or the like.

This crystal blank 1A has a convex central portion on one principal surface, and a step surface 5A on the outer Icti portion.

For this reason, the crystal piece 1A is a crystal piece that is similar to a plano-convex lens-like plano-convex type crystal piece, like the crystal piece 1A.

The first column ω indicates a row of crystal blanks 1B having stepped surfaces formed in several stages. This crystal is obtained by forming a large-diameter resist film from the state shown in (G) in which stepped surfaces 5B and 6B are formed, and then immersing it in the etching solution again to form three stepped surfaces 5C and 6C. . Crystal piece 1B has four arms similar to those of a compex-like crystal piece. The crystal blank 1B also has a drive of an appropriate shape, - pole (
l, 7i not shown. ) is formed.

Above mentioned crystal piece 1. The outer peripheral ends of IA and IB are held by a holding spring or the like. - As an example, the state in which the crystal blank 1 is held is shown in 3rd M. In the figure, a crystal resonator 9e which is a piezoelectric vibrator, a crystal piece 1, holding springs 10, 11, . Hermetic terminal 12 to which these retaining springs are fixed. It is composed of a cap (not shown) and the like that constitute a sealing container together with this airtight terminal. Airtight terminal 1
A retaining spring 10.11 is fixed to the upper end of the terminal pin 2,
The crystal piece 1 is held on the upper part of this holding spring and fixed with a four-electrode adhesive or the like, and the extraction electrodes 7a and 8m are connected to the holding spring 10 and 11, respectively.

Note that this does not matter when it comes to holding the crystal piece.

In this crystal resonator 9, the central part of the main surface facing the crystal blank 10 is a convex surface, and the outer peripheral part has a stepped surface of 5°6, so that the vibration energy is transferred to the crystal blank like the piconvex crystal blank. The vibration energy can be concentrated in the center, and the holding part has a thin wall to reduce leakage of vibration energy. In addition, the main surfaces 1a and 1b of the convex surface at the center of the crystal blank 1 remain as they are, and the oscillation frequency of the "thickness oscillation" determined by the thickness of the crystal blank has changed from the state before forming the stepped surface. do not have. .

In this way, since the C oscillation frequency does not change before and after processing the crystal piece, it is only necessary to set Jf accurately at the beginning, and this is particularly suitable for producing large waves.

In addition, since the stepped surface is formed by etching,
Unlike machining such as polishing, no machining strain remains on the piezoelectric element, and due to aging, there is less 6iI in the frequency ':.

Note that the resist film is not limited to riJfe or a film, but may be a metal film or other film that is not attacked by etching solutions such as hydrofluoric acid and ammonium fluoride that corrode crystal pieces. In this case, the gold 1@ film may be peeled off using aqua regia or the like, and then an electrode may be formed on the body.

Next, we will discuss other methods for manufacturing the piezoelectric vibrator of the present invention! The gun row will be explained with reference to FIG.

First, we will describe the method for manufacturing an approximate planocompex type crystal resonator.

In the figure, 13 is a crystal piece which is a piezoelectric element, and has approximately the same shape as the crystal piece 1 of the above embodiment.
A and 15b are facing each other 17. After that, as shown in (B), metal films 14 and 15 which will become drive electrodes are formed by sputtering, vacuum deposition, etc. A photoresist made of a substance is applied.The metal films 14 and 15 are two-layer films, in which a chromium layer is formed in close contact with the crystal piece 13, and a gold layer is formed on top of the chromium layer. The formed metal film 15 has a notch 15b corresponding to the portion that holds the crystal piece.

Next, the photoresist is solidified by exposure and development according to a normal photo process, and an acid-resistant film 17.
form 18. By covering the outer periphery with a mask when exposing the photoresist 16 on the main surface 13a and exposing the entire surface when exposing the photoresist 17 on the main surface 13b, an acid-resistant film 17 is formed in the center of the main surface 15a. is,
An acid-resistant coating 18 is formed on the entire main surface 13b. After this, the crystal piece 13 is immersed in a metal etching solution such as aqua regia.
As in No. 2.0, the bare metal film on which the acid-resistant film is not formed is removed to become drive electrodes 14A and 15A. Next, this crystal piece is immersed in a piezoelectric element etching solution such as hydrofluoric acid or ammonium fluoride to corrode the ridge of the piezoelectric element as shown in (g), thereby forming a step surface 19 on the main surface 13a side. Main surface 15
Since the entire surface of the b side is covered with the acid-resistant coating 18, it will not be corroded. After that, the acid-resistant film is removed using an acid-resistant film remover as shown in step 0. As a result, the drive electrodes 14A, 15A
is exposed.

