JP2000317814A - Piezoelectric element and method for working the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric element which is slightly thinner than the thickness of production limit, and a working tool and a working method for working the piezoelectric element and other material, which, have been previously difficult of realization. SOLUTION: A ring-like, a rectangular or any other shape groove or a step difference is formed on an upper surface of a first working jig 11. A cylindrical or any other shape second working jig 19 which is taller than the depth of the groove or step difference is fitted in the groove or step difference. There is set a cylindrical or any other shape piezoelectric element 13 to be polished which is equal in height to, or lower or higher than a protrusion of the second working jig 19 above an upper surface of the first working jig 11. Then, the piezoelectric element 13 to be polished is polished into an extremely thin workpiece by using two lapping plates of a lower lapping plate 17 and an upper lapping plate 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to barium titanate, quartz, lithium niobate or potassium niobate used for an acceleration sensor or an angular velocity sensor.
The present invention relates to a processing tool and a processing method for processing a piezoelectric element such as another single crystal, a piezoelectric ceramic, or another ceramic, an optical lens, or another substance.

[0002]

2. Description of the Related Art Quartz resonators, which are a type of piezoelectric element, are used for clock generation of microcomputers for general-purpose computers, OA information equipment, and home appliances, as well as oscillation sources of the reference frequency of communication equipment and measurement equipment. Although it is diverse,
In order to improve the performance of information processing and transmission, it is required to reduce the thickness of a vibrator and increase its natural vibration frequency. In order to obtain a high-quality vibrator, it has been proposed to finish it into a lens shape, and it has been used in a relatively low frequency range.

[0003] However, as a problem in reducing the thickness of the vibrator, there is currently a limit of production of 27.8 μm (= 60 MHz) in the production method using a double-sided lapping machine. Also, when the vibrator is finished in a lens shape, it is very difficult to create a curved surface on a thin section, and there has been no example manufactured so far.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a piezoelectric element and a method for processing the same, which are thinner than the manufacturing limit, which has been conventionally difficult.

[0005]

In order to solve the above-mentioned problems, a method of processing a piezoelectric element according to the present invention is directed to a method of manufacturing a piezoelectric element, comprising: In, to form a groove or a step of a ring shape or a square shape or other shape, and a little higher than the depth of the groove or the step, a cylindrical or other shape, glass or,
A second working aid made of super steel or iron or other material is fitted into the groove or the step, and the second working aid protrudes from the upper surface of the first working aid. The same as the height, or slightly lower than the protruding height, or high disk-shaped or other shape, the piezoelectric element polished object is installed, the piezoelectric element polished object, on the lower surface, the lower An extremely thin workpiece is polished by using two upper and lower wrapping plates of an upper wrapping plate on the lapping plate and the first processing aid.

[0006] As a method of fixing the first processing aid to the disk-shaped or other object to be polished, a circular shape formed on the upper surface of the first processing aid, or another method. A liquid of a viscous substance (for example, a substance such as a surfactant) is put into a groove or a step having a shape of the above, and the piezoelectric element to be polished so that the periphery of the lower surface of the piezoelectric element to be polished adheres to the liquid. By placing on the first processing aid and using the surface tension of the liquid or by freezing,
On the upper surface of the first processing aid, placed, on the hydrophilic thin plate impregnated with water, place the object to be polished piezoelectric element,
Using the surface tension of water included in the hydrophilic thin plate, or forming a plurality of holes in the first processing aid, syrup, honey, adhesive bond or grease, etc. in these holes By filling a viscous substance or another adhesive (for example, a rubber-based adhesive), the lower surface of the object to be polished with the piezoelectric element can be brought into close contact with the viscous substance. Said first processing aid, made of glass or super steel or iron or other metal,
Can be fixed using rosin, starch glue, or other adhesives.

In the piezoelectric element of the present invention, a pressure receiving surface made of a material having a piezoelectric effect, such as quartz, barium titanate, lithium niobate, or other ceramics, is formed at the center of the cylinder. A pair of electrodes is formed on the pressure receiving surface. The cylinder and the pressure receiving surface can be made of an integral material having a piezoelectric effect.

Further, the method for processing a piezoelectric element according to the present invention comprises:
Made of a material having a piezoelectric effect, from both ends of the round bar, respectively, using a grinding means, punch a cylindrical hole, at the center of the round bar, to form a pressure receiving surface of a predetermined thickness, the A pair of electrodes is provided on the pressure receiving surface to convert external air vibration into an amplified electric signal.
The grinding means forms a groove on the surface of the barrel-shaped grindstone, and by injecting compressed air or liquid into the groove, the grindstone is rotated, or using other mechanical means,
The barrel-shaped whetstone may be rotated. A barrel-shaped grindstone can also be formed using a steel ball close to a true sphere.

[0009]

Embodiments of the present invention will be described below. The present inventor has developed a new processing method classified as a grinding method, and has a 9 μm-thick uniconvex lens shape (Pl).
(ano-convex type) Quartz vibrator was successfully manufactured. Further, for the purpose of improving the performance of the crystal resonator, the relationship between the thickness and the electrical characteristics of the resonator having a thickness of 500 μm or less was investigated.

[0010] Since quartz is a hard and brittle material, it has been considered that applicable processing methods are limited to mechanical lapping or chemical etching. Therefore, the grinding method is hardly used for processing the high frequency crystal resonator.

As shown in FIG. 1, the grinding method developed by the present inventor is a method using a ball grinding stone 1 in which diamond abrasive grains are electrodeposited on steel balls. That is, a quartz plate 4 is attached on a cylindrical magnet 3 attached to a main shaft 2 of an ultra-precision lathe, and a tool holder 6 provided with a seat on which a ball rides is attached to a tip of a grinding spindle 5. When this is brought close to the cylindrical magnet 3, the steel ball is attracted and held by the tool holder 6 by magnetic induction. Since the tool holder 6 is smaller than the diameter of the cylindrical magnet 3, the magnetic flux density is smaller than that between the ball grinding wheel 1 and the cylindrical magnet 3.
The space between the ball grinding wheel 1 and the tool holder 6 is larger. For this reason, the ball grindstone 1 is strongly sucked into the tool holder 6, and does not come off even when rotated at a high speed, and is strongly integrated.

