JP2020006458A - Ferroelectric nanoparticle accumulation method, ferroelectric nanoparticle accumulation device, and electronic component manufacturing method - Google Patents

Abstract

To provide a method for accumulating ferroelectric nanoparticles, an accumulation device used therefor, and a method for manufacturing an electronic component.SOLUTION: A ferroelectric nanoparticle accumulation method is a method in which ferroelectric nanoparticles are dispersed in a dispersion medium, and a charged dispersion thereof is discharged toward a substrate charged to have a charge opposite to that of the dispersion, and the dispersion medium contained in an attached dispersion is removed while the dispersion is attached onto a surface of the substrate. The ferroelectric nanoparticles are ferroelectric tetragonal. Further, the dispersion is preferably discharged by electrostatic spraying. Electronic components can be manufactured by the ferroelectric nanoparticle accumulation method. A ferroelectric nanoparticle accumulation device includes a chamber, a nozzle for electrostatic spraying, a board for mounting the substrate placed at a position facing an opening of the nozzle for electrostatic spraying, and a heater for heating the board for mounting the substrate.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a ferroelectric nanoparticle accumulation method, a ferroelectric nanoparticle accumulation device used for accumulation of ferroelectric nanoparticles, and a method of manufacturing an electronic component for forming a ferroelectric nanoparticle accumulation on a surface of a substrate. .

  Ferroelectrics, for example, barium titanate which is ferroelectric at room temperature, have a large spontaneous polarization in the c-axis direction, and can be used as a pyroelectric substance, a piezoelectric substance, or the like. In addition, by regularly arranging such ferroelectric particles on the surface of the substrate and forming an integrated layer composed of ferroelectric particles, it can be used as various useful electronic components such as pyroelectric elements and piezoelectric elements. Can be used.

  As a method of regularly arranging the ferroelectric particles on the surface of the substrate, conventionally, a method in which a dispersion liquid in which the ferroelectric particles are dispersed in a dispersion medium is applied to the substrate surface by an inkjet method, and then the medium is removed A method of applying a dispersion to the surface of a substrate sheet and then removing the medium is known. More specifically, a substrate having an uneven structure is immersed in a supernatant liquid obtained by centrifuging a solution in which barium titanate nanocrystals and the like are dispersed in a nonpolar solvent, and the substrate is pulled up. 2. Description of the Related Art A method for manufacturing a nanocrystalline structure substrate on which crystals are arranged is known (for example, see Patent Document 1).

WO2006-60042

As described above, a technique for regularly arranging and accumulating nanoparticles by utilizing the capillary phenomenon is known, and can be used for manufacturing electronic devices and the like. Here, if an integrated layer composed of ferroelectric particles having a larger area can be formed, a ferroelectric nanoparticle aggregate useful in more applications such as electronic devices can be obtained.
The present invention has been made in view of the situation of the related art as described above, and has a method of accumulating ferroelectric nanoparticles for efficiently accumulating ferroelectric nanoparticles, an accumulating apparatus used for the accumulating method, and a ferroelectric device. An object of the present invention is to provide a method for manufacturing an electronic component that has a larger integrated area of dielectric nanoparticles and is useful in various applications.

The present invention is as follows.
1. A ferroelectric nanoparticle accumulation method for accumulating ferroelectric nanoparticles on a surface of a substrate,
The ferroelectric nanoparticles are dispersed in a dispersion medium, and the charged dispersion is discharged toward the substrate charged to have a charge opposite to that of the dispersion, and the surface of the substrate is charged with the charged dispersion. A method for accumulating ferroelectric nanoparticles, comprising removing a dispersion medium contained in the applied dispersion while applying the dispersion.
2. The above-mentioned 1., wherein the ferroelectric nanoparticles are tetragonal ferroelectrics. 3. The method for accumulating ferroelectric nanoparticles according to 1.
3. The above-mentioned 1. wherein the dispersion is discharged by electrostatic spraying. Or 2. 3. The method for accumulating ferroelectric nanoparticles according to 1.
4. 1. To 3. A ferroelectric nanoparticle accumulation device used in the ferroelectric nanoparticle accumulation method according to any one of the above,
A chamber for accommodating a substrate therein, an electrostatic spray nozzle attached to an upper portion of the chamber, and a substrate mounting member disposed at a position opposite to an opening of the electrostatic spray nozzle at a lower portion of the chamber. Board, a heater for heating the substrate mounting board, a power supply for applying a voltage to the electrostatic spray nozzle, and a power supply for applying a voltage to the substrate mounting board, A ferroelectric nanoparticle accumulation device, comprising:
5. 3. The above-mentioned 3. wherein the chamber is provided with a ventilation opening, and the chamber is provided with a pump for discharging gas in the chamber to the outside. 3. The ferroelectric nanoparticle accumulation device according to 1.
6. A method for manufacturing an electronic component comprising a substrate and a ferroelectric nanoparticle assembly formed on a surface of the substrate,
The ferroelectric nanoparticles are dispersed in a dispersion medium, and the charged dispersion is discharged toward the substrate charged to have a charge opposite to that of the dispersion, and the dispersion is dispersed on the surface of the substrate. A method for manufacturing an electronic component, comprising: removing a dispersion medium contained in a coated dispersion liquid while applying the liquid to form the ferroelectric nanoparticle aggregate.

