JP2009213980A - Coating apparatus and coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating apparatus and a coating method can make the coating thickness uniform in μm level by preventing a coating solution surface from moving up and down following the operation of charging or discharging a workpiece in or out of a solution tank and accordingly stabilizing and keeping the height of the solution surface constant when coating the workpiece by immersing the workpiece in the coating solution stored in the solution tank. <P>SOLUTION: The coating apparatus includes a solution tank 2 storing a coating solution 10, a workpiece-charging/discharging mechanism for charging/discharging the workpiece W in/out of the coating solution, and a volume element-charging/discharging mechanism for charging/discharging a volume element different from the workpiece W in/out of the coating solution and is so configured as to keep the surface height of the coating solution in the solution tank constant by operating the volume element-charging/discharging mechanism simultaneously with the charging/discharging operation of the workpiece by the charging/discharging mechanism. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coating apparatus and a coating method for coating a coating liquid on a workpiece using a coating method called a dipping method or a dipping method, and more specifically, a configuration of an optical printer, a copying machine, or the like. The present invention relates to a coating apparatus and a coating method for coating liquid onto cylindrical or columnar members, barrel-shaped members, or drum-shaped members used for photosensitive members, fixing rollers, developing rollers, transfer rollers, and the like.

Conventionally, a coating method is used to form a film on the surface of a flat surface, a free-form surface, a cylinder, or a columnar member. Coating by spraying or brushing is a suitable method because it can be made inexpensive with a simple structure to obtain a coating film having a thickness of several tens of μm to several mm. However, it is difficult to obtain a relatively thin film of 20 μm or less because the film thickness unevenness occurs when spraying or painting with a brush.
If the workpiece is a flat plate, it is conceivable to use a spin coating method that can obtain a uniform film of several to 20 μm. However, since the spin coating method is a method of obtaining a uniform film by blowing off the solution applied to the work with a centrifugal force, there is a drawback that it is difficult to form a uniform film unless the work surface is flat. For this reason, when application by spin coating is applied to a workpiece shape such as an uneven surface, a cylinder, or a column, unevenness of the coating film occurs, and therefore, a dipping method is used for such a workpiece.
In the coating method called dipping method or dipping method, the workpiece is immersed in a liquid tank filled with the solution, and the workpiece is pulled up from the solution to form a solution film on the workpiece surface, and then the membrane is dried. This is a method for forming a uniform coating film on the workpiece surface. The dipping method is widely used because it can form a precise thin film with simple equipment and is advantageous in terms of productivity and cost, but is generally often applied to film formation of several tens μm or more.

In recent years, components of printers and copiers, such as photoconductors, fixing rollers, developing rollers, and transfer rollers, have been required to form films of the order of several μm on the work surface in order to have various functions. . With the dipping method, a film of about several tens of μm can be obtained relatively easily, but in order to form a film of the order of several μm uniformly on the entire workpiece, the viscosity of the solution, the water repellency of the workpiece, the lifting speed, the drying speed of the membrane Need to be precisely controlled. In particular, when the workpiece is long, it may take several tens of minutes to one hour from the start of lifting until all the workpieces are lifted from the solution. The film thickness changes due to the difference in drying time between the upper part and the lower part, streaks are formed in the direction perpendicular to the pulling direction, and fish scale-like patterns occur due to the influence of disturbances such as wind. Know-how is required to obtain a uniform film, and it must be adjusted for each solution and work to be used.
The solutions used in the manufacturing process of the components of printers and copiers mentioned above include solvent-based and water-based solutions, and the functions of materials added to the solution include elasticity, conductivity, heat resistance, water repellency, Durability, optical functionality, etc. For this reason, silicon, rubber, fluorine, organic light materials, etc. can be considered as materials to be added to the solution by dipping.