The steel balls are electrodeposited and fixed with diamond abrasive grains to form the ball grinding stone 1. Since the steel balls are held by the magnetic force in the cylindrical tool holder 6, they are easily formed. The whetstone can be replaced. Moreover, since the steel balls are held by using the cylindrical tool holder 6 and the high-precision steel balls, the work of centering the grindstone 1 which is necessary at the time of replacement is unnecessary. It has a feature that the ball grindstone 1 used for the rough processing and the finishing processing can be quickly replaced. Since the movement of the ball grinding wheel 1 is controlled by the NC device, a curved surface can be created. Ball whetstone 1 made of steel balls used for ball bearings, etc.
The diameter of the diamond abrasive grains 57 to be electrodeposited and fixed is, for example, 30 μm used for rough machining, 16 μm used for medium finishing, and 4 μm used for finishing. In the case of, the diameters of the ball grinding stones 1 are different from each other by the diameter of the diamond abrasive grains 57. If the diameters of the diamond abrasive grains 57 are different,
When the ball grinding stone 1 is attracted to and held by the cylindrical tool holder 6 using the magnetic induction of the cylindrical magnet 3 on the main shaft 2 side, the diameter of the diamond abrasive grains 57 differs by the amount corresponding to each other. The center point of the ball grindstone 1 held by the tool holder 6 by magnetic force moves in the vertical direction. As a solution to this problem, as shown in FIG. 1B, the ball whetstone 1 is held by the tool holder 6.
If only the area of the holding portion 56 of the ball grindstone 1 is not fixed to the diamond grindstone 57 by electrodeposition and the ball grindstone 1 is used, as shown in FIG. Regardless of the thickness, the center axes of the vertical and horizontal χ and γ axes, particularly the vertical χ axis of the ball grinding wheel 1 are always fixed, so that the ball grinding wheel 1 for rough finishing can be used.
Even if the ball grinding stone 1 for the intermediate finishing and the ball grinding stone 1 for the finishing are exchanged for the ball grinding stone 1 for the finishing, respectively, χ, γ
As shown in FIG. 1C, the axis does not always change, so that the replacement of the ball grindstone 1 is facilitated.

The present inventor has used this processing method to obtain FIG.
As shown in (a), the Plano-convex type processing in which the holding portion 51 and the groove 52 were integrally formed was successfully performed. The curve connecting the holding portion 51 and the groove 52 is called a smooth line 53. As shown in FIG. 2 (b), the shape of the quartz crystal disk was ground at 25 μm.
The lens shape has a radius of curvature of 3 mm and a shape error of 0.1 μm or less. Heretofore, it has been considered that a crystal resonator having this shape is likely to be accompanied by sub-vibration, and cannot exhibit sufficient performance. However, as is apparent from FIG. 2C, the reactance frequency characteristic draws a sharp resonance curve and does not involve any sub-vibration, so that it is understood that it is almost ideal as a crystal resonator.

An attempt was made to produce a thinner crystal resonator, and a crystal resonator having a thickness of 9 μm and a radius of curvature of 200 mm was successfully processed. The surface was further removed by about 0.5 μm by polishing with cerium oxide, and as a result, FIG.
An element as shown in (a) was obtained. As shown in FIG. 3B, the reactance frequency characteristics of the resonance curve lack a little sharpness, suggesting that Q is slightly smaller than that of the crystal resonator of FIG. Is not accompanied at all. As a cause of the lack of sharpness of the resonance curve, it is expected that damage due to processing is inherent below the surface of the crystal unit, and the thickness of the crystal unit is reduced,
This is probably because the ratio of the thickness of the damaged layer was relatively increased. However, the characteristics can be improved by removing the damaged layer by an etching method.

Next, under the condition that the radius of curvature of the Plano-convex type is 30 mm and the thickness of the lens portion is
Tried to increase. Until it reaches a thickness of 125 μm
A sharp resonance curve without secondary vibration similar to FIG. 2 was maintained. However, beyond that, a phenomenon appeared with accompanying or no vibration.

On the other hand, as shown in FIG. 4 (a), the thickness of the vibrating portion is 27 μm in a planar shape (Inverted m).
esa type) was also manufactured. P with similar resonance frequency
Compared to the lan-convex type, as shown in FIG. 4B, it can be seen that although the electrical characteristics are somewhat inferior, there is no accompanying secondary vibration. Further Invcrted Mesa
When the thickness of the flat part of the mold is increased, the thickness becomes 30 μm
Beyond, a phenomenon that did not cause vibration appeared. Inv
In the erted mesa type, the radius of curvature of the lens portion is
It is considered to be an infinite Plano-convex type, and it can be said that this type of crystal resonator having a ring support has a region exhibiting good vibration characteristics and a region which cannot vibrate due to the thickness and curvature of the vibrating portion.

The following conclusions have been obtained by the method of the present invention. Until now, it has been considered that a favorable quartz-crystal vibrator without a sub-vibration cannot be obtained unless the shape is a Bi-convex type. However, even in the Plano-convex type, when a ring support is provided and the thickness is reduced to about 30 μm,
It has been found that a crystal resonator having ideal reactance frequency characteristics without secondary vibration can be obtained.

As described above, a result is obtained in which the performance of the quartz resonator can be expected to be improved in a thin region. But,
It was also found that when the thickness exceeds 125 μm, sub-vibration occurs or the vibration stops.

The present inventor has been studying a processing method for reducing the thickness of the crystal unit as much as possible. 5 and 6 show that the diameter and thickness of the polish point are 5 mm, 76.7 μm and 10 mm, respectively.
FIG. 9 shows a reactance frequency characteristic in the case of 0 μm. According to this, it is understood that the sub-vibration exists near the frequency of the main vibration. FIG. 7 shows the reactance frequency characteristics of a crystal resonator having a thickness of 33 μm.
No sub-vibration exists in the frequency range of 5 MHz.
However, as shown in FIG. 8, a complicated sub-vibration is seen in a frequency region separated by about 6 MHz. FIG. 9 shows that the thickness is 31 μm.
This shows the reactance frequency characteristic of the crystal resonator of m, and there is no sub-vibration in the ± 5 MHz region of the main vibration, but the frequency of the sub-vibration is higher than the frequency of the main vibration as shown in FIG. Are also about 8 MHz apart. From this, it can be seen that the sub-vibration departs from the frequency of the main vibration as the thickness of the crystal resonator decreases.

