JP4955962B2 - Piezoelectric actuator and manufacturing method thereof - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic substrate suitably used in electronic industry applications, a piezoelectric actuator used for positioning and pressurizing various devices by generating fine displacement, and particularly used for an ink jet recording head, and a method for manufacturing the same. .

  In recent years, with the spread of personal computers and the development of multimedia, the use of ink jet printers as recording apparatuses that output information to recording media is rapidly expanding. Piezoelectric actuators are widely used in the ink jet recording head of this printer. A piezoelectric ink jet recording head using this piezoelectric actuator is excellent in that the head can be easily reduced in size and thickness, and can be printed with high accuracy.

  This piezoelectric inkjet recording head has a plurality of plates stacked in a cavity unit provided with a pressure chamber, a nozzle communicating with the pressure chamber, and an ink flow path for supplying ink to the pressure chamber. The piezoelectric actuator is joined, and the ink in the pressure chamber can be pressurized by the deformation of the piezoelectric actuator, and ink droplets can be ejected from the nozzles using the pressure.

  Such a piezoelectric actuator usually has a polygonal shape such as a rectangular plane shape. When processing into such a shape, in general, a laminated body is produced by laminating a plurality of green sheets mainly composed of piezoelectric ceramic powder and an internal electrode layer, and the laminated body is rotated or pressed. The desired shape is obtained by cutting with a cutter or the like (see, for example, Patent Document 1).

  However, in the cutting method described in Patent Document 1, since the laminated body is cut with a cutter, the corners and the peripheral edge of the piezoelectric actuator have a substantially right cross section. Become. For this reason, there are problems that corners and peripheral edges are caught on the surface of the setter for firing during firing, causing shrinkage variation, and the corners exhibit abnormal shrinkage behavior, resulting in deformation and reduced dimensional accuracy. In particular, the corners tend to be caught on the surface of the firing setter.

In addition, when joining a piezoelectric actuator to a substrate such as a cavity unit for a print head, the corners and the peripheral portion having a substantially right cross section come into contact with the substrate surface, and a part of the substrate is scraped off. There was a problem that stable printing was difficult because the ink flowed into the pressure chambers, nozzles, flow paths, etc. of the unit and blocked the ink flow.
JP 2003-338426 A

  An object of the present invention is to provide a piezoelectric actuator having high dimensional accuracy and capable of suppressing generation of shavings even when bonded to a substrate, and a manufacturing method thereof.

In order to solve the above problems, the piezoelectric actuator of the present invention and the manufacturing method thereof have the following configurations.
(1) A piezoelectric actuator comprising a piezoelectric layer and a pair of electrodes arranged on both sides of the piezoelectric layer, wherein at least one main surface side corner is a curved surface having a substantially arc-shaped cross section. A piezoelectric actuator characterized in that the ratio (R / T) of the radius of curvature R of the arc and the thickness T of the piezoelectric actuator is as follows.
When T <10 μm (R / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (R / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (R / T) = 0.05 to 0.67
When T> 100 μm (R / T) = 0.02 to 0.33

(2) A piezoelectric actuator in which a plurality of piezoelectric layers and a plurality of electrodes are laminated, and the electrodes are arranged on both surfaces of at least one of the piezoelectric layers, and the corners on at least one main surface side The section is a curved surface having a substantially arc-shaped cross section, and the ratio (R / T) between the radius of curvature R of the arc and the thickness T of the piezoelectric actuator is as follows.
When T <10 μm (R / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (R / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (R / T) = 0.05 to 0.67
When T> 100 μm (R / T) = 0.02 to 0.33

(3) The peripheral portion on the main surface side is a curved surface having a substantially arc-shaped cross section, and the ratio (R / T) between the radius of curvature R of the arc and the thickness T of the piezoelectric actuator is as follows: ) Or the piezoelectric actuator according to (2).
When T <10 μm (R / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (R / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (R / T) = 0.05 to 0.67
When T> 100 μm (R / T) = 0.02 to 0.33

(4) A piezoelectric actuator comprising a piezoelectric layer and a pair of electrodes disposed on both sides of the piezoelectric layer, wherein at least one of the principal surface side corners is a slanted slope. In the cross section, assuming that the oblique line is a hypotenuse, one side is parallel to the main surface, and the other side is a right triangle perpendicular to the main surface, the length of the one side is ta, and the length of the remaining one side Is a ratio of ta and tb to the thickness T of the piezoelectric actuator, where tb is the following.
When T <10 μm (ta / T) = 0.3 to 1.0, (tb / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (ta / T) = 0.1 to 1.0, (tb / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (ta / T) = 0.05 to 0.67, (tb / T) = 0.05 to 0.67
When T> 100 μm (ta / T) = 0.02 to 0.33, (tb / T) = 0.02 to 0.33
(5) The piezoelectric actuator according to any one of (1) to (4), wherein a planar shape of the piezoelectric layer is substantially square.
(6) The piezoelectric device according to any one of (1) to (5), wherein a substrate is bonded via an adhesive layer to the main surface having a curved corner or the main surface having a curved corner. Actuator.

