JP2012120950A - Fine particle spraying apparatus and fine particle fixing method - Google Patents

Abstract

A fine particle spraying apparatus and a fine particle fixing method capable of fixing fine particles having a small particle diameter on a substrate without agglomeration.
A fine particle spraying apparatus 1 for spraying droplets of a suspension 2 in which fine particles are dispersed in a dispersion medium onto a substrate 6 to volatilize the dispersion medium and fix the fine particles on the substrate 6. A sprayer 3 for spraying two droplets, a drying casing 4 having a casing surface 9 disposed obliquely with respect to the spraying direction of the suspension 2, and a gas introduced into the drying casing 4 in the first A heater 5 for heating to a temperature; a heated air introduction pipe 12 for introducing a gas heated to a first temperature into the drying casing 4 along the casing surface 9; and a drying casing heated to the first temperature. 4, a heater 7 that holds the substrate 6 on the downstream side of the housing surface 9 of the gas flow introduced into the gas 4 and heats the substrate 6 to a second temperature higher than the first temperature. The liquid droplets of the suspension 2 sprayed toward the housing surface 9 are conveyed by the flow of gas heated to the first temperature. Blown to the substrate 6.
[Selection] Figure 1

Description

  The present invention relates to a fine particle spraying apparatus and a fine particle fixing method for fixing fine particles to a substrate.

  There is a technique disclosed in Patent Document 1 as a technique for extracting only fine particles from a liquid in which fine particles are dispersed. In the invention disclosed in Patent Document 1, fine particles dispersed in a liquid are sprayed into a drying chamber heated by a sprayer. In the sprayer, means for charging the liquid by applying a high voltage to the nozzle portion is provided, and the charged liquid (aerosol) is sprayed toward the substrate to be sprayed. A potential can be applied to the substrate to be sprayed, and the aerosol is attracted to the substrate by the potential difference between the aerosol and the substrate.

JP 2004-160388 A

  However, when the substrate is an insulator such as glass, the method of Patent Document 1 described above has a problem that the charged liquid adheres to the substrate itself, and the sprayed liquid cannot efficiently reach the substrate. is there. Further, depending on the type of liquid and the material of the contained fine particles, it becomes difficult to charge the liquid, and it is difficult to generate a fine droplet diameter.

  When the dispersion medium is sprayed by a method that does not use charging, there is a problem that coarse droplets are easily generated and aggregation of fine particles occurs.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a fine particle spraying apparatus and a fine particle fixing method capable of fixing fine particles having a small particle diameter on a substrate without agglomeration.

  In order to solve the above-described problems and achieve the object, the present invention sprays a liquid droplet of a suspension in which fine particles are dispersed in a dispersion medium, volatilizes the dispersion medium, and fixes the fine particles on the substrate. A spray device for spraying droplets of a suspension, a drying casing having an inclined surface arranged obliquely with respect to a spraying direction of the suspension, and a gas introduced into the drying casing A first heater that heats the gas to the first temperature, a means for introducing the gas heated to the first temperature into the drying casing along the inclined surface, and the heating to the first temperature in the drying casing A second heater for holding the substrate downstream of the inclined surface of the introduced gas flow and heating the substrate to a second temperature higher than the first temperature; The suspension sprayed droplets are conveyed by a gas stream heated to a first temperature; And wherein the blowing the plate.

  According to the present invention, there is an effect that fine particles having a small particle diameter can be fixed on a substrate without agglomerating.

FIG. 1 is a diagram showing a configuration of a first embodiment of a fine particle spray device according to the present invention. FIG. 2 is a photomicrograph of the substrate surface sprayed with pure water containing silicon fine particles having a particle size of several μm or less using the fine particle spraying apparatus according to the first embodiment. FIG. 3 is a diagram showing a configuration of a second embodiment of the fine particle spray device according to the present invention.

  Hereinafter, embodiments of a fine particle spraying apparatus and a fine particle fixing method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a first embodiment of a fine particle spray device according to the present invention. The fine particle spray device 1 sprays a suspension 2 in which fine particles are dispersed in a dispersion medium from a sprayer 3. The sprayer 3 is connected to the drying housing 4. A gas heated by a heater 5 as a first heater is introduced into the dry casing 4 through a heated gas introduction pipe 12. A substrate 6 for fixing the fine particles is placed under the sprayer 3 with the drying housing 4 interposed therebetween. The substrate 6 is heated by a heater 7 as a second heater.