FIGS. 11 to 19 show an apparatus for processing an ultra-thin quartz crystal unit. In this processing equipment,
As shown in FIG. 11, on the upper surface of the first processing aid 11,
A groove or step 12 having a ring shape or a square shape or another shape is formed, and as shown in FIG. 12, a cylindrical shape or a slightly higher depth than the depth of the ring or other shape groove or step 12 is formed. A second processing aid 19 having a shape is fitted therein, and as shown in FIG.
The second processing aid 19 is fitted into the inside of the disk-shaped member, and a disk-shaped or slightly higher or slightly higher than the projection height (for example, 40 μm) from the first processing auxiliary tool 11 or A piezoelectric element to be polished in another shape, in this example, a quartz plate 13 is provided. Further, as another processing order, the following is more preferable because the distortion generated at the stage of processing the quartz plate 13 is corrected. Before placing the quartz plate 13 on the first processing aid 11, as a pretreatment, a metal such as gold or silver or aluminum is vapor-deposited on one surface of the quartz plate 13, After forming a metal coating on one side of the plate 13 or using other means, the one side of the quartz plate 13 is subjected to a surface treatment so that the front and back surfaces of the quartz plate 13 can be distinguished. For example,
When an extremely thin metal coating is formed, the crystal plate 13 is placed on the first processing aid 11 with the surface on which the metal coating is formed facing downward, and The thickness of
For example, if both sides are polished and the thickness is 40 μm,
Even at the stage of polishing to a thickness of about 20 μm, considerable distortion occurs on the polished surface of the quartz plate 13.
In order to remove this distortion, at this stage, the processing aid formed by using the first processing aid 11 and the second processing aid 19, and the quartz plate being processed, 13 is taken out from the double-side polishing machine, washed well, and the surface of the metal film formed on the surface of the quartz plate 13 is turned up again. The quartz plate 13 having a thickness of 5 μm or less, which is a final target, is polished from the surface where the quartz plate 13 is placed on the surface of the processing aid 1 and is coated with a metal. Can be easily polished, and at the same time, the crystal plate 13 can be polished.
Is polished from both sides.
3, the generation of distortion generated by polishing from one side can be suppressed to a minimum,
Extremely thin, quartz plate 1 without changing the characteristics of quartz
3 can be polished. By the way, when the deposition is performed by using gold, the thickness of the deposition layer is 100 ° (angstrom) to 200 °, and the deposition layer can be formed uniformly on one surface of the quartz plate 13. Because you can
The thickness of the vapor deposition layer itself is a thickness that does not matter as compared with the thickness of the quartz plate 13 to be polished. By depositing a metal such as gold on one side of the crystal plate 13, even if the crystal plate 13 is processed halfway, the crystal mixed in the polishing agent such as cerium oxide. The plate 13 is easily separated from the crystal plate 13 by easily washing the abrasive and the crystal plate 13 with water.
Can be taken out.

The quartz plate 13 and the upper surface of the first processing aid 11 are usually fixed with an adhesive or polished without using an adhesive. Using an agent, on the upper surface of the first processing aid 11, on the entire surface,
When the adhesive is applied and attached, in the case of a thin plate (for example, a thickness of 10 μm) or a quartz plate, the quartz plate 13 receives a strong external stress due to a contraction force when the adhesive hardens. As a result, the characteristics of the crystal plate 13 are reduced due to the distortion, and the characteristics of the crystal plate 13 are lost. Therefore, it is not possible to apply an adhesive to the entire lower surface of the crystal plate 13 to perform bonding. Can not. Therefore, as shown in FIG. 14, a circular or other shape formed on the upper surface of the first processing aid 11 ', pure water is put in the groove 14, or rosin or other adhesive is applied. Put the crystal plate 1 in this pure water
3, the crystal plate 13 is placed so that the periphery of the lower surface is in close contact, and the surface tension of water is used, or water is frozen, or rosin or other adhesive is used. 1
The first processing aid 11 'and the crystal plate 13 are fixed using a part of only the outer peripheral portion of the groove 14, which has a circular or other shape formed on the upper surface of the processing aid 11'. can do.

As another example, as shown in FIG. 15, a suede 15 containing pure water is placed on the upper surface of the first processing aid 11, and a quartz plate is placed on the suede 15. The first processing aid 11 ″ and the crystal plate 13 are fixed to each other by using the surface tension of water that is placed on the suede 15.

Further, as another example, as shown in FIG. 17, a plurality of holes 16 are formed in the first processing aid 11, and two or three holes 16 are appropriate. This hole 16
By filling a viscous substance such as starch syrup, honey, a pound of adhesive or grease or other adhesive, the lower surface of the quartz plate 13 is brought into close contact with the viscous substance, and the first processing aid 11 and The crystal plate 13 is spotted and fixed only by the area of the hole 16. Note that the arrangement of the holes 16 is as shown in FIG.
As shown in FIG.
As shown in (b), there is a case where they are arranged concentrically, but it is not limited to these examples. Also, using the hole 16 formed in the first processing aid 11, the first processing aid 11 and the quartz plate 13 are separated by using the area of the area of the hole 16, In the case where the first processing aid 11 and the crystal plate 13 are spotted and fixed to only a part, the second processing aid 19 may not be used.