(7) A molding process for producing a green sheet mainly composed of piezoelectric ceramic powder, a coating process for producing a coated body by covering both main surfaces of the green sheet with a protective film, and punching the coated body A punching process for producing a molded body by punching into a predetermined shape using a mold, a firing process for removing a protective film from the molded body and firing to produce a sintered body, and both sides of the sintered body A method for manufacturing a piezoelectric actuator, comprising: an electrode forming step of forming a pair of electrodes.
(8) A forming step for producing a plurality of green sheets mainly composed of piezoelectric ceramic powder, an electrode forming step for forming electrodes on one main surface of at least a part of the green sheets, and a green sheet on which the electrodes are formed Laminating step of laminating a plurality of the green sheets containing a laminate, producing a laminate by coating both main surfaces of the laminate with a protective film, and punching the coated die A piezoelectric device comprising: a punching process for punching into a predetermined shape using a ceramic to produce a molded body; and a firing process for removing a protective film from the molded body and firing to produce a sintered body Actuator manufacturing method.
(9) The method for manufacturing a piezoelectric actuator according to (7) or (8), wherein the punching die is a curved surface having a substantially arc-shaped cross section in contact with the covering body.

  (10) A forming step for producing a plurality of green sheets mainly composed of piezoelectric ceramic powder, an electrode forming step for forming electrodes on one main surface of at least a part of the green sheets, and a green sheet on which the electrodes are formed Laminating a plurality of green sheets containing a laminate to produce a laminate, a covering step of coating one main surface of the laminate with a protective film to produce a covering, and A molding process for forming a molded body by molding into a shape, a chamfering process for chamfering a corner on the main surface side of the molded body not covered with the protective film, and protection from the chamfered molded body A method of manufacturing a piezoelectric actuator comprising: a firing step of removing a film and firing to produce a sintered body.

  (11) A forming step for producing a plurality of green sheets mainly composed of piezoelectric ceramic powder, an electrode forming step for forming electrodes on one main surface of at least a part of the green sheets, and a green sheet on which the electrodes are formed Laminating a plurality of green sheets containing a laminate to produce a laminate, a covering step of coating one main surface of the laminate with a protective film to produce a covering, and A molding step for forming a molded body by molding into a shape, a chamfering step for chamfering the peripheral portion of the main surface of the molded body not covered with the protective film, and protection from the chamfered molded body A method of manufacturing a piezoelectric actuator comprising: a firing step of removing a film and firing to produce a sintered body.

(12) The method for producing a piezoelectric actuator according to any one of (7) to (11), wherein the protective film is at least one selected from polyethylene terephthalate, polyethylene naphthalate, polyetherimide, and polyphenylene sulfide.
(13) The method for manufacturing a piezoelectric actuator according to any one of (7) to (12), wherein a planar shape of the molded body is a substantially square shape.
(14) (7) to (13) comprising a joining step of joining the substrate to the main surface of which the corner portion is processed into a curved surface or a slope as a step after the firing step via an adhesive layer. ) A method for manufacturing a piezoelectric actuator according to any one of the above.

  In the piezoelectric actuator of the present invention, at least one of the main surface side corners is a curved surface that satisfies the above-described conditions, so that the corners are not caught on the surface of the firing setter during firing, and shrinkage variation occurs. Can be suppressed. Thereby, a piezoelectric actuator with high dimensional accuracy can be obtained. Further, even when the piezoelectric actuator is used for a print head for an ink jet printer, it is possible to prevent the corners from scraping off part of the substrate surface of the cavity unit to generate shavings. This enables stable printing over a long period of time without disturbing the ink flow. In the piezoelectric actuator of the present invention, it is preferable that the peripheral portion has a curved surface as described above in addition to the corner portion. In addition, the piezoelectric actuator of the present invention can obtain the same effect even when the corners and the peripheral edge are not curved surfaces but are inclined surfaces that satisfy the above-described conditions.

  Further, in the method for manufacturing a piezoelectric actuator of the present invention, a coated body in which the principal surfaces of both the green sheet or the laminate composed of the green sheet and the electrode are coated with a protective film is produced, and the coated body is formed into a predetermined shape by a punching die. Punched into a shaped molded body. That is, when punching, since the shearing force of the punching die is applied to the corners and the peripheral part of the molded body before firing, the protective film at the corners and the peripheral part is plastically deformed in the direction of the shearing force. The corner and peripheral edge of the body are processed into a curved surface having a substantially arc-shaped cross section. Thereby, the piezoelectric actuator whose corner | angular part and peripheral part are curved surfaces which have a substantially circular arc-shaped cross section can be obtained. Further, in the method for manufacturing a piezoelectric actuator of the present invention, the corners and the peripheral part are not curved into a curved surface using a punching die, but the corners and the peripheral part of the molded body are, for example, curved or inclined as described above. You may chamfer it.

<First Embodiment>
Hereinafter, a piezoelectric actuator and a manufacturing method thereof according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1A is a plan view showing the piezoelectric actuator 1 of the present embodiment, and FIG. 1B is a sectional view taken along the line XX. This XX line is a diagonal line on the surface of the piezoelectric actuator 1. As shown in FIGS. 1 (a) and 1 (b), a piezoelectric actuator 1 is formed by laminating two piezoelectric ceramic layers (piezoelectric layers) 2 and 3 having a substantially square planar shape, an internal electrode 4 and a surface electrode 5. The internal electrode 4 and the surface electrode 5 are disposed on both surfaces of the piezoelectric ceramic layer 2. The piezoelectric actuator 1 can generate a piezoelectric vibration in the piezoelectric ceramic layer 2 immediately below the surface electrode 5 by applying a voltage between the surface electrode 5 and the internal electrode 4.

