JP4155466B2 - Evaluation method of piezoelectric ceramic sintered body, evaluation method of multilayer piezoelectric ceramic element, and evaluation apparatus for multilayer piezoelectric ceramic element - Google Patents

Description

  The present invention relates to a method for evaluating a ceramic sintered body, and more particularly to a method and apparatus suitable for evaluating a displacement amount of a laminated piezoelectric ceramic element.

  2. Description of the Related Art Conventionally, piezoelectric elements have been used as driving sources for various devices by utilizing the characteristic that electrical energy can be converted into mechanical energy by the inverse piezoelectric effect. A general piezoelectric element has a structure in which a conductive paste is printed and fired on both sides of a piezoelectric ceramic layer such as lead zirconate titanate (PZT) to form an electrode layer. However, since the amount of displacement obtained by one piezoelectric ceramic layer is small, when a large amount of displacement is desired, the amount of displacement is increased by stacking the piezoelectric ceramic layers. This is a multilayer piezoelectric ceramic element.

It is necessary to evaluate whether such a multilayer piezoelectric ceramic element can obtain a desired amount of displacement. As such evaluation methods, methods disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2003-39657) and Patent Document 2 (Japanese Patent Laid-Open No. 2004-296785) are known.
In Patent Document 1, for example, for a piezoelectric actuator used in a print head, a plurality of displacement elements are bonded to a support substrate, and the electrode portion of the laminated piezoelectric element and the wiring pattern of the support substrate are electrically connected with a conductive adhesive or the like. A fixed voltage is applied to each piezoelectric element, and the displacement amount of each displacement element is measured.
In the evaluation method described in Patent Document 1, since the piezoelectric actuator is determined to be defective after the piezoelectric actuator is bonded to the support member, the number of manufacturing steps increases, and when a defect occurs, the support member and the support member are bonded. The process was wasted, which was a major factor in increasing costs. Therefore, Patent Document 2 provides a piezoelectric actuator evaluation method and a measurement apparatus that can perform accurate measurement with a simple method without being bonded to a support member. In Patent Document 2, a piezoelectric actuator having a plurality of displacement elements provided on a vibration plate is placed on a holding plate having a plurality of through holes or grooves, and the outer peripheral portions of the displacement elements are individually restrained. The displacement amount generated by applying a constant voltage to the displacement element later is measured.

JP 2003-39657 A JP 2004-296785 A

Compared to the evaluation method disclosed in Patent Document 1, the evaluation method disclosed in Patent Document 2 can easily evaluate the amount of displacement. However, even in Patent Document 2, a predetermined voltage is applied after the final product shape is formed, and the amount of displacement generated is measured. That is, in the conventional evaluation method, since the displacement amount can be evaluated only after all the manufacturing processes are finished and processed, each process performed so far may be wasted.
Therefore, an object of the present invention is to provide an evaluation method capable of evaluating the displacement amount of a laminated piezoelectric ceramic element without applying a predetermined voltage. It is another object of the present invention to provide an evaluation apparatus that can evaluate the amount of displacement of a laminated piezoelectric ceramic element without applying a predetermined voltage.

  By the way, the firing temperature of lead zirconate titanate or the like for obtaining the piezoelectric ceramic layer is as high as 1100 to 1200 ° C. Therefore, the material constituting the electrode layer must be able to withstand this high firing temperature. Therefore, noble metal materials such as Ag / Pt and Ag / Pd have been used as conductive materials used for electrode layers. However, this expensive electrode layer has been a factor in increasing the manufacturing cost of the multilayer piezoelectric ceramic element. However, in recent years, piezoelectric ceramic materials have been fired at a low temperature, and accordingly, it is possible to use a base metal material such as Cu as a conductive material of an electrode layer, and reduction in manufacturing cost can be achieved (for example, Patent Document 3). (Special Table 2003-529917).

