JP4868043B2 - Method of manufacturing piezoelectric element piece and piezoelectric vibrating piece - Google Patents

Description

  The present invention relates to a method for producing a piezoelectric element piece having a convex cross section from a piezoelectric material thin plate such as a quartz wafer for use in a piezoelectric device such as a piezoelectric vibrator, and an electrode film on the surface of such a piezoelectric element piece. The present invention relates to a method for manufacturing a piezoelectric vibrating piece in which is formed.

  Conventionally, various electronic devices including information communication devices such as mobile phones and PHS, OA devices such as computers, and consumer devices such as electronic watches, have piezoelectric devices such as piezoelectric vibrators and piezoelectric oscillators as clock sources for electronic circuits. Widely adopted. Recently, with the improvement in performance of electronic devices, piezoelectric vibrators with higher frequency accuracy are required. Furthermore, particularly in the field of information and communication equipment, the piezoelectric device is further reduced in size and thickness due to the downsizing and thinning of the device, and a surface mount type piezoelectric device suitable for mounting on the circuit board of the device is provided. It is requested.

  A surface-mount type piezoelectric vibrator has a piezoelectric element formed of a strip of piezoelectric material, ie, a rectangular thin plate, and an excitation electrode formed on its base end, and cantilevered with a conductive adhesive at the connection terminal of the package. Many mounting structures are used. In such a strip-shaped piezoelectric vibrator, if the cross section of the vibration piece is not rectangular but is formed into a convex shape that gradually decreases in thickness from the center to the end where the excitation electrode is formed, the vibration at the end of the vibration piece It is known that the amount of displacement attenuation can be increased to enhance the energy confinement effect, improve the frequency characteristics such as the Q value, and the size of the vibrator can be smaller than when the cross-section of the resonator element is rectangular. (For example, see Patent Document 1).

  Conventionally, for example, a barrel polishing machine has been used to form such a piezoelectric element piece having a convex shape in cross section. A barrel grinder puts hundreds to thousands of piezoelectric vibrating pieces cut out from a piezoelectric material such as a quartz wafer into a rectangular shape with a polishing agent into a pot, and puts the pot at a constant speed for a predetermined time. By rotating, the edge part of the outer periphery of the piezoelectric vibrating piece is ground to form a convex convex shape in which the edge part has an upward convex shape on both the front and back surfaces.

  Further, in Patent Document 1, a sectional convex shape of a piezoelectric element piece is approximately replaced with a staircase shape, and this staircase shape is mechanically processed by etching or the like in which resist dimensions are changed stepwise, or a machine such as sandblasting. It is described that it is manufactured by mechanical processing. In addition, in order to manufacture a piezoelectric vibration element for use in a piezoelectric device, a plurality of non-separated base plate chips are simultaneously processed by simultaneously rotating a plurality of polishing members having concave polishing surfaces, and a sectional convex A method of manufacturing a circular piezoelectric element plate having a shape is known (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 11-355094 JP 11-298278 A

  However, the above-described processing by the conventional barrel polishing machine has a problem that manufacturing efficiency and productivity are low because it takes a long time. For example, in the case of a piezoelectric vibrator used in a low frequency band of about 4 MHz, processing time of 40 hours or more is required.

  Furthermore, as the convex shape of the piezoelectric vibrating piece cross section increases, the frequency change also increases. However, the processing by the barrel polishing machine described above is difficult to control the convex shape, the processing accuracy is relatively low, and individual piezoelectric element pieces Since the processing of the above cannot be controlled, the variation in cross-sectional shape becomes large. Further, since the abrasive acts on the entire surface of the piezoelectric vibrating piece, the central region where the excitation electrode is formed is roughened, and therefore there is a possibility that the frequency characteristics such as the CI value are deteriorated.

  On the other hand, a so-called biconvex-shaped piezoelectric element piece in which both front and back surfaces have a convex cross-sectional shape is not easy to mount on a package because the base end portions of both sides are not flat. On the other hand, a so-called plano-convex-shaped piezoelectric element piece having a convex shape on one side and a flat surface on the other side is more easily and stronger with a conductive adhesive on the package by using the flat surface. Can be mounted on. However, in the processing by the barrel polishing machine, it is impossible to process a so-called plano-convex piezoelectric element piece in which a piezoelectric element piece is always formed in a biconvex shape, one surface of which is a convex shape and the other surface is flat.