2 is an enlarged cross-sectional view of the vicinity of the corner portion K of the piezoelectric actuator 1, and FIG. 3 is an enlarged perspective view of the vicinity of the corner portion of the piezoelectric actuator 1 as viewed from the surface H side. As shown in FIGS. 1 to 3, in this piezoelectric actuator 1, four corners K on one surface H side are curved surfaces having a substantially arc-shaped cross section. The ratio (R / T) between the radius of curvature R of the arc and the thickness T of the piezoelectric actuator is as follows.
When T <10 μm, preferably 5 μm ≦ T <10 μm (R / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (R / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (R / T) = 0.05 to 0.67
When T> 100 μm, preferably 300 μm ≧ T> 100 μm (R / T) = 0.02 to 0.33

  Thereby, when shrinking at the time of firing, the corner of the piezoelectric actuator 1 is prevented from being caught on the surface of the setter for firing, and shrinkage variation is improved. As a result, warpage and undulation of the piezoelectric actuator are reduced, leading to an improvement in dimensional accuracy in the planar direction. Further, since the corner portion is a curved surface as described above, occurrence of chipping and chipping can be suppressed. On the other hand, when the R / T at each thickness T falls outside the above-described predetermined range, the above effect may be reduced. That is, when the R / T at each thickness T is smaller than the above range, improvement in shrinkage variation is not observed, and when the R / T is larger than the above range, the waviness of the outer peripheral portion increases.

  The radius of curvature R may be about 1 to 50 μm, preferably about 5 to 40 μm. Within this range, it is preferable that the R / T at each thickness T is within the predetermined range described above.

FIG. 4 is an enlarged perspective view showing a modification of the piezoelectric actuator according to the first embodiment. As shown in FIG. 4, in the piezoelectric actuator 1 ′, not only the corner portion K on the surface H side, but also the entire peripheral portion S including the corner portion K may be processed into a curved surface having a substantially arc-shaped cross section. The ratio (R / T) between the radius of curvature R of the arc and the thickness T of the piezoelectric actuator is preferably as follows as in the case of the corner K.
When T <10 μm, preferably 5 μm ≦ T <10 μm (R / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (R / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (R / T) = 0.05 to 0.67
When T> 100 μm, preferably 300 μm ≧ T> 100 μm (R / T) = 0.02 to 0.33

Examples of the piezoelectric ceramic layer 2 include piezoelectric ceramics of perovskite type compounds such as lead zirconate titanate compounds containing Pb, Zr and Ti [PbZrTiO ₃ -based compounds (PZT-based)], lead titanate compounds, barium titanate compounds, and the like. Raw materials are preferably used. Of these, it is preferable to use the PZT system in that a large displacement can be obtained. The piezoelectric ceramic layer 3 is preferably made of the same material as the piezoelectric ceramic layer 2. The piezoelectric ceramic layer 2 is polarized in the direction opposite to each other in the thickness direction.

  The internal electrode 4 is formed of a conductor made of Ag, Cu, Pd, Pt, Rh, Au, Ni alone or a combination of two or more, preferably a conductor containing Ag, more preferably an Ag—Pd alloy. Is good. The Ag—Pd alloy preferably contains 80% by mass or more, more preferably 90 to 95% by mass of Ag. Further, it is more preferable to add a material having substantially the same composition as that of the piezoelectric ceramic layer 2 to the internal electrode 4 as a co-material.

  As the surface electrode 5, a conductor made of Ag, Cu, Pd, Pt, Rh, Au-based material, Ni alone or a combination of two or more is used, and high conductivity can be obtained even if the layer is thinned. It is good to form with Au type material.

Next, a method for manufacturing the piezoelectric actuator will be described. 5A to 5H are process diagrams showing a method for manufacturing a piezoelectric actuator according to an embodiment of the present invention.
First, piezoelectric ceramic powders such as a lead zirconate titanate compound, a lead titanate compound, and a barium titanate compound are prepared. Next, the piezoelectric ceramic powder and the organic binder component are mixed to produce a tape-forming slurry. Using this slurry, a plurality of green sheets 6 are produced by a general tape forming method such as a roll coater method, a slit coater method, a doctor blade method, etc. [FIG. 5 (a): forming step].

  The average particle size of the piezoelectric ceramic raw material powder is preferably 1 μm or less, more preferably 0.7 μm or less, and even more preferably 0.5 μm or less. When the average particle diameter exceeds 1 μm, the thickness variation ratio (generally, C value: value obtained by dividing the standard deviation by the average value) of the green sheet increases, which may adversely affect the characteristics. Further, in the case of piezoelectric ceramics containing lead, the activity during sintering decreases, and the sintering temperature must be increased. As a result, evaporation of lead occurs and the variation in composition increases. Conversely, these problems are suppressed by setting the average particle diameter to 1 μm or less.

  Next, among the green sheets 6 obtained in the molding process, the internal electrode 4 is formed by printing a conductive paste containing the conductor on one main surface of some of the green sheets 6 by screen printing or vapor deposition. [FIG. 5B: Electrode forming step]. Next, the obtained green sheets 6 (with electrodes and without electrodes) are laminated in a desired configuration and brought into close contact to obtain a laminated body [FIG. 5 (c): laminating step]. As a method for adhering a plurality of green sheets, a method of using an adhering liquid containing an adhesive component, a method of adhering the organic binder component in the green sheet by heating, and adhering only with a pressure force A method etc. can be illustrated.

  Next, the laminated body obtained above is divided into individual product shapes. As this method, a punching method using a punching die composed of a punch 8 and a die 9 is employed. When punching, both main surfaces of the laminate are covered with the protective film 7. Thereby, the protective film itself undergoes plastic deformation at the time of punching, and curved portions can be given to the corners and the peripheral edge of the molded body by the deformation [FIG. 5 (d): covering step and punching step].

  In order to change the curvature radius R of the curved surface of the corner and the peripheral part, the clearance between the punch 8 and the die 9 is changed. When the clearance is small, the radius of curvature R is small. Conversely, when the clearance is large, the radius of curvature R is large. A preferable range of the clearance is 5 to 100 μm. Outside this range, undulation or the like may occur, and punching may not be performed properly.