The first processing aid 11 described above is connected to the first processing aid 11 shown in FIG.
As shown in (a), the upper wrapping plate 18
The upper and lower two wrapping plates of the lower wrapping plate 17 are used.
Quartz and cylindrical or other shapes are processed, and the upper lapping plate 18 is formed with a ring-shaped or square-shaped or other-shaped groove or step 12, and the lower surface is polished and polished on both sides. A very thin workpiece is polished by a machine. In addition, the first processing aid 11 is manufactured by using a metal such as super steel or iron or glass, which is difficult to grind, and the second processing aid is formed of glass or super steel. Or, when made using metal such as iron, the upper wrapping plate 1 made of metal such as iron
8 polishes the first processing aid 11 made of iron or the like, and the lower lapping plate 17 is made of a metal such as glass or super steel or iron. And processing the quartz plate 13 or FIG.
As shown in FIG. 16B, the second processing aid 19 and the quartz plate 13 are reversed in a state opposite to the means described with reference to FIG.
And the second processing aid 19 and the quartz plate 13 are polished by the upper lapping plate 18, and the first processing aid 11 is polished by the lower lapping plate 17. Good.

FIGS. 18 and 19 show the state of FIG.
3, a quartz plate 13 formed by using the first processing aid 11 and the second processing aid 19 and formed by polishing using the processing aid, The figure shows a polished shape. The reason why the shape of the quartz plate 13 shown in FIG. 18 is different from the shape of the quartz plate 13 shown in FIG. 19 is as follows.
The processing aid is manufactured using a material different from the material used for manufacturing the processing aid 19 of FIG. 19 and the material forming the second processing aid 19 shown in FIG. That's why. Second processing aid 19 shown in FIG.
The second processing aid 19 is formed by using a hard glass made of quartz and having substantially the same hardness as the quartz plate 13.
19, the second processing aid 19 shown in FIG. 19 is a hard metal, hard steel, harder to polish than the quartz plate 13, This is because the second processing aid 19 is manufactured using iron or the like. However, it is a condition that cerium oxide, alumina, GC, diamond, or another abrasive is used as the abrasive. The reason is that when an abrasive such as cerium oxide is used, the quartz plate 13 and the hard glass are made of the same quartz, and therefore, when cerium oxide is used, both can be polished well. However, metals such as super steel or iron can hardly be polished using cerium oxide. However, when an abrasive such as cerium oxide is used, the quartz plate 13 can be polished well. This is because the processing can be performed, and the polishing of the processing aid made of a metal such as super steel or iron can be delayed more than the polishing of the crystal plate 13. The difference is that the shape of the quartz plate 13 shown in FIG. 18 and the shape shown in FIG.
This is because the shape of the crystal plate 13 is different. The dimensions of the finished quartz plate 13 having the concave lens shape shown in FIG. 19 are the same as those of the quartz plate 13 shown in FIG. 26, and the holding portion 51 and the smooth line 53 are formed. Therefore, as a characteristic of the crystal unit, as in the case described with reference to FIGS. 2, 3, and 4, the crystal unit has an ideal shape exhibiting characteristics. ing. Another important point in performing the above-mentioned polishing process is that when performing the polishing process, usually, both sides are covered with a suede or a non-woven fabric (hereinafter, referred to as a suede) by wrapping plates 17 and 18. Is polished by using, as shown in FIG.
In the case of manufacturing a quartz plate 13 having a concave lens shape, for example, a wrapping plate 17 having one surface made of a metal plate such as iron is used, and the other surface is provided with a wrapping plate 18 having a suede. As shown in FIG. 16 (b), the upper lapping plate 18 is sueded by polishing, and the lower lapping plate 1 is used.
7 is made of a metal plate such as iron, using a wrapping plate 17 and polished to form a first processing aid 1 made of metal such as super steel or iron.
1 is made of a metal plate, and is polished using a lapping plate 17. Since the conditions are met, the hardness of the metal plate forming the wrapping plate 17 and the first processing aid 11 By making the hardness of the metal substantially the same, the back surface of the first processing aid 11
If it is difficult to perform polishing as much as possible, the condition is set, and the conditions are set, and polishing is performed using a suede stretched on the upper lapping plate 18, the quartz plate 1
3 can be easily improved. Another important point is that the suede is formed on the upper wrapping plate 18 by using a roughened or similar undulated suede.
Polishing is also an important condition in producing the quartz plate 13 having a concave lens shape. In addition, the quartz plate 1 having the shape shown in FIG.
3 can be polished, and the reproducibility or accuracy of the finished quartz plate 13 is extremely high. is there.

Although not shown in the drawings, the processing auxiliary tool formed by using the first processing auxiliary tool and the second processing auxiliary tool as the polishing means described above is used. As another method of use, even if a single-side polishing machine other than the double-side polishing machine is used, the concave lens-shaped quartz plate 13 having the shape shown in FIG. Can be polished.

Further, using the processing aids formed by using the first processing aid 11 and the second processing aid 19, the quartz plate is formed into a shape as shown in FIG. 13
Is polished using a double-side polishing machine or a single-side polishing machine, when previously polished into a concave lens shape using a processing means as shown in FIG. 25 or FIG. 26, by grinding the quartz plate 13 into a concave lens shape as shown in FIG.
A mask is applied to the central portion of the crystal plate 13, and a laser irradiation such as an excimer laser is performed only on the central portion, and the initial thickness of the crystal plate 13 is, for example, 40 μm.
For example, only the central portion is subjected to 0.1 mm by one heat irradiation pulse.
A processing layer of about 1 μm is removed, a heat irradiation pulse of about 200 pulses in total is performed, and a concave lens shape (inverted MESA type) having a depth of about 20 μm, for example, as shown in FIG. The shape is roughened by using an excimer laser or by using chemicals such as hydrofluoric acid (commonly called hydrofluoric acid) and ammonium chloride.
The quartz plate 13 is etched, and only the central portion of the quartz plate 13 is roughened into a concave lens shape, or
Using a processing means such as sanding, only the center portion of the quartz plate 13 is rough-processed into a concave lens shape, or
Using other means, the quartz plate 13 is roughened into a concave lens shape.
The quartz plate 13 roughly processed into a concave lens shape is polished using a processing aid as shown in FIG. 13, or a processing aid as shown in FIG. Without use, the carrier 37 shown in FIG.
Is directly formed on the quartz plate 13, the carrier 37 is used to make the quartz plate 13 planetary, and the quartz plate 13 is formed using a double-side polishing machine. Assuming that the process is performed to remove the layer, to perform the finishing, to perform the polishing process, and to perform the processing step, as shown in FIG.
The quartz plate 13 having a concave lens shape with high accuracy can be manufactured in a large amount in a short time.