Note that drive electrodes of a predetermined shape may be directly formed on the crystal piece by sputtering or the like without providing an acid-resistant coating.

As shown in FIGS. 4 and 5, the crystal piece 13 made in this manner is held at its outer peripheral end by a holding spring 20, 21 to form a crystal resonator 22. The drive electrode 15A on the back side is fixed to the holding spring 20 in a conductive state, and the drive electrode 15A on the front side
It is connected to the 4Aa holding spring 21 by a wire 25. The notch 15b of the metal film 15 shown in FIG. 2(6) prevents the connection between the holding spring 21 and the drive electrode 15A as shown in FIG.

Next, with reference to FIG. 2 again, the manufacturing method of the approximate pyconvex type crystal resonator will be described. , @ steps, metal films 14B, 15B and photoresist are formed on the entire surface. The photoresist is then exposed, developed, and solidified to form an acid-resistant film 17A18A. Both of these acid-resistant coatings are formed only on the central portion. Note that when leaving the extraction electrode, the extensions of the acid-resistant coating shown at 17m and 18a are also left. This crystal blank 15A is immersed in a metal etching solution, and then further immersed in a piezoelectric element etching solution. As shown in FIG. 6, the crystal piece 13A made in this manner has stepped surfaces 19A and 20A formed on both sides. Note that the crystal piece 13A shown in FIG.
4a, 15m, which is etched by leaving the extensions 17a, 18B of the acid-resistant coating shown in FIG. Since the surfaces 19A and 2OA are formed and the central portion is a convex surface, it is approximated to a biconvex lens-shaped pyconvex crystal piece.

The crystal blank 13B shown in FIG. 2 @' has a through hole 14C formed in the center of a metal protective film 14C formed on one main surface. When this crystal piece 13B is processed according to the steps described above, one drive electrode of the crystal piece can be made into an annular electrode having a through hole in the center.

The crystal pieces 13A and 13B described above are also held at their outer peripheral ends similarly to the crystal pieces 13 shown in the fourth and fifth figures.

FIG. 7 shows still another embodiment of the piezoelectric vibrator of the present invention.

In the figure, the crystal resonator 24 has a crystal piece 25 held by holding members 26 and 27, is directly fixed to a substrate (not shown), and is sealed in a sealed container (not shown). be. The crystal piece 25 is an approximate pyconvex type crystal piece having a rectangular parallelepiped shape, with a convex central part in the longitudinal direction of both main surfaces, and a step surface 28,29 on the outer periphery. There is a drive electrode 50.30A in the center.
is formed. Since this crystal piece 25 has a rectangular parallelepiped shape, it is suitable for batch processing in which crystal pieces are continuously formed on a large crystal plate, a large number of crystal pieces are etched at once, and finally separated one by one.

Next, still another embodiment of the present invention will be described with reference to FIG.

In the figure, a crystal piece, which is a piezoelectric element, has a substantially rectangular parallelepiped shape, and its central portion in the longitudinal direction is a convex surface, and its outer peripheral portion is a stepped surface. Further, a holding portion is integrally provided on the outer periphery of the stepped surface.

In FIG. 8, 3.1 is an AT-cut crystal resonator which is a thickness-beam piezoelectric resonator and has a substantially rectangular parallelepiped shape. The crystal resonator 31 has a main surface 21L facing the crystal piece 32.
, 32bK electrodes 53, 34 are provided, and stepped surfaces 35, 36 are formed by etching the bare portions of the main surfaces 32m, 32b where these electrodes are not provided. Electrode 33.
Reference numeral 34 is provided by vacuum evaporation, sputtering, etc. Drive electrodes 55a, 34a are provided opposite the central portions of the main surfaces 52a, 52b, and both ends of the main surfaces 32a, 32b. Holding electrodes 33b, 35c, and 34b provided opposite to each other.

34c and an extraction electrode 33d connecting the drive electrode 55a and the I holding electrode 53c on the main surface 32a.

It consists of an extraction electrode 34d that connects the drive electrode 34m and the holding electrode 54b on the main surface 52b. This crystal oscillator 51 can be used by being directly fixed to a substrate (not shown) K by a holding electrical contact.

Now, with reference to FIG. 9, the manufacturing method of this crystal resonator 1 will be described.

(2) shows the side view number of the crystal plate 32, and 32m and 52b are the opposing main surfaces. and main surfaces 52 a, 52
In b and ω), electrodes 33 and 34 are formed by vacuum evaporation, sputtering, etc. In this embodiment, chromium and gold are used as electrodes, and chromium is first vapor-deposited and then gold is vapor-deposited to form two layers.