  As a method of covering the laminate with the protective film 7, a general film laminating method may be used. If a protective film has already been placed on the surface of the laminate (when using a protective film when making a green sheet and laminating with a film in the laminating process, etc.), the coating process should be omitted. Can do.

  The protective film 7 is preferably at least one selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyetherimide (PEI), and polyphenylene sulfide (PPS). By using these materials, it becomes easy to attach curved surfaces to the corners and the peripheral edge of the molded body at the time of punching. The thickness of the protective film 7 is preferably about 10 to 100 μm.

  The molded body [FIG. 5 (e)] obtained in the punching process is prepared by removing the protective film 7 on both main surfaces [FIG. 5 (f)], and then removing the organic components in the molded body by degreasing if necessary. After the removal, firing is performed in the air or in an oxygen atmosphere to produce a sintered body (degreasing / firing step). As a method for removing the organic component, a method of performing a heat treatment with a temperature pattern suitable for the thermal decomposition behavior of the organic component to be removed, or the like is employed. When firing lead-containing ceramics, increasing the concentration of oxygen, which is a soluble gas (80% or more), increases the oxygen partial pressure and suppresses lead decomposition and gasification. Therefore, voids shrink and voiding is suppressed.

  Finally, a conductive paste containing the conductor is printed on one main surface of the sintered body by screen printing or vapor deposition, and fired at about 600 to 800 ° C. to form the surface electrode 5 [FIG. ]]. Thereby, the piezoelectric actuator 1 shown in FIG. 1 can be obtained.

  When the piezoelectric actuator 1 is applied to an ink jet print head or the like, as shown in FIG. 5 (h), the substrate 11 is formed on the surface on the side where the corners and the peripheral edge are processed into a curved surface via an adhesive layer. Are joined (joining step). The substrate 11 includes an ink flow path 13 having an ink discharge port 12 and a partition wall 14 that partitions each ink flow path 13. The surface electrode 5 is disposed so as to face the ink flow path 13. By bonding the substrate 11 to the surface on the side where the corners and the peripheral edge are processed into curved surfaces in this way, stress concentration due to external loads such as impact during the bonding is alleviated, and occurrence of chipping and chipping can be suppressed. , Leading to reduced generation of shavings.

  In the piezoelectric actuator of the first embodiment, in order to process the corners and the peripheral edge into a curved surface, in addition to the above method, the corner and the peripheral edge are chamfered into a curved surface by, for example, cutting with a cutter. Also good.

<Second Embodiment>
FIG. 6A is a bottom view showing a piezoelectric actuator according to a second embodiment of the present invention, and FIG. 6B is a sectional view taken along line YY. As shown in FIGS. 6A and 6B, the piezoelectric actuator 21 is formed by laminating two piezoelectric ceramic layers (piezoelectric layers) 2 and 3 having a substantially square planar shape, an internal electrode 3 and a surface electrode 5. The internal electrode 3 and the surface electrode 5 are disposed on both surfaces of the piezoelectric ceramic layer 2.

FIG. 7 is an enlarged cross-sectional view of the vicinity of the corner portion of the piezoelectric actuator 21. As shown in FIGS. 6 and 7, in this piezoelectric actuator 21, the four corners K ′ on one surface H side are chamfered on a slope whose cross section is oblique, and so-called C chamfering is performed. In this cross section, a diagonal triangle in which the oblique line L is the hypotenuse, the one side A is parallel to the surface H, and the remaining one side B is perpendicular to the surface H, the length of one side A is ta and the length of the remaining one side B is assumed. Where tb is the ratio of ta, tb to the thickness T of the piezoelectric actuator, is as follows.
When T <10 μm, preferably 5 μm ≦ T <10 μm (ta / T) = 0.3 to 1.0, (tb / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (ta / T) = 0.1 to 1.0, (tb / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (ta / T) = 0.05 to 0.67, (tb / T) = 0.05 to 0.67
When T> 100 μm, preferably 300 μm ≧ T> 100 μm (ta / T) = 0.02 to 0.33, (tb / T) = 0.02 to 0.33

  Thereby, when shrinking at the time of firing, the corners of the piezoelectric actuator 21 are prevented from being caught on the surface of the setter for firing, and shrinkage variation is improved. As a result, warpage and undulation of the piezoelectric actuator are reduced, leading to an improvement in dimensional accuracy in the planar direction. On the other hand, when (ta / T) and (tb / T) at each thickness T are smaller than the above range, improvement in shrinkage variation is not seen, and when larger than the above range, the swell of the outer peripheral portion becomes large.

  The chamfering of the corner K ′ may be performed so that the ratio of ta, tb and thickness T is within the predetermined range described above. The oblique line L, the side A and the side formed at the time of C chamfering The angle formed by B is not particularly limited. Specifically, for example, C chamfering may be performed so that the C surface dimensions (the dimensions of ta and tb) are equal, that is, the angle formed by the oblique line L and the sides A and B is 45 degrees. You may chamfer at a different angle.

  The C-plane dimension (the dimensions of ta and tb) is 1 to 50 μm, preferably about 1 to 40 μm. Within this range, (ta / T) and (tb / T) at each thickness T are It is preferable to configure so as to be within the predetermined range.

  As a manufacturing method of the piezoelectric actuator 21 according to the second embodiment as described above, a laminated body of a plurality of green sheets and electrodes is formed into a desired shape with a punching die or a cutter and laminated, and then a corner on the surface H side. The corner K ′ may be chamfered by pressing, for example, a flat file surface on the portion K ′ and fired. Further, the corner portion K ′ can be chamfered with a cutter.