By the way, in recent years, the possibility of direct exposure using a semiconductor process called a photolithography process is newly considered due to the development of laser technology, in particular, the invention of a blue laser having a wavelength of around 400 nm. Conventionally, since the semiconductor process is a method suitable for forming a film on a flat surface, it is considered that a cylindrical or cylindrical component such as a photoreceptor, a fixing roller, a developing roller, or a transfer roller is not suitable for forming a functional film in the semiconductor process. I came. However, if the resist can be thinly and uniformly applied to these workpieces, it can be considered to be an effective means for forming a functional film by direct exposure using a blue laser. It is not always necessary to perform exposure with a blue laser, and exposure with a xenon lamp or other methods may be used. However, when a negative resist is used, it is more efficient to use a blue laser.
However, the resist is about 10 to 1000 times more expensive than organic solvents and rubber materials used in the conventional dipping method. In addition, the resist has a disadvantage that it is easily oxidized and oxidized by oxygen in the atmosphere. Generally, in mass production by the dipping method, in consideration of efficiency, a method is adopted in which a large liquid tank, for example, a 1000 * 2000 * 600 mm size liquid tank is filled with the solution and 20 to 30 workpieces are immersed together. However, when such a method is used with a solution that easily oxidizes, such as a resist, the solution comes into contact with the air over a wide area, and there is a problem that the resist deteriorates in a short period of time.

Patent Document 1 (Japanese Patent Application Laid-Open No. 7-268662) discloses a drive motor for holding one end of a workpiece in a vertical posture by a fixing portion and moving the fixing portion up and down when forming a coating film on the surface of the workpiece. A method of manufacturing an image display device is disclosed in which a film is lowered and immersed in a liquid tank containing a solution by driving the workpiece and then the workpiece is lifted to form a coating film on the surface of the workpiece.
However, since the manufacturing method of Patent Document 1 does not have a mechanism for controlling the height of the liquid level, the liquid level is lowered by the volume of the workpiece by lifting the workpiece.
FIGS. 11A and 11B are conceptual diagrams of the dipping method, and the workpiece W is immersed in the coating liquid 102 in the liquid tank 101 at the time of loading shown in FIG. At this time, a so-called vapor layer in which the coating liquid evaporates and stays exists between the liquid surface 102 a of the coating liquid 102 and the upper end portion of the liquid tank 101. When the vapor layer in the state where the workpiece W shown in (a) is immersed is A, and the vapor layer in the state where the workpiece shown in (b) is pulled up is B, the vapor layer B is larger than the vapor layer A. The vapor layer is thicker. In this vapor layer, the evaporation of the coating liquid applied to the workpiece is slower than in normal air.For example, if the vapor layer is thicker than expected, the coating liquid is dragged downward by gravity. Therefore, there is a problem that the actual film thickness T2 becomes thinner than the desired coating film thickness T1. When the liquid level is changed by pulling up the workpiece W, the thickness of the vapor layer is also changed, so that the vapor layer is thin at the upper part of the work and the vapor layer is thick at the lower part of the work. For this reason, the time during which the coating film is dragged downward by gravity is different between the upper part and the lower part of the work, and as described above, the thickness of the coating film changes, or the work is pulled up.

Further, when the opening of the liquid tank 101 is wide, the solution of the coating solution evaporates with time, so that there is a problem that the viscosity of the coating solution is increased, thereby changing the thickness of the coating film. Also, if the coating solution is vulnerable to oxidation like a resist, in a liquid tank with a large area in contact with the atmosphere, the coating solution will deteriorate due to oxidation, and the expensive coating solution must be discarded without being used up to the end. .
Further, when the work is put into the coating liquid, the liquid level in the liquid tank rises, and when the work is pulled up, the liquid level drops by the volume of the work. For this reason, the coating liquid adheres to the inner surface of the liquid tank, but this coating liquid is in a semi-dry state because it is in the vapor layer. When this semi-dry coating solution is mixed with a coating solution to be replenished later in some state, it becomes a non-uniform coating solution, and uneven coating tends to occur at the time of dipping, which causes a deterioration in yield.