Special table 2003-529917 gazette

  A base metal material such as Cu is oxidized when fired in the air, and does not function as an electrode. Therefore, when an electrode layer is formed using a base metal material such as Cu, firing in a reducing atmosphere is required. Heating in a reducing atmosphere is performed not only in the firing step but also in the binder removal step. As is well known, this binder removal step is performed for the purpose of removing the organic binder added together with the ceramic powder in order to constitute the compact. However, binder removal in a reducing atmosphere cannot sufficiently remove the binder. Therefore, the binder remains in the molded body as C (carbon). C remaining in the formed body reduces PbO, which is a raw material of lead zirconate titanate (PZT), in the reducing atmosphere of the firing step to produce metallic lead (Pb). This metallic lead (Pb) reacts with Cu constituting the electrode layer, thereby causing a displacement amount defect in the multilayer piezoelectric ceramic element. What is necessary is just to measure the amount of carbon (residual carbon amount) remaining in the molded body after binder removal or the sintered body after firing. Can not. Therefore, after removing the binder or after firing, the molded body or sintered body was irradiated with predetermined light, and the relationship between the reflectance and the displacement amount as the multilayer piezoelectric ceramic element was investigated. The amount was found to correlate.

The present invention is based on the above knowledge, and the piezoelectric ceramic sintered body obtained by firing after removing the binder from the molded body containing the ceramic particles and the organic binder is subjected to a predetermined amount of displacement. a whether the evaluation methods and a step of irradiating light to the molded body or a piezoelectric ceramic sinter the binder removal process is performed, the reflectance of irradiated light in the molded body or a piezoelectric ceramics sintered body And a step of comparing a predetermined reference reflectance with the measured reflectance of the formed body or the piezoelectric ceramic sintered body, and a method for evaluating the piezoelectric ceramic sintered body comprising: It is. The reference reflectance may be determined based on the piezoelectric ceramics sintered body to have a predetermined displacement amount.

The above evaluation method can be applied to a laminated piezoelectric ceramic element. That is, the present invention is a method for evaluating whether or not a laminated piezoelectric ceramic element obtained by firing a laminated body in which a piezoelectric ceramic layer precursor and an internal electrode precursor are laminated has a predetermined displacement amount , A step of irradiating the laminated body or laminated piezoelectric ceramic element from which the organic binder contained in the internal electrode precursor has been removed is irradiated with inspection light, and the reflected light of the inspection light from the laminated body or laminated piezoelectric ceramic element is observed. A method for evaluating a laminated piezoelectric ceramic element, wherein the observation of the reflected light of the inspection light comprises comparing the reflectance of the reflected light with a predetermined reference reflectance To do.

  As described above, there is a problem of residual carbon from the organic binder when the internal electrode is Cu. Therefore, when the conductive material of the internal electrode precursor is Cu, the evaluation method of the multilayer piezoelectric ceramic element of the present invention is as follows. It is particularly meaningful. When the internal electrode is Cu, the organic binder is removed and / or baked in a reducing atmosphere.

For observing the reflected light, in addition to the reflectance, chromaticity, luminance, glossiness, and the like can be used, but it is preferable to measure the reflectance of the inspection light.
Further, the present invention can evaluate whether or not the multilayer piezoelectric ceramic element has a predetermined amount of displacement, but may be used as an index for evaluating other characteristics such as porcelain density, dielectric constant, and driving reliability. it can.

The present invention provides an apparatus for carrying out the above-described method for evaluating a laminated piezoelectric ceramic element. This apparatus is an evaluation apparatus for a laminated piezoelectric ceramic element obtained by firing a laminated body in which a piezoelectric ceramic layer precursor and an internal electrode precursor are laminated, and is used as a piezoelectric ceramic layer precursor and an internal electrode precursor. A light source for irradiating inspection light to the laminated body or laminated piezoelectric ceramic element from which the organic binder contained is removed, a light receiving element for receiving reflected light from the laminated body or laminated piezoelectric ceramic element, and reflection for the inspection light Measuring means for obtaining the reflectance of light, and evaluation means for evaluating the amount of displacement of the multilayer piezoelectric ceramic element by comparing the reflectance with a predetermined reference reflectance .

  It is preferable to provide a selection means for selecting the laminated body or the laminated piezoelectric ceramic element based on the evaluation result by the evaluation means. The laminated body or the laminated piezoelectric ceramic element having a poor evaluation result is not subjected to subsequent steps, and waste in the manufacturing process can be eliminated.