  FIG. 8 is a bottom view showing a modification of the piezoelectric actuator according to the second embodiment, and FIG. 9 is an enlarged cross-sectional view taken along the line ZZ. As shown in FIGS. 8 and 9, in this piezoelectric actuator 21 ′, not only the corner portion K ′ on the surface H side but also the entire peripheral edge portion S ′ may be chamfered into a slope shape. Such chamfering in the piezoelectric actuator 21 ′ can be performed as follows, for example. First, the peripheral edge S ′ is chamfered by pressing, for example, a flat file surface on the peripheral edge S ′ on the surface H side. Next, the corner portion K ′ is chamfered by pressing a flat file surface or the like against the corner portion K ′ on the surface H side. Further, the corner K ′ and the peripheral edge S ′ can be chamfered with a cutter. Bake after this chamfering.

In the piezoelectric actuator 21 ′, it is preferable that the ratio of ta and tb to the thickness T of the piezoelectric actuator is as follows in the cross section at the peripheral edge S ′ as in the case of the corner K ′.
When T <10 μm, preferably 5 μm ≦ T <10 μm (ta / T) = 0.3 to 1.0, (tb / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (ta / T) = 0.1 to 1.0, (tb / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (ta / T) = 0.05 to 0.67, (tb / T) = 0.05 to 0.67
When T> 100 μm, preferably 300 μm ≧ T> 100 μm (ta / T) = 0.02 to 0.33, (tb / T) = 0.02 to 0.33

  As mentioned above, although embodiment of this invention was shown, it cannot be overemphasized that this invention is applicable not only to embodiment mentioned above but what was changed and improved in the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the case where one internal electrode is provided has been described, but two or more internal electrodes may be provided. Alternatively, a plurality of surface electrodes may be arranged on the main surface of the piezoelectric ceramic layer.

  In addition, the planar shape of the piezoelectric ceramic layer is usually a rectangle such as a rectangle, square, trapezoid, parallelogram, rhombus, etc., but a triangle, pentagon, hexagon, octagon, decagon, dodecagon, etc. It may be a polygon.

  In the above embodiment, the ratios (R / T), (ta / T), and (tb / T) at the corners are evaluated based on a cross-sectional view taken along a diagonal line on the surface of the piezoelectric actuator. However, for example, the ratio can also be evaluated based on a cross-sectional view taken along a cross section that is substantially perpendicular to the surface of the piezoelectric actuator and substantially bisects the corners.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further in detail, this invention is not limited to a following example.

  First, lead zirconate titanate powder having a particle size (D50: average particle size of powder) of 0.5 μm was prepared as a piezoelectric ceramic raw material powder, and an aqueous acrylic solution was mixed with this to prepare a slurry. Using this slurry, a green sheet was formed on a polyethylene terephthalate (PET) film having a thickness of 30 μm by a roll coater method so as to have a thickness of 40 μm.

  Next, an Ag-Pd electrode paste having a Ag: Pd ratio (Ag: Pd) of 70:30 is applied to the green sheet obtained in the molding process by a printing method. Formed.

  Next, the green sheet with no internal electrode formed thereon is aligned with the green sheet with the internal electrode formed on the lower layer so that the PET film faces the outside of the laminated surface, and is pressed and sealed at a pressure of 10 MPa and a temperature of 70 ° C. The laminate was obtained by wearing.

  Thereafter, the laminate was punched into a product shape using a punching die having a punch-to-die clearance of 10 μm. After the PET film on both sides of the punched product was peeled off, it was loaded on a firing setter so that the punch surface was facing up.

  Finally, the obtained laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then baked for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90%. A surface electrode was formed to obtain a piezoelectric actuator.

  When the corner and periphery of the obtained piezoelectric actuator were observed in the cross-sectional direction with a scanning electron microscope (SEM), a curved surface having an arc-shaped cross section was formed at the corner and periphery of one main surface. It was. When the curvature radius of this curved surface and the entire thickness of the actuator were measured, the curvature radius R was 15 μm and the total thickness T was 60 μm (R / T = 0.25). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.2%.

  Furthermore, it joined so that the principal surface side where the corner | angular part and peripheral part of a produced piezoelectric actuator may be curved may contact | abut with a flow-path member (board | substrate), and the print head for inkjet printers was assembled. Thereafter, ink was filled into the head and ink ejection was evaluated. As a result, stable ink ejection characteristics were obtained, and no abnormality was observed.

  In the same manner as in Example 1, a green sheet was formed on a PET film having a thickness of 10 μm so as to have a thickness of 5 μm, and an internal electrode having a thickness of 3 μm was formed thereon. Next, pressure adhesion was performed in the same manner as in Example 1, and then punched into a product shape using a punching die having a punch-to-die clearance of 5 μm. After the PET film on both sides of the punched product was peeled off, it was loaded on a firing setter so that the punch surface was facing up.

  Finally, the obtained laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then baked for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90%. A surface electrode was formed to obtain a piezoelectric actuator.

  When measured by the same method as in Example 1, the radius of curvature R was 9 μm and the total thickness T was 9 μm (R / T = 1.0). Moreover, when the baking shrinkage ratio variation was evaluated from the outer dimension before firing and the outer dimension after firing, the standard deviation was 0.3%.

  The produced piezoelectric actuator was joined so that the principal surface side where the corners and the peripheral part are curved surfaces are in contact with the flow path member (substrate), and a print head for an ink jet printer was assembled. Thereafter, ink was filled into the head and ink ejection was evaluated. As a result, stable ink ejection characteristics were obtained, and no abnormality was observed.

