JP2005223354A - Manufacturing method of multilayer piezoelectric body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a multilayer piezoelectric body by which thin layers of not more than 100 μm are formed while reducing in-plane variations in thickness. <P>SOLUTION: This manufacturing method of the multilayer piezoelectric body comprises following processes of: mixing a piezoelectric ceramic powder of not more than 1 μm in average particle diameter and an organic binder component, and then producing slurry for tape formation; forming a green sheet by performing tape formation by using the slurry obtained in the mixing process; pressing the green sheet formed in the forming process; laminating the green sheets to form a laminate article; and baking the laminate article obtained in the lamination process. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to various printers, recorders, facsimiles for printing characters and images by ejecting ink droplets from fine ink ejection holes, or printing apparatuses such as printing machines used for pattern formation in the textile and ceramic industries. The present invention relates to a method for manufacturing a laminated piezoelectric material that is suitably used as an actuator for an inkjet print head or the like to be mounted.

  In recent years, with the penetration of multimedia, non-impact recording devices using inkjet and thermal transfer methods have been developed in place of impact recording devices, and the range of use is expanding in various industrial and general household fields. is there.

  Among such non-impact recording apparatuses, a recording apparatus using an ink-jet system is attracting attention because it is easy to increase the number of gradations and colors and has a low running cost.

  For example, as shown in FIG. 3A, a print head using an ink jet system has a plurality of grooves arranged in parallel as ink flow paths 23a, and a flow path in which partition walls 23b are formed as walls that partition the ink flow paths 23a. An actuator is provided on the member 23.

  That is, an actuator in which a common electrode 25 is formed on one main surface of the piezoelectric layer 24 and a plurality of individual electrodes 26 are formed on the other main surface and a plurality of displacement elements 27 are provided is provided in the flow path member 23. The actuator and the flow path member 23 are bonded so that the individual electrode 26 is disposed immediately above the ink flow path 23a, which is the opening of the ink.

  By applying a voltage between the common electrode 25 and the individual electrode 26 to vibrate the displacement element 27, the ink in the ink flow path 23 a is pressurized, and the ink discharge hole 28 opened on the bottom surface of the flow path member 23. It is structured to eject ink droplets.

  Further, as shown in FIG. 3B, a print head is provided in which a large number of individual electrodes 26 are arranged in parallel on the piezoelectric layer 24 at an equal pitch, and a large number of displacement elements 27 are provided. Thus, it is possible to contribute to speeding up and high accuracy of the ink jet printer.

  However, in recent years, inkjet printers have been pursuing higher speed and higher accuracy. As a result, the displacement element 27, particularly the piezoelectric layer 24, which is directly related to ink ejection, has a thin layer and high-precision piezoelectric characteristics. Specifically, there is a need for a piezoelectric actuator with little variation in characteristics.

By the way, as a means for making the thickness of the ceramic layer and the piezoelectric layer uniform, in order to reduce the thickness variation in drying, the amount of solvent in the slurry for tape forming is reduced to about 1/3 of the conventional one, and Attempts have been made to reduce the variation of a 500 μm thick green sheet by passing the slurry between a plurality of rolls and making it uniform when it is made uniform.
Japanese Patent Laid-Open No. 11-34321 FIG. Japanese Patent Laid-Open No. 2000-2332035

  However, in the method of Patent Document 2 for reducing the amount of solvent, the slurry for tape molding has a high viscosity and the thickness of the tape to be molded is increased, and further, the drying shrinkage is small. There is a problem that only thick-layer tape molding can be performed, and thin-layer tape molding of 50 μm or less, especially several tens of μm level cannot be performed.

  Conversely, if a thin layer tape is to be formed, the amount of solvent in the tape forming slurry must be increased, resulting in a thickness variation in the drying process. There was a problem that it was not possible to form a thin layer tape with a small amount.

  An object of the present invention is to provide a method for producing a laminated piezoelectric material having a thin layer of 100 μm or less with reduced in-plane thickness variation.

  In the present invention, in a multilayer piezoelectric body of 100 μm or less, it is important to suppress the in-plane variation of the thickness of the multilayer piezoelectric body in order to reduce the displacement variation of a plurality of displacement elements provided on the main surface of the ceramic substrate. In order to realize this and to realize it, tape molding is performed using fine raw material powder, and in-plane variation of the overall thickness is reduced by pressurizing the green sheet to reduce the piezoelectric properties. Based on the new knowledge that it can produce excellent multilayer piezoelectric materials, it can produce thin-layer piezoelectric ceramics, and realize high-speed, high-definition, and high-precision printers by using them in the print heads of inkjet printers. It becomes possible to do.