  According to the present invention, it is possible to evaluate the displacement amount of the laminated piezoelectric ceramic element without applying a predetermined voltage. Further, according to the present invention, it is possible to provide an evaluation apparatus that can evaluate the displacement amount of the multilayer piezoelectric ceramic element without applying a predetermined voltage.

Hereinafter, the present invention will be described in detail based on embodiments.
FIG. 4 is a cross-sectional view illustrating a configuration example of the multilayer piezoelectric ceramic element 1 which is an evaluation object of the present invention. 4 is merely an example, and it is needless to say that the evaluation object of the present invention is not limited to the multilayer piezoelectric ceramic element 1 of FIG. The multilayer piezoelectric ceramic element 1 includes a multilayer body 10 in which a plurality of piezoelectric ceramic layers 11 and a plurality of internal electrodes 12 are alternately stacked. The thickness per layer of the piezoelectric ceramic layer 11 is preferably about 1 to 100 μm, for example, but the thickness of the piezoelectric ceramic layers 11 (11a, 11c) at the upper and lower ends is thicker than the piezoelectric ceramic layer 11 sandwiched between the internal electrodes 12. May form. Further, the number of stacked piezoelectric ceramic layers 11 is determined according to a target displacement amount.

  The piezoelectric ceramic constituting the piezoelectric ceramic layer 11 is not particularly limited. However, since the present invention is premised on firing at a low temperature of, for example, 1080 ° C. or lower, it is desirable that the piezoelectric ceramic can be fired at such a low temperature. In the present invention, piezoelectric ceramics that can be fired at a low temperature can be widely applied.

  The internal electrode 12 contains a conductive material. In the present invention, a base metal such as Cu, Ni, or a Cu—Ni alloy or an alloy thereof can be used as the conductive material. Since the multilayer piezoelectric ceramic element 1 according to the present invention is premised on firing at a low temperature of, for example, 1080 ° C. or lower, these low melting point conductive materials can be used.

The internal electrodes 12 are alternately extended in the opposite direction, and a pair of terminal electrodes 21 and 22 electrically connected to the internal electrode 12 are provided in the extending direction. The terminal electrodes 21 and 22 are electrically connected to an external power source (not shown) via a lead wire (not shown), for example.
Moreover, the terminal electrodes 21 and 22 may be formed by sputtering metals, such as Au, Ag, and Cu, for example, and may be formed by baking the paste for terminal electrodes. The terminal electrode paste contains, for example, a conductive material, glass frit, and a vehicle, and the conductive material contains at least one selected from the group consisting of, for example, Au, Ag, Cu, Ni, Pd, and Pt. Those are preferred. Although the thickness of the terminal electrodes 21 and 22 is suitably determined according to a use etc., it is 10-50 micrometers normally.

  Next, a preferred manufacturing method of the multilayer piezoelectric ceramic element 1 will be described with reference to FIG. 5, and an evaluation method that is a feature of the present invention will be mentioned. FIG. 5 is a flowchart showing a manufacturing process of the multilayer piezoelectric ceramic element 1.

First, as a main component starting material, for example, an oxide such as PbO powder, ZrO ₂ powder, TiO ₂ powder, etc. is prepared and weighed (step S101). As a starting material, not an oxide but a material that becomes an oxide by firing, such as carbonate or oxalate, may be used. As these raw material powders, those having an average particle diameter of about 0.5 to 10 μm are usually used.

If necessary, starting materials for subcomponents are prepared and weighed (step S101). As a starting material for the auxiliary component, oxides such as Ta ₂ O ₅ powder, Sb ₂ O ₃ powder, NiO powder, CoO powder, Fe ₂ O ₃ powder, and CuO powder can be used. However, instead of an oxide, a material that becomes an oxide by firing, such as carbonate or oxalate, may be used. These subcomponents have the effect of improving the sinterability and lowering the firing temperature.

Subsequently, the starting materials of the main component and the subcomponent are wet pulverized and mixed using, for example, a ball mill to form a raw material mixture (step S102).
In addition, although the starting material of a subcomponent may be added before temporary baking (step S103) mentioned later, you may make it add after temporary baking. However, it is preferable to add it before calcination because a more uniform piezoelectric ceramic can be produced. When added after calcination, it is preferable to use an oxide as a starting material for the auxiliary component.