  In addition, as described in Patent Document 1, the method of etching a resist by changing its dimensions in stages is complicated and requires a large number of steps, which may lead to a decrease in productivity and an increase in cost. is there. Further, the manufacturing method using the polishing member having the concave polishing surface disclosed in Patent Document 2 is suitable for processing a circular piezoelectric vibrating piece, but the rectangular piezoelectric vibrating piece is formed into a convex shape in cross section. It is difficult to process.

  Therefore, in order to solve the above-mentioned problems of the prior art, the present invention can reduce the surface of the central region where the excitation electrode is formed without roughening the surface of the piezoelectric element piece having a convex cross-sectional shape in a shorter processing time. Production of a piezoelectric element piece and a piezoelectric vibrating piece that can be produced by controlling the convex shape relatively easily, and can be formed into a planar convex shape in which only one side is processed or a biconvex shape in which both sides are processed as required. It aims to provide a method.

  In order to achieve the above object, a method for manufacturing a piezoelectric element piece according to the present invention is to manufacture a piezoelectric element piece having a rectangular outer shape and a convex cross section from a piezoelectric material thin plate, for example, an AT-cut quartz wafer. A first mask provided with a first opening composed of mutually parallel slits provided along two opposing sides of one of the rectangular sides of the piezoelectric element piece is disposed on at least one surface of the piezoelectric material thin plate Then, the surface of the piezoelectric material thin plate exposed from the first opening by spraying fine abrasive grains from the nozzle disposed above the first mask vertically at a uniform density toward at least one surface of the piezoelectric material thin plate. After the first mask is removed, a second mask provided with a second opening made of mutually parallel slits provided along each of the two opposite sides of the rectangular piezoelectric element piece is provided. , Piezoelectric material Fine abrasive grains are arranged on the at least one surface of the thin plate and sprayed at a uniform density perpendicularly to at least one surface of the piezoelectric material thin plate from a nozzle disposed above the second mask, to form a second opening. Blasting the surface of the piezoelectric material thin plate exposed from the portion, wherein the first and second masks have a constant width on their lower surfaces and on both sides of the first and second openings, respectively. By having a portion removed so as to define a gap with a certain thickness between one surface and a part of the fine abrasive grains sprayed through the first and second openings during the blasting process The surface of the piezoelectric material thin plate that enters the gap with the piezoelectric material thin plate and faces the gap is also ground.

  As described above, by using the first and second masks, the surface of the piezoelectric material thin plate is in the range of a certain width centered on the outline of the piezoelectric element piece, that is, each of the two opposing sides of the rectangle. Further, the portions exposed to the second openings are concave upward, and the blasting is performed in a cross-sectional shape in which both side portions are convex upward from the exposed portions toward the gaps between the first and second masks and the piezoelectric material thin plate. Is done. At this time, since the central region of the piezoelectric element piece on which the excitation electrode is to be formed is covered with the first and second masks, there is no risk of roughening by blasting, and the desired cross-sectional convex shape can be obtained in a very short time. A piezoelectric element piece having a shape can be manufactured.

  Further, the first and second masks can be formed with first and second openings made of a plurality of parallel slits corresponding to the outer shapes of the plurality of piezoelectric element pieces, respectively. A plurality of piezoelectric element pieces can be manufactured simultaneously from a thin plate. The first and second masks can be formed of a metal plate and can be used repeatedly. Also, depending on the type and thickness of the piezoelectric material thin plate to be processed, the processing conditions such as the height of the nozzle from the surface of the piezoelectric material thin plate, the type of fine abrasive grains to be used, particle size, injection pressure, and injection time By selecting appropriately, it is possible to control the convex shape and surface roughness to be processed relatively easily. These processing conditions can be changed during processing as required.

  In one embodiment, the nozzle is blasted with a fixed nozzle position relative to the piezoelectric material sheet by using a nozzle having an aperture sized to cover the entire blasted area of at least one surface of the piezoelectric material sheet. The processing apparatus can be processed and means for moving the nozzle relative to the piezoelectric material thin plate is not required, and the configuration of the entire processing apparatus is simplified. Furthermore, even when a plurality of piezoelectric element pieces are manufactured from one piezoelectric material thin plate, there is no variation in individual piezoelectric element pieces, which is advantageous in that mass production is possible.

  When only one surface of the piezoelectric material thin plate is blasted, a piezoelectric element piece having a plano-convex cross section in which the other surface is flat can be processed.