  The dispersion medium is selected according to the material and surface state of the fine particles used. For example, since fine silicon particles whose surfaces are oxidized exhibit hydrophilicity, pure water can be used as a dispersion medium. In the case of fine particles made of a material that is difficult to disperse in pure water, an alcohol or a surfactant may be added as appropriate. Further, in order to improve the stability of the fine particle dispersion in the dispersion medium, the dispersion medium in which the fine particles are dispersed may be stirred with ultrasonic waves or a stirring rod. The particle size of the fine particles depends on the performance of the sprayer 3, but is preferably several tens of μm or less from the viewpoint of dispersion stability.

  The nebulizer 3 may be a nebulizer used in a mass spectrometer, for example. When spraying silicon fine particles, a nebulizer made of quartz is used as the sprayer 3 to prevent the silicon fine particles from sticking into the nebulizer and closing the outlet. Therefore, the nebulizer made of quartz is more preferable than the nebulizer made of resin in terms of suppressing the clogging of the fine particles at the outlet of the sprayer 3. A suspension 2 in which fine particles are dispersed in a dispersion medium and a carrier gas 8 are introduced into the sprayer 3. The carrier gas 8 is ejected from the narrow tube at the tip of the sprayer 3 at a high speed. The type of carrier gas 8 may be any gas type that does not react with the dispersion medium or fine particles. For example, nitrogen gas or argon gas is suitable.

  The suspension 2 introduced into the tip of the sprayer 3 by a narrow tube different from the carrier gas 8 is discharged to the outside of the sprayer 3 due to the pressure in the vicinity of the jet outlet being reduced by the Bernoulli effect. The suspension 2 discharged from the sprayer 3 by the gas flow ejected at high speed becomes minute droplets. The diameter of the droplet depends on the flow rate of the gas, the viscosity of the liquid, and the surface tension, but is about 10 to 20 μm when pure water is used. The suspension 2 can be naturally sucked without using a pump by utilizing the pressure drop due to the Bernoulli effect as described above, but the ratio of the fine particles to the dispersion medium is large. When natural suction is difficult, liquid may be sent with a peristaltic pump. In addition, since the particle size of the droplet increases as the flow rate of the carrier gas 8 increases, the flow rate of the carrier gas 8 is a range in which the suspension 2 can be formed into droplets and the particle size of the droplets does not become too large. It is preferable that For example, when a commercially available nebulizer is used as the nebulizer 3, the flow rate of the carrier gas 8 is desirably in the range of 0.5 to 2 L / min.

  The nebulizer 3 is not limited to a nebulizer, and may have any configuration that can eject droplets containing fine particles having a particle size of several tens of μm. For example, as a known technique, an aerosol generating device or an ultrasonic mist generating device using a vibrating orifice may be used.

  As shown in FIG. 1, the dispersion medium containing the sprayed fine particles is introduced into the drying casing 4, but the gas heated by the heater 5 and introduced into the drying casing 4 through the heated gas introduction pipe 12. By adjusting the temperature and the flow velocity of the liquid, the dispersion medium contained in the droplets of the suspension 2 is set to a condition that does not completely evaporate in the dry casing 4 (below the boiling point of the dispersion medium). For example, when pure water is used as the dispersion medium, it is preferable to set the temperature of the heater 5 so that the average temperature in the dry casing 4 is 80 to 90 ° C. Moreover, the flow rate of the gas introduced into the drying housing 4 through the heated gas introduction pipe 12 is preferably set in the range of 1 to 5 L / min. If the flow rate of the gas introduced into the dry casing 4 through the heated gas introduction pipe 12 is too small, the number of liquid droplets that collide with the casing surface 9 as an inclined surface increases and the material efficiency decreases. Conversely, if it is too large, coarse droplets will land on the substrate 6 without colliding with the housing surface 9. However, the above-described flow velocity is merely an example, and changing the flow velocity of the heated gas according to the size of the dry casing 4 is a design category. The heated gas may be any gas that does not react with the dispersion medium and the fine particles. For example, when pure water is used as the dispersion medium and silicon is used as the fine particles, argon may be used as the heated gas.

  It is also effective to activate the surface of the fine particles by introducing the plasmad gas into the dry casing 4 using an atmospheric pressure plasma apparatus that converts the gas heated by the heater 5 into plasma. For example, it is possible to remove the natural oxide film on the surface of the silicon fine particles by adding 2 to 3 vol% of hydrogen gas to the gas to make the gas into plasma and irradiating the fine particle silicon. The occurrence of hydrogen explosion can be prevented by setting the amount of hydrogen gas below the explosion limit concentration. It is also possible to activate the surface of the fine particles using a reducing gas other than hydrogen.