Next, the raw material mixture is dried and, for example, pre-baked at a temperature of 750 to 950 ° C. for 1 to 6 hours (step S103). This calcination may be performed in the air, or may be performed in an atmosphere having a higher oxygen partial pressure or in a pure oxygen atmosphere than in the air. After calcination, for example, the calcination product is wet pulverized and mixed in a ball mill to obtain a calcination powder containing a main component and, if necessary, subcomponents (step S104).
Next, an organic binder is added to the temporarily fired powder to produce a piezoelectric ceramic layer paste (step S105). Specifically, it is as follows. First, a slurry is obtained by wet pulverization using, for example, a ball mill. At this time, water or an alcohol such as ethanol, or a mixed solvent of water and ethanol can be used as a solvent for the slurry. The wet pulverization is preferably performed until the average particle size of the calcined powder becomes about 0.5 to 2.0 μm.

  The resulting slurry is then dispersed in an organic vehicle. The organic vehicle is obtained by dissolving an organic binder in an organic solvent, and the organic binder used in the organic vehicle is not particularly limited, and may be appropriately selected from ordinary various binders such as ethyl cellulose, polyvinyl butyral, and acrylic. . Also, the organic solvent used at this time is not particularly limited, and may be appropriately selected from organic solvents such as terpineol, butyl carbitol, acetone, toluene, MEK (methyl ethyl ketone), and terpineol depending on the method used, such as a printing method and a sheet forming method. Just choose.

  When the piezoelectric ceramic layer paste is used as a water-based paint, a water-based vehicle in which a water-soluble binder, a dispersant, or the like is dissolved in water and a pre-fired powder may be kneaded. The water-soluble binder used for the water-based vehicle is not particularly limited, and for example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, or the like may be used.

Also, an internal electrode layer paste is prepared (step S106). The internal electrode layer paste is prepared by kneading the various conductive materials described above or various oxides, organometallic compounds, resinates, and the like, which become the conductive materials described above after firing, and the above-described organic vehicle.
Further, the terminal electrode paste is prepared in the same manner as the internal electrode layer paste (step S107).
In the above, the piezoelectric ceramic layer paste, the internal electrode layer paste, and the terminal electrode paste are produced in order, but it goes without saying that they may be produced in parallel or in the reverse order.

  The content of the organic vehicle in each paste is not particularly limited, and may be a normal content, for example, about 5 to 10% by weight for the binder and about 10 to 50% by weight for the solvent. Each paste may contain an additive selected from various dispersants, plasticizers, dielectrics, insulators and the like as necessary.

Next, a green chip (laminated body) to be fired is manufactured using the above paste (step S108).
When producing a green chip using a printing method, a piezoelectric ceramic layer paste is printed a plurality of times on a substrate such as polyethylene terephthalate with a predetermined thickness, and as shown in FIG. 11a is formed. Next, the internal electrode layer paste is printed in a predetermined pattern on the green outer piezoelectric ceramic layer 11a to form a green internal electrode layer (internal electrode layer precursor) 12a. Next, a piezoelectric ceramic layer paste (piezoelectric ceramic layer precursor) 11b is formed on the internal electrode layer 12a in the green state by printing the piezoelectric ceramic layer paste at a predetermined thickness a plurality of times in the same manner as described above. To do. Next, the internal electrode layer paste is printed in a predetermined pattern on the green piezoelectric ceramic layer 11b to form the green internal electrode layer 12b. The internal electrode layers 12a, 12b,... In the green state are formed so as to be opposed to each other and exposed at different end surfaces. The above operation is repeated a predetermined number of times, and finally, the piezoelectric ceramic layer paste is printed a plurality of times at a predetermined thickness on the green internal electrode 12 to form the green external piezoelectric ceramic layer 11c. To do. Then, it pressurizes and pressure-bonds, heating, cut | disconnects to a predetermined shape, and is set as a green chip (laminated body).
In the above, an example in which a green chip is manufactured by a printing method has been described. However, a green chip can also be manufactured by using a sheet forming method.

