JP2009094055A - Manufacturing method of insulating layer for field emission element, and manufacturing method of the field emission element substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method in which a manufacturing process of a field emission element substrate can be simplified markedly. <P>SOLUTION: In the manufacturing method of an insulating layer for the field emission element in which a process to form a coating film 7 containing beads 6 and a process for removing the beads 6 are included, in this order, a particle diameter of the beads 6 are larger than the thickness of the coating film, in a region that does not contain the beads, and the porosity of the insulating layer obtained from the coating film in a region that does not contain the beads 6 is 10% or lower. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an insulating layer for a field emission device, a method for manufacturing a field emission device substrate, and a composition for an insulating layer.

  In recent years, field electron emission displays (FEDs), liquid crystal backlights using field electron emission, and illumination have been actively developed. As an example of a field emission device substrate used in the FED, the most general structure of a field emission device substrate using carbon nanotubes as a field emission material is shown in FIG. A cathode electrode 3, an insulating layer 2 in which a via hole is formed on a glass substrate 4, and a gate electrode 1, and a (field) electron emission layer (CNT emitter 5) containing carbon nanotubes on the cathode electrode exposed in the via hole. Is formed. A general FED includes a field emission device substrate shown in FIG. 1, and a front substrate on which an anode transparent electrode and a phosphor layer are opposed to each other with a spacer interposed therebetween. Electrons are extracted from the field electron emission layer by the gate electrode, and light is emitted by irradiating the phosphor layer on the anode electrode.

  In manufacturing a field emission device substrate at a low cost, how to form a via hole in an insulating layer and a gate electrode is a big problem in how many processes are reduced. Therefore, in Patent Document 1, for example, a transparent cathode is formed on a transparent substrate, and a large number of particles opaque to ultraviolet light are placed in a dispersed state on the cathode surface to partially cover the cathode surface, and a dispersion mask is formed. After forming a negative photosensitive insulating material layer on it, exposing and developing from the back of the substrate, removing the insulating material layer present on the dispersion mask, and further forming a conductive layer thereon, A method of manufacturing a field emission device substrate by removing a dispersion mask and an overlying conductive layer is disclosed. In this method, a field emission device substrate can be manufactured by self-alignment without using an exposure mask. Therefore, there is an advantage that expensive manufacturing equipment such as a mask aligner is not required. However, since a negative photosensitive insulating material is used, the step of exposure and development is essential, and further simplification of the process is desired.

Further, for example, Patent Document 2 discloses a method for manufacturing an inorganic porous thin film having a large number of holes whose openings are substantially circular and whose inner peripheral surface is substantially spherical. Since this method does not use a photosensitive material, a step of exposing and developing is unnecessary. However, when the gate electrode as shown in FIG. 1 is formed using the disclosed inorganic porous thin film, there is a concern that dielectric breakdown may occur, and it could not be used for the field emission device substrate having the configuration shown in FIG.
JP-A-2005-116417 (Claim 1) JP-A-2005-231966 (Claim 5)

  The present invention pays attention to the above problems, and an object thereof is to provide a manufacturing method capable of greatly simplifying the manufacturing process of a field emission device substrate.

  That is, the present invention is a method for manufacturing an insulating layer for a field emission device including a step of forming a coating film containing beads and a step of removing beads in this order, wherein the beads have a particle size not including beads. This is a method for producing an insulating layer for a field emission device in which the porosity of the insulating layer obtained from the coating film in the region not including beads is 10% or less. The present invention also provides a method for manufacturing a field emission device substrate, which includes a step of forming a coating film containing beads, a step of forming a layer containing a conductive material on the coating film, and a step of removing beads. The bead particle size is larger than the total thickness of the coating film in the region not containing the bead and the layer containing the conductive material, and the porosity of the insulating layer obtained from the coating film in the region not containing the bead is 10%. It is the manufacturing method of the field emission element substrate which is the following.

  According to the present invention, the number of manufacturing processes of a field emission device substrate having a high dielectric breakdown voltage and high reliability can be greatly simplified.

  A method for manufacturing the insulating layer for a field emission device according to the present invention will be described. The method for producing an insulating layer for a field emission device of the present invention includes a step of forming a coating film containing beads and a step of removing the beads in this order, and the coating film in the region where the particle size of the beads does not include the beads. It is characterized in that the porosity of the insulating layer obtained from the coating film in the region which is larger than the thickness and does not contain beads is 10% or less. FIG. 2 shows a schematic diagram of a method for manufacturing an insulating layer for a field emission device. An insulating layer composition coating film 7 is formed so that the beads 6 are in contact with the cathode electrode 3 on the glass substrate 4. Next, by removing the beads, an insulating layer in which a via hole is formed can be manufactured. A composition coating containing a field emission source material may be further formed on the cathode electrode 3 on the glass substrate 4.