The upper and lower wrapping plates 17,
18, the carrier 37 on which the first processing aid 11 is mounted is rotated by the rotation together with the supply of the slurry (free abrasive grains), as shown in FIGS.
And the internal gear 38, and the processing aid 1
1 is revolved around the sun gear 39 and revolves around the planetary gear to make planetary motion. When the other side of the auxiliary tool 11 is polished using the upper lapping plate 18, the extremely thin quartz plate 13 can be easily polished. When a single-side polishing machine is used, the quartz plate 13 can be polished by the same means as the above-mentioned polishing means.

Further, after processing the extremely thin quartz plate 13 by the above means (for example, when the thickness is 10 μm)
In this case, since the quartz plate 13 is extremely thin, it is difficult to handle it, and it is difficult to form electrodes on the quartz plate 13. Therefore, as shown in FIG. The quartz plate 13 is set in the center of the fixing frame 48, and a very thin gold wire 49 (for example, about 50 μm) is used to attach the crystal plate 13 to the fixing frame 48 using a bonding machine. The plate 13 is fixed. After the crystal plate 13 is fixed to the fixing frame 48, the gold wire 49 has slack as shown in FIG. 23A, and therefore, as shown in FIG. 13 from above, or
Correct the slack of the gold wire 49 by other means, and
It is even better if 9 is in a linear state. Further, FIG. 22 shows a state in which the crystal plate 13 is fixed from at least three directions by using the gold wire 49 for the fixing frame 48 by means as shown in FIG.
Is fixed, the extremely thin gold wire 49 is used to fix the quartz plate 13 in the air, so that the gold wire 49 absorbs the vibration of the quartz plate 13. The characteristics of the crystal are not degraded to the utmost.

Further, as shown in FIG. 23, the quartz plate 13 is fixed to a fixing frame 48 using a gold wire 49, and then, as shown in FIG. Using a bonding machine, a connection is made between the quartz plate 13 and the fixing frame 48 using a gold wire 49 from both sides of the quartz plate 13, and the gold wire 49 is attached to the quartz plate 13. By being used as the electrode 50 to be attached, the electrode 50 is provided only on the center portion of the crystal plate 13 in comparison with an electrode conventionally used (for example, an electrode formed by vapor deposition on the front and back of the crystal plate). Can be formed, so that the characteristics of the crystal are not reduced. The gold wire 49 used as the electrode 50 may be a very thin gold wire of about 50 μm.

FIG. 25 shows an apparatus for manufacturing a crystal plate 13 having a concave surface on one side. In FIG. 25, 11 is the first
, A reference numeral 19 denotes a second processing aid, and 41 denotes a low-speed rotation of the processing aids 11 and 19 (for example, 100 to 300 rpm).
m), a motor 43 for rotating the polishing tool 44 at a high speed (for example, 5000 rpm). As the polishing tool 44, a soft tool such as a felt, a cotton pad, a buff or the like is used, and a polishing agent such as cerium oxide or GC or diamond is used to polish at about 1 μm per minute. As shown in FIG. 26, a disk-shaped crystal plate having an initial thickness of about 40 μm is finished into a concave lens-shaped crystal plate 13 having a thickness of 10 to 5 μm at the center. Further, the crystal plate 13 can be roughly processed into a concave lens shape by using a device having a structure as shown in FIG. 25.
When the polishing tool 44 is made of an electroplated foil of diamond abrasive grains as the polishing tool 44, the quartz plate 13 can be easily roughened into a concave lens shape. Then, when the quartz plate 13 roughly processed into a concave lens shape is polished using a double-side polishing machine or a single-side polishing machine, the quartz plate 13 having a concave lens shape as shown in FIG. , Can be polished and finished.

As the processing aid, in addition to the structure shown in FIG. 25, as shown in FIG.
1 "or a ring-shaped processing aid 11a and a disk-shaped processing aid 11b shown in FIG. 28 are combined, integrated with an adhesive or the like, and a quartz plate 13 is placed thereon. You can also.

As shown in FIG. 29, an aluminum adhesive tape 45 having a hole formed on the upper surface of the crystal plate 13 and extending over the periphery is attached to the second processing aid 19, By polishing with a polishing apparatus shown in FIG. 25, it is possible to manufacture a crystal plate 13 having a concave portion only at the central portion as shown in FIG.

Next, as an application example of the piezoelectric element of the present invention,
The acoustic-electric converter will be described. Conventionally, seismic exploration and prediction include ocean observation, underground structure exploration, geomagnetic observation, observation by GPS, and measurement of the movement of the earth's core by laser measurement of the distance between two points. Observing the vibration of air due to an earthquake or tsunami is another predictive method.

As a means for converting the vibration of air into an electric signal which can be easily recorded and analyzed, there is a sound collecting microphone.

FIGS. 30 (a) to 30 (e) show embodiments of an acoustic-electric converter using the piezoelectric element of the present invention. The acoustic-electric converter includes quartz, lithium niobate, or another single crystal. A cylinder 21 made of a material having a piezoelectric effect, such as crystal or barium titanate or other ceramics
Alternatively, the pressure receiving surface 22 is formed in the center of the cylinder 54, and a pair of electrodes 23 and 24 are formed on the pressure receiving surface 22.
Amplifier 25 for measuring the induced voltage between 3, 24
Are connected. (Only the electrodes 23 and 24 and the amplifier 25 are shown in FIG. 30A). 30 (a) is a biconvex lens (bi-convex) type, (b) is a biconcave lens type, (c) is a planar type, (d) is a planar type with R formed around it, and (e) is a uniconvex ( (plano-convex) type. As shown in FIG.
Is sealed using two pieces, and the inside of the cylinder 21 is sealed.
A chamber is formed, the inside of the cylinder 54 is sealed, and a chamber B is formed,
The left and right cylinders 21 of the cylinders 21 and 54 both have a structure in which the inside of the cylinder 21 is sealed and the inside of the cylinder A is sealed, and the inside of the cylinder 54 and the inside of the chamber B are both decompressed (preferably in a vacuum state). And the cylinder 54 catches vibrations in the horizontal axis direction and the vertical axis direction, and forms the pressure receiving surface 22 formed in the center portion of the cylinder 21 and the cylinder 54, when the cylinder 21 and the cylinder 54 are not formed. In comparison, the pressure receiving surface 22 has a structure that catches vibration more strongly. In addition,
For the above reasons, the smaller the diameter and the longer the length of the cylinders 21 and 54 are, the more the vibration from the outside is generated by the pressure receiving surface 2.
2 is easy to receive, so that a highly accurate pressure sensor can be made.

