JP2000340854A - Manufacture of sheared piezoelectric element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable effectively manufacturing a sheared type piezoelectric element, wherein the polarizing direction and the sense of polarization can be easily judged from external appearance. SOLUTION: In this manufacturing method, a plurality of linear conductor patterns 22a-22c for polarization are formed in parallel at specific intervals on the surface of a piezoelectric plate 20. After polarizing is performed by applying a DC electric field across the conductor patterns, electrodes 24 are formed at least on both surfaces of polarized regions between the linear conductor patterns of the piezoelectric plate. Elements are cut into a rectangular plate shape from the polarized regions. Protrusions 23a and recesses 23b are formed in pairs on the linear conductor patterns which are made pairs at the time of the polarizing treatment, and elements are cut out so that the protrusions are left. It is also possible that electrodes are formed so as to have mask traces (nonelectrode parts) along the linear conductor patterns for polarization, and elements are cut so that the mask traces are left. By using the positions of the protruding parts or the mask traces which are left on the respective elements, the sense of polarization can be discriminated visually.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a shear-type piezoelectric element, and more particularly, to a method for manufacturing a shear-type piezoelectric element utilizing a thickness-shear vibration mode, which has a structure in which the direction of polarization can be easily visually determined. The present invention relates to a method for manufacturing such a method. Although this shearing type piezoelectric element is not particularly limited, it is useful, for example, for an actuator of a fine movement mechanism, a high-sensitivity shock detection sensor, and the like.

[0002]

2. Description of the Related Art There are various types of devices using piezoelectric ceramics, and a typical example thereof is a piezoelectric device utilizing a longitudinal effect and a lateral effect of electric field induced strain. There are structures or laminated structures, the latter being tubular structures. These piezoelectric elements are used in combination with a displacement enlargement mechanism, a displacement accumulation mechanism, and the like. In this type of piezoelectric element, the electrode used for the polarization processing can be used as it is as a drive electrode or a detection electrode.

As another piezoelectric element, there is a shearing type piezoelectric element that slides and vibrates along a surface. This is a special structure in which the polarization direction of the element is perpendicular to the direction connecting the two driving electrodes or detection electrodes (the direction in which an electric field is applied or the direction in which the electric field is detected). This shear type piezoelectric element is schematically shown in FIG.
Shown in The piezoelectric body 10 has been subjected to polarization processing in the direction of the arrow, and electrodes 12 are provided on the entire surfaces of both surfaces. When a voltage is applied between the electrodes 12, the piezoelectric body 10 undergoes shear strain as shown by a dotted line. Conversely, when an external force is applied in the polarization direction to generate shear strain, a voltage is generated between the electrodes on the front and back surfaces.

[0004] In recent years, the shear-type piezoelectric element having such a structure is used for devices such as an actuator of a fine movement mechanism and a sensor for detecting an impact. For example, in an actuator of a fine movement mechanism, there is a configuration in which a pair of shear-type piezoelectric elements are attached to a displacement enlarging mechanism so that the directions of polarization are opposite to each other. Are provided in the orthogonal direction (to face the X direction and the Y direction) according to the detection direction.

[0005]

If these shearing type piezoelectric elements are not incorporated in the device in a manner such that the polarization direction or direction is predetermined, the desired characteristics cannot be obtained. If the element shape is a rectangular plate, the polarization direction can be determined from the long side and the short side (for example, if the polarization direction is set parallel to the long side, the polarization direction can be determined from the appearance).

However, even in such a case, the direction of polarization (which side has been subjected to polarization processing to the positive electrode and which side has been subjected to the polarization processing) cannot be determined from the appearance. In the actuator of the fine movement mechanism as described above, it is necessary to attach a pair of shearing type piezoelectric elements to the displacement enlarging mechanism so that the polarization directions are the same but the polarization directions are opposite. If the element shape is a square plate, even the polarization direction cannot be determined from the appearance. Therefore, in the prior art, in order to indicate the direction of polarization, marking is performed with a writing tool, paint, or the like, or a jig with a sharp tip.

[0007] However, for each small shear-type piezoelectric element, the operation of forming a minute mark indicating the direction of polarization is extremely complicated and inefficient.

As a method for solving such a drawback,
When the present inventors first cut out an element into a rectangular plate shape from the polarization region, a step is formed on one end surface of each element after cutting and separation by performing grooving along one cutting position of each element. A technique was proposed in which the direction of polarization could be determined based on the position of the step (Japanese Patent Application No. 10-3669).
No. 59). However, since the grooving process is required, the number of processing steps is increased, and the manufacturing efficiency is not always sufficiently high.

An object of the present invention is to provide a method for efficiently manufacturing a shear-type piezoelectric element in which the polarization direction and the polarization direction can be easily determined from the appearance even if the element shape is a square plate. It is.

[0010]

According to the present invention, a plurality of linear conductor patterns for polarization are formed in parallel at intervals on the surface of a piezoelectric plate, and a DC electric field is applied between them to perform polarization processing. After the application, electrodes are formed on both surfaces of at least the polarization region between the linear conductor patterns of the piezoelectric plate, and a method of manufacturing a shear-type piezoelectric element in which an element is cut out from the polarization region into a rectangular plate shape. . In the present invention, a method of forming a pair of convex and concave portions in a linear conductor pattern for polarization forming a pair during the polarization process, and cutting out an element so as to leave the convex portion, or a linear conductor for polarization An electrode is formed so that a mask mark (electrode-free portion) is provided along the pattern, and the element is cut out so as to leave the mask mark. The direction of polarization depends on the position of the convex portion or mask mark remaining on each element. Is configured to be visually distinguishable.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a first embodiment of the present invention, a pair of linear conductor patterns for polarization, which are paired during the polarization process, have a large number of convex portions on one of their opposing edges and the other on their other edges. A large number of recesses are formed in a positional relationship facing each other and are arranged in a shape arranged for each element to be cut out, and after forming the electrodes, at least a part of the protrusions when cutting out the element in a rectangular plate shape from the polarized region. Is cut so as to remain on the element side, and the direction of polarization can be determined based on the position of the remaining protrusion. Here, it is preferable that the convex portion and the concave portion have the same dimensions and shape. Then, the spacing between the pair of linear conductor patterns for polarization during the polarization process can be made constant over the entire length in the longitudinal direction, and disturbance in the polarization direction hardly occurs.
Further, it is preferable that the convex portion and the concave portion have a shape having a circular arc shape (a semicircular shape or a semielliptical shape). The arc shape (shape without corners) can prevent the electric field from being concentrated during the polarization process.

In the second embodiment of the present invention, a mask pattern is formed near one of the opposing edges of a pair of linear conductor patterns for polarization, and electrodes are formed on almost the entire surface of the piezoelectric plate. By removing the mask pattern, the electrode portions on the mask pattern are removed together to form a mask mark. Then, when the element is cut out from the polarized region into a rectangular plate, at least a part of the mask mark is cut so as to remain on the element side, and the direction of polarization can be determined based on the position of the remaining mask mark. For example, the mask pattern formed near one of the opposing edges of the linear conductor pattern for polarization may be a linear pattern formed along the linear conductor pattern for polarization, or may be a linear pattern formed on the linear conductor pattern for polarization. A large number of dot patterns arranged along the line may be used.

[0013]

FIG. 1 is a process explanatory view showing one embodiment of a method of manufacturing a shearing type piezoelectric element according to the present invention, and shows plan views in each process. As shown in FIG. 1A, a piezoelectric plate 20 made of sintered piezoelectric ceramics (for example,
mm, a thickness of about 0.2 to 0.5 mm), and a plurality of (three in the drawing) linear conductor patterns 2 for polarization on the surface thereof.
2a, 22b, and 22c are formed parallel to each other at appropriate intervals. The linear conductor patterns are provided on both front and back surfaces of the piezoelectric plate 20. The linear conductor patterns 22a and 22c have a width of 2 mm.
The linear conductor pattern 22b has a width of about 4 mm, and is formed by, for example, applying a silver paste by screen printing and baking. Therefore, the thickness of each linear conductor pattern for polarization is about several μm.

Each of the linear conductor patterns for polarization on the surface side of the piezoelectric plate 20 has a large number of convex portions 23a on one of its opposing edges and a large number of concave portions 23b on the other. The shape is arranged for each element to be cut out. Here, the convex portion 23a and the concave portion 23b have a semicircular shape having the same size and shape, and are provided so that a pair of concave and convex portions correspond to the formation region of each element. That is, a convex portion 23a is provided on the right edge of the left linear conductive pattern 22a, a concave portion 23b is provided on both edges of the central linear conductive pattern 22b, and a convex portion 23a is provided on the left edge of the right linear conductive pattern 22c. Are provided so as to face each other. Only the front side of the piezoelectric plate may be a linear conductor pattern for polarization having such protrusions and recesses, and the rear side may be a linear conductor pattern for polarization having no protrusions and recesses as in the related art. A linear conductor pattern for polarization having such convex portions and concave portions on both surfaces may be used.

Then, as shown in FIG. 1B, polarization processing is performed in the in-plane direction of the piezoelectric plate 20 using the linear conductor patterns 22a,..., 22c. The direction of polarization is indicated by an arrow. Here, the polarization process is performed in such a manner that the center linear conductor pattern 22b becomes a positive electrode and the linear conductor patterns 22a and 22c on both sides become a negative electrode. For example, in insulating oil at 120 ° C, 1.5k
This is performed by applying a DC electric field of V / mm or more for 30 minutes or more. Since the convex portion and the concave portion are arranged to face each other, the interval between the linear conductor patterns 22 can be made constant over the entire length direction. Further, by arranging the convex portions and the concave portions in an arc shape and symmetrically disposing them, it is possible to prevent the electric field from being concentrated during the polarization process.

Next, as shown in FIG.
An electrode 24 is formed over the entire surface of the front and back surfaces of the linear electrode patterns 22a,..., 22c for polarization.
The electrodes are formed by depositing a metal film such as chromium or gold by a sputtering method or a vapor deposition method so that the piezoelectric plate 20 is not depolarized (that is, the polarization state is maintained). This is because in baking silver paste, the polarization state is impaired by excessive heating. Therefore, the thickness of the electrode 24 is about 0.5 μm.

Thereafter, as shown in FIG. 1D, a large number of devices having a predetermined shape are cut out from the polarized regions (regions between the linear conductor patterns) using a dicing saw or the like. The broken lines indicate the positions where the cutting is performed vertically and horizontally. As shown in the figure, when the element is cut out from the polarization region into a rectangular plate, the projection is cut so that at least a part of the projection 23a remains on the element side. First, the piezoelectric plate 20 is attached to a dummy substrate (not shown) and set in a cutting device. The height of the blade is adjusted, and the plate is cut vertically and horizontally at a predetermined cutting position. Thereafter, by removing the element from the dummy substrate, an element having a rectangular plate shape (rectangular plate shape or square plate shape) is taken out. From the piezoelectric plate of the above dimensions (about 25mm square)
About 100 elements can be cut out.

FIG. 2 shows the sheared piezoelectric element 30 cut out. In this embodiment, at least a part of the projection 23a remains on the negative electrode side in the polarization direction in each element after cutting and separation. The front and back surfaces of the shearing type piezoelectric element 30 are covered with gold electrodes 24, but the protrusions 23a are a burn-in film having a thickness of several μm, and the gold electrodes are a vapor deposition film or a sputter film having a thickness of about 0.5 μm. Therefore, the convex portion 23a is slightly raised, and the presence or absence thereof can be easily determined visually. The direction of polarization is indicated by an arrow.

FIG. 3 shows an example in which the fine movement mechanism is applied to an actuator. The displacement enlarging mechanism 40 includes a trapezoidal portion 44 having a pivot hole 42 serving as a fulcrum of oscillation near the center, and rectangular portions 46 on both sides formed of a metal plate having a continuous shape by a narrow connecting portion. Each of the portions 46 has a structure in which the shear-type piezoelectric element 30 is adhered on one surface thereof with a conductive adhesive. Here, the shear type piezoelectric element 30 has a size of, for example, 2 mm long and 1.5 mm wide. The other surface of both shearing type piezoelectric elements 30 is a base member (not shown).
Fixed to. Here, the polarization directions of the two shearing type piezoelectric elements 30 need to be parallel, and the polarization directions need to be opposite to each other as shown by arrows. In the shearing type piezoelectric element 30 obtained by the present invention, since the protruding portion 23a that can be clearly distinguished is left on the negative electrode side of the polarization, as shown in FIG. If they are combined in the opposite direction, the direction of polarization will always be opposite.
When an alternating drive voltage is applied to both shear-type piezoelectric elements in the same phase, both rectangular portions 46 of the displacement magnifying mechanism 40 oscillate in the polarization direction in the opposite phase, so that the tip of the trapezoidal portion 44 is indicated by an arrow s. To shake.

FIG. 4 shows an example in which the present invention is applied to a sensor for detecting an impact. Each of the metal weights 5 is provided on the substrate 50.
Two sets of the shearing type piezoelectric element 30 on which 2 is mounted are mounted. Here, they are fixed with a conductive adhesive so that they are orthogonal to each other, that is, one is such that the polarization direction is in the X direction, and the other is so that the polarization direction is in the Y direction. Here, the shear type piezoelectric element 30
Has a size of, for example, 4 mm in length and 3 mm in width, and a convex portion that can be clearly distinguished is left on the negative electrode side of polarization.
As shown in the drawing, the polarization direction can be set to a desired state by combining the two shear-type piezoelectric elements 30 so that their convex portions are located at the end face in the X direction and the end face in the Y direction.
The electrodes on the lower surface side of the shearing type piezoelectric element 30 are pulled out from the common conductive pattern 54, and the electrodes on the upper surface side of the shearing type piezoelectric element 30 are soldered to the respective conductive patterns 58 by lead wires 56 via a metal weight 52. Then pull out. With this configuration, the component of the shock in the X direction can be detected by the voltage generated from the shear-type piezoelectric element on the X side, and the component of the shock in the Y direction can be detected by the voltage generated from the shear-type piezoelectric element on the Y side.

FIG. 5 is a process explanatory view showing another embodiment of the method of manufacturing the shearing type piezoelectric element according to the present invention. Materials, shapes, processes, and the like to be used may be the same as those in the embodiment shown in FIG. 1 unless otherwise specified. As shown in FIG. 5A, a plurality of (three in the drawing) linear conductor patterns 62 for polarization are formed on the surface of a piezoelectric plate 60 made of piezoelectric ceramics at appropriate intervals in parallel with each other. The linear conductor patterns 62 are provided on the front and back surfaces of the piezoelectric plate 60 so as to have the same shape. Then, as shown in FIG. 5B, a polarization process is performed in the in-plane direction of the piezoelectric plate 60 using the linear conductor pattern 62. The direction of polarization is indicated by an arrow.

Next, as shown in FIG. 5C, one surface of the piezoelectric plate 60 is adjacent to one of the opposing edges of the pair of linear conductor patterns for polarization (here, the negative electrode side in the polarization direction). (Ie, along the right edge of the left linear conductor pattern and the left edge of the right linear conductor pattern) to form a linear mask pattern 64. The mask material to be used is a resin material that can be removed by a solvent or ultrasonic cleaning after drying, and is formed into a pattern by screen printing.

Next, as shown in FIG. 5D, an electrode 66 is formed over the linear electrode pattern 62 for polarization and the mask pattern 64 over the entire front and back surfaces of the piezoelectric plate. This electrode formation is performed by depositing a metal film such as gold by a sputtering method or a vapor deposition method so that the piezoelectric plate 20 is not depolarized thereby.

Thereafter, the mask pattern is removed by dipping in a solvent or by performing ultrasonic cleaning. When the mask pattern is peeled, the electrode portion placed thereon is also removed. Therefore, as shown in FIG. 5E, the removed portion becomes a linear mask mark 68, and the surface of the piezoelectric plate is exposed.