  Here, the bead is a substantially spherical material that is finally removed, and indicates a particle having a particle diameter of 3 μm or more. The material may be organic or inorganic. In the case of an organic substance, for example, spherical particles such as polystyrene can be used. In the case of an inorganic substance, for example, spherical particles such as glass, silica and zirconia can be used. From the viewpoint of easy availability and particle size uniformity, liquid crystal spacer materials such as silica and glass beads and size standard samples such as polystyrene spheres are preferably used. Moreover, an organic substance is more preferable from the viewpoint of simplifying the process in the step of removing beads described later.

  By making the particle size of all the beads larger than the thickness of the coating film in the region not containing the beads, it is possible to prevent the formation of cavities in the insulating layer formed from the coating film. As a result, the porosity of the insulating layer can be reduced to 10% or less, and a decrease in dielectric breakdown voltage and a decrease in mechanical strength can be suppressed. Even in the case of having a plurality of beads, it is necessary to make the particle size of all the beads larger than the thickness of the coating film. Here, the thickness of the coating film refers to the thickness of the film obtained after removing the solvent by drying when a coating liquid containing a solvent is applied. The thickness of the coating film can be measured by observing the cross section with an electron microscope (for example, a transmission electron microscope H7100 manufactured by Hitachi, Ltd.). The particle size of the beads can be measured with an electron microscope (for example, a transmission electron microscope H7100 manufactured by Hitachi, Ltd.). The diameter of the via hole to be formed can be adjusted by the particle diameter of the beads. In order to suppress an electrical short circuit or dielectric breakdown between the gate electrode and the field emission device, the generally used field emission device insulating layer preferably has a thickness of 3 μm or more. Therefore, the bead particle size in the present invention is 3 μm or more. It is. In order to adjust the number of via holes per unit area to an appropriate range, the particle size of the beads is preferably 100 μm or less. If the bead particle size is small, the distance between the opening at the bottom of the via hole where the electron emission source is formed and the edge of the via hole where the gate electrode is formed can be shortened, and the voltage applied to the gate voltage can be reduced. Can do. Therefore, it is more preferably 70 μm or less. More preferably, it is 25 μm or less, and a general-purpose drive driver for liquid crystal can be used.

  The coating film containing beads refers to a coating film of a composition containing beads and an insulating material. The insulating material may be an organic insulating material such as polyimide or an inorganic insulating material such as glass powder or ceramic powder. An inorganic insulating material-containing coating film is preferable because it can remove organic components through a baking process and has little outgas even in a vacuum. In particular, it is preferable that the coating film containing beads includes glass powder that can be fired at a lower temperature than ceramic powder. Here, the glass powder refers to those having a particle size of less than 3 μm, and spherical glass particles having a particle size of 3 μm or more are classified as beads. An insulating thin film such as silica produced by a vacuum thin film process such as vapor deposition, sputtering, or CVD can also be used. The thickness of the coating film in the region not containing the beads is generally 3 μm or more in order to suppress electrical short circuit and dielectric breakdown between the gate electrode and the field emission device as described above. Moreover, 100 micrometers or less are preferable. By setting the thickness to 100 μm or less, the gate voltage for emitting electrons can be further reduced. More preferably, it is 30 micrometers or less, More preferably, it is 10 micrometers or less. Since the electron emission start voltage of CNT often emits electrons when the gate voltage is 10 V / μm or less, a general-purpose IC driver with a withstand voltage of 100 V can be used as the gate electrode driver if the thickness of the coating film is 10 μm or less. .

  In order to suppress dielectric breakdown of the insulating layer formed from the coating film, the porosity needs to be 10% or less. More preferably 5% or less, and even more preferably 3% or less, the possibility of dielectric breakdown can be further reduced.

The porosity (P) of the insulating layer is calculated by the following equation by measuring the true specific gravity (dth) and the apparent specific gravity (dex) of the insulating layer.
P = (dth−dex) / dth × 100
The true specific gravity (dth) and apparent specific gravity (dex) of the insulating layer are calculated using the so-called Archimedes method. The insulating layer is pulverized to a level of 325 mesh or less with a mortar so that it does not feel on the fingertip, and the true specific gravity is determined by the method described in JIS-R2205 (1992). The apparent specific gravity (dex) can be measured using the Archimedes method in the same manner as described above except that the insulating layer portion is scraped so as not to break the shape and is not pulverized.