  In another embodiment, a piezoelectric element piece having a biconvex cross section in which both surfaces form a convex shape is processed by blasting both front and back surfaces of a piezoelectric material thin plate. In this case, the first mask is disposed on both sides of the piezoelectric material thin plate, and the nozzles are disposed on both sides of the piezoelectric material thin plate, and both the front and back surfaces of the piezoelectric material thin plate are simultaneously blasted to remove the first mask. After that, the second mask is disposed on both sides of the piezoelectric material thin plate, and the nozzles are disposed on both sides of the piezoelectric material thin plate, and the front and back surfaces of the piezoelectric material thin plate are simultaneously blasted, so that The piezoelectric element piece can be processed in a shorter time.

  In another embodiment, the blasting using the first and second masks is performed so as to leave a certain thickness portion of the piezoelectric material thin plate, and the remaining piezoelectric material thin plate portion is used as the outline of the piezoelectric element piece. Along the line, it can be cut by a conventionally known appropriate technique such as laser cleaving. In this case, if only one side of the piezoelectric material thin plate is blasted, a piezoelectric element piece having a plano-convex cross section in which the blasted one side has the above-described uneven convex shape and the opposite side is cut vertically is obtained. . Further, when both the front and back surfaces of the piezoelectric material thin plate are blasted, a piezoelectric element piece having a biconvex cross section in which both surfaces have the above-described concave and convex shape sandwiching a vertical cut surface along the peripheral edge thereof is obtained.

  Furthermore, the method of manufacturing a piezoelectric vibrating piece according to the present invention includes a process of forming a piezoelectric element piece using the above-described method of the present invention, and forming an electrode film in a desired shape on the surface of the piezoelectric element piece. Features.

  According to the method of manufacturing a piezoelectric element piece of the present invention, as described above, a convex-shaped cross section can be processed in a very short time without roughening the central region where the excitation electrode is formed, and the convex shape is controlled. Therefore, it is possible to improve the productivity, efficiently manufacture a piezoelectric vibrator having a low CI value and an improved frequency characteristic such as a Q value. Moreover, even when a plurality of piezoelectric element pieces are manufactured from a single piezoelectric material thin plate, the individual piezoelectric element pieces do not vary, so that high-quality piezoelectric element pieces can be mass-produced and the manufacturing cost can be reduced. Can be significantly reduced. In addition, a plano-convex cross-section in which only one surface of the piezoelectric material thin plate is blasted, and a bi-convex cross-section in which both front and back surfaces are blasted can be selected as necessary, and in particular has a plano-convex cross-section. In such a case, the mounting of the piezoelectric vibrator is facilitated by mounting on the package using a flat surface, and the mounting strength and impact resistance are improved.

The schematic block diagram of the processing apparatus used for 1st Example of this invention. The perspective view which shows the point which processes a quartz wafer using the apparatus of FIG. FIGS. A and B are enlarged sectional views sequentially showing the progress of processing of a quartz wafer in the first embodiment. The fragmentary sectional perspective view of the piezoelectric element piece manufactured by the 1st example. Sectional drawing of the piezoelectric vibrator using the piezoelectric element piece of FIG. FIGS. 4A and 4B are enlarged views similar to FIG. 3 showing the progress of processing of the quartz wafer in order in the modification of the first embodiment. FIGS. 4A and 4B are enlarged sectional views similar to FIG. 3 showing the progress of processing of the quartz wafer in order in another modification of the first embodiment. The schematic perspective view which shows the processing point of the crystal wafer in 2nd Example of this invention. FIGS. 4A and 4B are enlarged cross-sectional views similar to FIG. 3 showing the progress of processing of the quartz wafer in order in the second embodiment. FIGS. 9A and 9B are enlarged cross-sectional views similar to FIG. 9 showing the progress of the processing of the quartz wafer in order in the modification of the second embodiment. FIGS. 4A and 4B are schematic perspective views showing a processing procedure for a crystal wafer in a third embodiment. FIGS. 5A and 5B are enlarged sectional views similar to FIG. 3 showing the progress of processing of the quartz wafer in order in the third embodiment. FIGS. 9A and 9B are enlarged cross-sectional views similar to FIG. 3 showing the progress of processing of the quartz wafer in order in a modification of the third embodiment.

  In the following, a preferred embodiment of the present invention is applied to manufacture a piezoelectric element piece having a desired cross-sectional convex shape with a strip shape, that is, a rectangular thin plate, particularly used for a thickness-shear mode piezoelectric vibrator. This will be described in detail with reference to FIG.