According to the ferroelectric nanoparticle accumulation method of the present invention, the charged dispersion is discharged toward the charged substrate so as to have a charge opposite to that of the dispersion. As a result, the ferroelectric nanoparticles are arranged in the plane direction of the substrate, and the nanoparticles are sequentially stacked and integrated to form an integrated body useful as various electronic components.
When the ferroelectric nanoparticles are ferroelectric tetragonal, each crystal is sequentially accumulated from the surface of the substrate to easily form an aggregate having a thickness useful as various electronic components. it can.
Further, when the dispersion liquid is discharged by electrostatic spraying, a homogeneous aggregate can be easily formed.
According to the ferroelectric nanoparticle accumulating device used in the ferroelectric nanoparticle accumulating method of the present invention, the electrostatic spray nozzle attached to the upper part of the chamber and the opening of the electrostatic spray nozzle at the lower part of the chamber A substrate mounting board disposed at a position facing the substrate. This makes it possible to discharge and apply the dispersion onto the surface of the substrate mounted on the substrate mounting board, and to accurately form an integrated body having a thickness useful as various electronic components. Can be.
In addition, when the chamber is provided with an opening for ventilation and the chamber is provided with a pump for discharging the gas in the chamber to the outside, the dispersion medium is efficiently removed and the integrated body is easily formed. can do.
According to the electronic component manufacturing method of the present invention, the charged dispersion liquid is discharged toward the charged substrate so as to have a charge opposite to that of the dispersion liquid. As a result, an integrated body having a required thickness is formed on the surface of the substrate, and electronic components useful in various applications including the substrate and the ferroelectric nanoparticle integrated body can be manufactured.

It is a schematic diagram of an example of an integration device used for a ferroelectric nanoparticle integration method. 3 is an image of the ferroelectric nanoparticle assembly of Example 1 observed with an electron microscope. 5 is an image of the ferroelectric nanoparticle assembly of Example 2 observed with an electron microscope. 5 is an image of the ferroelectric nanoparticle assembly of Comparative Example 1 observed with an electron microscope. 9 is an image of the ferroelectric nanoparticle assembly of Comparative Example 2 observed with an electron microscope. 4 is an image obtained by observation with an electron microscope showing the particle packing ratio of the ferroelectric nanoparticle assembly of Example 1. 6 is an image obtained by observation with an electron microscope showing a particle filling rate of the ferroelectric nanoparticle assembly of Comparative Example 1. 3 is an X-ray diffraction image of the ferroelectric nanoparticle aggregates of Example 1 and Comparative Examples 1 and 2.

Hereinafter, the present invention will be described in detail with reference to the drawings.
[1] Ferroelectric nanoparticle accumulating method The ferroelectric nanoparticle accumulating method according to the present invention is characterized in that a ferroelectric nanoparticle is dispersed in a dispersion medium and a charged dispersion is charged with a charge opposite to that of the dispersion. The method is characterized in that the dispersion medium is discharged toward a charged substrate so that the dispersion medium is applied to the surface of the substrate and the dispersion medium contained in the applied dispersion liquid is removed.