  When the coating film containing beads includes glass powder, the average particle size of the glass powder is preferably 0.05 μm or more, and more preferably 0.1 μm or more in order to prevent thickening of the coating film. In order to form an insulating layer having smooth and high-definition via holes, the average particle size of the glass powder is preferably small, preferably 2 μm or less, and more preferably 1 μm or less. Here, the average particle diameter of the glass powder refers to a cumulative 50% particle diameter obtained using a particle size distribution meter (for example, Microtrack 9320HRA manufactured by Nikkiso Co., Ltd.). Moreover, it is preferable that the glass softening point of the glass powder is 600 ° C. or lower because an inexpensive glass substrate can be used. More preferably, it is 500 ° C. or less, and an inexpensive soda lime glass substrate can be used. Furthermore, when carbon nanotubes are used as a field emission source, the field emission characteristics deteriorate when the carbon nanotubes are baked at 500 ° C. or higher. However, if the glass softening point of the glass powder is 450 ° C. or lower, the field emission characteristics are maintained. It is more preferable because it can be fired simultaneously with the carbon nanotubes. As the glass powder, low softening point glass such as lead glass, bismuth glass, and alkali glass can be used. Bismuth glass and alkali glass are preferable from the viewpoint of environmental load.

  The coating film containing beads may contain a filler and a dispersant as necessary. The filler is one having a particle size of less than 3 μm. Glass powder can be used if the inorganic oxide, ceramics, and softening point are higher than the firing temperature. The average particle size of the filler is preferably 0.05 μm or more, and more preferably 0.1 μm or more in order to prevent thickening of the coating film. Further, in order to form an insulating layer having a smooth and high-definition via hole, it is preferably 2 μm or less, and more preferably 1 μm or less.

  The pattern shape and porosity can be adjusted by the content ratio of the glass powder and filler. As the filler ratio is increased, the pattern shape is easily maintained, but the porosity is increased. Therefore, although depending on the firing temperature and the softening point of the glass powder, in order to maintain the pattern shape and reduce the porosity to 10% or less, glass powder / filler = 95/5 to 65/35 is preferable in volume ratio. More preferably, it can be made 5% or less by making it 95 / 5-70 / 30. More preferably, it can be made 3% or less by making it 95/5 to 90/10.

  As a process of forming a coating film containing beads, a bead-containing composition is prepared in advance, a method of applying the bead-containing composition on a substrate, a coating film is prepared in advance using a composition not containing beads, And a method of arranging the beads in advance, and a method of arranging the beads in advance and applying a composition containing no beads from the beads. In view of the small number of processes, a method of preparing a bead-containing composition in advance and applying the bead-containing composition on a substrate is preferable. Regardless of whether or not the beads are contained, a known coating method such as screen printing, a slit die coater, or a spinner can be used as a coating method of the composition. Screen printing and a slit die coater are more preferable because the coating area can be easily controlled.

After forming the coating film containing beads, it is preferable to further include a step of applying a force substantially downward downward to the coating film containing beads. Here, “vertically downward” refers to a direction in which a coating film containing beads is vertically pressed against a substrate. By applying a vertical downward force, the contact area between the bead and the underlying cathode electrode or composition coating containing the electron emitting material is increased. As a result, the opening area after removing the beads can be widened to increase the region where the electron emission source can be formed, and the field electron emission characteristics (current voltage characteristics) can be improved. The opening area is preferably 1 μm ² or more. For example, as shown in FIG. 4, when the composition coating film 11 containing the electron emission material is formed on the cathode electrode 3, the bead is pushed into the composition coating film containing the electron emission material, whereby the bottom of the via hole The opening area can be increased. Further, as shown in FIG. 5, when the beads are organic, the opening area of the bottom of the via hole can be increased by crushing the beads themselves.

  In the step of applying force substantially vertically downward to the coating film containing beads, it is preferable to apply heat together with the force. By applying heat, the fluidity of the bead or the coating film containing the bead can be improved, and the opening area of the bottom of the via hole can be further expanded. When the beads are organic, it is preferable to apply heat above the glass transition temperature of the beads, so that the beads can be easily crushed and the opening area can be further expanded. When the coating film containing beads contains a polymer component such as a binder, it is preferable to apply heat so as to be higher than the glass transition temperature of the polymer component, thereby improving the fluidity of the coating film containing beads. The opening area can be further increased. It is more preferable to apply heat above the glass transition temperature of the bead and the coating film including the beads because both the flexibility of the bead and the fluidity of the coating film including the beads are improved. The glass transition temperature is measured using a differential scanning calorimeter (for example, DSC-50 type measuring device manufactured by Shimadzu Corporation), and the temperature is increased at a constant rate of temperature to start the baseline deviation. Can be the glass transition temperature.