  The suspension 2 (liquid in which fine particles are dispersed in a dispersion medium) sprayed from the sprayer 3 is sprayed on the housing surface 9 inclined in the substrate direction with respect to the spraying direction. On the other hand, the gas heated by the heater 5 is sprayed in a direction along the surface of the housing surface 9 to which the suspension 2 is sprayed. With this configuration, particles having large diameters and droplets collide with the casing surface 9 of the dry casing 4, while those having small diameters and droplets have small diameters along the casing surface 9 due to the flow of heated gas. Flowing in the direction With the above configuration, particles having relatively large diameters of fine particles and droplets can be separated. That is, since the droplet having a large diameter collides with the housing surface 9 because the influence of the air flow generated by the gas heated by the heater 5 is smaller than the gravity, the droplet having the small diameter is heated by the heater 5. Since the influence of the air flow made by the gas is stronger than the gravity, the air flows in the direction along the housing surface 9. Moreover, it is possible to prevent the coarse particles from falling onto the substrate 6 by installing the collecting plate 10 for collecting the coarse particles on the housing surface 9 located on the extension line from the sprayer 3. As the collection plate 10, for example, a mesh plate made of fine metal wires, a metal plate roughened with blasting, or the like is suitable.

  The substrate 6 is disposed on the extended line of the housing surface 9 inclined in the substrate direction via the dry housing 4 (on the downstream side of the gas flow heated by the heater 5). The heater 7 on which the substrate 6 is loaded is preferably set to a temperature equal to or higher than the boiling point of the dispersion medium. For example, when pure water is used as the dispersion medium, it is preferably 100 ° C. or higher, and preferably in the range of 120 to 180 ° C. Here, in order to prevent the drying casing 4 from being heated by the heat of the heater 7, the upper limit is 180 ° C. However, if the drying casing 4 is not affected by the heat of the heater 7, the heater It is also possible to set 7 to a temperature higher than this. In a state where the dispersion medium is partially evaporated by the dry casing 4, the droplets of the suspension 2 composed of the fine particles and the dispersion medium land on the substrate 6. When the amount of the dispersion medium is large when the droplets of the suspension 2 land on the substrate 6, the dispersion medium takes in the surrounding fine particles that have landed, and the aggregation of the fine particles occurs. It becomes possible to suppress the aggregation of the fine particles by appropriately adjusting. Here, if the heater 7 is at a temperature lower than the boiling point of the dispersion medium or has only one of the heater 5 and the heater 7, the dispersion medium of the droplets that have landed on the substrate 6 is not completely volatilized. Since the next droplet of the suspension 2 comes to land and the dispersion medium increases in an integrated manner, the entire surface of the substrate 6 gets wet with the dispersion medium. With the configuration of the present embodiment, it is possible to volatilize the dispersion medium almost simultaneously with landing on the substrate 6, so that the mass of droplets of the dispersion medium is utilized while suppressing the aggregation of fine particles by the dispersion medium. By doing so, fine particles having a small particle diameter can be landed on the substrate 6 more efficiently. That is, since the fine particles are included in the dispersion medium droplets and sprayed as the suspension 2, even if the fine particles themselves have a small particle size, they can be landed efficiently on the substrate 6.

  FIG. 2 is a photomicrograph of the substrate surface sprayed with pure water containing silicon fine particles having a particle size of several μm or less using the fine particle spraying apparatus according to the first embodiment. It can be confirmed that even fine particles having a particle diameter of submicrometer to several micrometers can be fixed to the substrate. That is, the fine particles can be fixed to the substrate by the fine particle spray device according to the present embodiment.

  Although not shown in FIG. 1, a mechanism for moving the sprayer 3 relative to the substrate 6 may be provided. That is, it is good also as a structure which sprays the droplet of the suspension liquid 2 changing the position of the sprayer 3 with respect to the board | substrate 6 of a large area, the drying housing | casing 4, etc. FIG.

  As described above, since the fine particle spraying device according to the present embodiment sprays droplets containing fine particles toward the substrate without charging, even when an insulator such as glass is used as the substrate, the droplets land. Does not charge the substrate. Therefore, the droplets can be efficiently landed on the substrate and the fine particles can be fixed on the substrate.

  Further, since the solid state fine particles can be diffused and arranged on the substrate, the material efficiency is higher and the amount of raw materials can be reduced compared with the case where the fine particles are deposited on the substrate using the material gas. Moreover, since the process which makes material gas into plasma is unnecessary, energy consumption can be reduced and the environmental load in a manufacturing process can be reduced. Furthermore, since the solid particles can be easily separated from the dispersion medium, they can be recycled.

Embodiment 2. FIG.
FIG. 3 is a diagram showing a configuration of a second embodiment of the fine particle spray device according to the present invention. The fine particle spray device 1 sprays a suspension 2 in which fine particles are dispersed in a dispersion medium from a sprayer 3. The sprayer 3 is connected to the drying housing 4. A casing heater 11 as a third heater is installed on the outer periphery of the dry casing 4 so as to surround the casing. The atmosphere in the dry casing 4 is heated by heat radiation or heat transfer from the heated dry casing 4.