  In the same manner as in Example 1, a green sheet was formed on a PET film having a thickness of 30 μm so as to have a thickness of 20 μm, and an internal electrode having a thickness of 5 μm was formed thereon. Next, pressure adhesion was performed in the same manner as in Example 1, and then punched into a product shape using a punching die having a punch-to-die clearance of 10 μm. After the PET film on both sides of the punched product was peeled off, it was loaded on a firing setter so that the punch surface was facing up.

  Finally, the obtained laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then baked for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90%. A surface electrode was formed to obtain a piezoelectric actuator.

  When measured by the same method as in Example 1, the radius of curvature R was 20 μm, and the total thickness T was 32 μm (R / T = 0.625). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.2%.

  The produced piezoelectric actuator was joined so that the principal surface side where the corners and the peripheral part are curved surfaces are in contact with the flow path member (substrate), and a print head for an ink jet printer was assembled. Thereafter, ink was filled into the head and ink ejection was evaluated. As a result, stable ink ejection characteristics were obtained, and no abnormality was observed.

  In the same manner as in Example 1, a green sheet was formed on a PET film having a thickness of 30 μm so as to have a thickness of 75 μm, and an internal electrode having a thickness of 5 μm was formed thereon. Next, pressure adhesion was performed in the same manner as in Example 1, and then punched into a product shape using a punching die having a punch-to-die clearance of 10 μm. After the PET film on both sides of the punched product was peeled off, it was loaded on a firing setter so that the punch surface was facing up.

  Finally, the obtained laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then baked for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90%. A surface electrode was formed to obtain a piezoelectric actuator.

  When measured by the same method as in Example 1, the radius of curvature R was 30 μm, and the total thickness T was 110 μm (R / T = 0.273). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.15%.

  The produced piezoelectric actuator was joined so that the principal surface side where the corners and the peripheral part are curved surfaces are in contact with the flow path member (substrate), and a print head for an ink jet printer was assembled. Thereafter, ink was filled into the head and ink ejection was evaluated. As a result, stable ink ejection characteristics were obtained, and no abnormality was observed.

  A laminate was obtained in the same manner as in Example 1. Then, the laminated body was cut into a product shape together with the PET film by push cutting (guillotine cut) with a cutter. After peeling the PET film on both sides of the laminate, chamfer the outer peripheral edge (corner and peripheral edge) of the laminate surface corresponding to the firing setter loading surface with a cutter so that the cross section becomes a slanted slope (C Chamfering). The cutting amount of the cutter at this time was 20 μm.

  Finally, the obtained laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then baked for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90%. A surface electrode was formed to obtain a piezoelectric actuator.

  When the corners and the peripheral edge of the obtained piezoelectric actuator were observed in the cross-sectional direction with a scanning electron microscope (SEM), the outer peripheral edge of one main surface had a cross section with a slanted slope (C surface shape). Was. The C-plane dimension (dimensions of ta and tb) and the total thickness of the actuator were measured. The C-plane dimension was 15 μm and the total thickness T was 60 μm (ta / T = 0.25, tb / T = 0.25). ). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.15%.

  Furthermore, it joined so that the principal surface side where the corner | angular part and peripheral part of a produced piezoelectric actuator may be curved may contact | abut with a flow-path member (board | substrate), and the print head for inkjet printers was assembled. Thereafter, ink was filled into the head and ink ejection was evaluated. As a result, stable ink ejection characteristics were obtained, and no abnormality was observed.

  In the same manner as in Example 1, a green sheet was formed on a PET film having a thickness of 10 μm so as to have a thickness of 5 μm, an internal electrode having a thickness of 3 μm was formed thereon, pressure contact was performed, and the laminate was formed. Obtained. Then, C chamfering of the outer peripheral edge portion of the laminate was performed in the same manner as in Example 5. The cutting amount of the cutter at this time was 5 μm.

  Finally, the obtained laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then baked for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90%. A surface electrode was formed to obtain a piezoelectric actuator.

  When measured by the same method as in Example 1, the C-plane dimension was 4 μm and the overall thickness T was 9 μm (ta / T = 0.55, tb / T = 0.55). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.2%.

  The produced piezoelectric actuator was joined so that the principal surface side where the corners and the peripheral part are curved surfaces are in contact with the flow path member (substrate), and a print head for an ink jet printer was assembled. Thereafter, ink was filled into the head and ink ejection was evaluated. As a result, stable ink ejection characteristics were obtained, and no abnormality was observed.

  In the same manner as in Example 1, a green sheet is formed on a PET film having a thickness of 30 μm so as to have a thickness of 20 μm, an internal electrode having a thickness of 5 μm is formed thereon, and pressure adhesion is performed. Got. Then, C chamfering of the outer peripheral edge portion of the laminate was performed in the same manner as in Example 5. The cutting amount of the cutter at this time was 25 μm.

  Finally, the obtained laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then baked for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90%. A surface electrode was formed to obtain a piezoelectric actuator.

  When measured by the same method as in Example 1, the C-plane dimension was 20 μm and the overall thickness T was 32 μm (ta / T = 0.625, tb / T = 0.625). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.2%.

  The produced piezoelectric actuator was joined so that the principal surface side where the corners and the peripheral part are curved surfaces are in contact with the flow path member (substrate), and a print head for an ink jet printer was assembled. Thereafter, ink was filled into the head and ink ejection was evaluated. As a result, stable ink ejection characteristics were obtained, and no abnormality was observed.

  In the same manner as in Example 1, a green sheet was formed on a PET film having a thickness of 30 μm so as to have a thickness of 75 μm, an internal electrode having a thickness of 5 μm was formed on the green sheet, and pressure adhesion was performed. Got. Then, C chamfering of the outer peripheral edge portion of the laminate was performed in the same manner as in Example 5. The cutting amount of the cutter at this time was 32 μm.

  Finally, the obtained laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then baked for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90%. A surface electrode was formed to obtain a piezoelectric actuator.

  When measured by the same method as in Example 1, the C-plane dimension was 30 μm and the overall thickness T was 110 μm (ta / T = 0.273, tb / T = 0.273). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.12%.

  The produced piezoelectric actuator was joined so that the principal surface side where the corners and the peripheral part are curved surfaces are in contact with the flow path member (substrate), and a print head for an ink jet printer was assembled. Thereafter, ink was filled into the head and ink ejection was evaluated. As a result, stable ink ejection characteristics were obtained, and no abnormality was observed.

[Comparative Example 1]
A laminate was obtained in the same manner as in Example 1. After that, the product shape is divided by a sharp cutter, the PET films on both sides of the product are peeled off, loaded on a baking setter, degreased at 450 ° C. for 5 hours in the atmosphere, and then at a temperature of 1000 ° C. and an oxygen concentration Firing was performed in a 90% atmosphere for 2 hours to obtain a piezoelectric actuator.

  When the corner portion and the peripheral portion of the obtained piezoelectric actuator were observed with a scanning electron microscope (SEM) in the cross-sectional direction, they were substantially perpendicular. Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.5%.

  The manufactured actuator was joined so as to come into contact with the flow path member, and after assembling a head for an ink jet printer, ink was filled into the head and ink ejection was evaluated. As a result, no abnormality was observed in the initial stage. However, when continuous discharge was performed, discharge abnormality due to one-point nozzle clogging occurred.

[Comparative Example 2]
A laminate was obtained in the same manner as in Example 1. Thereafter, the product was punched into a product shape using a punching die having a punch-to-die clearance of 200 μm. After peeling the PET film on both sides of the punched product, it was loaded on a baking setter so that the punch surface was facing up, and after degreasing treatment at 450 ° C. for 5 hours in the atmosphere, a temperature of 1000 ° C. and an oxygen concentration of 90 The piezoelectric actuator was obtained by baking for 2 hours in a% atmosphere.

When the corner and periphery of the obtained piezoelectric actuator were observed in the cross-sectional direction with a scanning electron microscope (SEM), a large undulation occurred in the periphery, the curvature radius R of the cross-sectional curved surface was 60 μm, and the actuator The overall thickness T was 60 μm (R / T = 1.0). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.9%.
An attempt was made to contact the manufactured actuator with the flow path member, but it was impossible to join due to the undulation of the peripheral edge.

[Comparative Example 3]
A laminate was obtained in the same manner as in Example 1. Then, the laminated body was cut into a product shape together with the PET film by push cutting (guillotine cut) with a cutter. After peeling off the PET films on both sides of the laminate, the outer peripheral edge of the laminate surface corresponding to the firing setter loading surface was chamfered with a cutter. The cutting depth of the cutter at this time was 70 μm. After degreasing treatment at 450 ° C. for 5 hours in the air, firing was performed for 2 hours in an atmosphere at a temperature of 1000 ° C. and an oxygen concentration of 90% to obtain a piezoelectric actuator.

  When the corner portion and the peripheral portion of the obtained piezoelectric actuator were observed with a scanning electron microscope (SEM) in the cross-sectional direction, large undulation was generated in the peripheral portion, and the outer peripheral portion of one main surface was C It had a planar cross section. When the C-plane dimension and the entire actuator thickness were measured, the C-plane dimension was 60 μm and the total thickness T was 60 μm (ta / T = 1.0, tb / T = 1.0). Further, when the variation in the firing shrinkage rate was evaluated from the outer side dimension before firing and the outer side dimension after firing, the standard deviation was 0.5%.

  Furthermore, it was tried to assemble a print head for an ink jet printer by joining the piezoelectric actuator so that the main surface side where the corners and the periphery of the piezoelectric actuator are curved faces abut against the flow path member (substrate). Due to the swell, it was impossible to join.

(a) is a top view which shows the piezoelectric actuator concerning the 1st Embodiment of this invention, (b) is the XX sectional drawing. It is sectional drawing to which the corner | angular part vicinity of the piezoelectric actuator concerning 1st Embodiment was expanded. It is the expansion perspective view which looked at the corner | angular part vicinity of the piezoelectric actuator concerning 1st Embodiment from the surface H side. It is an expansion perspective view which shows the modification of the piezoelectric actuator concerning 1st Embodiment. (a)-(h) is process drawing which shows the manufacturing method of the piezoelectric actuator concerning 1st Embodiment. (a) is a bottom view which shows the piezoelectric actuator concerning the 2nd Embodiment of this invention, (b) is the YY sectional view taken on the line. It is sectional drawing to which the corner | angular part vicinity of the piezoelectric actuator concerning 2nd Embodiment was expanded. It is a bottom view which shows the modification of the piezoelectric actuator concerning 2nd Embodiment. It is an expanded sectional view of the ZZ line cross section of FIG.