  A ferroelectric is a dielectric in which electric dipoles are aligned without an external electric field, and the direction of the dipole can be changed by an electric field. Examples of the ferroelectric include barium titanate, cadmium titanate, and lead zirconate titanate. Barium titanate is often used. Further, the shape of the ferroelectric nanoparticles is preferably a tetragonal crystal. For example, in a tetragonal crystal of barium titanate, the vertical length is about 1% longer than the horizontal, and the central titanium and the peripheral oxygen are cubic. The ferroelectricity is exhibited by being stabilized at a position slightly deviated from that of.

  Here, the relative dielectric constant of the ferroelectric material constituting the nanoparticles is 100 to 10000, particularly 1000 to 5000. If the nanoparticles are made of a ferroelectric substance having such a relative dielectric constant, the integrated body can be used as an electronic device or the like that is useful in various applications.

  Further, the ferroelectric nanoparticles are microparticles in which the largest dimension of the ferroelectric particles (in the case of a rectangular parallelepiped, the dimension of the largest dimension of each side) is in nanometer units. The maximum particle size of the ferroelectric nanoparticles is not particularly limited, but may be 10 to 50 nm, particularly 15 to 45 nm. Note that the ferroelectric nanoparticles can be particles having a small size difference, and the standard deviation of the average value of the maximum size of the ferroelectric particles can be 10% or less. Therefore, the average particle diameter of the dielectric nanoparticles is in a numerical range that is not much different from the above-described maximum dimension.

  The ferroelectric nanoparticles are dispersed in a dispersion medium and used as a charged dispersion. As the dispersion medium, a high boiling point solvent having a boiling point (pressure; 760 mmHg) of about 150 to 200 ° C. is preferable. Examples of such a high-boiling solvent include 1,3,5-trimethylbenzene (boiling point: 165 ° C), benzaldehyde (boiling point: 178 ° C), cyclohexanol (boiling point: 161 ° C), N, N-dimethylacetamide ( Boiling point: 163-166 ° C.), N, N-dimethylformamide (boiling point: 153 ° C.) and the like. If the solvent has such a high boiling point, after dispensing, a small amount of the dispersion medium evaporates before being applied, and a required amount of the dispersion medium remains in the dispersion applied on the surface of the substrate. Ferroelectric nanoparticles can be efficiently accumulated on the surface of the substrate.

  The amount of the ferroelectric nanoparticles dispersed in the dispersion medium is not particularly limited, depending on the required amount of the ferroelectric nanoparticles to be accumulated, but is 2 to 20 mg / mL, particularly 4 to 15 mg / mL. can do. With such an amount of dispersion, the ferroelectric nanoparticles can be efficiently accumulated on the substrate. Furthermore, the flow rate of the dispersion, in other words, the discharge amount of the dispersion is also not particularly limited by the required accumulation amount of the ferroelectric nanoparticles, but when the dispersion amount is as described above, By setting the flow rate to 20 to 150 μL / min, particularly 40 to 120 μL / min, ferroelectric nanoparticles can be efficiently accumulated on the substrate.

  The temperature and pressure of the atmosphere when the dispersion is discharged toward the substrate are not particularly limited, and the temperature may be an ambient temperature, for example, room temperature (25 to 35 ° C.). do not have to. The pressure may be normal pressure (atmospheric pressure), and it is not particularly necessary to increase or decrease the pressure. The discharged dispersion liquid may be applied as droplets on the surface of the substrate.

  The method for charging and discharging the dispersion is not particularly limited, but electrostatic spraying, which can discharge while discharging the dispersion with the same equipment, is preferable. In the case of electrostatic spraying, the entire amount of the discharged dispersion liquid is applied as fine droplets on the surface of the substrate. The method of electrostatically spraying the dispersion and discharging the dispersion toward the substrate is not particularly limited, and a conventionally known electrostatic spraying device or its principle can be used. Further, the charged and discharged dispersion liquid is discharged toward a charged substrate having a charge opposite to that of the dispersion liquid, and is applied to the surface of the substrate. The substrate is usually placed on a metal board, and the board is charged by charging the board.

  The voltage applied to the dispersion and the voltage applied to the substrate depend on the type and size of the ferroelectric nanoparticles, the required amount of the ferroelectric nanoparticles, and the like. Can be 2 to 20 kV, especially 2 to 15 kV. Further, the voltage applied to the substrate charged to have the opposite charge to that of the dispersion can be 1 to 15 kV, particularly 2 to 10 kV.