  FIG. 1 schematically shows the configuration of an apparatus for processing a number of piezoelectric element pieces from a thin plate of piezoelectric material using the first embodiment of the present invention. This processing apparatus has a nozzle 1 having a relatively small diameter and arranged vertically downward in order to continuously inject fine abrasive grains. A table 2 that is movable in the horizontal direction with respect to the nozzle 1 is disposed immediately below the nozzle 1, and a crystal wafer 3 as a piezoelectric material thin plate is horizontally held thereon. Since the quartz wafer 3 is very thin and fragile, in this embodiment, the crystal wafer 3 is bonded to the surface of a reinforcing plate 4 such as a glass plate using a suitable adhesive means such as a double-sided adhesive sheet 5 on the table 2. Placed on. At this time, the quartz wafer 3 and the reinforcing plate 4 are preferably positioned and fixed on the table 2 using an appropriate jig (not shown). As such a processing apparatus, for example, a commercially available microblast apparatus can be used. In another embodiment, conversely, the table 2 side can be fixed and the nozzle 1 can be moved in the horizontal direction with respect to the table.

  FIG. 2 schematically shows a state in which the surface of a square crystal wafer 3 set on the table 2 is blasted with fine abrasive grains ejected from the nozzle 1. The table 2 is moved so that the nozzle 1 scans the surface of the crystal wafer 3 along the vertical and horizontal outlines 6a and 6b of the piezoelectric element piece to be manufactured. 3 (A) and 3 (B) show the state of the crystal wafer 3 to be blasted partially enlarged and sequentially shown along its progress. The fine abrasive grains 7 are sprayed at a predetermined pressure as thin jets around the outlines 6a and 6b while relatively moving the nozzle 1 from the surface of the crystal wafer 3 at a constant height. At this time, the fine abrasive grains 7 coming out of the nozzle 1 spread in a narrow angle range θ as shown in the figure, and therefore the surface of the quartz wafer 3 is compared with a desired width on both sides of the outlines 6a and 6b. Each narrow area is cut into an upwardly convex shape. Other regions on the surface of the crystal wafer 3, particularly the central region where the excitation electrodes of the piezoelectric vibrator are arranged, are preferably not processed by the fine abrasive grains 7 in order to form an electrode film in a later step.

  The processing conditions such as the diameter of the nozzle 1, the height from the surface of the quartz wafer 3, the type / grain size / jetting pressure of the fine abrasive grains 7 to be used, and the moving speed of the table 2 are as follows: Then, the crystal wafer is selected appropriately according to the type / thickness, convex shape, processing range, surface roughness, and the like. In one embodiment, the diameter of the nozzle 1 is set to about 0.2 mm to 2 mm, preferably 0.3 mm, and the height from the surface of the crystal wafer 3 to the nozzle 1 opening is set to about 2 mm to 10 mm. The fine abrasive grains 7 having a particle diameter of about 3 to 40 [mu] m, preferably 27 [mu] m are used and sprayed at a pressure of about 0.5 to 1.0 MPa, preferably 1.0 MPa. The table 2 is moved as shown in FIG. 2 at a speed of, for example, 10 mm / second while spraying fine abrasive grains from the nozzle 1 to blast the entire surface of the crystal wafer 3.

  When the quartz wafer 3 is thin, the nozzle 1 is scanned once, and the desired convex shape is blasted along the outlines 6a and 6b as shown in FIGS. 3 (A) and 3 (B). In addition, the quartz crystal wafer 3 can be completely cut, and a large number of desired piezoelectric element pieces can be processed simultaneously. When the quartz wafer 3 is thick, the nozzle 1 is scanned a plurality of times and repeatedly blasted along the outlines 6a and 6b, thereby similarly processing a large number of piezoelectric element pieces having a desired sectional convex shape. can do. In a plurality of scans, the processing conditions such as the diameter of the nozzle 1 and the height from the surface of the quartz wafer 3, the type of fine abrasive grains 7 to be used, the particle diameter and spray pressure, and the moving speed of the table 2 are determined each time. By changing and controlling, a desired convex shape can be obtained in a desired processing state.

  When the quartz wafer 3 is heated by, for example, a hot plate (not shown) to be peeled off from the reinforcing plate 4 and washed, a piezoelectric element piece 8 made of a plano-convex rectangular quartz thin plate is obtained as shown in FIG. A pair of excitation electrodes 9 and extraction electrodes 10 are formed on both the front and back surfaces of the piezoelectric element piece 8 by using a conventionally known method to manufacture the piezoelectric vibrating piece 11 of the present invention. As illustrated in FIG. 5, the piezoelectric vibrating reed 11 is formed by using a conductive adhesive 14 on the extraction electrode 10 at one base end, and connecting electrodes 13 on the surface of a rectangular box-shaped base 12 made of an insulating material such as ceramic. Mount it fixed on your hand. When a metal lid 16 is joined to the upper end of the base 12 via a seal ring 15 and the package 17 is sealed, a surface-mounted piezoelectric vibrator is completed.