For the step of applying a force substantially vertically downward to the coating film containing beads, a known one such as a roller or a press can be used. For the process of applying heat to the coating film containing beads approximately vertically downward with force, a known one such as a heat press or a heated roller press can be used. The force applied vertically downward is preferably 10 ⁻¹ to 10 ⁵ N per 1 m ² area, although it depends on the thickness of the glass substrate. By setting it as this range, the opening area of the via hole bottom can be expanded without breaking the glass substrate.

  Examples of the step of removing the beads include a method of removing using a solvent in which the beads are selectively dissolved, a method of forcibly removing by an air blow, and a method of thermally decomposing by heating. A preferred method can be selected depending on the type of beads used. When the beads are organic, a method of removing them using a solvent in which the beads are selectively dissolved, or a method of removing them by thermal decomposition by heating is preferable. When the beads are inorganic, a method of removing them using a solvent that selectively dissolves the beads, or a method of forcibly removing them by air blow or the like is preferable. From the viewpoint of simplifying the process, a method of removing by thermal decomposition by heating using organic beads is more preferable.

  When the bead-containing composition contains glass powder, the insulating layer can be formed by subjecting the coating film to a baking treatment. When firing, firing may be performed in the step of removing the beads, or a separate firing step may be provided after removing the beads.

Next, the manufacturing method of the field emission device substrate of the present invention will be described. The method for manufacturing a field emission device substrate of the present invention includes a step of forming a coating film containing beads and a step of removing the beads in this order, and the bead particle size is larger than the thickness of the coating film in the region not containing the beads. The porosity of the insulating layer obtained from the coating film in the region not containing beads is 10% or less. It is also preferable as another aspect of the method for producing a field emission device substrate of the present invention to include a step of forming a layer containing a conductive substance on the coating film after the step of forming a coating film containing beads. . FIG. 3 shows a schematic diagram of a method for manufacturing a substrate for a field emission device. An insulating layer composition coating film 7 is formed so that the beads 6 are in contact with the cathode electrode 3 on the glass substrate 4, and further a conductive substance-containing composition coating film 8 is formed. Next, by removing the beads, an insulating layer in which a via hole is formed and a layer containing a conductive substance can be manufactured. A layer containing a conductive substance can be preferably used as a gate electrode. The conductive substance means a substance having a volume resistivity of 10 ⁵ Ωcm or less.

  Note that a composition coating containing an electron emission source material may be further formed on the cathode electrode 3 on the glass substrate 4. In this case, the composition coating film 7 for the insulating layer can be formed so that the beads 6 are in contact with the composition coating film containing the electron emission source material.

  The layer containing a conductive substance refers to a layer obtained from a conductive substance or a composition containing a conductive substance. Even a coating film of a conductive substance-containing composition such as metal particles may be a conductive thin film produced by a vacuum thin film process such as vapor deposition, sputtering, or CVD. The thickness of the layer containing the conductive substance is 0.5 to 5 μm in the case of the coating film of the conductive substance-containing composition, and 0.05 to 1 μm in the case of the conductive thin film produced by the vacuum thin film process. This is preferable in that the resistance of the layer containing a conductive substance can be lowered.

  The conductive material-containing composition is preferably composed mainly of metal particles or conductive particles of a conductive oxide, a binder polymer, and a solvent, and if necessary, contains glass particles to obtain adhesion to the base. May be. The conductive particles are preferably metal particles from the viewpoint of conductivity, and silver particles are more preferable in that they are difficult to oxidize and are easy to handle.

  The step of forming the coating film containing beads is as described above in the method for manufacturing the insulating layer for field emission elements. As described above, it is preferable to further include a step of applying a force substantially downward downward to the coating film including beads after the formation of the coating film including beads. Moreover, it is preferable to apply heat together with the force in the step of applying a force substantially downward downward to the coating film containing beads. These steps may be performed before or after the step of forming a layer containing a conductive material on a coating film containing beads. The step of forming a layer containing a conductive substance on the coating film includes a method of forming a metal material or a conductive oxide by a vacuum process such as vapor deposition or sputtering, or a method of applying a composition containing a conductive substance. Can be mentioned. From the viewpoint of process cost, a method of applying a conductive substance-containing composition is preferred. The conductive material is preferably gold, silver or copper. Moreover, you may contain glass particle and can improve adhesiveness with a foundation | substrate. As a conductive material-containing composition coating method, known coating methods such as screen printing, slit die coater, and spinner can be used. Screen printing and a slit die coater are more preferable because the coating area can be easily controlled.

  Next, the composition for insulating layers of the present invention will be described. In the method for producing an insulating layer for a field emission device and the method for producing a field emission device substrate, the composition is preferably used in a step of forming a coating film containing beads.