FIG. 31 is a top view shown in FIGS. 30 (a) and 30 (e). The vibrated vibration caused the cylinder 21 and the cylinder 54 to vibrate from the portion A to the portion B or from the portion B to the portion A shown in FIGS. 30 (a) and 30 (e). Vibration
By freely moving from both ends, the cylinder 21 and the cylinder 5
Vibration (vibration of part A,
Vibration caused by vibrating the portion B) is caused by the cylinder 21 and the cylinder 54
By freely moving from both ends, the vibration that vibrated the portion A and the vibration that vibrated the portion B resonated in the center portion, causing a resonance phenomenon, and When the space portion 47 is not formed, the pressure receiving surface 22 formed in the center portion is vibrated stronger than the space portion 47 by comparison.

Next, a method of forming the pressure receiving surface 22 will be described. Basically, as shown in FIG. 32, quartz or barium titanate, lithium niobate or other ceramics, and other materials having a piezoelectric effect,
A round bar 30 made of a material is attached to a chuck 31 of a processing machine such as a lathe.
A processing tool 33 having a grindstone 32 with a diamond stone attached to the surface of a metal ball and a rotatably provided grinding wheel 32 at the tip is gripped by a tool holder 34. Whetstone 32
As shown in FIG. 33, is a sphere whose opposing surface is cut,
It is rotatably mounted. On the peripheral surface of the whetstone 32,
FIG. 34A is an enlarged cross-sectional view of FIG.
As shown in (b), a V-shaped groove 32a is formed, and one of the inner walls of the groove 32a has a directionality included in a plane passing through the center of the grindstone 32. This whetstone 32
Is rotated at high speed (preferably 8.000 to 50.000 rpm) by a jet stream of air, which is tangentially jetted from the air nozzle 40 to the peripheral surface of the grindstone 32,
Take the surface to be ground slowly (for example, 1μ
m) Sharpening. During this grinding, from the fountain nozzle 41
Water is injected to cool the grindstone 32 and discharge shavings. When the grindstone 32 is driven to rotate, the round bar 30
As shown in FIG. 2, a circular or cylindrical hole is formed by the grindstone 32 driven to rotate around the axis. As another method of using the grinding or polishing means described above, the use of a grindstone 32 ″ as shown in FIG. The shape shown in FIG. 4 or another shape can be applied to grinding or polishing.

When the polished surface of the pressure receiving surface 22 is convex, a drum-shaped whetstone 32 'is used as shown in FIG. 36 ((a) is a front view, and (b) is a plan view). When the polished surface of the pressure receiving surface 22 is flat, as shown in FIG.
A flat grindstone 32 "is used. Alternatively, as shown in FIG. 37, a grindstone 32 'having a diameter much smaller than the hole diameter is used, and the same rotational drive as the machining tool 33 shown in FIG. 33 is applied to the grindstone 32'. The grindstone 32 'is rotated while moving the processing tool 33' along a curved surface of the pressure receiving surface by an NC device or the like, and at the same time, the pressure receiving surface is processed while rotating the chuck 31 and the round bar 30. When the grindstone 32 ″ having a shape as shown in FIG. 36D is used as a means for forming the hole or space portion 47, the hole or space portion 47 can be easily processed while leaving the holding portion 47. Can be done. Further, as means for forming the hole or the space portion 47,
Even if you use a drill electrodeposited with ordinary diamond,
It is possible to form a hole or space part 47.

For machining a circular hole, a tool rotating around a normal axis can also be used. A spherical grinding wheel as shown in FIG. 38 and a disk grinding wheel as shown in FIG. 39 can also be used. Can be used. When the grinding process is completed using the grindstone 32, a polishing grindstone 32 ″ for polishing having the same structure as the grindstone 32 is manufactured using a material such as a felt or a buff and polished. When the grinding wheel 32 ″ is replaced with the grinding wheel 32 ″ and the polishing is performed using the grinding wheel 32 ″, the finishing process can be performed. Also, like the means for rotating and driving the grindstone 32, the groove 32
If (a) is formed and the air nozzle 40 is used to perform a rotational drive, the polishing can be easily performed.

FIGS. 40 and 41 are fabrication views of a grinding and polishing apparatus having the structure shown in FIG. The diameter of the whetstone 32 actually manufactured is 2
0 mm, the depth of the groove 32 (a) is 1 mm, and the number of the grooves is 16, and the air is sprayed tangentially to the peripheral surface of the grindstone 32 from the air nozzle 40 to a grinding and polishing apparatus having a structure formed with 16 grooves. I do.

In the grinding and polishing apparatus having the structure shown in FIGS. 40 and 41, a metal such as iron, aluminum, or copper, or a buff or
36. A polishing grindstone 32 ″ ″ (e) shown in FIG. 36 is made of felt, glass, plastic, ceramics, or another polishing material, and the polishing grindstone 32 ″ ″ (e) is formed. , As an abrasive, diamond paste or cerium oxide or alumina or GC or
Using other abrasives, a crystal is formed into a shape as shown in FIGS. 2A, 3A and 4A by using the processing method shown in FIG. Such as a piezoelectric material,
Grinding and polishing are performed simultaneously. Grinding and polishing can be performed simultaneously because the rotation speed of the grinding wheel 32 "" (e) is limited to the rotation speed up to 50.000 rotations, which is the limit that the bearing can withstand. Since the grinding wheel 32 "" (e) can be easily driven, the polishing process can be performed efficiently and in a very short time only by the polishing process. With a piezoelectric material such as this, two processes of grinding and polishing can be performed simultaneously using a polishing grindstone 32 ″ ″ (e) made of felt, buff, iron, or the like.