Next, the binder removal process is performed on the green chip (step S109).
In the binder removal treatment, it is necessary to consider the oxidation of the conductive material in the internal electrode layer precursor, and heating in a reducing atmosphere should be employed. The binder removal treatment is preferably performed in a temperature range of 300 to 650 ° C. If the temperature of the binder removal process is less than 300 ° C., the binder removal cannot be performed smoothly, and if it exceeds 650 ° C., the effect of the binder removal corresponding to the temperature cannot be obtained, resulting in wasted energy. The binder removal time needs to be determined depending on the temperature and atmosphere, but can be selected in the range of 0.5 to 50 hours. Further, the binder removal treatment can be performed independently of the firing and can be performed continuously with the firing. In the case where the firing is continuously performed, the binder removal process may be performed in the firing temperature increasing process. Note that carbon (C) derived from the organic binder remains on the green chip due to the binder removal treatment in a reducing atmosphere.

  After the binder removal processing, displacement amount evaluation (step S110) is performed. This displacement amount evaluation can be performed by irradiating a predetermined region of the green chip (laminated body) with inspection light and measuring the reflectance. The reflectance may be measured according to JIS Z 8722 (color measurement method—reflectance and transmissive object color), and the reflectance of the present invention is a value based on JIS Z 8722. For example, a halogen lamp can be used as a light source used for measuring the reflectance, and a photodiode can be used as a light receiving element for reflected light. When measuring the reflectance, irradiate the inspection light from a direction perpendicular to the region (surface) to which the inspection light is irradiated and receive the reflected light in a direction of 45 ° with respect to the region (surface). Good. The reflectance measurement is not limited to the above, and it is also possible to collect the reflected light with an integrating sphere by a method based on JIS.

  In the evaluation of the displacement amount by measuring the reflectance, a reference reflectance is obtained in advance, and this reference reflectance is compared with the measured reflectance. For the reference reflectance, the multilayer piezoelectric ceramic element 1 having a predetermined amount of displacement is measured at the stage after the binder removal, and is used as the reference reflectance. For example, the reference reflectance after debinding can be set to 40%, and when the measured reflectance is 40% or more, it can be evaluated that a predetermined amount of displacement can be obtained. Here, the amount of displacement of the multilayer piezoelectric ceramic element 1 is evaluated, but it is also possible to evaluate characteristics other than the amount of displacement by comparing the measured reflectance with the reference reflectance. Characteristics that may be deteriorated due to residual C include porcelain density, dielectric constant, drive reliability, and the like, and these characteristics can be evaluated. However, it goes without saying that specific reference reflectances may be different from each other.

  Baking (step S111) is performed after the displacement amount evaluation. Firing is performed in a reducing atmosphere. This is for preventing or suppressing oxidation of base metal such as Cu used for the internal electrode 12. If the firing temperature is less than 800 ° C., a dense sintered body cannot be obtained, and if it exceeds 1080 ° C., there is a concern about melting of the conductive material constituting the internal electrode 12, so the firing temperature is in the range of 800 to 1080 ° C. It is preferable to select.

  After firing, displacement amount evaluation (step S112) is performed. This displacement amount evaluation can be performed by irradiating a predetermined region of the multilayer piezoelectric ceramic element 1 with inspection light and measuring the reflectance. The measurement of the reflectance and the evaluation of the displacement amount based thereon can be the same as the displacement amount evaluation after the binder removal. However, the reference reflectance is different from that for the laminated body (green chip) after the binder removal. As shown in the examples to be described later, the reference reflectance of the multilayer piezoelectric ceramic element 1 can be 24%, and a predetermined displacement can be obtained if the measured reflectance is 24% or less. Can be evaluated.

The laminated body 10 manufactured through the above steps is subjected to end face polishing, for example, by barrel polishing or sand blasting, and the terminal electrodes 21 and 22 are formed by printing or baking the terminal electrode paste described above (step S113). In addition to printing or baking, the terminal electrodes 21 and 22 can also be formed by sputtering.
As described above, the multilayer piezoelectric ceramic element 1 shown in FIG. 4 is obtained. In the above, the displacement amount evaluation is performed twice after the binder removal and after the firing, but one of them can be omitted. That is, the evaluation of the displacement amount in this embodiment may be performed only after the binder removal, or may be performed only after firing. The evaluation of the displacement amount in this embodiment may be performed after the binder removal and after the firing.

Next, a configuration example of a device that performs displacement amount evaluation will be described with reference to FIG.
FIG. 6 is a block diagram showing a configuration of the displacement amount evaluation apparatus 100. The displacement amount evaluation apparatus 100 is provided along the first conveyance path 106 that conveys the green chip (laminated body) 105 from which the binder has been removed. In addition, the 1st conveyance path 106 shall convey the green chip (laminated body) 105 evaluated as a good product in the direction perpendicular | vertical to a paper surface. A second transport path 107 is disposed in parallel with the first transport path 106. The second conveyance path 107 conveys the green chip (laminated body) 105 evaluated as a defective product.

The displacement amount evaluation apparatus 100 includes a light source 101 that irradiates a green chip (laminated body) 105 with inspection light. The light source 101 is not particularly limited, and a known light source such as a halogen lamp can be used. The light emitted from the light source 101 is reflected from the green chip (laminated body) 105. The displacement amount evaluation apparatus 100 includes a light receiving element 102 that receives the reflected light. As the light receiving element 102, a known element such as a photodiode can be used.
The displacement amount evaluation apparatus 100 includes an actuator 104. The actuator 104 transfers green chips (laminated bodies) 105 evaluated as defective products from the first transport path 106 to the second transport path 107 and selects them. .

The displacement amount evaluation apparatus 100 includes a controller 103. The controller 103 has the following functions.
(1) Control of the light source 101 The controller 103 irradiates the inspection light from the light source 101 when the green chip (laminated body) 105 is conveyed to a predetermined position. Whether or not the green chip (laminated body) 105 has been transported to a predetermined position can be determined based on information from the sensor provided separately. Further, it can be determined whether or not the green chip (laminated body) 105 has been transported to a predetermined position in terms of time.
(2) Calculation of reflectance The controller 103 calculates the reflectance based on the reflected light received by the light receiving element 102 and the inspection light from the light source 101. That is, the controller 103 can obtain the reflectance (C2 / C1) from the light quantity (C1) of the inspection light and the light quantity (C2) of the reflected light.
(3) Evaluation of Displacement The controller 103 has information on the reference reflectance (R1), and compares the calculated reflectance (R2) with the reference reflectance (R1). When the calculated reflectance (R2) is equal to or higher than the reference reflectance (R1), the controller 103 evaluates the green chip (laminated body) 105 as a non-defective product. The controller 103 determines that the calculated reflectivity (R2) is less than the reference reflectivity (R1) after degreasing after degreasing and is equal to or higher than the reference reflectivity (R1) after firing after firing. In some cases, the green chip (laminated body) 105 is evaluated as a defective product.

(4) Operation Control of Actuator 104 The controller 103 controls the operation of the actuator 104 based on the displacement amount evaluation result. That is, when the green chip (laminated body) 105 is evaluated as a non-defective product, the controller 103 does not operate the actuator 104. Therefore, the green chip (laminated body) 105 is transported to the next process through the first transport path 106. When the green chip (laminated body) 105 is evaluated as a defective product, the controller 103 moves the actuator 104 to extend and contract to transfer the green chip (laminated body) 105 to the second transport path 107. The green chip (laminated body) 105 transported in the second transport path 107 is discarded.

In the displacement amount evaluation apparatus 100 described above, the actuator 104 is used as the sorting means for the green chip (laminated body) 105, but the use of other sorting means is not excluded.
Moreover, in the displacement amount evaluation apparatus 100 described above, the displacement amount is evaluated based on the reflectance of light, but other evaluation criteria using reflected light can also be applied. For example, the displacement amount can be evaluated based on chromaticity such as whiteness. In accordance with the international standard, the whiteness scale is set to 100 for the whiteness of the surface on which white smoke (magnesium oxide fine powder) produced by the burning of the magnesium ribbon is adhered, and to 0 for the dark body without incident light. Is divided into 100 equal parts. In addition to chromaticity, by observing reflected light as shown in L ^* a ^* b ^* color system chromaticity diagram (hue and saturation) based on JIS Z 8730 (color difference display method), laminated piezoelectric ceramics The displacement amount of the element 1 can also be evaluated.

Hereinafter, the present invention will be described based on specific examples.
<Sample preparation method>
PZT ceramic powder prepared in advance (composition: PbTiO ₃ ; 40 mol%, PbZrO ₃ ; 45 mol%, Pb (Zn _1/3 Nb _2/3 ) O ₃ ; 15 mol%, specific surface area: 2.0 m ² / A binder, a solvent and the like were mixed with g) to make a slurry, and a green sheet was formed by a doctor blade method. On this green sheet, the electrode paste composition containing Cu particles was screen printed using SUS400 mesh and dried at 100 ° C. for 10 minutes. Next, green sheets on which electrode paste was printed and green sheets on which electrode paste was not printed were alternately stacked. At this time, the electrode paste coating layers were stacked so as to alternately protrude toward the symmetrical side, and the PZT ceramic layers sandwiched between the electrode paste layers were stacked so as to be 100 layers. After processing this laminated body with a hot press, it was cut into a predetermined shape and debindered in a reducing atmosphere.

The binder removal was performed under the following four conditions.
Experimental Example 1: Holding at 550 ° C. for 20 hours in a reducing atmosphere with a water vapor amount of 15.5 mol% and a hydrogen concentration of 1 ppm Experimental Example 2: Holding at 550 ° C. for 10 hours in a reducing atmosphere with a water vapor amount of 15.5 mol% and a hydrogen concentration of 1 ppm Experimental Example 3: Holding at 550 ° C. for 20 hours in a reducing atmosphere with a water vapor amount of 15.5 mol% and a hydrogen concentration of 1 ppm Experimental Example 4: Holding at 550 ° C. for 15 hours in a reducing atmosphere with a water vapor amount of 15.5 mol% and a hydrogen concentration of 1 ppm

  After the binder removal, the residual carbon (ppm) of the laminate was measured and the reflectance was measured. The results are shown in Table 1. The measuring method is as follows.

  The debindered laminate was heated to 950 ° C. at a rate of 5 ° C./min, and baked by maintaining the temperature for 8 hours. The firing atmosphere was controlled to an atmosphere in which Cu in the internal electrode layer was not oxidized and PZT ceramics were not reduced. The reflectance was measured in the same manner as after binder removal after firing. Moreover, the displacement amount was measured using the obtained multilayer piezoelectric ceramic element. The results are shown in Table 1. In addition, the measuring method of displacement amount is shown below. FIG. 1 shows the relationship between the amount of residual carbon in the molded body and the displacement amount of the laminated piezoelectric ceramic element, and FIG. 2 shows the light reflectance with respect to the molded body after debinding and the displacement amount of the laminated piezoelectric ceramic element. FIG. 3 shows the relationship between the reflectance of light with respect to the sintered body after firing and the amount of displacement of the multilayer piezoelectric ceramic element.

As shown in Table 1 and FIG. 1, when the amount of residual carbon in the molded body after binder removal increases, the amount of displacement tends to decrease. However, as in Experimental Example 4, even when the residual carbon is about 350 ppm, a desired displacement amount of 8 μm may be obtained. This indicates that the amount of displacement cannot be evaluated only by the amount of residual carbon in the molded body after the binder removal.
As shown in Table 1 and FIG. 2, it can be seen that there is a correlation between the reflectance of light and the amount of displacement with respect to the molded body after the binder removal. From the results shown in Table 1 and FIG. 2, in the present invention, when the reflectance of the molded body after the binder removal is 40% or more, the multilayer piezoelectric ceramic element can be evaluated as a non-defective product with respect to the displacement. Further, as shown in Table 1 and FIG. 3, it can be seen that there is a correlation between the reflectance of light and the amount of displacement with respect to the sintered body after firing. From the results shown in Table 1 and FIG. 3, in the present invention, when the reflectance of the sintered body is 24% or less, the multilayer piezoelectric ceramic element can be evaluated as a good product with respect to the displacement.