  The composition for an insulating layer of the present invention contains beads having a particle size of 3 μm or more and 100 μm or less, a polymer, glass powder, and a solvent, and may contain a filler and a dispersant as necessary.

  As the beads, those exemplified above in the description of the method for producing an insulating layer for a field emission device can be used.

  As the polymer, an acrylic or ethyl cellulose low-temperature pyrolyzed polymer is preferably used. The thermal decomposition temperature of the polymer is preferably 500 ° C. or lower because a soda lime glass substrate can be used. In order to prevent firing deterioration of the carbon nanotube, 400 ° C. or lower is more preferable. Here, the thermal decomposition temperature can be obtained, for example, by the following method. Set a sample of about 5 mg in a TG measuring device (TGA-50, manufactured by Shimadzu Corporation), and raise the temperature to 800 ° C. at a flow rate of 20 ml / min and a heating rate of 10 ° C./min in an air or nitrogen atmosphere. To do. As a result, a chart in which the relationship between temperature (vertical axis) and weight change (horizontal axis) is plotted is printed. The temperature at the intersection is taken as the thermal decomposition temperature.

  As glass powder, what was illustrated in description of the manufacturing method of the insulating layer for field emission elements previously can be used.

  As the solvent, a high boiling point solvent having a boiling point of 150 ° C. or higher and 250 ° C. or lower is preferably used in consideration of coating stability.

  As the filler, those exemplified above in the description of the method for producing an insulating layer for a field emission device can be used.

  A method for manufacturing a field emission element substrate using carbon nanotubes as a field emission source and a method for manufacturing a backlight using the same will be described below with reference to FIG. However, the present invention is not limited to this, and can also be applied to a method of manufacturing a field emission device substrate using a field emission material other than carbon nanotubes.

A cathode electrode 3 having a desired pattern is formed on a glass substrate 4 such as PD200 manufactured by Asahi Glass Co., which is a heat resistant glass for soda glass or a plasma display panel (PDP). The material of the cathode electrode 3 is preferably ITO, SnO ₂ , Cr, Al or the like. Examples of the pattern processing method include known methods such as an etching process using a photosensitive resist.

  Next, a carbon nanotube-containing composition is applied onto the cathode electrode 3 and dried. As a coating method, a known coating method such as screen printing, a slit die coater, or a spinner can be used. Screen printing is more preferable because the application area can be easily controlled. The carbon nanotube-containing composition contains carbon nanotubes, a binder polymer, and a solvent as main components, and preferably contains glass powder in order to adhere the carbon nanotubes on the cathode electrode. Further, a conductive material may be included to reduce the contact resistance between the carbon nanotube and the cathode electrode. In the film obtained by applying and drying the carbon nanotube-containing composition, the binder polymer is removed by baking to form a carbon nanotube-containing field emission film (CNT emitter 5). After the carbon nanotube-containing composition is applied, it may be fired, or when there is a firing process in the subsequent process, it may be fired all at once.

  On this, the coating film containing the above-mentioned beads is formed. For example, an insulating layer composition containing organic beads such as polystyrene is applied and dried to form a coating film containing beads. A layer containing a conductive material is formed thereon. For example, the conductive material-containing composition can be applied and dried.

  Next, the beads are removed. If the beads are polystyrene, the polystyrene can be dissolved and removed by dipping in an organic solvent such as limonene that dissolves the polystyrene. Moreover, when removing by thermally decomposing | disassembling by heating, it can decompose and remove by heating the coating film containing a bead more than the thermal decomposition temperature of a bead. The step of heating above the thermal decomposition temperature of the beads can also serve as the baking step when the coating film contains glass powder or when a layer containing a conductive substance is formed. Accordingly, when the firing step is performed, a method of thermally decomposing and removing the beads by heating is preferable because the number of processes can be reduced.

  When the step of removing the beads does not serve as the firing step, it is preferable to perform the firing after removing the beads. Thereby, the binder removal treatment of the film obtained by applying and drying the carbon nanotube-containing composition is performed. Moreover, when the coating film containing beads contains glass powder, the glass powder is baked to obtain the insulating layer 2. In addition, the gate electrode 1 is obtained by performing a binder removal treatment on the layer containing a conductive substance. The firing temperature needs to be higher than the softening point of the glass, but it is preferably 600 ° C. or lower because a glass substrate can be used, and more preferably 500 ° C. or lower because a cheaper soda glass substrate can be used. Since deterioration can be suppressed, 450 degrees C or less is more preferable. The firing atmosphere may be an air atmosphere or a nitrogen atmosphere, but firing in a nitrogen atmosphere is preferred in order to suppress firing deterioration of the carbon nanotubes.