Next, the crystal plate 32 provided with the electrodes 53 and 54 is immersed in an etching solution. This etching solution is made by heating hydrofluoric acid or ammonium fluoride solution to around 60 degrees Celsius, and corrodes crystal, but hardly corrodes gold, chromium, etc. When the crystal plate 32 provided with the electrodes 35 and 54 is immersed in this etching solution for 1 to 2 hours, the electrodes become a protective film and the crystal plate is not corroded, leaving the bare crystal plate without electrodes. is corroded. This embodiment uses a 4 MHz band crystal resonator, and the thickness of the crystal plate 32 is approximately Q, 41Ell.
The depth of corrosion is approximately 0.1 mm from one side.
This corroded surface is defined as a step surface 55.56. It is also possible to adjust the oscillation frequency of the crystal resonator 31 depending on the corrosion depth.

The crystal resonator 51 manufactured as described above has drive electrodes 33a, ! The central part where i4a is provided is a convex surface,
Holding electrode 3! The peripheral portions continuous to ib, 54b, 55c, and 34c are thin with stepped surfaces 35,5<S.

Therefore, it has the same proximal shape as a pyconvex type crystal resonator whose main surface is biconvex), and it is possible to reduce the leakage of vibration energy from the surrounding holding parts. In the case of a piconvex type crystal resonator, the thickness of the crystal piece that determines the oscillation frequency is changed by polishing to form a biconvex surface, but in the crystal resonator 31 of the present invention, the crystal piece of the central drive electrode part is formed with a biconvex surface. Since the periphery of the crystal plate 32 is etched to form stepped surfaces 35 and 36 to form an approximate convex surface without changing the thickness of the crystal plate 32, the thickness of the crystal plate 32 can be precisely matched at first. Therefore, it is most suitable for manufacturing a large number of crystal resonators at once. Furthermore, compared to the case where the main surface is polished to have a convex surface, this crystal resonator 51 also has no processing distortion at all.

Another embodiment of the present invention will be described with reference to FIGS. 10 and 11. A crystal resonator 41 is shown in a state before etching treatment,
The crystal piece 42 is a substantially rectangular AT-cut crystal resonator elongated in the X-axis direction. And the plane 4, 7 on the X axis -2 which is the main surface facing the crystal piece 420! Driving WL poles 43, 44 are provided at the center in the longitudinal direction of a142b, and extraction electrodes 43a, 44a are formed continuously from these driving electrodes up to the holding portions at both ends. The drive electrode 45 is located on one of the X-axis -
It is formed in contact with the Y-axis end surface 42c and at a distance d from the other X-axis-Y-axis end surface 42d. Further, the drive electrode 44 is formed in contact with the other X-axis-Y'-axis end surface 42d and at a distance d from one X-axis-Y'-axis end surface 42c. That is, as shown in FIG.
It is formed to be shifted by d. And the shifted drive electrode 43
, 44 and the inclined surfaces 42e and 42f connecting the ends of the X-axis
When the angle formed by the Y'-axis end faces 42C and 42d is V, and the thickness of the crystal piece 42 is t, tan/=t/d, and d is adjusted so that θ is approximately 5 degrees in the two axis directions. is set. That is, when the oscillation frequency of the crystal resonator 41 is in the 4 MHz band, the thickness t is 0.4 mm), tan5 =
Since it is 0.084, the distance d is set to 0.0336II11. In addition, when the oscillation frequency is 8 MHz band, the thickness t is Q, 20, and the distance d is 0.016813.
It is set to 1.

When the crystal piece 42 provided with the drive electrodes 45 and 44 in this manner is immersed in an etching solution, the main surface 42a.

The bare portion of 42b is corroded to form stepped surfaces 45 and 46, and the X-axis and Y-axis end surfaces 42c and 42d are also corroded. The X-axis and Y-axis end faces are drive electrodes 43, which are protective films.
Since 44 is installed out of alignment, it is corroded and the 4g oblique', 7xi
42 e, 42 f (shown in Figure 12).

The crystal resonator 41 manufactured in this way can weaken the coupling with the vibration of the self-system, resulting in pure thickness-slide imaging, which is particularly effective when miniaturizing the crystal piece 42. .

Note that the shape of the crystal piece is a rectangular parallelepiped (other suitable shapes may be used).

Further, although one small electrodynamic i was provided on both sides of the opposing main surfaces, it may be provided only on one surface.

As described above, according to the present invention, the vibration energy of the thickness shear vibration can be concentrated in the center part of the piezoelectric element, and a thickness shear piezoelectric vibrator with less leakage of 4ttkb energy from the holding part can be extremely easily provided.