  6A and 6B show the state of the quartz wafer 3 blasted by the modification of the first embodiment, partially enlarged similarly to FIG. 3, and sequentially showing the progress thereof. . In this modification, first, as in the case of the first embodiment, as shown in FIG. 6 (A), the quartz wafer 3 has a certain thickness on the lower surface side from the upper surface to the middle along the outlines 6a and 6b. Blasting is performed, leaving the part, and a convex cross section is processed. Next, as shown in FIG. 6B, the remaining part is cut along the outlines 6a and 6b by a conventionally known appropriate method such as laser cleaving. Thereafter, similarly, the quartz wafer 3 is heated with a hot plate or the like to be peeled off from the reinforcing plate 4 and washed, so that the upper surface is a convex convex shape and the lower surface side is cut vertically. A piezoelectric element piece is obtained.

  7A and 7B show the state of the quartz wafer 3 blasted according to another modification of the first embodiment, partially enlarged as in FIG. 3, and sequentially showing the progress thereof. ing. In this modification, a pair of nozzles 1a, 1b for injecting fine abrasive grains are horizontally arranged opposite to each other, and a quartz wafer 3 is placed vertically between them using an appropriate jig or holding means, and The nozzles are movably arranged with respect to both the nozzles. As in the case of the first embodiment, the quartz wafers are simultaneously ejected with the fine abrasive grains 7a and 7b while moving both nozzles 1a and 1b relative to the outer shape of the piezoelectric element piece along the lines 6a and 6b. The front and back surfaces of 3 are blasted simultaneously.

  As in the case of the modification of FIG. 6, first, as shown in FIG. 7A, the quartz wafer 3 is blasted along the outlines 6a and 6b from its both sides to the middle, leaving a certain thickness at the center. Process both sides into a convex shape. Next, as shown in FIG. 7B, the remaining portion is similarly cut along the outlines 6a and 6b by a known appropriate technique such as laser cleaving. Thereby, the piezoelectric element piece 8 which consists of a rectangular quartz thin plate of the biconvex cross section in which both surfaces make a convex shape across the vertical cut surface along the periphery is obtained.

  FIG. 8 shows a procedure for manufacturing a large number of piezoelectric element pieces having a convex cross-sectional shape by blasting the quartz wafer 3 according to the second embodiment of the present invention. As in the first embodiment, a mask 18 made of a photoresist is formed on the surface of the quartz wafer 3 bonded to the surface of the reinforcing plate 4 such as a glass plate with the double-sided adhesive sheet 5. The mask 18 is formed by applying a photoresist on the surface of the quartz wafer 3 and forming a pattern by using a photolithography technique, so that a desired shape is formed around the vertical and horizontal outlines 6a and 6b of the piezoelectric element piece to be manufactured. An opening 19 made of a grid-like groove having a width is provided. The opening 19 is preferably provided so as to cover the central region where the excitation electrode of the piezoelectric vibrating piece is formed by the mask 18 in order to form an electrode film in a later step.

  Above the quartz wafer 3, a nozzle 20 having a large diameter is arranged vertically downward. Fine abrasive grains 21 are sprayed from the nozzle 20 toward the crystal wafer 3 at a substantially uniform density, and the surface of the crystal wafer 3 exposed from the opening 19 of the mask 18 is uniformly blasted. When the diameter of the nozzle 20 is large enough to cover the entire processing region of the quartz wafer 3, it is advantageous because the nozzle 20 can be processed with the position of the nozzle 20 fixed with respect to the quartz wafer 3. When the nozzle 20 has a diameter that cannot cover the entire processing area of the quartz wafer 3, the fine abrasive grains 21 are ejected while the nozzle 20 is moved relative to the quartz wafer 3, and the quartz wafer is ejected. 3 is processed uniformly.

  FIGS. 9A and 9B show the state of the quartz wafer 3 to be blasted in the present embodiment in a partially enlarged manner in the same manner as in FIG. In this embodiment, unlike the first embodiment in which fine abrasive grains are intensively sprayed using a nozzle having a small diameter, the fine abrasive grains 21 are exposed to the exposed surface of the crystal wafer 3 through the openings 19 of the mask 18. Therefore, as shown in FIG. 9A, the surface of the crystal wafer 3 is ground into an upward concave shape centering on the outlines 6a and 6b. The processing conditions such as the height of the nozzle 20 from the surface of the crystal wafer 3 and the type, grain size, spraying pressure, and spraying time of the fine abrasive grains 21 to be used are determined by the piezoelectric material thin plate to be processed (the crystal wafer in this embodiment). Select appropriately according to the type, thickness, convex shape to be processed, surface roughness, etc. Moreover, these processing conditions can be changed in the middle of processing as needed.