Explanation of symbols

1,21 Piezoelectric actuator 2,3 Piezoelectric ceramic layer (piezoelectric layer)
4 Internal electrode 5 Surface electrode

Claims (14)

A piezoelectric layer, a piezoelectric actuator that includes a pair of electrodes disposed on both surfaces of the piezoelectric layer, the corners of at least one main surface is curved in a circular arc-shaped cross-section, of the arc A piezoelectric actuator characterized in that the ratio (R / T) between the radius of curvature R and the thickness T of the piezoelectric actuator is as follows.
When T <10 μm (R / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (R / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (R / T) = 0.05 to 0.6 7 A piezoelectric actuator in which a plurality of piezoelectric layers and a plurality of electrodes are laminated, and the electrodes are arranged on both surfaces of at least one of the piezoelectric layers, and a corner portion on at least one main surface side is a cross section There is a circular arc-shaped curved surface, a piezoelectric actuator, wherein the ratio between the thickness T of the circular arc of the radius of curvature R and the piezoelectric actuator (R / T) is as follows.
When T <10 μm (R / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (R / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (R / T) = 0.05 to 0.6 7 The periphery of the main surface is a curved surface section is a circle arc, and the thickness T of the circular arc of the radius of curvature R and the piezoelectric actuator the ratio (R / T) of claim 1 or 2, wherein as follows Piezoelectric actuator.
When T <10 μm (R / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (R / T) = 0.1 to 1.0
When 50 μm <T ≦ 100 μm (R / T) = 0.05 to 0.6 7 A piezoelectric actuator comprising a piezoelectric layer and a pair of electrodes arranged on both sides of the piezoelectric layer, wherein at least one of the principal surface side corners has a slanted cross section, Assuming that the diagonal line is a hypotenuse, one side is parallel to the main surface, and the other side is a right triangle perpendicular to the main surface, the length of the one side is ta, and the length of the remaining one side is tb. In this case, the ratio of ta and tb to the thickness T of the piezoelectric actuator is as follows.
When T <10 μm (ta / T) = 0.3 to 1.0, (tb / T) = 0.3 to 1.0
When 10 μm ≦ T ≦ 50 μm (ta / T) = 0.1 to 1.0, (tb / T) = 0.1 to 1.0
50 [mu] m <When T ≦ 100μm (ta / T) = 0.05~0.67, (tb / T) = 0.05~0.6 7 The piezoelectric actuator according to any one of claims 1 to 4 , wherein a plurality of one of the pair of electrodes are arranged on a main surface of the piezoelectric layer .   The piezoelectric actuator according to any one of claims 1 to 5, wherein a substrate is bonded via an adhesive layer to the principal surface having a curved corner or the principal surface having a slope. Forming process for producing green sheet mainly composed of piezoelectric ceramic powder;
A coating process for producing a coated body by covering both main surfaces of the green sheet with a protective film;
Using this punching die, a punching step of punching the coated body into a predetermined shape so that the corner on at least one main surface side becomes a curved surface having an arcuate cross section ,
A firing step of removing the protective film from this molded body and firing to produce a sintered body,
The method for manufacturing a piezoelectric actuator according to claim 1, further comprising an electrode forming step of forming a pair of electrodes on both surfaces of the sintered body. A molding process for producing a plurality of green sheets mainly composed of piezoelectric ceramic powder;
An electrode forming step of forming an electrode on one main surface of at least a part of the green sheet;
A laminating step of laminating a plurality of the green sheets including a green sheet on which an electrode is formed to produce a laminate;
A coating step in which both main surfaces of the laminate are coated with a protective film to produce a coated body;
Using this punching die, a punching step of punching the coated body into a predetermined shape so that the corner on at least one main surface side becomes a curved surface having an arcuate cross section ,
The method for producing a piezoelectric actuator according to claim 2, further comprising a firing step of removing the protective film from the formed body and firing to produce a sintered body. The punching die method for manufacturing a piezoelectric actuator according to claim 7 or 8 peripheral portion is a cross Men'en arcuate curved surface in contact with the covering member. A molding process for producing a plurality of green sheets mainly composed of piezoelectric ceramic powder;
An electrode forming step of forming an electrode on one main surface of at least a part of the green sheet;
A laminating step of laminating a plurality of the green sheets including a green sheet on which an electrode is formed to produce a laminate;
A coating step in which one main surface of the laminate is coated with a protective film to produce a coated body;
A molding step of forming this covering body into a predetermined shape to produce a molded body,
A chamfering step of chamfering a corner on the main surface side of the molded body not covered with the protective film,
The method for manufacturing a piezoelectric actuator according to claim 4, further comprising: a firing step of removing a protective film from the chamfered molded body and firing to produce a sintered body. A molding process for producing a plurality of green sheets mainly composed of piezoelectric ceramic powder;
An electrode forming step of forming an electrode on one main surface of at least a part of the green sheet;
A laminating step of laminating a plurality of the green sheets including a green sheet on which an electrode is formed to produce a laminate;
A coating step in which one main surface of the laminate is coated with a protective film to produce a coated body;
A molding step of forming this covering body into a predetermined shape to produce a molded body,
A chamfering step of chamfering the peripheral portion on the main surface side of the molded body that is not covered with the protective film;
The method for producing a piezoelectric actuator according to claim 10, further comprising: a firing step of removing a protective film from the chamfered molded body and firing to produce a sintered body.   The method for producing a piezoelectric actuator according to any one of claims 7 to 11, wherein the protective film is at least one selected from polyethylene terephthalate, polyethylene naphthalate, polyetherimide, and polyphenylene sulfide. Method for manufacturing a piezoelectric actuator according to any one of claims 7-12 planar shape of the molded body is a four square.   The process according to any one of claims 7 to 13, further comprising, as a process subsequent to the baking process, a bonding process of bonding the substrate to the main surface of which the corner portion is processed into a curved surface or a slope via an adhesive layer. Manufacturing method of the piezoelectric actuator.

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