Moreover, since the piezoelectric element is processed by etching, no machining φ remains, and a thickness-shear pressure 1 vibrator with stable frequency aging characteristics can be provided. In addition, the outer periphery can be made thinner due to the stepped surface without changing the main surface of the piezoelectric element.
The oscillation frequency does not change before and after machining, and if the thickness of the main surface is set to a certain level of accuracy at the beginning, it has great effects such as being able to stably supply a large quantity of parts with the same accuracy.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing one embodiment of the manufacturing method of the present invention. FIG. 2 is a process diagram showing another embodiment. FIG. 3 is a perspective view of one embodiment of the piezoelectric vibrator of the present invention. 5 is a front view of another embodiment, and FIG. 5 is a partially omitted rear view thereof. FIG. 6 is a perspective view of still another embodiment in which the holding part is omitted;
Fig. 7 is a perspective view of still another embodiment, Fig. 8 is a perspective view of still another embodiment;
0 is a front view of yet another embodiment, FIG. 11 is a sectional view taken along line XI-XI in FIG. 10, and FIG. 12 is a perspective view thereof. 1, IA, IB, 13.1! IA, 13B, 25.
Lo 2, 42...Crystal piece 6, 4. RoA
, 4A...Resist film 5, 6.5A, 19.
19A, 2OA, 28.29.35, 3445.4
6...Step surface 7.8, 7A, 8A, 14A, 15A, 30, 30A
, 33a. 54a, 43, 44... I electrode 17.18 on drive
, 17A, 18A... Acid extraction resistance 14a, 15a
, just d, 34d, 43a, 44 &... drawer part 9
, 22.24.51.41...Crystal resonator. That's all for Idene. Munikai Shi Seiko Rei Agent - YP Rishishi Mogami Tsumugi Figure 2; tb 34 Jb Figure 10
Figure 11

Claims (1)

[Claims] 1. A piezoelectric element that performs thickness-shear vibration has two opposing principal surfaces (both surfaces have a convex central portion and a stepped surface on the outer periphery, and a driving electrode is provided on at least one of the principal surfaces. 2. In claim 1, one main surface has a convex central portion. A thickness-shear piezoelectric vibrator characterized in that the outer peripheral part is a stepped surface and the other main surface is a flat surface. Thickness slip pressure 'f: vibrator characterized by a convex surface and a stepped surface on the outer periphery. 4. A thickness slip characterized by having a plurality of stepped surfaces in the first term of the range of @permission request. Piezoelectric vibrator. 5. At least one of the opposing principal surfaces of the piezoelectric element that performs thickness-shear vibration has a central portion and a drawn-out portion extending toward the outer periphery from the central portion, and the outer periphery excluding the drawn-out portion is a convex surface. A thickness-slide piezoelectric vibrator, characterized in that the part is a stepped surface, and a drive electrode is formed on at least the convex surface and is held at the outer periphery of the drawer part. 6. Claim No. 5. The thin piezoelectric vibrator according to item 5, wherein the other main surface is a flat surface, and drive electrodes are provided on substantially the entire surface except for the outer peripheral end facing the lead-out portion of the - surface. 2. A thickness shear piezoelectric vibrator according to claim 5, characterized in that a convex surface and a stepped surface are formed on both main surfaces. 8. Opposing piezoelectric elements that perform thickness shear vibration. A resist film of an etching solution that corrodes the piezoelectric element is formed on one main surface in the center and on the other surface at least in the center, and the piezoelectric element is immersed in the etching solution [2. The bare portion of the element on which the resist film is not formed is etched by η (eroding) to form a stepped surface with respect to the main surface, and after the resist film is removed, a drive electrode is formed on the main surface of the piezoelectric element. Thickness shear pressure 't1. Method of manufacturing a vibrator. 2 A piezoelectric element that performs thickness shear vibration has a super-fJJJ in the center on one side of the opposing main surfaces, and on the other side at least in the center.
A piezoelectric element is formed facing it, and the piezoelectric element is etched under the above pressure, and the piezoelectric element is immersed in an etching solution that does not corrode the drive electrode (u1'), and the drive electrode is used as a protective film.
Corrosion of the bare part of the piezoelectric element that does not form the drive electrode f′1
lLz, a method for manufacturing a vibrator with a thickness and a slip pressure of 1, where the yF characteristic is to form a 9 difference between the drive electrode surface and the corroded surface of the bare part. 10. In claim 7, an acid-resistant coating is formed on the upper part of the drive electrode [,,te,! A method for manufacturing a thickness-slip type shaker which is characterized by the following characteristics: