Method for manufacturing dielectric film

Abstract

To provide a manufacturing method of a dielectric film capable of suppressing the degradation of measurement accuracy of an ultrasonic sensor.SOLUTION: The manufacturing method of a dielectric film includes: a step of adjusting the particle size distribution of the particles of the dielectric substance within a prescribed range; a step of obtaining a slurry by kneading the particles after adjusting the particle size distribution and the dispersion medium; and a step of molding the slurry into a film to obtain a film-shaped molded product.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a dielectric film. [Background technology]

[0002] A dielectric film (such as a piezoelectric ceramic film) that has been subjected to a polarization process may be used as a piezoelectric body for an ultrasonic sensor such as a thickness sensor.

[0003] For example, in the ultrasonic thickness sensor disclosed in Patent Document 1, a thin sheet is formed from a slurry containing a ceramic piezoelectric material powder, and the sheet is attached to one surface of a thin metal plate that serves as one electrode of the sensor, sintered to form a film-like sintered body, and then polarized to use the piezoelectric body. This ultrasonic thickness sensor is used in a state where it is attached to the object to be measured via an adhesive layer provided between the other surface (the surface on which the piezoelectric body is not provided) of the above-mentioned metal plate (one electrode) and the surface of the object to be measured for thickness. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-140887 A Summary of the Invention [Problem to be solved by the invention]

[0005] A thin ultrasonic sensor including a film-shaped piezoelectric body (dielectric film) is highly flexible and therefore suitable for measuring the thickness of a measurement object (such as a pipe) with a curved surface. In addition, such a thin ultrasonic sensor is easy to install on the measurement object at all times, making it easy to measure the measurement object continuously or suppressing the variation in measurement accuracy over time.

[0006] On the other hand, in conventional thin ultrasonic sensors that use a dielectric film (such as that disclosed in Patent Document 1), the measurement accuracy may decrease over time due to deterioration of the adhesive layer between the ultrasonic sensor and the surface of the object to be measured.

[0007] In view of the above circumstances, an object of at least one embodiment of the present invention is to provide a method for manufacturing a dielectric film that can suppress a decrease in the measurement accuracy of an ultrasonic sensor. [Means for solving the problem]

[0008] A method for producing a dielectric film according to at least one embodiment of the present invention includes the steps of: adjusting the particle size distribution of the particles of the dielectric material within a specified range; A step of kneading the particles after the particle size distribution is adjusted with a dispersion medium to obtain a slurry; A forming step of forming the slurry into a film to obtain a film-shaped body; Equipped with. Effect of the Invention

[0009] According to at least one embodiment of the present invention, there is provided a method for manufacturing a dielectric film that can suppress a decrease in the measurement accuracy of an ultrasonic sensor. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic configuration diagram of an ultrasonic sensor to which a dielectric film according to an embodiment is applied; [Diagram 2] 2 is a flowchart of a method for manufacturing a dielectric film 2 according to an embodiment. [Figure 3A] 1 is a schematic diagram of a film forming tool used in a manufacturing method according to an embodiment. [Figure 3B] 1 is a schematic diagram of a film forming tool used in a manufacturing method according to an embodiment. [Figure 4A] 1 is a schematic diagram of a film forming tool used in a manufacturing method according to an embodiment. [Figure 4B]1 is a schematic diagram of a film forming tool used in a manufacturing method according to an embodiment. [Figure 5A] 1A to 1C are diagrams for explaining the procedure of a manufacturing method according to an embodiment. [Figure 5B] 1A to 1C are diagrams for explaining the procedure of a manufacturing method according to an embodiment. [Figure 5C] 1A to 1C are diagrams for explaining the procedure of a manufacturing method according to an embodiment. [Figure 6A] 1A to 1C are diagrams for explaining the procedure of a manufacturing method according to an embodiment. [Figure 6B] 1A to 1C are diagrams for explaining the procedure of a manufacturing method according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0012] (Example of ultrasonic sensor configuration) First, as an application example of a dielectric film manufactured by a manufacturing method according to some embodiments, an ultrasonic sensor to which a dielectric film according to one embodiment is applied will be described. Fig. 1 is a schematic diagram of an ultrasonic sensor to which a dielectric film according to one embodiment is applied. In this specification, the term "piezoelectric body" refers to a concept that includes dielectrics, and a dielectric body (film) that has been subjected to a polarization process and exhibits piezoelectricity is called a piezoelectric body (film).

[0013] 1 is an ultrasonic sensor for inspecting an inspection object 30, and includes a dielectric film 2 (piezoelectric film 3), an electrode 4, and lead wires 6 and 8. In the example described below, the ultrasonic sensor 1 is a thickness measurement sensor configured to measure the thickness (wall thickness) of the inspection object 30 (e.g., a pipe).

[0014] The piezoelectric film 3 of the ultrasonic sensor 1 shown in FIG. 1 is provided on the surface of the test object 30, and a thin plate-shaped electrode 4 is provided on the surface of the piezoelectric film 3. That is, the piezoelectric film 3 is located between the test object 30 and the electrode 4, and the test object 30 contacts one surface of the piezoelectric film 3, and the electrode 4 contacts the other surface of the piezoelectric film 3. Of the pair of lead wires 6 and 8, the lead wire 6 is connected to the electrode 4, and the lead wire 8 is connected to the test object 30. That is, the test object 30 functions as an electrode paired with the electrode 4. In the ultrasonic sensor 1 configured in this way, an electric signal is applied to the piezoelectric film 3 via the pair of electrodes (the electrode 4 and the test object 30) to drive the piezoelectric film 3 to generate ultrasonic waves, and the ultrasonic waves are irradiated to the test object 30.

[0015] In some embodiments, the ultrasonic sensor 1 may employ an electrode other than the object of inspection 30 as an electrode paired with the electrode 4. That is, the piezoelectric film 3 may be provided on the surface of one of the pair of electrodes. In this case, the ultrasonic sensor 1 is used by being adhered to the object of inspection 30 via an adhesive layer provided between one of the pair of electrodes and the object of inspection 30, as in the case of Patent Document 1. The adhesive layer may be formed of, for example, silver paste or glass paste.

[0016] (Method of manufacturing dielectric film) Hereinafter, a method for manufacturing the dielectric film 2 according to some embodiments will be described.

[0017] 2 is a flowchart of a method for manufacturing the dielectric film 2 according to an embodiment. As shown in the figure, the method for manufacturing the dielectric film 2 according to an embodiment includes a step of adjusting the particle size distribution of the particles of the dielectric material (step S2), a step of preparing a slurry containing the particles obtained in step S2 (step S4), a step of forming the slurry to obtain a film-like molded body (dielectric film 2) (step S6), a step of sintering the film-like molded body (dielectric film 2) (step S8), and a step of performing a polarization treatment on the sintered film-like molded body (dielectric film 2) (step S10).

[0018] (Adjusting the particle size distribution of the dielectric material particles; Step S2) In step S2, the particle size distribution of the particles of the dielectric material is adjusted to fall within a specified range.

[0019] In this way, by adjusting the particle size distribution of the particles of the dielectric material within a specified range, even if a film-like molded body formed from a slurry containing the particles of the dielectric material is sintered in a subsequent step while being provided on the surface of the test object 30, the dielectric material can have an appropriate particle size distribution such that the sintered film-like molded body is unlikely to peel off from the surface of the test object 30. Therefore, the sintered product of the above-mentioned film-like molded body can be formed directly on the surface of the test object without using an adhesive or the like. The film-like molded body does not necessarily have to be formed on the surface of the test object, and may be formed on the surface of a thin plate-like electrode.

[0020] In one embodiment, in step S2, the particle size distribution of the particles of the dielectric material is adjusted so that D50 is in the range of 0.5 μm to 0.7 μm. Alternatively, in step S2, the particle size distribution of the particles of the dielectric material may be adjusted so that D50 is in the range of 0.55 μm to 0.65 μm. By using particles whose particle size distribution is adjusted to the above range, even if a film-like molded body formed from a slurry containing the particles is sintered in a state where it is provided on the surface of the test object 30, the film-like molded body after sintering is unlikely to peel off from the surface of the test object. Therefore, it is easy to form the sintered product of the above-mentioned film-like molded body (film-like sintered body) directly on the surface of the test object without using an adhesive or the like.

[0021] In this specification, D50 means the particle size at an integrated value of 50% in the particle size distribution determined by a laser diffraction / scattering method.

[0022] The type of dielectric material is not particularly limited, but for example, particles of PZT (lead zirconate titanate) can be used. Furthermore, commercially available particles of dielectric materials such as PZT can be used.

[0023] In one embodiment, in step S2, particles of the dielectric material (eg, PZT) may be pre-fired to at least partially fuse the particles together, thereby adjusting the particle size distribution of the particles.

[0024] The temperature for calcining the particles of the dielectric material may be 800° C. or more and 1000° C. or less. The time for calcining the particles of the dielectric material may be 2 hours or more and 5 hours or less.

[0025] In this way, by calcining the particles of the dielectric material, even if a film-like molded body formed from a slurry containing the calcined particles is sintered in a state where it is provided on the surface of the test object, the dielectric material (calcined particles) can have an appropriate particle size distribution such that the sintered film-like molded body is unlikely to peel off from the surface of the test object. Also, by calcining within the above-mentioned temperature range, it becomes easier to impart such an appropriate particle size distribution to the dielectric material (calcined particles).

[0026] (Preparation of slurry; step S4) In step S4, the particles of the dielectric material obtained in step S2 (i.e., particles with adjusted particle size distribution) are kneaded with a dispersion medium to obtain a slurry. The preparation of the slurry in step S4 may be performed, for example, by adding a dispersion medium to the above-mentioned particles and kneading them using a roll mill, a ball mill, or the like. In addition, a rotary evaporator or the like may be used to perform a defoaming process and a desolvation process (volatilization and removal of the solvent) at the same time to obtain a slurry with a predetermined viscosity. The viscosity of the slurry obtained in step S4 may be a viscosity suitable for film formation in the subsequent step of obtaining a film-like formed body. The viscosity of the slurry generated in step S4 may be, for example, 1500 mPa·s or more and 20000 mPa·s or less.

[0027] In some embodiments, the dispersion medium used to prepare the slurry is a solution of a resin dissolved in an organic solvent.

[0028] The above-mentioned resin may contain a substance capable of appropriately adjusting the viscosity of the dispersion medium. This makes it easier to appropriately adjust the viscosity of the resulting slurry. For example, polyvinyl butyral (PVB) can be used as the above-mentioned resin.

[0029] The organic solvent may contain a substance having a relatively low vapor pressure and being difficult to evaporate (e.g., a substance having a vapor pressure lower than that of ethanol). This makes it difficult for the viscosity of the prepared slurry to change over time, making it easier to form a film-like formation in the subsequent step. As the organic solvent, for example, an alcohol such as butanol can be used.

[0030] The concentration of the solution in which the resin is dissolved in the organic solvent may be, for example, 10% by weight or more and 20% by weight or less.

[0031] In some embodiments, the dispersion medium used to prepare the slurry does not contain a sol component as a binder. That is, the dispersion medium used to prepare the slurry (the dispersion medium to be kneaded with the particles of the dielectric material) does not contain a dispersoid constituting the sol as a binder. Such a dispersoid is, for example, a metal salt such as a metal alkoxide or a metal carboxylate having a function as a binder. The metal atom constituting the metal salt may be the same type as the metal atom constituting the above-mentioned dielectric material. That is, when the dielectric material is PTZ, the metal atom constituting the metal salt may contain titanium, zirconium, or lead. More specifically, when the dielectric material is PTZ, the above-mentioned metal salt may be titanium butoxide, zirconium butoxide, and lead acetate.

[0032] Usually, when preparing a slurry, a dispersion medium containing a sol component having a binder function is used. When the dispersion medium contains the above-mentioned sol component, the binder function is exerted by a dehydration condensation reaction between the sol components when a film-shaped molded body formed from the slurry is sintered.