  Next, the carbon nanotube-containing field emission film is activated as necessary. For this activation treatment, a known method such as tape peeling, sand blasting or laser irradiation can be used.

  Next, a front substrate is produced. An anode electrode 10 is formed by depositing ITO on a glass substrate such as soda lime glass or PD200 manufactured by Asahi Glass Co., Ltd., which is a heat resistant glass for PDP. A white phosphor layer 9 is laminated on the anode electrode 10 by a printing method. The field emission device substrate and the front substrate are bonded to each other with a spacer glass interposed therebetween, and a backlight using field emission can be manufactured by vacuum evacuation through an exhaust pipe connected to the container. By supplying a pulse voltage of 1 to 10 kV to the anode electrode and 1 to 200 V to the gate electrode, electrons are emitted from the carbon nanotubes and phosphor emission can be obtained.

  FIG. 7 shows a comparison table of an example of a process for manufacturing the field emission device substrate of the present invention and a process for manufacturing the field emission device substrate described in Patent Document 1. The number of manufacturing processes of the present invention can be reduced to half or less. Further, since an exposure and development process is not necessary, an expensive exposure apparatus is also unnecessary.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to this. The materials used for each composition are as follows.
Bead 1: Polystyrene beads (Microbeads manufactured by Techno Chemical Co., Ltd., particle size 4.7 to 5.49 μm, glass transition temperature 100 ° C.)
Bead 2: Polystyrene beads (Megabeads manufactured by Techno Chemical Co., Ltd., particle size 9.7 to 10.5 μm, glass transition temperature 100 ° C.)
Bead 3: Polystyrene beads (Technochemical Co., Ltd. mega beads, particle size 19.2 to 20.8 μm, glass transition temperature 100 ° C.)
Bead 4: Polystyrene beads (Mega beads manufactured by Techno Chemical Co., Ltd., particle size 48.0 to 52.0 μm, glass transition temperature 100 ° C.)
Bead 5: Polystyrene beads (Mega beads manufactured by Techno Chemical Co., Ltd., particle size 96.0 to 104 μm, glass transition temperature 100 ° C.)
Bead 6: Polystyrene beads (Mega beads manufactured by Techno Chemical Co., Ltd., particle size 122 to 128 μm, glass transition temperature 100 ° C.)
Bead 7: Zirconia beads (Torayserum manufactured by Toray Industries, Inc., particle size 30 μm)
Bead 8: Zirconia beads (Traceram manufactured by Toray Industries, Inc., particle size 50 μm)
Binder 1: Polymethyl methacrylate, glass transition temperature 105 ° C
Solvent 1: α-terpineol (manufactured by Wako Pure Chemical Industries, Ltd.)
Solvent 2: 3-methoxymethylbutanol (manufactured by Wako Pure Chemical Industries, Ltd.)
Glass powder 1: bismuth-based glass (bismuth oxide: 85 wt%, boron oxide: 4 wt%, silicon oxide: 1.5 wt%, zinc oxide: 9.5 wt%), glass softening point 415 ° C., average particle size 0.5 μm, Density 6g / cm ³
Filler powder 1: titania (Ishihara Sangyo Co., Ltd., TTO-55, particle size 35 to 45 nm, density 4.26 g / cm ³ )
Conductive particles 1: Silver powder, manufactured by Mitsui Mining & Smelting Co., Ltd., SPQ05S, specific surface area 1.08 m ² / g, density 10.5 g / cm ³ , average particle size 0.53 μm
Carbon nanotube 1: Shinzhen Nanotech PortCo. , Ltd., Ltd. S-DWNT made.

Measuring method of bead particle size The bead particle size used was measured with a transmission electron microscope H7100 manufactured by Hitachi, Ltd.

Measuring method of average particle diameter of glass powder, conductive particles and filler Using cumulative particle size distribution measuring device (Nikkiso Co., Ltd., Microtrac 9320HRA) for the used glass powder, conductive particles and filler. Measured.

Measurement of glass softening point The glass transition temperature of the glass powder used was measured using a thermomechanical analyzer (manufactured by Seiko Instruments Inc., EXTER6000 TMA / SS). Glass particles were melted at 800 ° C. and processed into a cylindrical shape having a diameter of 5 mm and a height of 2 cm to obtain a measurement sample.

Preparation method of composition for beads-containing insulating layer 3 g of beads, 26 g of glass powder 1, 4 g of filler powder, 20 g of binder 1, 20 g of solvent 2 so that the volume ratio of glass powder / filler powder is 82/18 After weighing 47 g, the mixture was mixed with a hybrid mixer (manufactured by Keyence Corporation, HM-500).