  That is, the method for producing a laminated piezoelectric material of the present invention was obtained by mixing a piezoelectric ceramic powder having an average particle size of 1 μm or less and an organic binder component to produce a tape-forming slurry, and the mixing step. A tape forming slurry is used to form a green sheet by tape forming, a pressure step for pressing the green sheet obtained in the molding step, and a green sheet obtained in the pressure step. It is characterized by comprising a laminating step of laminating the green sheets to obtain a laminated molded body after applying the electrode, and a firing step of firing the laminated molded body obtained in the laminating step.

As a result, the laminated piezoelectric material can be obtained.

  In particular, in the pressurizing step, it is preferable to pressurize using at least one method of a roll pressurization method, a plane pressurization method, and a hydrostatic pressure pressurization method. As a result, more uniform thickness control is possible, and thickness control can be easily performed.

  Moreover, it is preferable that the pressurization pressure in the said pressurization process is 10-100 Mpa. By applying pressure in this pressure range, the thickness variation of the green sheet can be reduced and the thickness can be made uniform, and there is an effect of suppressing composition variation by improving sinterability, further reducing variation variation. Can contribute.

  Furthermore, it is preferable that the pressurization temperature in the said pressurization process is 0-300 degreeC. Thereby, the green sheet thickness can be controlled uniformly, and at the same time, the green density can be homogenized.

  Furthermore, it is preferable that the thickness variation of the green sheet obtained by the said pressurization process is 15% or less. Thereby, it becomes easy to suppress the thickness variation of the laminated molded body obtained in the laminating process to 15% or less, and the in-plane variation of the thickness of the laminated piezoelectric body obtained in the firing process can be made 10% or less. It becomes easy.

  The present invention has made it possible to provide a method for producing a laminated piezoelectric material having a thin layer of 100 μm or less that is capable of high-speed response with little in-plane variation in the thickness of the piezoelectric laminate.

  In particular, a fine raw material powder is used and the green body is pressed to make the thickness uniform, thereby increasing the green density and obtaining a green sheet with a uniform thickness. A laminated piezoelectric body composed of piezoelectric ceramic layers can be manufactured.

  Since the laminated piezoelectric material manufactured by the manufacturing method of the present invention is controlled in each layer and the total thickness and has little variation in thickness, when used in a print head of an inkjet printer, high speed, high definition, and high accuracy can be realized.

  The case where the laminated piezoelectric material manufactured by the manufacturing method of the present invention is used for an actuator employed in an ink jet print head will be described as an example.

  As shown in FIG. 1, the laminated piezoelectric material manufactured by the manufacturing method of the present invention has the piezoelectric layer 4 sandwiched between the common electrode 5 and the individual electrode 6 on the surface of the ceramic substrate 2 on which the ceramic layer 2 a is laminated. The displacement element 7 provided as described above is formed, and the thickness of the entire laminated piezoelectric body is indicated by T, and the thickness of each ceramic layer 2a and the piezoelectric layer 4 is indicated by t.

  The laminated piezoelectric material manufactured by the manufacturing method of the present invention is formed by laminating ceramic layers 2a. For example, the piezoelectric layer 4 and the common electrode 5 are individually provided on the surface of the ceramic substrate 2 composed of four ceramic layers 2a. A plurality of displacement elements 7 composed of electrodes 6 are formed. The thickness t of each piezoelectric layer and piezoelectric layer is determined as appropriate depending on the material characteristics, element dimensions, and the like of the material used.

  Specifically, the thickness of the laminated piezoelectric body, that is, the total thickness T of the actuator is important to be 100 μm or less, particularly 80 μm or less, and more preferably 60 μm or less in order to obtain a large displacement. The reason why the ceramic substrate 2 and the piezoelectric layer 4 are formed as a laminate is that it is easy to incorporate an electric circuit in the laminate piezoelectric body, and each layer of the ceramic layer 2a and the piezoelectric layer 4 constituting the laminate. It is important that the thickness t is 50 μm or less, particularly 35 μm or less, more preferably 20 μm or less. In particular, t is preferably 20 μm or less and T is 60 μm or less in order to obtain excellent characteristics as an actuator.