<Reflectance measurement method>
JIS Z 8722 compliant Optical conditions: Vertical illumination-45 ° direction light reception (irradiated on the external terminal electrode surface of the laminated piezoelectric ceramic element)
Light source: Halogen lamp Light receiving element: Photo diode

<Measurement method of residual carbon>
Measuring method: Carbon / sulfur analyzer (Horiba EMIA-520)
A calibration curve was prepared using 1.7 g of tungsten powder (combustible material) as carbon 0 wt% and a standard sample 050-6 (carbon 0.38 wt%) manufactured by the Japan Iron and Steel Institute as a standard sample.

<Displacement measurement method>
Silver paste was applied to the external terminal electrode surface and sintered, and the length of fluctuation was measured when the laminate was polarized at a polarization voltage of 2.0 kV / mm and driven at 100 V and at a frequency of 0.1 Hz.

It is a graph which shows the relationship between the residual carbon amount of a molded object, and the displacement amount of a lamination type piezoelectric ceramic element. It is a graph which shows the relationship between the reflectance of the light with respect to the molded object after a binder removal, and the displacement amount of a lamination type piezoelectric ceramic element. It is a graph which shows the relationship between the reflectance of the light with respect to the sintered compact after baking, and the displacement amount of a lamination type piezoelectric ceramic element. It is a figure which shows one structural example of the lamination type piezoelectric ceramic element in this Embodiment. It is a flowchart which shows the manufacture procedure of the lamination type piezoelectric ceramic element in this Embodiment. It is a block diagram which shows the structure of the displacement amount evaluation apparatus in this Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Displacement evaluation apparatus, 101 ... Light source, 102 ... Light receiving element, 103 ... Controller, 104 ... Actuator, 105 ... Green chip (laminated body), 106 ... 1st conveyance path, 107 ... 2nd conveyance path

Claims (7)

It is a method for evaluating whether or not a piezoelectric ceramic sintered body obtained by firing after performing a binder removal process for removing the organic binder from a molded body containing ceramic particles and an organic binder has a predetermined amount of displacement. And
Irradiating the shaped body or the piezoelectric ceramic sintered body subjected to the binder removal treatment with light;
Measuring the reflectance of the light irradiated on the molded body or the piezoelectric ceramic sintered body;
For the molded body or the piezoelectric ceramic sintered body, a step of comparing the measured reflectance with a predetermined reference reflectance;
A method for evaluating a piezoelectric ceramic sintered body comprising: The reference reflectance, the evaluation method of the piezoelectric ceramic sintered body according to claim 1, characterized in that is determined based on the piezoelectric ceramics sintered body to have a predetermined displacement amount. A method for evaluating whether or not a laminated piezoelectric ceramic element obtained by firing a laminate in which a piezoelectric ceramic layer precursor and an internal electrode precursor are laminated has a predetermined displacement amount ,
Irradiating inspection light to the laminated body or the laminated piezoelectric ceramic element in which the organic binder contained in the internal electrode precursor is removed; and
Observing reflected light of the inspection light from the laminated body or the laminated piezoelectric ceramic element;
With
The method for evaluating a laminated piezoelectric ceramic element, wherein the observation of the reflected light of the inspection light is to compare the reflectance of the reflected light with a predetermined reference reflectance.   The method for evaluating a laminated piezoelectric ceramic element according to claim 3, wherein the conductive material of the internal electrode precursor is Cu.   The method for evaluating a laminated piezoelectric ceramic element according to claim 3 or 4, wherein the organic binder is removed and / or fired in a reducing atmosphere. An apparatus for evaluating a laminated piezoelectric ceramic element obtained by firing a laminate in which a piezoelectric ceramic layer precursor and an internal electrode precursor are laminated,
A light source for irradiating inspection light to the laminated body or the laminated piezoelectric ceramic element in which the organic binder contained in the internal electrode precursor has been removed;
A light receiving element that receives reflected light from the laminate or the laminated piezoelectric ceramic element;
Measuring means for obtaining a reflectance of the reflected light with respect to the inspection light;
An evaluation means for evaluating the amount of displacement of the multilayer piezoelectric ceramic element by comparing the reflectance with a predetermined reference reflectance;
An apparatus for evaluating a laminated piezoelectric ceramic element, comprising: 7. The apparatus for evaluating a stacked piezoelectric ceramic element according to claim 6 , further comprising a selecting means for selecting the laminated body or the stacked piezoelectric ceramic element based on an evaluation result by the evaluating means.

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