  The blasting is performed so that a portion of a certain thickness is left on the lower surface side from the upper surface to the middle of the quartz wafer 3. Next, as shown in FIG. 9B, the remaining portion is cut along the outlines 6a and 6b by an appropriate method such as laser cleaving. Thereafter, the mask 18 is removed from the quartz wafer 3 and heated by a hot plate or the like to be peeled off from the reinforcing plate 4 and cleaned. As a result, a piezoelectric element piece made of a rectangular quartz thin plate having a plano-convex cross section in which the upper surface is a concave convex shape and the lower surface side is cut vertically is obtained.

  FIGS. 10A and 10B show the state of the quartz wafer 3 that is blasted according to the modification of the second embodiment partially in the same manner as in FIG. . In this modification, masks 18a and 18b formed by patterning a photoresist are provided on both surfaces of the quartz wafer 3 in the same manner as the mask 18 of the second embodiment shown in FIG. A pair of nozzles 20a and 20b for injecting fine abrasive grains are horizontally disposed opposite to each other, and the crystal wafer 3 is vertically disposed at an intermediate position thereof using an appropriate jig or holding means. Similarly to the case of the second embodiment, the front and back surfaces of the crystal wafer 3 are simultaneously blasted by simultaneously injecting fine abrasive grains 21a and 21b from both nozzles 20a and 20b at a uniform density.

  As shown in FIG. 10A, the surfaces of the quartz wafer 3 exposed from the openings 19a and 19b of the masks 18a and 18b are ground into outward concave shapes centering on the outlines 6a and 6b, respectively. The blasting is performed so as to leave a certain thickness portion in the center from the surface of the quartz wafer 3 to the middle. Similarly, the separation conditions of the nozzles 20a and 20b from the front and back surfaces of the quartz wafer 3 and the processing conditions such as the type, particle diameter, injection pressure, and injection time of the fine abrasive grains 21 to be used are as follows: In the embodiment, it is selected appropriately according to the type and thickness of the crystal wafer), the convex shape to be processed, the surface roughness, and the like. Moreover, these processing conditions can be changed in the middle of processing as needed. Next, after removing the masks 18a and 18b from the crystal wafer 3, as shown in FIG. 10 (B), the remaining portions are taken along the outlines 6a and 6b by an appropriate method such as laser cleaving. Disconnect. As a result, a piezoelectric element piece made of a rectangular quartz thin plate having a biconvex cross section in which both surfaces form a convex shape across a vertical cut surface along the periphery thereof is obtained.

  FIGS. 11A and 11B show a procedure for producing a large number of piezoelectric element pieces having a convex cross-sectional shape by blasting a crystal wafer 3 according to the third embodiment of the present invention. In this embodiment, a mask made of a thin metal plate that can be used repeatedly is used instead of the mask made of the photoresist of the second embodiment.

  First, as shown in FIG. 11A, as in the first and second embodiments, a thin metal is formed on the surface of the crystal wafer 3 bonded with the double-sided adhesive sheet 5 on the surface of the reinforcing plate 4 such as a glass plate. A first mask 22 made of a plate is disposed. The first mask 22 is provided with an opening 23 formed of a plurality of parallel slits having a desired width centered on, for example, the vertical outline 6a of one of the piezoelectric element pieces to be manufactured. Above the quartz wafer 3, a nozzle 20 having a large diameter is arranged vertically downward as in the second embodiment, and fine abrasive grains 21 are sprayed toward the quartz wafer 3 at a substantially uniform density. The surface of the quartz wafer 3 exposed from the opening 23 of the mask 22 is uniformly blasted. Next, the first mask 22 is removed, and the second mask 24 is placed on the surface of the crystal wafer 3. The second mask 24 is provided with an opening 25 composed of a plurality of parallel slits having a desired width centered on the other outer side of the piezoelectric element piece to be manufactured, for example, the lateral outline 6b. Then, fine abrasive grains 21 are sprayed from the nozzle 20 toward the quartz wafer 3 at a substantially uniform density, and the surface of the quartz wafer 3 exposed from the opening 25 of the second mask 24 is uniformly blasted.