  The thickness T of the laminated piezoelectric body is preferably as small as possible from the viewpoint of increasing the displacement. However, the lower the thickness T, the lower the mechanical strength and withstand voltage. In order to have mechanical strength that does not break during operation and to withstand the applied voltage, it is preferably 10 μm, particularly 15 μm, and more preferably 20 μm.

  Further, the lower limit value of t needs to have a mechanical strength and a withstand voltage that do not break during handling or operation. Specifically, it is preferably 5 μm, particularly 7 μm. Then, the variation in displacement amount and the variation in thickness of each layer and the whole are further improved, and a laminated piezoelectric material exhibiting stable displacement is obtained by combining t in the range of 5 to 15 μm and T in the range of 20 to 60 μm. Is more desirable because it is possible.

  Further, it is preferable that the displacement elements 7 are formed in large numbers on the surface of the ceramic substrate 2 and are regularly arranged two-dimensionally in order to increase the saturation and accuracy. The plurality of displacement elements 7 are important to have an in-plane thickness variation of 10% or less, particularly 8% or less, and more preferably 6% or less.

  By controlling the in-plane variation of the thickness in this way, it becomes possible to precisely control the ink discharge amount, and as a result, a high-speed, high-definition, high-precision print head and inkjet printer can be realized. .

  Here, the in-plane variation in thickness indicates the total thickness of the piezoelectric layer 4, the electrodes 5, 6 and the ceramic substrate 2 as shown in FIG. It does not say the difference from the part not provided, but compares the parts provided with the individual electrodes 6 and compares the parts not provided with the individual electrodes 6 and is the same in design. This means the thickness distribution.

  Displacement variation means that a predetermined voltage is sequentially applied to all the displacement elements 7 and driven to measure the displacement amount of each displacement element to calculate an average value, and the difference between each measurement data and the average value is the maximum. A value obtained by dividing the maximum difference by the average value is shown as displacement variation. For example, a laser Doppler vibrometer is used to measure the amount of displacement of the displacement element 7 in the laminated piezoelectric body, and the amount of displacement of the displacement element 7 is measured at any 10 locations, and the maximum difference from the average displacement is obtained. It can be evaluated by dividing by the average displacement.

  The piezoelectric layer 4 constituting the displacement element 7 is preferably made of a perovskite crystal structure type material such as a lead zirconate titanate compound, a lead titanate compound, or a barium titanate compound. Among these, a PbZrTiO3 compound (PZT) is particularly preferable in that a large displacement is generated. The piezoelectric layer 4 may be a single layer or a plurality of layers.

  The material of the individual electrode 6 and the common electrode 5 may be any material as long as it has conductivity. For example, Au, Ag, Pd, Pt, Cu, Al, or an alloy thereof can be used. Further, the thickness of the electrode should be such that it has conductivity and does not hinder displacement, and is preferably 0.5 to 5 μm, particularly preferably 1 to 2 μm.

  With such a configuration, in-plane variations in the thickness of the piezoelectric laminate are suppressed, and therefore, the displacement variations of the large number of displacement elements 7 constituting the piezoelectric laminate are each suppressed. As a result, for example, printing as shown in FIG. A print head for forming the head can be manufactured. As a result, it is possible to realize a print head suitable for high-quality inkjet with little discharge unevenness.

  2 has a configuration in which the actuator 11 is provided on a flow path member 13 including an ink flow path 13a including a plurality of grooves and a partition wall 13b for separating the ink flow path 13a. It has become. The actuator 11 is made of a laminated piezoelectric material manufactured by the manufacturing method of the present invention, and a displacement element is arranged such that an individual electrode 16 is disposed directly on an ink flow path 13a on a ceramic substrate 12 on which a ceramic layer 12a is laminated. 17 has a structure arranged.

  Next, the manufacturing method of the laminated piezoelectric material of this invention is demonstrated.

  First, it is important that the average particle size of the piezoelectric ceramic powder is 1 μm or less, particularly 0.7 μm or less, more preferably 0.5 μm or less. By setting the average particle size to 1 μm or less, the activity during sintering can be increased, and as a result, the sintering temperature can be reduced. In particular, in the case of piezoelectric ceramics containing lead, when the sintering temperature is lowered, lead evaporates, reducing the in-plane variation of the composition and reducing the displacement variation of the displacement element.