Finally, as shown in FIG. 5F, a polarized region (a region between the linear conductor patterns) using a dicing saw or the like.
A number of devices having a predetermined shape are cut out from the device. The broken lines indicate the positions where the cutting is performed vertically and horizontally. As shown in the drawing, when the device is cut out in a rectangular plate shape from the polarization region, the device is cut so that at least a part of the linear mask mark 68 is left on the device side.

FIG. 6 shows the sheared piezoelectric element 70 cut out. In this embodiment, at least a part of the linear mask mark 68 remains on the negative electrode side in the polarization direction in each element after cutting and separation. Although most of the surface of the shearing type piezoelectric element 70 is covered with the gold electrode 66, the mask mark 68 can be easily visually discriminated by the gold color of the gold electrode and the ground color of the ceramic (the color of the mask mark). The direction of polarization is indicated by an arrow.

FIG. 7 is a process explanatory view showing still another embodiment of the method of manufacturing a shearing type piezoelectric element according to the present invention. The basic steps are the same as in the embodiment shown in FIG. As shown in FIG. 7A, a plurality (three in the drawing) of linear conductor patterns 82 for polarization are formed on the surface of a piezoelectric plate 80 made of piezoelectric ceramics in parallel at appropriate intervals. Each linear conductor pattern 82 is provided on the front and back surfaces of the piezoelectric plate 80 so as to have the same shape. Then, as shown in FIG. 7B, polarization processing is performed in the in-plane direction of the piezoelectric plate 80 using the linear conductor pattern 82. The direction of polarization is indicated by an arrow.

Next, as shown in FIG.
Near one of the opposing edges of the pair of linear conductor patterns for polarization (here, the negative side in the polarization direction) (ie, the right edge of the left linear conductor pattern and the right linear conductor pattern). (Along the left edge of the conductor pattern) a dot-shaped mask pattern 8
4 is formed. The dot-shaped mask pattern is provided so as to correspond to each element.

Next, as shown in FIG. 7D, an electrode 86 is formed over the linear electrode pattern 82 for polarization and the mask pattern 84 over the entire front and back surfaces of the piezoelectric plate. This electrode formation is performed by attaching a metal film such as gold by a sputtering method or an evaporation method.

Thereafter, the mask pattern is removed by dipping in a solvent or by performing ultrasonic cleaning. When the mask pattern is peeled, the electrode portion placed thereon is also removed. Therefore, as shown in FIG. 7E, the removed portion becomes a dot-shaped mask mark 88, and the surface of the piezoelectric plate is exposed.

Finally, as shown in FIG. 7F, a large number of devices having a predetermined shape are cut out of the polarization region using a dicing saw or the like. The broken lines indicate the positions where the cutting is performed vertically and horizontally. As shown in the drawing, when the element is cut out from the polarization region into a rectangular plate shape, the element is cut so as to leave a dot-shaped mask mark 88 on the element side.

FIG. 8 shows the sheared piezoelectric element 90 cut out. In this embodiment, a dot-like mask mark 88 remains on the negative electrode side in the polarization direction in each element after cutting and separation.
Although most of the surface of the shearing type piezoelectric element 90 is covered with the gold electrode 86, the mask mark 88 can be easily visually discriminated by the gold color of the gold electrode and the ground color of the ceramic (the color of the mask mark). The direction of polarization is indicated by an arrow.

In each of the above embodiments, the method of forming the convex portions and the concave portions in the linear electrode pattern for polarization has good productivity without increasing the number of steps. The method of forming the mask mark is because no swelling occurs on the electrode surface.
This is convenient for applications where the entire surface is bonded to another member. By making the mask trace linear, it is possible to freely cope with various element dimensions. In the case of the dot shape, since the cutting position is limited, it is necessary to arrange the dots at a pitch corresponding to the element size. It is preferable that the mask mark remaining on the element has a minimum necessary size for checking the polarization direction so as not to adversely affect the characteristics.

[0034]

As described above, according to the present invention, a pair of convex and concave portions are formed in a pair of linear conductor patterns for polarization during polarization processing, and the element is cut out so as to leave the convex portions. Since it is a method, it is possible to extremely easily and efficiently form a bulge due to a convex portion on each element. Even when the element is cut into a square plate shape, the direction of polarization and the direction of polarization can be clearly discriminated visually by the swelling due to the protrusion.

Further, as described above, the present invention is a method of forming a mask mark on an electrode along a linear conductor pattern for polarization and cutting out an element so as to leave the mask mark. The color difference from the ground color of ceramics occurs,
Mask traces can be easily found. As a result, even when the element is cut into a square plate, the polarization direction and the polarization direction can be clearly discriminated visually.

As described above, since the shearing type piezoelectric element obtained by the method of the present invention has a portion on one end surface which can clearly determine the direction of polarization, it can be used for various devices such as actuators and sensors. It can be assembled accurately and easily in the desired orientation, and there is no risk of assembly errors.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing one embodiment of a method for producing a shear-type piezoelectric element according to the present invention.

FIG. 2 is a perspective view showing a shear-type piezoelectric element obtained by the method.

FIG. 3 is an explanatory view showing an example in which a shear-type piezoelectric element obtained by the method of the present invention is applied to an actuator of a fine movement mechanism.

FIG. 4 is an explanatory view showing an example in which a shear-type piezoelectric element obtained by the method of the present invention is applied to an actuator of a fine movement mechanism.

FIG. 5 is a process explanatory view showing another embodiment of the method for producing a shear-type piezoelectric element according to the present invention.

FIG. 6 is a perspective view showing a shear-type piezoelectric element obtained by the method.

FIG. 7 is a process explanatory view showing still another embodiment of the method for producing a shearing piezoelectric element according to the present invention.

FIG. 8 is a perspective view showing a shear-type piezoelectric element obtained by the method.

FIG. 9 is an explanatory view showing an example of the structure and operation of a shear-type piezoelectric element.

[Explanation of symbols]

 20 piezoelectric plate 22a, 22b, 22c linear conductor pattern for polarization 23a convex portion 23b concave portion 24 electrode

Claims (3)

[Claims] 1. A plurality of linear conductor patterns for polarization are formed in parallel on a surface of a piezoelectric plate at intervals, and a DC electric field is applied between them to perform a polarization process. In a method of manufacturing a shear-type piezoelectric element in which electrodes are formed on at least both surfaces of a polarization region between linear conductor patterns and a device is cut out from the polarization region into a rectangular plate, a pair of polarization lines forming a pair during polarization processing The conductor pattern is
A large number of convex portions are formed on one of the opposing edges, and a large number of concave portions are formed on the other side in a positional relationship facing each other and arranged for each element to be cut out. When cutting out the element in a plate shape, the projection is cut so that at least a part of the projection remains on the element side, and the direction of polarization can be determined by the position of the remaining projection. Device manufacturing method. 2. The method of manufacturing a shear-type piezoelectric element according to claim 1, wherein the convex portion and the concave portion have a shape having an arc-shaped contour of the same dimension. 3. A plurality of linear conductor patterns for polarization are formed in parallel on the surface of the piezoelectric plate at intervals, and a DC electric field is applied between them to perform a polarization process. In a method of manufacturing a shear-type piezoelectric element in which electrodes are formed on at least both surfaces of a polarization region between linear conductor patterns and a device is cut out from the polarization region into a rectangular plate, a pair of polarization lines forming a pair during polarization processing A mask pattern is formed near one of the opposing edges of the conductor pattern, electrodes are formed on almost the entire surface of the piezoelectric plate, and then the mask pattern is removed, so that the electrode portion on the mask is also removed and the mask trace is removed. Is formed, and when the element is cut into a rectangular plate shape from the polarization region, the mask is cut so that at least a part of the mask mark remains on the element side, so that the direction of polarization can be determined based on the position of the remaining mask mark. Method of manufacturing a shear-type piezoelectric elements, characterized in that.