  The first and second masks 22 and 24 are provided so that the central region for forming the excitation electrode of the piezoelectric vibrating piece is not exposed in any of the openings 23 and 25 in order to form an electrode film in a later step. preferable. Further, as in the case of the second embodiment, when the diameter of the nozzle 20 is large enough to cover the entire processing area of the crystal wafer 3, the nozzle 20 can be processed while being fixed with respect to the crystal wafer 3. However, when the diameter of the nozzle 20 is not large enough to cover the entire processing area of the quartz wafer 3, the fine abrasive grains 21 are sprayed while the nozzle 20 is moved relative to the quartz wafer 3 to obtain the quartz wafer. 3 is processed uniformly.

  FIGS. 12A and 12B show the state of the quartz wafer 3 to be blasted in this embodiment partially enlarged as in FIG. 3 and sequentially showing the progress. In the masks 22 and 24 of the present embodiment, a portion having a certain width on both sides of the openings 23 and 25 on the lower surface defines a gap 26 having a certain thickness between the surface of the quartz wafer 3. Has been removed. For this reason, the fine abrasive grains 21 sprayed from the nozzle 20 are sprayed from the openings 23 and 25 onto the exposed surface of the crystal wafer 3, and at the same time, a part of the fine abrasive grains 21 enters the gap 26 and faces the gap. Grind the surface. As a result, as shown in FIG. 12A, the surface of the quartz wafer 3 is blasted into a cross-sectional shape in which the central portion has an upward concave shape centering on the outlines 6a and 6b and the both side portions have upward convex shapes. The The processing conditions such as the height of the nozzle 20 from the surface of the crystal wafer 3 and the type, grain size, spraying pressure, and spraying time of the fine abrasive grains 21 to be used are determined by the piezoelectric material thin plate to be processed (the crystal wafer in this embodiment). Select appropriately according to the type, thickness, convex shape to be processed, surface roughness, etc. Moreover, these processing conditions can be changed in the middle of processing as needed.

  The blasting is performed so that a portion of a certain thickness is left on the lower surface side from the upper surface to the middle of the quartz wafer 3. After the quartz wafer 3 is blasted using the first and second masks 22 and 24, the remaining portion is, for example, laser cleaved along the outlines 6a and 6b as shown in FIG. Cut by appropriate method. As a result, a piezoelectric element piece made of a rectangular quartz thin plate having a convex shape having a concave shape on the upper surface and a convex shape on the inner surface and having a plano-convex section whose lower surface side is cut vertically is obtained.

  FIG. 13 shows the state of the quartz wafer 3 that is blasted according to the modification of the third embodiment partially in the same manner as in FIG. In this modification, two sets of first masks 22a and 22b and second masks 24a and 24b having the same configuration as the first and second masks 22 and 24 of the third embodiment are used on both the front and back surfaces of the crystal wafer 3. To do. First, as described above with reference to FIG. 11A, the first masks 22a and 22b are arranged on the front and back surfaces of the crystal wafer 3, respectively, and the vertical outline 6a of the piezoelectric element piece to be manufactured is formed. Blasting along. Next, as in FIG. 11B, the second masks 24a and 24b are respectively disposed on the front and back surfaces of the crystal wafer 3, and blasted along the longitudinal outline 6b of the piezoelectric element piece to be manufactured. I do.

  As shown in FIG. 13 (A), a pair of nozzles 20a and 20b for injecting fine abrasive grains are horizontally arranged opposite to each other, and the first or second mask is mounted at an intermediate position between them. Are placed vertically using a suitable jig or holding means. As in the case of the third embodiment, the front and back surfaces of the crystal wafer 3 are simultaneously blasted by simultaneously injecting fine abrasive grains 21a and 21b from both nozzles 20a and 20b at a uniform density. Thereby, each surface of the crystal wafer 3 is blasted into a cross-sectional shape in which the central portion has an upward concave shape centering on the outlines 6a and 6b and the both side portions have upward convex shapes. The processing conditions such as the height of the nozzle 20 from the surface of the crystal wafer 3 and the type, grain size, spraying pressure, and spraying time of the fine abrasive grains 21 to be used are determined by the piezoelectric material thin plate to be processed (the crystal wafer in this embodiment). Select appropriately according to the type, thickness, convex shape to be processed, surface roughness, etc. Moreover, these processing conditions can be changed in the middle of processing as needed.