FIG. 42 (a) shows a quartz plate 13 using hydrofluoric acid or other chemicals.
, And a central portion, for example, having a diameter of 1.
The shape of the quartz plate 13 formed by etching a concave lens shape (inverted MESA shape) of 5 mm is illustrated. When the quartz plate 13 or other piezoelectric material is etched using a chemical such as hydrofluoric acid, the shape of the outer peripheral portion, which is indicated by oblique lines, is shaped like a square (floor moat) In the case where an electrode is formed by using vapor deposition, a hatched portion becomes a shadow, and it is difficult to form an electrode.

FIG. 42B shows the state shown in FIG.
In order to correct the disadvantages of the etching process described in (a), using a double-side polishing machine shown in FIG. 20, for example, the upper lapping plate 18 has a suede 15 And the lower wrapping plate 17 is made of a metal wrapping plate such as iron, as shown in FIG.
When the etched concave lens-shaped portion of the quartz plate 13 is polished using a suede 15 and an abrasive such as cerium oxide, a smooth line 53 as shown in FIG. Is a first advantage. Further, the second advantage is that since the abrasive is accumulated inside the concave lens shape, the inside of the concave lens shape is moved to the upper lapping plate 1.
8 can be polished steadily and stepwise, and the lower lapping plate 17 can be polished from both sides,
Even if the crystal plate 13 that is thin, for example, up to about 0.5 μm, is extremely thin, is polished, the thickness of the holding portion 51 is
Since the thickness of about 40 μm to about 30 μm can be maintained, there is no difficulty in maintaining the strength and handling of the concave lens portion even if it is extremely thin. Further, a third advantage is that the concave lens shape can be polished using a plane polishing machine. The above three advantages are provided by a processing means using both an etching process and a double-side polishing machine.

[0045]

According to the present invention, the object to be polished is rough-processed by etching, and then the surface is polished by using a double-side polishing machine, thereby forming a smooth line which cannot be formed by etching. Since it can be formed, formation of an electrode by vapor deposition becomes easy. Further, thereby, it is possible to provide a vibrator with less auxiliary vibration.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an outline of a processing method of the present invention.

FIGS. 2A and 2B show a first example of manufacturing a quartz oscillator, and FIG.
7A shows a cross-sectional shape of the vibrator, FIG. 6B shows a Nomarski micrograph of the vibrator, and FIG. 6C shows a reactance frequency characteristic. The surface material is AT cut, the thickness of the material is 103μ
m, the diameter is 5 mm, the processing size is 25 μm in thickness, and the radius of curvature is 30 mm.

FIGS. 3A and 3B show a second example of manufacturing a crystal unit, and FIG.
Shows the cross-sectional shape of the vibrator, and (b) shows the reactance frequency characteristics. The surface material is AT cut, the thickness of the material is 103 μm, the diameter is 5 mm, the processing size is 9 μm in thickness, and the radius of curvature is 200 mm.

FIG. 4 shows a third example of manufacturing a quartz oscillator, in which (a)
Shows the cross-sectional shape of the vibrator, and (b) shows the reactance frequency characteristics. The surface material is AT cut, the thickness of the material is 77 μm, the diameter is 5 mm, and the processing size is 27 μm.

FIG. 5 is a diagram showing a reactance frequency characteristic of a crystal resonator having an AT cut and a thick quartz resonator.

FIG. 6 is a diagram showing a reactance frequency characteristic of a quartz crystal unit having a thick AT-cut surface material.

FIG. 7 is a diagram showing the reactance frequency characteristics of a quartz crystal unit having a thin AT-cut surface material.

FIG. 8 is a diagram showing a reactance frequency characteristic of a thin quartz crystal unit in which a surface material is AT-cut and has a small thickness.

FIG. 9 is a diagram showing the reactance frequency characteristics of a quartz oscillator having a thinner AT material and a thinner thickness.

FIG. 10 is a diagram showing the reactance frequency characteristics of a quartz oscillator having a thinner AT material and a thinner thickness.

FIG. 11 is a sectional view of a first processing aid in the processing method of the present invention.

FIG. 12 is a sectional view of a second processing aid in the processing method of the present invention.

FIG. 13 is a cross-sectional view of a state in which a second processing aid and a quartz plate are set on the first processing aid.

FIG. 14 is a sectional view showing another example of the processing apparatus of the present invention.

FIG. 15 is a sectional view showing another example of the processing apparatus of the present invention.

FIG. 16 is a cross-sectional view showing a state where the processing apparatus of the present invention is sandwiched between lapping plates.

FIG. 17 is a plan view of a first processing aid in the processing apparatus of the present invention.

FIG. 18 is a cross-sectional view of a quartz plate manufactured using the processing aid of FIG.

19 is a cross-sectional view of a quartz plate manufactured using the processing aid of FIG.

FIG. 20 is a plan view showing the movement of the wrapping plate.

FIG. 21 is a plan view showing the movement of the wrapping plate.

FIG. 22 is a top view showing an embodiment of the present invention.

FIG. 23 is a sectional view showing an embodiment of the present invention.

FIG. 24 is a sectional view showing an embodiment of the present invention.

FIG. 25 is a cross-sectional view showing an example of the processing apparatus of the present invention.

FIG. 26 is a sectional view of a quartz plate manufactured by the apparatus of FIG. 25;

FIG. 27 is a cross-sectional view showing another example of the processing aid.

FIG. 28 is a cross-sectional view showing another example of the processing aid.

FIG. 29 is a cross-sectional view showing another example of the processing aid.

FIG. 30 is a sectional view showing an embodiment of the present invention.

FIG. 31 is a top view showing an embodiment of the present invention.

FIG. 32 is a cross-sectional view showing a processing method according to the present embodiment.