  The dispersion medium is removed from the dispersion liquid applied to the substrate to form a ferroelectric nanoparticle aggregate in which a required amount of ferroelectric nanoparticles is accumulated on the substrate. At this time, in order to efficiently accumulate the ferroelectric nanoparticles on the substrate, it is necessary that a required amount of the dispersion medium remains in the dispersion applied to the surface of the substrate. Therefore, the above-mentioned high boiling point solvent is used as the dispersion medium. In order to quickly and surely remove such a high boiling point solvent, it is necessary to heat the substrate.

  Although the heating temperature of the substrate is not particularly limited, a high-boiling solvent of about 150 to 200 ° C. is usually used as the dispersion medium, and thus the heating temperature is preferably 50 to 90 ° C., particularly preferably 50 to 70 ° C. Further, it is preferable that the heated and evaporated dispersion medium is promptly removed from the atmosphere in which the ferroelectric nanoparticles are accumulated. Thereby, the removal of the dispersion medium from the dispersion liquid applied to the substrate is continuously and efficiently performed. (This is an image of the ferroelectric nanoparticle aggregate from which the dispersion medium has been removed by electron microscope observation. 2 and 3).

[2] Ferroelectric Nanoparticle Accumulator The ferroelectric nanoparticle accumulator (see FIG. 1) of the present invention is an accumulator used for the ferroelectric nanoparticle accumulating method of the present invention, in which a substrate is housed. Chamber, a nozzle for electrostatic spraying attached to the upper part of the chamber, a board for mounting a substrate disposed at a position facing the opening of the nozzle for electrostatic spraying at the lower part of the chamber, and a board for mounting the substrate , A power supply for applying a voltage to the electrostatic spray nozzle, and a power supply for applying a voltage to the substrate mounting board.

  As the ferroelectric nanoparticle accumulator, for example, a ferroelectric nanoparticle accumulator 10 as shown in FIG. 1 can be used. In the integrated device 10 of FIG. 1, the chamber 1 may be formed of an electrically insulating material, or may be formed of an electrically conductive material. The electric insulating material is not particularly limited, but it is preferable to use a thermoplastic resin which is easy to mold. The thermoplastic resin is not particularly limited, and acrylic resins such as polymethyl methacrylate, polyolefin resins such as polyethylene and polypropylene, and polyamide resins such as nylon 6 and nylon 66 can be used. The electrically conductive material is not particularly limited, and stainless steel or the like can be used. When the chamber 1 is made of an electrically conductive material, it is necessary to dispose a member for electrical insulation at a required position in contact with the nozzle 2 for electrostatic spraying (the insulation of FIG. 1). See section 12).

  Although the shape of the chamber 1 is not particularly limited, it can be usually a rectangular parallelepiped or a cube, particularly a rectangular parallelepiped like the chamber 1 in FIG. When the material of the chamber 1 is an electrically insulating material, a method of joining each edge of a thermoplastic resin sheet having a square shape or a rectangular shape with an adhesive or heat-sealing the material when the material is an electrically insulating material is used. Can be formed. On the other hand, when the material is an electrically conductive material, the material can be formed by bending a material having a square shape or a rectangular shape in plan view and joining necessary portions as necessary.

  An electrostatic spray nozzle 2 is attached to the upper part of the chamber 1. Since the electrostatic spray nozzle 2 needs to be charged so as to have either positive or negative charge, it is formed of a metal tubular body. The metal is not particularly limited, and includes stainless steel, aluminum and the like. However, stainless steel is preferable in consideration of strength, corrosion resistance and the like. The cross-sectional shape in the radial direction of the nozzle 2 for electrostatic spraying is not particularly limited, and may be a circle, an ellipse, a square, or the like.

  In addition, a substrate mounting board 3 is disposed in a lower portion of the chamber 1 at a position facing the opening 21 of the electrostatic spray nozzle 2. Since the substrate mounting board 3 needs to be charged so as to have a charge opposite to that of the dispersion together with the substrate 4 to which the charged dispersion discharged from the electrostatic spray nozzle 2 is applied. , Made of a metal plate. The metal is not particularly limited, and includes stainless steel, aluminum and the like. However, stainless steel is preferable in consideration of strength, corrosion resistance and the like.

  Further, in order to accumulate the ferroelectric nanoparticles on the surface of the substrate 4, it is necessary to remove the dispersion medium from the dispersion applied to the surface of the substrate 4. Therefore, the substrate mounting board 3 is heated. Heater 5 is provided. The substrate mounting board 3 does not need to be heated to a particularly high temperature and is made of a metal, and is easily heated because it is a plate-like body. As the heater 5, various kinds of heaters such as a halogen lamp heater and an infrared lamp heater are available. Heater can be used.

  In the ferroelectric nanoparticle accumulating apparatus 10, a pump 6 for discharging gas in the chamber 1 to the outside is provided below the chamber 1, and a ventilation opening 11 is provided above the chamber 1. Is preferred. Although the dispersion medium is removed from the dispersion applied to the surface of the substrate 4, if the removed dispersion medium stays in the chamber 1, further removal of the dispersion medium is hindered. Therefore, by disposing the pump 6, the gas in the chamber 1 is quickly discharged to the outside, and the dispersion medium can be efficiently removed from the dispersion applied to the surface of the substrate 4.

  It is sufficient that the pump 6 can quickly and quantitatively discharge the gas in the chamber 1, and a diaphragm pump or the like can be used as the pump 6. Further, the air is sucked from the ventilation opening 11 provided in the upper part of the chamber 1 with the exhaust, and the atmosphere in the chamber 1 can be kept substantially constant. The ventilation opening 11 only needs to be quickly sucked in with the same amount of air as the air is exhausted. A tubular body made of resin, metal or the like having a required opening area is inserted through the wall surface of the chamber 1. Alternatively, an opening having a predetermined area may be provided on the wall surface of the chamber 1.

  The ferroelectric nanoparticle accumulating apparatus 10 includes a dispersion liquid supply unit 7 for sending and supplying the dispersion liquid to the electrostatic spray nozzle 2 through a pipe, in addition to the various members described above. The dispersion liquid supply means 7 only needs to be able to quantitatively supply the dispersion liquid to the electrostatic spray nozzle 2, and for example, a syringe pump or the like can be used. Further, the ferroelectric nanoparticle accumulation device 10 includes a power supply 81 for applying a voltage to the nozzle 2 for electrostatic spraying and a power supply 82 for applying a voltage to the board 3 for mounting a substrate. The electrostatic spray nozzle 2 and the substrate mounting board 3 are charged by these power sources 81 and 82, whereby the dispersion liquid and the substrate 4 can be charged to have opposite charges. The distance between the electrostatic spray nozzle 2 and the substrate 4 can be changed according to the application area and the like. Further, the power supplies 81 and 82 may be a single power supply having outputs of both positive and negative polarities.

[3] Method of Manufacturing Electronic Component The method of manufacturing an electronic component according to the present invention is characterized in that ferroelectric nanoparticles are dispersed in a dispersion medium, and a charged dispersion is charged so as to have a charge opposite to that of the dispersion. The method is characterized in that the dispersion medium is ejected toward the substrate, and the dispersion liquid is applied to the surface of the substrate, while the dispersion medium contained in the applied dispersion liquid is removed to form a ferroelectric nanoparticle aggregate. I do.

  In this method of manufacturing an electronic component, the description of the ferroelectric nanoparticles, the dispersion medium, and the substrate are the same as those described in the above [1] Ferroelectric nanoparticle accumulation method and [2] Ferroelectric nanoparticle accumulation device. Can be applied. Further, regarding the charging of the dispersion medium and the substrate, the discharge of the dispersion, the application of the dispersion to the substrate surface, and the removal of the dispersion medium, the above-mentioned [1] Ferroelectric nanoparticle integration method and [2] Ferroelectricity The description for each of the body nanoparticle accumulation devices can be applied as it is.

  Further, according to the method of manufacturing an electronic component, various useful electronic components can be manufactured. Examples of the electronic component include a multilayer ceramic capacitor, a ceramic capacitor, a PTC thermistor, a temperature sensor, a piezoelectric element, and a ferroelectric memory. , An infrared detecting element, an X-ray generating element, an actuator and the like.

Hereinafter, the present invention will be specifically described with reference to examples.
A ferroelectric nanoparticle assembly was formed on the surface of the substrate 4 using the ferroelectric nanoparticle accumulation device 10 as shown in FIG. The apparatus 10 is configured such that a dispersion liquid in which positively charged ferroelectric nanoparticles are dispersed in a dispersion medium is continuously flowed down by an electrostatic spraying nozzle 2 charged by a power supply 81 in a chamber 1 to be preheated. This is an apparatus that discharges toward the negatively charged substrate 4 on the substrate mounting board 3, removes the dispersion medium while accumulating, and forms a ferroelectric nanoparticle aggregate on the surface of the substrate 4.

  In the ferroelectric nanoparticle accumulating apparatus 10, a dispersion liquid supply means 7 for containing the dispersion liquid and supplying it quantitatively to the electrostatic spray nozzle 2 is disposed above the outside of the chamber 1, and the dispersion liquid is supplied. The dispersion liquid is supplied from the dispersion liquid supply means 7 to the electrostatic spray nozzle 2 disposed from the upper part of the chamber 1 toward the inside through a stainless steel pipe. The silicon wafer substrate 4 on which the ferroelectric nanoparticles were to be accumulated was placed on the substrate placing board 3 at a distance of 40 mm immediately below the opening 21 at the lower end of the electrostatic spray nozzle 2.

  Using the integrated device 10 as described above, a DC voltage is applied to the substrate 4 mounted on the substrate mounting board 3 by the power supply 82, while a positive voltage is applied to the electrostatic spray nozzle 2 by the power supply 81. Thus, the dispersion liquid discharged from the electrostatic spray nozzle 2 is made to have a positive charge, and the dispersion liquid is discharged toward the substrate 4 having a negative charge by applying a negative voltage from the power supply 82. Further, in order to promote the accumulation of the ferroelectric nanoparticles, a heater 5 (halogen lamp) for heating the substrate mounting board 3 on which the substrate 4 is mounted to a required temperature is provided.

  Further, with the vaporization of the dispersion medium (high-boiling-point solvent) contained in the dispersion, the vaporized dispersion medium is prevented from filling the chamber 1, and the formation of the ferroelectric nanoparticle accumulation having a predetermined thickness is suppressed. An opening 11 for ventilation was provided above the side surface of the chamber 1 so as to be maintained, and a pump 6 (diaphragm pump) was provided on the lower surface of the chamber 1. Thereby, the inside of the chamber 1 was maintained at the atmospheric pressure by ventilating the inside of the chamber 1 by the exhaust by the pump 6 and the inflow of the atmosphere from the ventilation opening 11.

Example 1
Barium titanate nanoparticles having an average particle size of 29.6 nm (with a standard deviation of 10% or less) are supplied from the dispersion liquid supply means 7 to the electrostatic spray nozzle 2 which is grounded by the power supply 81 and charged to +4 kV. While supplying a dispersion liquid dispersed in mesitylene at a concentration of 7 mg / mL at a flow rate of 70 μL / min for 30 seconds, mounted on the substrate mounting board 3 and grounded by a power source 82; It was integrated on a substrate 4 charged to -2 kV. Further, in order to vaporize mesitylene from the accumulated dispersion liquid and remove it efficiently, the substrate mounting board 3 on which the substrate 4 was mounted was heated to 60 ° C. from below by a halogen lamp. Further, the gas was exhausted by the pump 6 so that the vaporized mesitylene did not stay in the chamber 1. As a result, the inside of the chamber 1 was kept in the atmosphere by the air flowing from the ventilation opening 11 simultaneously with the exhaust.

  As described above, the barium titanate nanoparticles are arranged and accumulated on the surface of the substrate 4 and have a thickness of about 500 nm as shown in the scanning electron microscope observation image of FIG. Could be formed. The number of layers calculated from the thickness of the ferroelectric nanoparticle assembly and the average particle size of the barium titanate nanoparticles is approximately 17 layers.

Example 2
A ferroelectric nanoparticle assembly was formed in the same manner as in Example 1 except that the substrate 4 charged at -4 kV was used. As a result, barium titanate nanoparticles are arranged on the surface of the substrate 4 and formed into a ferroelectric nanoparticle aggregate having a thickness of about 500 nm as shown in the image observed by the scanning electron microscope in FIG. I was able to.

Comparative Example 1
An attempt was made to form a ferroelectric nanoparticle aggregate in the same manner as in Example 1 except that no voltage was applied to the substrate 4. As a result, as shown in the image observed by the scanning electron microscope in FIG. 4, relatively large droplets adhered to the surface of the substrate 4, and a uniform integrated layer was not formed.

Comparative Example 2
An attempt was made to form a ferroelectric nanoparticle aggregate in the same manner as in Example 1, except that the electrostatic spray nozzle 2 was charged to +12 V and no voltage was applied to the substrate 4. As a result, as shown in the image observed by the scanning electron microscope in FIG. 5, the particles were agglomerated on the surface of the substrate 4 and secondary particles of about several hundred nm were deposited.

  In addition, the ferroelectric nanoparticle aggregate of Example 1 and the aggregate of the comparative example 1 in which relatively large droplets adhere to the surface of the substrate 4 have a ferroelectric substance with respect to the entire area of the aggregate surface. The proportion of nanoparticles present, in other words the particle packing, was measured. As a result, in the ferroelectric nanoparticle aggregate of Example 1 (see FIG. 6), the particle filling rate was about 96%, and in the aggregate of Comparative Example 1 (see FIG. 7), the particle filling rate was about 79%. Also, it can be seen from the particle packing ratio that in Comparative Example 1, the nanoparticles were not sufficiently accumulated, and that there were many voids.

  Further, according to the X-ray diffraction image of FIG. 8, in Comparative Example 1 (the lower diffraction line of the three diffraction lines) and Comparative Example 2 (the middle diffraction line of the three diffraction lines). The peak on the 110 plane indicating that the nanoparticles are not oriented in the predetermined direction is high, and the peak on the 200 plane indicating that the nanoparticles are oriented in the predetermined direction is low. On the other hand, in Example 1 (the upper diffraction line of the three diffraction lines), the peak on the 110 plane was low and the peak on the 200 plane was extremely high, indicating that the nanoparticles were in a predetermined direction, that is, charged. It turns out that it is fully oriented in the direction. Thus, it can be seen that in Example 1, a ferroelectric nanoparticle assembly useful as an electronic component was formed.

  INDUSTRIAL APPLICABILITY The present invention includes ferroelectric nanoparticles having various characteristics integrated on a substrate, and can be suitably used in the technical field of various electronic components such as a multilayer ceramic capacitor, a PTC thermistor, and a piezoelectric element.

  Reference Signs List 10: ferroelectric nanoparticle accumulating device, 1: chamber, 11: ventilation opening, 12: insulating portion, 2: electrostatic spray nozzle, 21; electrostatic spray nozzle opening, 3: substrate mounting Board, 4; substrate, 5; heater, 6; pump, 7; dispersion liquid supply means, 81, 82;

Claims (6)

A ferroelectric nanoparticle accumulation method for accumulating ferroelectric nanoparticles on a surface of a substrate,
The ferroelectric nanoparticles are dispersed in a dispersion medium, and the charged dispersion is discharged toward the substrate charged to have a charge opposite to that of the dispersion, and the surface of the substrate is charged with the charged dispersion. A method for accumulating ferroelectric nanoparticles, comprising removing a dispersion medium contained in an applied dispersion while applying the dispersion.   The ferroelectric nanoparticle accumulation method according to claim 1, wherein the ferroelectric nanoparticles are tetragonal ferroelectrics.   3. The method according to claim 1, wherein the dispersion is discharged by electrostatic spraying. A ferroelectric nanoparticle accumulation device used in the ferroelectric nanoparticle accumulation method according to any one of claims 1 to 3,
A chamber for accommodating a substrate therein, an electrostatic spray nozzle attached to an upper portion of the chamber, and a substrate mounting member disposed at a position opposite to an opening of the electrostatic spray nozzle at a lower portion of the chamber. Board, a heater for heating the substrate mounting board, a power supply for applying a voltage to the electrostatic spray nozzle, and a power supply for applying a voltage to the substrate mounting board, A ferroelectric nanoparticle accumulation device, comprising:   The ferroelectric nanoparticle accumulation device according to claim 4, wherein the chamber has an opening for ventilation, and the chamber is provided with a pump for discharging gas in the chamber to the outside. A method for manufacturing an electronic component including a substrate and a ferroelectric nanoparticle assembly formed on a surface of the substrate,
The ferroelectric nanoparticles are dispersed in a dispersion medium, and the charged dispersion is discharged toward the substrate charged so as to have a charge opposite to that of the dispersion, and the dispersion is dispersed on the surface of the substrate. A method for producing an electronic component, comprising: forming a ferroelectric nanoparticle assembly by removing a dispersion medium contained in a coated dispersion liquid while applying the liquid.