  Such a raw material powder and an organic binder component are mixed to produce a tape-forming slurry (mixing step). Next, a green sheet is produced by a general tape forming method such as a roll coater method, a slit coater method, a doctor blade method, etc., using the tape forming slurry obtained in the mixing step (forming step).

  Next, it is important to pressurize the green sheet obtained in the molding process (pressurizing process). A publicly known method can be adopted as the pressurizing method, but a roll pressurizing method, a plane pressurizing method, a hydrostatic pressurizing method, etc. can be particularly used for pressurization because it is easy to obtain a uniform thickness. Thus, the thickness variation of a tape can be reduced by performing the pressurization process of a green sheet after tape shaping | molding. This is because the tape after drying has voids from which the slurry solvent is removed, and the thickness of the tape varies due to the size of the voids. By crushing this gap by pressurization, the tape becomes homogeneous and the variation in thickness is reduced.

  The pressure to be applied varies depending on the material composition, the amount of the organic binder, the thickness of the green sheet, and the like. Further, it is preferable to pressurize at a pressure of 30 to 40 MPa.

  If the temperature at the time of pressurization is too high, deformation due to pressurization may become excessively large. In order to cause the binder to exhibit an appropriate viscosity and to remove pores, depending on the binder used, 300 It is preferable that the temperature is not higher than ° C, particularly not higher than 250 ° C, more preferably not higher than 200 ° C, and more preferably not higher than 150 ° C. Moreover, a lower limit is 0 degreeC, especially 20 degreeC, Furthermore, 35 degreeC, More preferably, it is 50 degreeC.

  Note that the surface of the mold to be pressed may be subjected to a surface treatment for improving releasability, or may be pressed by disposing a release sheet on the tape surface. Furthermore, a pressure-regulating mechanism for making the in-plane applied pressure uniform can be used as appropriate.

  Such pressure treatment has the effect of removing pores, but also has the effect of increasing the green density, and can increase the contact area between the ceramic particles, resulting in improved sintering speed and fine particles. In combination with this, the sintering temperature can be lowered. In particular, for piezoelectric ceramics containing lead, evaporation of lead during sintering can be suppressed, compositional variation can be suppressed, and as a result, displacement variation can also be suppressed.

  When the thickness variation of each green sheet obtained by the pressurizing step is 15% or less, particularly 10% or less, it is easy to reduce the thickness variation of the laminate and to reduce the thickness variation of the sintered body. Become.

  Next, an electrode is formed on a part of the green sheet obtained in the pressing step. That is, the common electrode and the individual electrode are formed by a known method such as a printing method. In addition, via holes and via conductors are formed to communicate between the electrodes as desired.

  The obtained green sheets (with electrodes, with via holes, without electrodes, etc.) are laminated in a desired configuration and brought into close contact to obtain a laminated molded body (lamination step). In addition, as a method of performing adhesion, there are a method using an adhesion liquid containing an adhesive component, a method of adhering to the organic binder component in the green sheet by heating, a method of adhering only by applying pressure, and the like. It can be illustrated.

  The laminated molded body obtained in the laminating step is subjected to degreasing treatment to remove organic components in the laminated molded body, if desired, and then fired in an oxygen atmosphere or the like to obtain a laminated piezoelectric body (firing step).

  In addition, as a method of removing an organic component, the method of heat-processing with the temperature pattern according to the thermal decomposition behavior of the organic component to remove is employ | adopted. The firing atmosphere is preferably an oxygen concentration of 80% or more, particularly 90% or more. By increasing the oxygen concentration in this way, especially when firing piezoelectric ceramics containing lead, increasing the concentration of oxygen, which is a soluble gas, increases the oxygen partial pressure and suppresses the decomposition and gasification of lead. At the same time, since the pore internal pressure is lowered, the pores contract and void formation is suppressed.

  By adopting the manufacturing method including such a process, composition variation is suppressed and pores can be reduced. Therefore, from a thin layer sintered body having a thickness of 100 μm or less with reduced in-plane displacement variation. The laminated piezoelectric material can be provided and can be suitably used as a print head for an ink jet printer.

  First, a mixing step in which a lead zirconate titanate powder having a particle size (D50: average particle size of powder) shown in Table 1 is prepared as a piezoelectric ceramic powder, and an aqueous acrylic solution is mixed with the powder to produce a slurry. Carried out.

  Using the slurry obtained in the mixing step, a green sheet was formed by a roll coater method so as to have a thickness of 20 μm (forming step).