Next, Patent Document 2 (Japanese Patent Laid-Open No. 8-314163) discloses an overflow type dipping method.
The coating apparatus disclosed in Patent Document 2 is configured to supply the coating liquid from the lower part of the liquid tank and to make the liquid level constant by overflowing the same amount of coating liquid. In order to ensure a stable liquid level without disturbance, the coating liquid supplied from the lower part of the liquid tank becomes a laminar flow and rises in the liquid tank, and flows evenly from the upper end of the liquid tank to the outer peripheral direction of the liquid tank. It is necessary to continue. By the way, in order to reduce the amount of expensive coating liquid used in the coating apparatus, it is effective to increase the outer diameter of the workpiece with respect to the inner diameter of the liquid tank. However, when this configuration is adopted in the apparatus of Patent Document 2, the coating liquid supplied from the lower part of the liquid tank is pushed to the outer peripheral part of the liquid tank by the lower part of the work and rises in the liquid tank along the work. Liquid flow tends to be turbulent. When the coating liquid rises to the liquid level in the turbulent flow, the moving direction of the coating liquid changes to the outer peripheral direction of the liquid tank, so that a vortex is generated near the liquid surface, and the liquid level moves up and down microscopically. Therefore, the coating film formed on the surface of the workpiece has a problem that concentric coating unevenness occurs in a direction orthogonal to the pulling direction and the film thickness of the workpiece changes.

In addition, if the work volume is larger than the liquid tank volume, the overflow flow rate increases, the supply amount on the supply side also increases, and the pumping pressure of the coating liquid in the pipe rises. The direction of the coating film formed on the surface of the workpiece is perpendicular to the pulling direction in order to create a flow, the flow of the coating liquid in the liquid tank varies, the vortex is generated, the liquid level is disturbed, and the liquid level is slightly raised and lowered. There is a problem that the film thickness of the workpiece changes due to the occurrence of concentric coating unevenness.
Further, when overflowed, the liquid temperature of the coating liquid gradually rises due to frictional heat with the piping due to circulation, and the viscosity of the coating liquid changes, so that the film thickness gradually changes.
In addition, the functional material dispersed in the coating liquid, for example, the optical functional material, deteriorates due to sliding resistance in the pump and piping due to circulation. There is also a problem that a difference occurs in the exposure characteristics.
Further, the circulation pipe may be composed of a plurality of members in order to facilitate maintenance. For connection between these members, packing using rubber or the like is often provided at the connection portion. However, there is a problem in that the coating liquid adheres to the connecting portion and it becomes difficult to separate the pipes, thereby reducing the maintainability, and the fixed coating liquid is mixed into the circulating coating liquid to cause defects in the workpiece.

Moreover, in the structure which overflows, since it contacts with air | atmosphere in a saucer, overflow piping, and a storage tank besides a liquid tank, the area which a coating liquid oxidizes and deteriorates becomes large. Since the coating liquid in the vicinity of the liquid surface is also agitated by the circulation, the coating liquid just before being applied to the workpiece is exposed to oxygen, and there is also a problem that the coating liquid is further deteriorated.
In addition, since the contact area with the air is widened, the solvent in the coating solution gradually evaporates and concentrates, so that the resin and optical functional materials in the coating solution deposit on the wall of the overflow pipe and storage tank. Sometimes it came. The deposited substance may be mixed again in the coating tank, and if it adheres to the workpiece, it causes a defect in the workpiece.
Japanese Patent Laid-Open No. 7-268662 JP-A-8-314163

  The present invention has been made in view of the above, and when coating a workpiece by immersing the workpiece in the coating solution contained in the liquid tank, the coating liquid is accompanied by the operation of loading and discharging the workpiece into the liquid tank. An object of the present invention is to provide a coating apparatus and a coating method capable of uniformly obtaining a film thickness in units of μm by preventing the surface from moving up and down and maintaining the liquid surface height to be constant and stable. Yes.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a coating apparatus for applying a coating liquid to a workpiece by a dipping method, and a liquid tank containing the coating liquid, and the work being charged into and discharged from the coating liquid. A workpiece loading / discharging mechanism, and a volume element loading / discharging mechanism for loading / discharging a volume element different from the workpiece into the coating liquid, and the workpiece loading / discharging operation by the workpiece loading / discharging mechanism. The liquid element height of the coating liquid in the liquid tank is maintained constant by operating the volume element loading / unloading mechanism in synchronization with the volume element.
According to the present invention, it is possible to obtain a coating apparatus having a stable liquid level with a constant liquid level and no fluctuation even when a workpiece is charged into or discharged from the liquid tank.
The invention of claim 2 is characterized in that, in claim 1, the volume element is a solid member.
According to the present invention, a volume element with good handleability is ensured.
According to a third aspect of the present invention, in the second aspect, the solid member has the same cross-sectional area as the workpiece in a plane orthogonal to the pulling-up direction of the workpiece.
According to the present invention, the input / discharge speed of the workpiece and the input / discharge speed of the volume element can be made the same.