Method for Producing Conductive Particle-Containing Composition 59 g of conductive particles 1, 1 g of glass powder 1, 15 g of binder 1, and 25 g of solvent 2 are weighed and then mixed in a hybrid mixer (manufactured by Keyence Corporation, HM-500). did.

Method for Producing Carbon Nanotube-Containing Composition 1 g of carbon nanotube 1, 1 g of glass powder 1, 18 g of binder 1 and 80 g of solvent 1 were weighed and then kneaded with three rollers.

Method for Measuring Porosity The porosity (P) was calculated from the following equation by measuring the true specific gravity (dth) of the insulating layer and the apparent specific gravity (dex) of the insulating layer.
P = (dth−dex) / dth × 100
The true specific gravity (dth) of the insulating layer was calculated using a so-called Archimedes method. The insulating layer was pulverized to a level of 325 mesh or less using a mortar. And true specific gravity was calculated | required by the method of JIS-R2205 (1992). Next, the apparent specific gravity (dex) was measured using the Archimedes method in the same manner as described above except that the insulating layer portion was shaved so as not to break the shape and pulverization was not performed.

Method for measuring the thickness of the coating film in the region not containing beads The substrate was made into a small piece, and the cross section of 15 μm width was observed 10 times at 5000 times with an electron microscope (transmission electron microscope H7100 manufactured by Hitachi, Ltd.). The intermediate point between the maximum value and the minimum value was taken as the thickness.

Dielectric breakdown voltage measurement method Using a withstand voltage / insulation resistance tester TOS9201 manufactured by Kikusui Electronics Co., Ltd., boosting the voltage at 100 V DC / second and detecting the current exceeding 10 mA caused by the dielectric breakdown. It was.

Method of measuring the area of the opening at the bottom of the via hole The area of the opening at the bottom of the via hole was measured using an image analysis software obtained by observing the Nikon optical microscope ECLIPSE L200 accompanied with the Nikon digital camera DXM1200F. ACT-2U vers. 40 and analyzed.

Measuring method of field electron emission characteristics (current-voltage characteristics) A back substrate in which a 1 cm × 1 cm square field emission device is formed on an ITO substrate in a vacuum chamber having a degree of vacuum of 5 × 10 ⁻⁴ Pa, and an ITO substrate A front substrate on which a phosphor layer (P22) having a thickness of 5 μm was formed was opposed to each other with a 100 μm gap film interposed therebetween. Next, the current-voltage curve obtained when 1 kV was applied to the ITO electrode on the front substrate, the cathode electrode on the rear substrate was ground, and a pulse voltage with a duty ratio of 50% and a pulse width of 5 msec was applied to the gate electrode while gradually increasing. The voltage reaching 1 mA was determined. The voltage is preferably as low as possible, and particularly preferably below 40V, because a general-purpose drive driver for liquid crystal can be used.

Examples 1-6
A cathode electrode was formed by sputtering ITO on a 1.8 mm thick soda glass substrate. On the obtained cathode electrode, the carbon nanotube-containing composition was applied by screen printing and dried. On the carbon nanotube-containing coating film, the composition for bead-containing insulating layer using the beads shown in Table 1 was printed and dried by screen printing. Furthermore, on the coating film formed from this composition for bead containing insulating layers, the electroconductive particle containing composition was printed and dried by screen printing. Baking was performed at 450 ° C. for 15 minutes in a nitrogen atmosphere (temperature increase rate: 5 ° C./min) to obtain a field emission device substrate. The carbon nanotube film was activated with a tape having a peel adhesion strength of 0.5 N / 20 mm.

  Moreover, the phosphor was printed on the glass substrate which newly sputtered ITO, and the anode substrate was produced. A field emission device panel was fabricated by bonding a field emission device substrate and an anode substrate with a spacer glass sandwiched between them and evacuating them with an exhaust pipe connected to a container. A voltage of 1 kV was supplied to the anode electrode and a pulse voltage of 100 V was supplied to the gate electrode, and phosphor emission due to electron emission obtained from CNTs was confirmed.

Comparative Example 1
A field emission device substrate was produced in the same manner as in Example 1 except that instead of the beads 1, micro-beads (polystyrene beads, particle size 0.6 to 1.4 μm) manufactured by Techno Chemical Co., Ltd. were used. Most of the microbeads manufactured by Techno Chemical Co., Ltd. were encapsulated in the insulating layer coating film, and a via hole could not be formed. Moreover, the composition for insulating layers containing the microbeads made from Techno Chemical Co., Ltd. thickened, and the coating film thickness was not uniform. Moreover, the dielectric breakdown voltage was less than 100V.