  Next, the green sheet obtained in the molding step was pressed under the pressurization conditions shown in Table 1 by a roll pressurization method, a plane pressurization method, or a hydrostatic pressurization method (pressurization step).

  After forming a common electrode and an individual electrode having a thickness of 5 μm on the green sheet by a printing method using an Ag—Pd electrode paste with an Ag: Pd of 70:30 on the green sheet obtained in the pressing step, A green sheet on which individual electrodes are formed is laminated on the upper layer, and a green sheet on which a common electrode is formed is laminated on the lower layer, laminated so as to have the structure shown in FIG. The resulting lamination process was performed.

  Finally, the resulting laminated molded body was degreased at 450 ° C. for 5 hours in the air, and then fired for 2 hours at the temperature and atmosphere shown in Table 1 to obtain a laminated piezoelectric body (firing step). .

  From the photograph which observed the cross section of the obtained laminated piezoelectric material with the scanning electron microscope (SEM), the thickness of each layer and the thickness of the whole laminated molded object were measured. Then, in order to examine the in-plane distribution of the multilayer molded body with respect to the thickness of the entire multilayer molded body, the thickness was measured at any 20 locations in the plane of the multilayer piezoelectric body, and the variation was measured. The variation is calculated as an average thickness value at 20 locations, calculated as a difference from the average value of the maximum value or the minimum value, and the larger one is shown in Table 1 as the variation.

The d31 of the actuator was measured at 10 locations by a resonance method using an impedance analyzer, the average value was calculated, and the maximum value of the difference between each value and the average value was divided by the average value to obtain d31 variation. The results are shown in Table 1.

  Sample No. of the present invention. In 1-4, 6, 7, and 9-33, the thickness variation of the entire actuator was 8% or less, and the d constant variation was 10% or less.

  On the other hand, since the raw material particle size is as large as 1.5 μm, the variation in the thickness T of the actuator is as large as 12%. No. 5 had a d constant variation of 15%.

  In addition, since the pressurizing step is not included, the sample No. 5 outside the scope of the present invention has a large variation in the actuator thickness T of 14%. No. 8 had a d constant variation of 19%.

  Furthermore, the thickness of the entire actuator is as large as 150 μm, and sample No. No. 34 had an overall thickness variation of 5%, but the d constant was as small as 199 pm / V, and the variation of the d constant was 11%.

It is a schematic sectional drawing which shows the laminated piezoelectric material produced by the manufacturing method of this invention. It is a schematic sectional drawing which shows the structure of the inkjet print head which employ | adopted the laminated piezoelectric material produced by the manufacturing method of this invention. The laminated piezoelectric material produced by the conventional manufacturing method is shown, (a) is a schematic sectional drawing, (b) is a schematic plan view.

Explanation of symbols

2, 12 ... Ceramic substrates 2a, 12a ... Ceramic layers 4, 14 ... Piezoelectric layers 5, 15 ... Common electrodes 6, 16 ... Individual electrodes 7, 17 ... Displacement element 11 ..Actuator 18 ... Ink ejection hole T ... Total thickness t of laminated piezoelectric material t ... Thickness of ceramic layer and piezoelectric layer

Claims (5)

A tape forming is performed using a mixing step of mixing a piezoelectric ceramic powder having an average particle size of 1 μm or less and an organic binder component to produce a tape forming slurry, and a tape forming slurry obtained in the mixing step. A green sheet forming step, a pressurizing step for pressing the green sheet obtained in the forming step, an electrode is applied to the green sheet obtained in the pressurizing step, and then the green sheet is laminated. A method for producing a laminated piezoelectric body comprising: a lamination step for obtaining a laminated molded body; and a firing step for firing the laminated molded body obtained in the lamination step. 2. The method of manufacturing a multilayer piezoelectric body according to claim 1, wherein in the pressing step, the pressing is performed by using at least one method of a roll pressing method, a plane pressing method, and a hydrostatic pressing method. The method for producing a laminated piezoelectric material according to claim 1 or 2, wherein the pressurizing pressure in the pressurizing step is 10 to 100 MPa. The method for producing a laminated piezoelectric material according to any one of claims 1 to 3, wherein a pressurizing temperature in the pressurizing step is 0 to 300 ° C. The method for manufacturing a multilayer piezoelectric body according to any one of claims 1 to 4, wherein the thickness variation of the green sheet obtained in the pressing step is 15% or less.

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