[0033] In contrast, in the above-mentioned embodiment, as already described, since particles of a dielectric material having an appropriate particle size distribution are used, even if a slurry is prepared using a dispersion medium that does not contain a sol component as a binder, a film-like molded body that is difficult to peel off from the surface of the test object after sintering can be formed. Therefore, it is possible to more easily manufacture a dielectric film that can suppress a decrease in the measurement accuracy of the ultrasonic sensor.

[0034] (Forming of film-like molded body; step S6) In step S6, the slurry prepared in step S4 is molded to obtain a film-like molded body (dielectric film 2). When forming a film-like molded body to be used for an ultrasonic sensor, the film-like molded body formed in step S6 may have a thickness of 60 μm or more and 80 μm or less. By making the film-like molded body have a thickness of 60 μm or more, the detection accuracy of an ultrasonic sensor using this film-like molded body can be improved. In addition, by making the film-like molded body have a thickness of 80 μm or less, the flexibility of the film-like molded body becomes appropriate, and for example, an ultrasonic sensor can be appropriately installed on an inspection object having a curved surface.

[0035] Here, Figures 3A and 3B, and Figures 4A and 4B are schematic diagrams of a film-forming tool 10 used to form a film-shaped body in a manufacturing method according to an embodiment. Figures 3A and 4A are schematic plan views of the film-forming tool 10, and Figures 3B and 4B are schematic side views of the film-forming tool 10. Figures 5A to 5C, and Figures 6A and 6B are diagrams for explaining a procedure for forming a film-shaped body in a manufacturing method according to an embodiment.

[0036] In some embodiments, the slurry may be formed into a film by a screen printing method to obtain a film-shaped body (dielectric film 2). In this case, the slurry may be formed into a film by using, for example, a film-forming tool 10 shown in FIG. 4A and FIG. 4B.

[0037] 3A and 3B includes a thin screen sheet 12 and a mesh portion 14 provided inside holes 12a formed in the screen sheet 12. The thickness t1 of the screen sheet 12 is relatively thin and is suitable for producing a dense film.

[0038] When forming a film-like molded body using this film-forming tool 10, the screen sheet 12 is placed on the surface of the object (e.g., an object to be inspected) on which the film-like molded body is to be formed, and an appropriate amount of the slurry prepared in step S4 is poured onto the screen sheet 12 to fill the gaps in the mesh portion 14 with the slurry, and then the screen sheet 12 is removed from the surface of the object. This forms a thin film of the slurry on the surface of the object. After this film is dried, another thin film is formed on top of the film using the film-forming tool 10 in the same manner. This procedure is repeated until the slurry film reaches a desired thickness, thereby obtaining a film-like molded body.

[0039] In this way, a film-shaped molded product can be obtained relatively easily by forming the slurry into a film by the screen printing method. In addition, by forming the slurry into a film by the screen printing method, the shape and thickness of the film can be easily adjusted, so that a film-shaped molded product with good dimensional accuracy or shape accuracy can be obtained.

[0040] In some embodiments, the slurry may be formed into a film shape by a stencil printing method to obtain a film-shaped molded body (dielectric film 2). In this case, the slurry may be formed into a film shape using, for example, a film-forming tool 10 shown in FIG. 5A and FIG. 5B.

[0041] 4A and 4B has a thin plate-like template 18 having holes 18a. The thickness t2 of the template is relatively large, and a relatively thick slurry film can be formed in a single operation, making it suitable for simple film production.

[0042] When forming a film-like molded body using this film-forming tool 10, a template 18 is placed on the surface of an object (e.g., an object to be inspected) on which the film-like molded body is to be formed (see FIG. 5A), and an appropriate amount of the slurry 20 prepared in step S4 is poured from above (see FIG. 5B). After filling the inside of the hole 18a with the slurry, the template 18 is removed from the surface of the object (see FIG. 5C). This forms a film of the slurry on the surface of the object. In this manner, a film-like molded body 5 (dielectric film 2) can be obtained.

[0043] In this way, by forming the slurry into a film by the stencil printing method, a film-shaped molded product can be obtained relatively easily. Also, by forming the slurry into a film by the stencil printing method, a film-shaped molded product having a relatively large thickness can be obtained with a relatively small number of operations, which is more convenient.

[0044] In one embodiment, as shown in Figures 5A to 5C, for example, in step S6, the film-like molded body (dielectric film 2) is formed directly on the surface of the inspection object 30 (for example, a pipe). In this case, in the subsequent step, the film-like molded body (dielectric film 2) on the surface of the inspection object 30 is sintered (step S8), and then the sintered product (dielectric film 2) of the film-like molded body on the surface of the inspection object 30 is subjected to a polarization treatment (step S10), thereby obtaining the piezoelectric film 3 (dielectric film 2).

[0045] In one embodiment, for example, as shown in FIG. 6A, in step S6, the film-like molding 5 (dielectric film 2) is formed on a release sheet 22. Then, as shown in FIG. 6B, the film-like molding 5 peeled off from the release sheet 22 is attached to the surface of an object 30 to be inspected by an ultrasonic sensor. Then, in the subsequent step, the film-like molding (dielectric film 2) on the surface of the object 30 to be inspected is sintered (step S8), and then the sintered product (dielectric film 2) of the film-like molding on the surface of the object 30 to be inspected is subjected to a polarization treatment (step S10) to obtain a piezoelectric film 3 (dielectric film 2).

[0046] The above-mentioned release sheet 22 is a sheet that can be easily peeled off after the film-like molding 5 is formed. For example, the release sheet 22 may be provided with a water-soluble paste layer such as cellulose. If the above-mentioned film-like molding 5 is formed on the surface of the paste layer of this release sheet 22, the film-like molding 5 can be easily peeled off from the release sheet 22 by immersing the release sheet 22 in water, and the film-like molding 5 peeled off from the release sheet 22 can be easily attached to the surface of the inspection object 30. Therefore, the process of forming the film-like molding 5 on the release sheet 22 can be performed in a factory, for example, and the process of attaching the film-like molding 5 to the surface of the inspection object 30 can be performed in a plant, for example, and these processes can be performed in different places, so that the work at the installation site of the inspection object 30 can be made easier.

[0047] In one embodiment, although not shown, the above-mentioned film-like molding (dielectric film 2) may be formed on a thin plate-like electrode in step S6. An ultrasonic sensor including such a film-like molding (dielectric film 2) is adhered to the test object 30 via an adhesive layer provided between the electrode and the test object 30, as in the case of Patent Document 1. Then, the film-like molding (dielectric film 2) on the electrode is sintered (step S8), and then the sintered product (dielectric film 2) of the film-like molding on the electrode is subjected to a polarization treatment (step S10), thereby obtaining a piezoelectric film 3 (dielectric film 2).

[0048] (Sintering of film-shaped body; step S8) In step S8, the film-like molding formed in step S6 is sintered. In step S8, for example, an induction heating device or the like may be used to locally heat only the location where the film-like molding is placed on the inspection target 30 or the like, thereby sintering the film-like molding.

[0049] The temperature at which the film-like molded body is sintered in step S8 may be, for example, 600° C. or higher and 700° C. or lower. Usually, the temperature at which the film-like molded body formed from the slurry is sintered is in a higher temperature range, but in this embodiment, since the film-like molded body is formed from the calcined particles having an appropriate particle size distribution by performing the calcination in step S2, it is possible to appropriately sinter the film-like molded body even in a relatively low temperature range.

[0050] (Polarization treatment of film-like molded body; step S10) In step S10, the sintered product of the film-like molding obtained in step S8 is subjected to a polarization treatment to obtain a piezoelectric film 3 (dielectric film 2). The polarization treatment can be performed, for example, as shown in Fig. 1, by applying a voltage between a pair of electrodes (electrode 4 and test object 30 in the example shown in Fig. 1) provided on both sides of the film-like molding (dielectric film 2).

[0051] The contents described in each of the above embodiments can be understood, for example, as follows.

[0052] (1) A method for producing a dielectric film (2) according to at least one embodiment of the present invention includes the steps of: A step of adjusting the particle size distribution of the particles of the dielectric material within a specified range (for example, step S2 described above); A step of kneading the particles after the particle size distribution is adjusted with a dispersion medium to obtain a slurry (for example, the above-mentioned step S4); A forming step (for example, the above-mentioned step S6) of forming the slurry into a film to obtain a film-shaped body; Equipped with.

[0053] In the above method (1), the particle size distribution of the particles of the dielectric material is adjusted within a specified range. By using particles with such an adjusted particle size distribution, even if a film-like molded body formed from a slurry containing the particles is sintered on the surface of an object to be inspected (30; object to be measured for thickness, etc.), the dielectric material can have an appropriate particle size distribution such that the film-like molded body after sintering is unlikely to peel off from the surface of the object to be inspected. Therefore, the sintered product of the above-mentioned film-like molded body (film-like sintered body) can be formed directly on the surface of the object to be inspected without using an adhesive or the like. Therefore, according to the above method (1), a dielectric film can be obtained that can suppress the decrease in the measurement accuracy of the ultrasonic sensor (1) caused by the deterioration of the adhesive or the like.

[0054] (2) In some embodiments, in the method of (1), In the adjusting step, the particle size distribution of the particles of the dielectric material is adjusted so that D50 falls within the range of 0.5 μm to 0.7 μm.

[0055] According to the method (2) above, the D50 of the particles of the dielectric material is adjusted to be within the range of 0.5 μm to 0.7 μm, so that by using particles with adjusted particle size distribution in this way, even if a film-like molded body formed from a slurry containing the particles is sintered on the surface of the test object, the film-like molded body after sintering is unlikely to peel off from the surface of the test object. Therefore, it is easy to form the sintered product of the film-like molded body (film-like sintered body) directly on the surface of the test object without using an adhesive or the like.

[0056] (3) In some embodiments, in the method of (1) or (2), In the adjusting step, the particles of the dielectric material are pre-fired to at least partially fuse the particles together.

[0057] According to the method (3) above, the particles of the dielectric material are pre-fired to partially fuse the particles together. Therefore, even when a film-like molding formed from a slurry containing the pre-fired particles is sintered while being placed on the surface of the object to be inspected, the dielectric material (pre-fired particles) can have an appropriate particle size distribution such that the sintered film-like molding is unlikely to peel off from the surface of the object to be inspected.

[0058] (4) In some embodiments, in the method of (3), The particles are calcined at a temperature of 800°C or higher and 1000°C or lower.

[0059] According to the method (4) above, the particles of the dielectric material are pre-fired at a temperature of 800°C to 1000°C, so that even if a film-like molded body formed from a slurry containing the pre-fired particles is sintered in a state where it is provided on the surface of the test object, the dielectric material (pre-fired particles) can be easily provided with an appropriate particle size distribution such that the sintered film-like molded body is unlikely to peel off from the surface of the test object. Therefore, it is easy to obtain a dielectric film that can suppress the decrease in the measurement accuracy of the ultrasonic sensor caused by the deterioration of the adhesive, etc.

[0060] (5) In some embodiments, in any of the methods (1) to (4) above, The method for producing the dielectric film includes the steps of: The method includes a step of sintering the film-shaped body (for example, the above-mentioned step S8).

[0061] According to the method of (5) above, the film-shaped molding obtained by the method described in (1) above is sintered to obtain a sintered film-shaped molding. Then, the sintered product is polarized to obtain a film-shaped piezoelectric body. Therefore, by using the piezoelectric body thus obtained for an ultrasonic sensor, it is possible to suppress the decrease in the measurement accuracy of the ultrasonic sensor, as described in (1) above.

[0062] (6) In some embodiments, in any of the methods (1) to (5) above, The dispersion medium is a solution in which a resin is dissolved in an organic solvent.