According to a fourth aspect of the present invention, in the second or third aspect, the solid member has the same outer shape as the workpiece.
According to the present invention, the input / discharge speed of the workpiece and the input / discharge speed of the volume element can be made the same.
The invention according to claim 5 is the operation according to any one of claims 1 to 4, wherein the work is charged / discharged into / from the liquid tank by the work charging / discharging mechanism, and the volume element charging / discharging mechanism is It is characterized in that an interlocking mechanism is provided that interlocks the operation of loading / discharging the volume element into / from the liquid tank.
According to the present invention, a mechanism (actuator) for driving a workpiece and a volume element can be linked to form one unit.
The invention of claim 6 is characterized in that, in claim 1, the volume element is a coating solution.
A seventh aspect of the invention is characterized in that, in the first aspect, the volume element is an auxiliary tank, and the application liquid is charged into and discharged from the liquid tank by moving the auxiliary tank up and down.
According to the present invention, a charging / discharging mechanism for a liquid volume element can be obtained.

The invention of claim 8 is characterized in that, in claim 7, the cross-sectional area of the auxiliary tank and the cross-sectional area of the work in the plane orthogonal to the direction in which gravity acts are the same.
According to the present invention, the work loading / unloading speed and the vertical movement speed of the auxiliary tank can be made the same.
The invention of claim 9 is characterized in that, in claim 7 or 8, the internal shape of the auxiliary tank and the external shape of the workpiece are the same.
According to the present invention, the work loading / unloading speed and the vertical movement speed of the auxiliary tank can be made the same.
According to a tenth aspect of the present invention, in any one of the seventh to ninth aspects, the auxiliary tank is fixed to the work input / discharge mechanism and moves up and down simultaneously with the work.
According to the present invention, the drive mechanism (actuator) for the workpiece and the auxiliary tank can be made one.
The invention of claim 11 is the liquid level sensor for detecting the liquid level height of the coating liquid according to any one of claims 1 to 10, and a workpiece input / discharge mechanism according to the output of the liquid level sensor, Or a control means for controlling the operation of either or both of the volume element loading / unloading mechanisms.
According to the present invention, it is possible to detect the height of the liquid level and control the dipping start position.

According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the liquid tank includes a replenishing unit that replenishes a new coating liquid.
According to the present invention, it is possible to always ensure a constant coating liquid in the liquid tank.
A thirteenth aspect of the invention is characterized in that in any one of the first to twelfth aspects, the coating liquid filtering means is provided.
According to the present invention, foreign matters mixed in the coating liquid can be removed.
The invention of claim 14 is a method of applying and applying the coating liquid to the workpiece by loading and discharging a workpiece into and from the coating liquid stored in the liquid tank, and storing the coating liquid in the liquid tank; A step of charging / discharging the coating liquid with a volume element different from that of the workpiece while synchronizing with the charging / discharging operation of the workpiece, and maintaining the liquid level of the coating liquid constant. Features.
According to the present invention, it is possible to obtain a coating method having a stable liquid level with a constant liquid level and no fluctuation even when a work is charged into or discharged from the liquid tank.