  As shown in FIG. 13A, the blasting is performed so as to leave a portion of a certain thickness at the center from the surface of the quartz wafer 3 to the middle. After both surfaces of the quartz wafer 3 are blasted along the outlines 6a and 6b, as shown in FIG. 13B, the remaining portion is applied along the outlines 6a and 6b, for example, by laser cutting. Cut by various methods. As a result, a piezoelectric element piece made of a rectangular quartz thin plate having a biconvex cross section in which both surfaces have the above-described concave-convex convex shape sandwiching a vertical cut surface along the periphery thereof is obtained.

  It will be apparent to those skilled in the art that the present invention is not limited to the above-described embodiments and can be implemented with various modifications and changes. For example, the present invention can be similarly applied to piezoelectric vibrating pieces using various piezoelectric materials such as lithium tantalate and lithium niobate other than quartz. In addition, when both surfaces of the quartz wafer are blasted, it is possible to process into different convex cross sections on the front and back surfaces of the piezoelectric element piece by changing the processing conditions of each surface.

DESCRIPTION OF SYMBOLS 1, 1a, 1b ... Nozzle, 2 ... Table, 3 ... Quartz wafer, 4 ... Reinforcement plate, 5 ... Double-sided adhesive sheet, 6a, 6b ... Outline line, 7, 7a, 7b ... Fine abrasive grain, 8 ... Piezoelectric element piece 9 ... excitation electrode, 10 ... extraction electrode, 11 ... piezoelectric vibrating piece, 12 ... base, 13 ... connection electrode, 14 ... conductive adhesive, 15 ... seal ring, 16 ... lid, 17 ... package, 18, 18a, 18b ... mask, 19, 19a, 19b, 23, 25 ... opening, 20, 20a, 20b ... nozzle, 21, 21a, 21b ... fine abrasive grains, 22, 22a, 22b ... first mask, 24, 24a, 24b ... second mask, 26 ... gap.

Claims (6)

In order to manufacture a piezoelectric element piece having a rectangular outer shape and a convex-shaped cross section from a piezoelectric material thin plate,
A first mask provided with a first opening composed of mutually parallel slits provided along each of two opposing sides of the rectangle is disposed on at least one surface of the piezoelectric material thin plate;
The piezoelectric material thin plate exposed from the first opening by injecting fine abrasive grains from a nozzle disposed above the first mask toward the at least one surface of the piezoelectric material thin plate with a uniform density perpendicularly. Blasting the surface of
After removing the first mask, a second mask provided with a second opening made of mutually parallel slits provided along each of the other two opposite sides of the rectangle is formed on the piezoelectric material thin plate. Placed on at least one side,
The piezoelectric material thin plate exposed from the second opening by spraying fine abrasive grains from a nozzle disposed above the second mask toward the at least one surface of the piezoelectric material thin plate with a uniform density vertically. With the process of blasting the surface of
The first and second masks have gaps on their lower surfaces, with a constant width on both sides of the first and second openings, and with a constant thickness between the at least one surface of the piezoelectric material thin plate. A part of the fine abrasive grains sprayed through the first and second openings during the blasting process enters the gap and faces the gap. A method for manufacturing a piezoelectric element piece, wherein the surface of the piezoelectric material thin plate is also ground.   2. The method of manufacturing a piezoelectric element piece according to claim 1, wherein the nozzle has a diameter that covers the entire blasted region of the at least one surface of the piezoelectric material thin plate.   The first mask is disposed on both front and back surfaces of the piezoelectric material thin plate, and the nozzles are disposed on both sides of the piezoelectric material thin plate, so that the front and back surfaces of the piezoelectric material thin plate are simultaneously blasted, and the first mask Then, the second masks are arranged on both the front and back surfaces of the piezoelectric material thin plate, and the nozzles are disposed on both sides of the piezoelectric material thin plate, so that the front and back surfaces of the piezoelectric material thin plate are simultaneously blasted. The method for manufacturing a piezoelectric element piece according to claim 1 or 2.   The blasting process using the first and second masks is performed so as to leave a portion of the piezoelectric material thin plate having a certain thickness, and the remaining portion of the piezoelectric material thin plate is moved along the outline of the piezoelectric element piece. The method for manufacturing a piezoelectric element piece according to any one of claims 1 to 3, wherein the piezoelectric element piece is cut.   5. The method of manufacturing a piezoelectric element piece according to claim 1, wherein the piezoelectric material thin plate is an AT cut quartz wafer.   6. A method of manufacturing a piezoelectric vibrating piece, comprising: forming a piezoelectric element piece using the method according to claim 1; and forming an electrode film in a desired shape on a surface of the piezoelectric element piece. Method.

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