[0063] According to the method (6) above, in preparing the slurry containing particles of the dielectric material, a solution in which a resin is dissolved in an organic solvent is used as a dispersion medium, so that a slurry suitable for forming a film-like molded body that is difficult to peel off from the surface of the test object after sintering can be obtained. Therefore, it becomes easier to obtain a dielectric film that can suppress a decrease in the measurement accuracy of the ultrasonic sensor.

[0064] (7) In some embodiments, in the method of (6), The resin includes polyvinyl butyral.

[0065] According to the above method (7), since a resin containing polyvinyl butyral is used in the preparation of the slurry, it is possible to obtain a slurry having a viscosity suitable for forming a film-like molding.

[0066] (8) In some embodiments, in the method of (6) or (7), The organic solvent includes butanol.

[0067] According to the method (8) above, butanol, which is a relatively difficult-to-evaporate alcohol, is used as the organic solvent, so that the viscosity of the slurry after preparation is unlikely to change with time, and therefore a film-like molded body can be efficiently formed from the slurry.

[0068] (9) In some embodiments, in any of the methods (6) to (8) above, The concentration of the resin in the solution is 10% by weight or more and 20% by weight or less.

[0069] According to the method (9) above, since the resin concentration in the solution is set within the above range, it is possible to obtain a slurry having a viscosity suitable for forming a film-like molding.

[0070] (10) In some embodiments, in any of the methods (1) to (9) above, The dispersion medium does not contain a sol component as a binder.

[0071] According to the method (10) above, as described in (1) above, since particles of a dielectric material having an appropriate particle size distribution are used in the preparation of the slurry, even if the slurry is prepared using a dispersion medium that does not contain a sol component as a binder, a film-like molded body that is difficult to peel off from the surface of the test object after sintering can be formed. Therefore, it is possible to more easily manufacture a dielectric film that can suppress the deterioration of the measurement accuracy of the ultrasonic sensor.

[0072] (11) In some embodiments, in any of the methods (1) to (10) above, In the forming step, the film-like molded product is formed to have a film thickness of 60 μm or more and 80 μm or less.

[0073] According to the method of (11) above, the film thickness of the film-like molding is set to 60 μm or more, so that the detection accuracy of the ultrasonic sensor using this film-like molding can be improved. Also, according to the method of (11) above, the film thickness of the film-like molding is set to 80 μm or less, so that the flexibility of the film-like molding is appropriate, and for example, the ultrasonic sensor can be appropriately installed on an object to be inspected having a curved surface.

[0074] (12) In some embodiments, in any of the methods (1) to (11) above, In the forming step, the slurry is formed into a film by a screen printing method.

[0075] According to the above method (12), a film-shaped molded product can be obtained relatively easily by forming the slurry into a film by the screen printing method. Also, a film-shaped molded product having good dimensional accuracy or shape accuracy can be obtained by forming the slurry into a film by the screen printing method.

[0076] (13) In some embodiments, in any of the methods (1) to (11) above, In the forming step, the slurry is formed into a film by a stencil printing method.

[0077] According to the above method (13), the slurry is formed into a film by stencil printing, so that a film-like molded product can be obtained relatively easily.

[0078] (14) In some embodiments, in any of the methods (1) to (13) above, the dielectric film is a dielectric film for a piezoelectric body of an ultrasonic sensor, In the forming step, the film-like molding is formed on a surface of an object to be inspected by the ultrasonic sensor, The method further comprises a step of sintering the film-like molding on the surface of the object to be inspected.

[0079] According to the method (14) above, the film-like molding obtained by the method (1) above is formed on the surface of the test object (e.g., object to be measured for thickness), so that when the film-like molding on the surface is sintered, the film-like molding after sintering is unlikely to peel off from the surface of the measurement object. Therefore, by using this sintered product, a dielectric film that can suppress the decrease in the measurement accuracy of the ultrasonic sensor caused by the deterioration of the adhesive, etc. can be obtained.

[0080] (15) In some embodiments, in any of the methods (1) to (13) above, In the forming step, the film-like formed body is formed on a release sheet (22).

[0081] According to the method of (15) above, since the film-like molding is formed on the release sheet, the film-like molding peeled off from the release sheet can be attached to the surface of the object to be inspected, whereby the film-like molding can be installed on the surface of the object to be inspected, and an ultrasonic sensor can be produced from the film-like molding thus installed. That is, according to the method of (15) above, the film-like molding can be produced at a location away from the object to be inspected, and the film-like molding peeled off from the release sheet can be easily installed on the surface of the object to be inspected, so that the work at the installation location of the object to be inspected can be made easier.

[0082] (16) In some embodiments, in the method of (15), the dielectric film is a dielectric film for a piezoelectric body of an ultrasonic sensor, The method for producing the dielectric film includes the steps of: A step of attaching the film-like molding peeled off from the release sheet to a surface of an object to be inspected by the ultrasonic sensor; and a step of sintering the film-like molding on the surface of the object to be inspected.

[0083] According to the method of (16) above, the film-like molding formed on the release sheet by the method of (15) above is attached to the surface of the test object (e.g., thickness measurement object), so that when the film-like molding on the surface is sintered, the sintered film-like molding is unlikely to peel off from the surface of the test object. Therefore, by using this sintered product, a dielectric film can be obtained that can suppress the decrease in measurement accuracy of the ultrasonic sensor caused by the deterioration of the adhesive, etc. In addition, according to the method of (16) above, the process of forming the film-like molding on the release sheet and the process of attaching the film-like molding to the surface of the test object can be performed in different places, so that the work at the installation site of the test object can be made easier.

[0084] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0085] In this specification, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," do not only strictly represent such a configuration, but also represent a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. In addition, in this specification, the expressions "comprise," "include," or "have" a certain element are not exclusive expressions that exclude the presence of other elements. [Explanation of symbols]

[0086] 1 Ultrasonic sensor 2. Dielectric film 3. Piezoelectric film 4 electrodes 5. Film-like molding 6 Lead Wire 8 Lead Wire 10 Film deposition equipment 12 Screen Sheet 12a hole 14 Mesh section 18 Templates 18a hole 20 Slurry 22 Release sheet 30 Inspection object

Claims

1. adjusting the particle size distribution of the particles of the dielectric material within a specified range; A step of kneading the particles after the particle size distribution is adjusted with a dispersion medium to obtain a slurry; A forming step of forming the slurry into a film to obtain a film-shaped body; Equipped with The dispersion medium is a solution consisting of a resin dissolved in an organic solvent and the resin and the organic solvent. A method for manufacturing a dielectric film, comprising the steps of: the dielectric film is a dielectric film for a piezoelectric body of an ultrasonic sensor, In the forming step, the slurry is poured onto a surface of an object to be inspected by the ultrasonic sensor to form the film-like molded body; sintering the film-like molding on the surface of the test object. A method for manufacturing a dielectric film.

2. In the adjusting step, the particle size distribution of the particles of the dielectric material is adjusted so that D50 is within a range of 0.5 μm to 0.7 μm. The method for producing the dielectric film according to claim 1 .

3. In the adjusting step, the particles of the dielectric material are pre-fired to at least partially fuse the particles together. The method for producing the dielectric film according to claim 1 or 2.

4. The particles are calcined at a temperature of 800° C. or more and 1000° C. or less. The method for producing the dielectric film according to claim 3 .

5. A step of sintering the film-shaped body is provided. The method for manufacturing a dielectric film according to claim 1 .

6. The resin is polyvinyl butyral, The organic solvent is butanol. The method for manufacturing the dielectric film according to claim 1 .

7. The concentration of the resin in the solution is 10% by weight or more and 20% by weight or less. The method for manufacturing the dielectric film according to claim 1 .

8. The dispersion medium does not contain a sol component as a binder. The method for manufacturing a dielectric film according to claim 1 .

9. In the forming step, the film-like molded body is formed to a film thickness of 60 μm or more and 80 μm or less. The method for manufacturing the dielectric film according to claim 1 .

10. In the forming step, the slurry is formed into a film shape by a screen printing method. The method for manufacturing the dielectric film according to claim 1 .

11. In the forming step, the slurry is formed into a film shape by a stencil printing method. The method for manufacturing the dielectric film according to claim 1 .

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