According to the first aspect, even a long workpiece can be applied efficiently without forming a uniform thin coating film on the order of several μm at high speed and without deteriorating the resist.
According to the second aspect, the liquid level can be adjusted.
According to the third aspect, dipping is possible with a simple control system.
According to claim 4, dipping is possible with a simple control system.
According to the fifth aspect, since the number of actuators can be reduced, the apparatus becomes compact and the cost can be reduced.
According to the sixth aspect, the liquid level can be adjusted.
According to the seventh aspect, the liquid level can be kept constant.
According to the eighth and ninth aspects, dipping is possible with a simple control system. Same as claim 3.
According to claim 10, the apparatus can be made compact and the cost can be reduced.
According to the eleventh aspect, the dipping start position can be determined.
According to the twelfth aspect, it is possible to replenish the consumed coating liquid and make the liquid level constant.
According to the thirteenth aspect, even a long workpiece can be applied efficiently without forming a uniform thin coating film on the order of several μm at high speed and without degrading the resist.
According to the fourteenth aspect, it is possible to obtain a method for efficiently applying a uniform thin coating film on the order of several μm at a high speed even for a long workpiece without deteriorating the resist.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIGS. 1A, 1B, and 1C are diagrams showing the principle of the coating apparatus of the present invention, and showing the state in which a volume element is put into a solution.
That is, the coating apparatus 1 that applies the coating liquid to the workpiece W by the dipping method of the present invention includes a liquid tank 2 in which the coating liquid 10 is placed, and a workpiece input / discharge mechanism that inputs / discharges the workpiece W into / from the coating liquid 10. The application liquid in the liquid tank is provided by the volume element input / discharge mechanism that inputs / discharges the volume element different from the work into the application liquid while synchronizing with the work input / discharge operation by the work input / discharge mechanism. The liquid level is kept constant.
The workpiece input / discharge mechanism and the volume element input / discharge mechanism include a holding means that can hold the workpiece or the volume element and can be moved forward and backward in a fixed path, a moving mechanism (gear, pulley, wire, etc.), and a drive source ( Those equipped with motors and solenoids can be used.
According to the present embodiment, the height of the liquid level is kept constant even when the workpiece W is charged / discharged by applying / discharging the volume element to / from the coating liquid 10 in the same liquid tank 2. Can keep.

The coating apparatus 1 in FIG. 1A has a configuration in which a bottom portion (volume element = solid member) 3 of a cylindrical liquid tank 2 whose upper surface is open is moved up and down by a volume element input / discharge mechanism (actuator) (not shown). By moving the bottom portion (bottom plate) 3 up and down, it is possible to prevent the liquid level of the coating liquid (for example, resist solution) 10 from fluctuating up and down due to loading and discharging of the workpiece W.
FIG. 1B shows a coating apparatus 1 according to another embodiment. In this coating apparatus 1, as a volume element, an airtight hole 3 a provided in the bottom plate 3 of the liquid tank 2 is introduced into the coating liquid 10 in the liquid tank. It moves up and down so that the solid member 4 appears and disappears. The liquid level is controlled by causing one or more solid members 4 to appear and disappear in the coating liquid. At this time, when the outer shapes of the workpiece W and the solid member (volume element) 4 are different, the volume charged / discharged into the coating liquid is also different, so that the charging / discharging speed of the workpiece W and the solid member 4 is different. Controllability is reduced. On the other hand, if the cross-sectional area of the solid member 4 and the cross-sectional area of the work W in the plane (horizontal plane) orthogonal to the pulling-up direction (vertical direction) of the work W are equal, the input / discharge speed of the work and the solid member is the same. By doing so, the liquid level of the liquid tank can be made constant, and there is an advantage that controllability is improved. For example, as shown in FIG. 1C, a solid member (volume element) 5 having the same outer shape as the outer shape of the workpiece W is sealed from a leak-proof seal portion (not shown) from an airtight hole 2 a provided on the side surface of the liquid tank 2. ), The volume of the workpiece W is the same as the volume of the solid member 5 that is charged into and discharged from the coating solution, so that the workpiece and the solid member 5 are the same. Can be charged and discharged at a speed (opposite direction). Moreover, it is comprised so that the liquid level height of a coating liquid may be detected with the ultrasonic sensor (not shown) which detects a liquid level height. The control means (not shown) operates the volume element input / discharge mechanism to input / discharge the solid member 5 when the liquid level is not at a specified height based on the detection information from the ultrasonic sensor. Control the liquid level to a specified height.