Examples 7-8
The amount of the glass powder and the filler powder in the bead-containing insulating layer composition is 23.4 g of the glass powder and 6.6 g of the filler powder so that the volume ratio of the glass powder / filler powder is 72/28 in Example 7. In Example 8, a field emission device substrate was prepared in the same manner as in Example 2, except that 22.5 g of glass powder and 7.5 g of filler powder were used so that the volume ratio of glass powder / filler powder was 68/32. did.

Comparative Example 2
Example 1 except that the amount of glass powder and filler powder in the bead-containing insulating layer composition is 21 g of glass powder and 9 g of filler powder so that the volume ratio of glass powder / filler powder is 62/38. Similarly, a field emission device substrate was produced. Although the via hole was formed, the dielectric breakdown voltage was less than 100 V, and no voltage could be applied to the gate electrode.

Comparative Example 3
A field emission device substrate was prepared in the same manner as in Example 2 except that the bead-containing composition for insulating layer was printed and dried three times by screen printing. The thickness of the coating film in the region not containing the beads was 30 μm, and the beads were encapsulated in the insulating layer composition coating film, making it impossible to form a via hole.

Examples 9-16
After forming the coating film of the composition for bead-containing insulating layer shown in Table 3, the substrate was heated to 120 ° C. on a hot plate, and then a glass substrate heated to 120 ° C. was placed on the coating film and vertical for 5 minutes A field emission device substrate was fabricated in the same manner as in Example 1 except that a step of applying a force of 6.3 × 10 ² N per 1 m ² area downward was added.

Examples 17-18
A field emission device substrate was produced in the same manner as in Example 1 except that the bead-containing composition for insulating layer shown in Table 4 was used.

Examples 19-20
A field emission device substrate was produced in the same manner as in Example 9 except that the bead-containing composition for insulating layer shown in Table 4 was used.

  The result of each Example and a comparative example is shown to Tables 1-4.

Schematic diagram of a field emission device substrate using carbon nanotubes as an electron emission material Schematic diagram of manufacturing method of insulating layer for field emission device Schematic diagram of manufacturing method of field emission device substrate Schematic diagram of the process of applying force to the coating film containing beads approximately vertically downward Schematic diagram of the process of applying force to the coating film containing organic beads in a substantially vertical downward direction Schematic diagram of a backlight using carbon nanotubes as an electron emission source Comparison of field emission device manufacturing processes

Explanation of symbols

1: Gate electrode 2: Insulating layer 3: Cathode electrode 4: Glass substrate 5: CNT emitter 6: Beads 7: Composition coating for insulating layer 8: Conductive material-containing composition coating 9: Phosphor layer 10: Anode Electrode 11: Coating film containing electron emission material

Claims (12)

A method of manufacturing an insulating layer for a field emission device including a step of forming a coating film including beads and a step of removing beads in this order, and the thickness of the coating film in a region where the particle size of the beads does not include beads A method for producing an insulating layer for a field emission device, wherein the porosity of the insulating layer obtained from a coating film in a larger area not containing beads is 10% or less. The method for producing an insulating layer for a field emission device according to claim 1, wherein the beads are organic. The method for producing an insulating layer for a field emission device according to claim 1 or 2, wherein the particle size of the beads is 3 µm or more and 100 µm or less. The manufacturing method of the insulating layer for field emission elements in any one of Claims 1-3 in which the coating film containing a bead contains glass powder. A method of manufacturing a field emission device substrate, comprising: a step of forming a coating film containing beads; a step of forming a layer containing a conductive material on the coating film; and a step of removing beads. Field emission in which the bead particle size is larger than the total thickness of the coating film in the region not containing the bead and the layer containing the conductive material, and the porosity of the insulating layer obtained from the coating film in the region not containing the bead is 10% or less A method for manufacturing an element substrate. 6. The method of manufacturing a field emission device substrate according to claim 5, wherein the beads are organic. The method of manufacturing a field emission device substrate according to claim 5 or 6, wherein the bead has a particle size of 3 µm or more and 100 µm or less. The manufacturing method of the insulating layer for field emission elements in any one of Claims 5-7 in which the coating film containing a bead contains glass powder. The manufacturing method of the field emission element substrate in any one of Claims 1-8 which further includes the process of applying force to the coating film containing a bead substantially perpendicularly downward. The method of manufacturing a field emission device substrate according to claim 9, wherein in the step of applying a force substantially vertically downward to the coating film including beads, heat is applied together with the force. A composition for an insulating layer, comprising beads having a particle size of 3 μm or more and 100 μm or less, a polymer, glass powder having a particle size smaller than the particle size of the beads, and a solvent. The composition for insulating layers according to claim 11, wherein the beads are organic.

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