  A gas heated by the heater 5 is introduced into the dry casing 4. The suspension 2 sprayed from the sprayer 3 is sprayed onto the housing surface 9 inclined in the substrate direction with respect to the spraying direction. On the other hand, the gas heated by the heater 5 is sprayed in a direction along the surface of the housing surface 9 to which the suspension 2 is sprayed.

  The substrate 6 is disposed on the extended line of the inclined casing surface 9 (on the downstream side of the gas flow heated by the heater 5) via the dry casing 4. The substrate 6 is heated by the heater 7. The details of the suspension 2 in which the fine particles are dispersed in the dispersion medium and the sprayer 3 may be the same as those in the first embodiment.

  In the present embodiment, since the atmosphere in the dry casing 4 is heated by the casing heater 11, it is possible to reduce the temperature difference of the gas inside the dry casing 4, and in the vicinity of the collecting plate 10. The occurrence of convection can be suppressed. As a result, the collision of coarse particles with the collection plate 10 is less likely to be hindered by the rising air flow generated in the vicinity of the collection plate 10, and the coarse particles can be collected more reliably by the collection plate 10. It becomes possible. For example, the temperature difference in the dry casing 4 can be reduced by setting the set temperature of the casing heater 11 to the same temperature as the set temperature of the heater 5.

  The airflow in the dry housing 4 becomes convection due to a temperature difference and airflow from the sprayer 3. By reducing the temperature difference in the dry housing 4, the air flow generated by factors other than the sprayer 3 can be reduced, which is advantageous in making the spray state in the substrate surface uniform. As a means for reducing the temperature difference in the housing, convection can be reduced by installing a plurality of housing heaters 11 for heating the dry housing 4 and setting the temperature respectively. Since the heated gas tends to collect at the upper part of the dry casing 4, it is effective to set the temperature of the casing heater 11 at the upper part of the drying casing 4 to be lower than that at the lower casing heater 11.

  As described above, the fine particle spraying apparatus and the fine particle fixing method according to the present invention are useful in that fine particles having a small particle diameter can be fixed on a substrate without agglomeration, and in particular, fine particles on an insulating substrate such as glass. Suitable for fixing.

DESCRIPTION OF SYMBOLS 1 Fine particle spray apparatus 2 Suspension 3 Sprayer 4 Drying housing 5, 7 Heater 6 Substrate 8 Carrier gas 9 Housing surface 10 Collection plate 11 Housing heater 12 Heated air introduction pipe

Claims (6)

A fine particle spraying device that sprays droplets of a suspension in which fine particles are dispersed in a dispersion medium onto a substrate, volatilizes the dispersion medium and fixes the fine particles on the substrate,
A sprayer for spraying droplets of the suspension;
A drying housing having an inclined surface arranged obliquely with respect to the spraying direction of the suspension;
A first heater for heating the gas introduced into the dry casing to a first temperature;
Means for introducing the gas heated to the first temperature into the drying casing along the inclined surface;
The substrate is held on the downstream side of the inclined surface of the gas flow heated to the first temperature and introduced into the drying casing, and the substrate is held at a second temperature higher than the first temperature. A second heater for heating to
A fine particle spraying apparatus, wherein the droplets of the suspension sprayed from the sprayer toward the inclined surface are conveyed by a gas flow heated to the first temperature and sprayed onto the substrate.   The fine particle spray apparatus according to claim 1, wherein the second temperature is equal to or higher than a boiling point of the dispersion medium.   The fine particle spraying device according to claim 1 or 2, wherein the first temperature is lower than a boiling point of the dispersion medium.   The fine particle spraying device according to any one of claims 1 to 3, further comprising a third heater for heating the dry casing.   The fine particle spraying device according to any one of claims 1 to 4, wherein means for collecting droplets of the suspension are provided on the inclined surface. A fine particle fixing method of spraying droplets of a suspension in which fine particles are dispersed in a dispersion medium onto a substrate, volatilizing the dispersion medium, and fixing the fine particles on the substrate,
Introducing the gas heated to the first temperature into the dry casing along the inner surface of the casing;
Spraying the suspension liquid droplets obliquely toward the inner surface of the housing along which the gas heated to the first temperature flows;
The substrate installed on the downstream side of the flow of gas heated to the first temperature on the inner surface of the housing and heated to a second temperature higher than the first temperature is set to the first temperature. And a step of spraying droplets of the suspension conveyed by the heated gas flow.