FIG. 33 is a side view showing a working tool in the present embodiment.

34A and 34B are a side view and an AA cross-sectional view illustrating an example of a grindstone according to the present example.

FIG. 35 is a cross-sectional view showing a processed example in the present example.

FIG. 36 is a side view and a plan view showing another example of the grindstone in the present embodiment.

FIG. 37 is a sectional view showing another example of the working tool according to the present embodiment.

FIG. 38 is a cross-sectional view showing another example of the working tool in the present embodiment.

FIG. 39 is a cross-sectional view showing another example of the working tool in the present embodiment.

FIG. 40 is a side view and a top view showing an actual production drawing of the working tool in the present embodiment.

FIG. 41 is a longitudinal sectional view and a sectional view of an enlarged view showing an actual production drawing of the working tool in the present embodiment.

FIG. 42 is a cross-sectional view showing a processed example in the present example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ball whetstone, 2 spindles, 3 cylindrical magnets, 4 quartz plates, 5 grinding spindles, 6 tool holders, 11 first processing aids, 12 ring or square or other shaped grooves or steps, 13 Quartz plate, 14 circular or other shaped grooves, 15 suede, 16
Hole, 17 lower wrapping plate, 18 upper wrapping plate, 19 second processing aid, 21 and 54
Cylinder, 22 pressure receiving surface, 23, 24 electrodes, 25 amplifier, 30 circles, 31 chuck, 32, 32 ', 3
2 ", 32", 32 "grinding or polishing whetstone, 32
(A) Groove, 33 33 ', 33 "machining tool, 34 tool holder, 35 support arm, 36 bearing, 37 carrier, 38 internal gear, 39 sun gear, 4
0 air nozzle, 41 fountain nozzle, 42, 43 motor, 44 polishing tool, 45 adhesive tape, 46 hole or space portion, 47 holding portion, 48 fixing frame, 49 gold wire, 50 electrode, 51 holding portion, 52 groove, 53 Smooth line, 55 stopper, 56 holding part, 57 diamond abrasive, 58 piezoelectric plate, 59 adhesive layer,

Claims (12)

[Claims] 1. A ring-shaped or square-shaped or other-shaped groove or step is formed on an upper surface of a first processing aid,
The depth of the groove or the step, a little higher than the depth, a cylindrical or other shape, a second processing aid is fitted into the groove or the step, the first of the second processing aid, A processing aid, a disk-shaped or other shaped piezoelectric element to be polished, which is the same as, or slightly lower or higher than, the protruding height from the upper surface, is installed; Using an upper lapping plate on the upper surface of the polished object and an upper and lower wrapping plate of a lower lapping plate below the first processing aid, an extremely thin workpiece is polished. A method for processing a piezoelectric element. 2. A liquid is poured into a circular or other shaped groove or step formed on the upper surface of the first processing aid, and the periphery of the lower surface of the object to be polished of the piezoelectric element is in close contact with the liquid. So that the object to be polished is placed on the first processing aid, and the liquid is used for surface tension or by freezing, so that the first processing aid is 2. The method for processing a piezoelectric element according to claim 1, wherein the object to be polished is fixed to the object to be polished. 3. The object to be polished is placed on a hydrophilic thin plate containing water placed on the upper surface of the first processing aid, and the polishing object is included in the hydrophilic thin plate. 2. The method for processing a piezoelectric element according to claim 1, wherein the first processing aid is fixed to the object to be polished by using surface tension of water. 4. A plurality of holes are formed in the first processing aid, and the holes are filled with a viscous substance such as starch syrup, honey, an adhesive bond or grease or other adhesive. The lower surface of the object to be polished is brought into close contact with the viscous substance, and the first processing aid and the object to be polished are spotted and fixed only by the area of the hole. The method for processing a piezoelectric element according to claim 1. 5. The method according to claim 5, wherein the first processing aid and the second processing aid are formed by using rosin, starch paste or other adhesive.
The method for processing a piezoelectric element according to claim 1, wherein the piezoelectric element is fixed. 6. A mask is applied to the object to be polished of the piezoelectric element, and only the center portion is roughly processed into an inverted MESA shape (concave lens shape) by using a chemical etching means, and thereafter, is used as a subsequent processing means. And a finishing method using a double-side polishing machine. 7. A quartz or lithium niobate, potassium niobate or other single crystal or
A method for processing a piezoelectric element, comprising: forming a pressure receiving surface made of a material having a piezoelectric effect, such as barium titanate, piezoelectric ceramics, or other ceramics, and forming a pair of electrodes on the pressure receiving surface. 8. The method for processing a piezoelectric element according to claim 7, wherein the cylinder and the pressure receiving surface are made of an integral material having a piezoelectric effect. 9. A round bar made of a material having a piezoelectric effect, holes are drilled from both ends using a grinding means, and a pressure-receiving surface having a predetermined thickness is formed at a central portion of the round bar. Furthermore, the air vibrations, which have entered the outer peripheral portion of the pressure receiving surface from left and right, come and go so that the air vibration of the cylinder, which has entered from the left and right, can resonate at the center portion. In order to be able to form a hole or space part, the air vibration entered from the left and right of the cylinder,
A method for processing a piezoelectric element, characterized by causing resonance at a central portion of a cylinder to cause a resonance phenomenon and causing a pressure-receiving surface located at the central portion to vibrate more strongly. 10. A round hole made of a material having a piezoelectric effect, a cylindrical hole is formed from each of both ends using grinding means, and a pressure-receiving surface having a predetermined thickness is formed in the center of the round bar. Forming a pair of electrodes on a pressure receiving surface thereof, and converting the external air vibration into an amplified electric signal to obtain an amplified electric signal. 11. The grinding means forms a groove in the surface of the barrel-shaped grindstone, and rotates the grindstone by injecting air or liquid into the groove, or uses other mechanical means. The method for processing a piezoelectric element according to claim 10, wherein the barrel-shaped grindstone is rotated. 12. The method for processing a piezoelectric element according to claim 10, wherein the barrel-shaped grindstone is formed using a steel ball close to a true sphere.