FIGS. 2A to 2E are diagrams showing a configuration example and procedure when dipping a plurality of workpieces W1 and W2 into separate liquid tanks A and B, respectively. For example, one or a plurality of cylindrical liquid tanks 2 having a flat bottom surface are installed on a horizontal surface, and the side surfaces of the respective liquid tanks 2 are connected and communicated with each other through a pipe 15 so that the coating liquid in the liquid tanks is communicated. Allow movement. FIG. 2 shows an example in which two workpieces W1 and W2 are immersed in two liquid tanks A and B, respectively.
First, in FIG. 2A, the workpiece W1 is not put into the liquid tank A, and the workpiece W2 is put into the liquid tank B. Both the workpieces W1, W2 have the same outer shape. Next, as shown in FIG. 2B, the workpiece W1 is put into the liquid tank A at a desired speed, and the work W2 is discharged from the liquid tank B at the same speed and timing. In the liquid tank A, the liquid level rises by the volume of the workpiece W1, but when the excess coating liquid 10 flows into the liquid tank B connected by the pipe 15, the liquid level of the liquid tank A becomes constant. In the liquid tank B, the liquid level is raised by the flowing coating liquid. However, the volume of the work W2 is reduced by pulling up and discharging the work W2 that has been put in advance, and as a result, the liquid level in both liquid tanks. The height of is constant. Therefore, if the input / discharge speeds of the two workpieces are the same, the liquid levels in the liquid tanks A and B are always constant. At this time, it is necessary to drive by at least two or more actuators (work input / output mechanism, not shown) for input / discharge of the work.

Next, as shown in FIG. 2 (c), the workpiece W2 is pulled up on the liquid tank B side, and is temporarily stopped when the bottom surface of the workpiece W2 coincides with the liquid level, and excess liquid adhering to the workpiece W2 due to surface tension is applied to the coating liquid. Return to.
Next, as shown in FIG. 2 (d), a new workpiece W 2 ｀ is put into the liquid tank B instead of the pulled workpiece W 2. Next, as shown in FIG. 2 (e), contrary to (a), the work W1 is pulled up from the liquid tank A, and the work W2 is poured into the liquid tank B at the same speed as the work W1 in the liquid tank A. . Thereafter, the steps of FIGS. 2B to 2D are sequentially repeated with the liquid tanks A and B reversed. Of course, since the coating liquid is applied to the workpiece, the liquid level gradually decreases. In that case, the coating liquid is replenished in the liquid tank, or the liquid level is returned to the original level while adjusting the viscosity and concentration of the coating liquid with an appropriate dispersion medium. Further, the liquid level height of the coating liquid is detected by an ultrasonic sensor (not shown) that detects the liquid level height. If the liquid level is not at the specified height, the workpiece is controlled to be at the specified height by loading and unloading the workpiece.

FIGS. 3A and 3B show an example in which the work input / discharge procedure of FIG. 2 is realized by another configuration. In FIG. 2, at least two or more actuators are required corresponding to the two workpieces. In FIG. 3A, in order to reduce the number of unillustrated workpiece loading / unloading mechanisms (actuators) for loading / unloading workpieces, the workpieces W1, W2, Alternatively, a workpiece gripping mechanism (not shown) is connected by a wire 16, and the wire 16 is wound around a pulley 17 and suspended. According to this structure, the entire coating apparatus can be driven by using only one workpiece loading / unloading mechanism for rotating the pulley 17. Of course, an actuator for driving may be used not on the pulley side but on the wire 16 side. Further, it is not necessarily a wire, and a metal or resin belt or chain may be used.
As shown in FIG. 3B, the same effect can be obtained even if a balance-like link mechanism 18 is used instead of the pulley. That is, the center portion of the balance rod 18b is supported by the fulcrum 18a, and wires (or rods such as metal arms) 18c are attached to both ends of the balance rod 18b and suspended, and the workpieces W1 and W2 are attached to the tips thereof. May be.
In this way, it is equipped with an interlocking mechanism that links the operation of loading and unloading the workpiece into the liquid tank by the workpiece loading and unloading mechanism and the operation of loading and unloading the volume element into and from the liquid tank by the volume element loading and unloading mechanism. Thus, both mechanisms can be integrated into one unit.

Next, FIGS. 4A to 4D show configuration examples of the liquid tank. FIG. 4A is a configuration example of the liquid tank used in FIG. Alternatively, a U-shaped tube may be used as the liquid tank 2 as shown in FIG. 4B, or an 8-shaped liquid tank 2 may be used as shown in FIG. Moreover, you may comprise so that a vapor | steam layer may be stabilized by attaching the lid | cover 19 to both the opening parts of the U-shaped liquid tank 2 like (d).
Note that the configurations shown in FIGS. 4A to 4D are not necessarily established between a workpiece of any size and shape and the liquid tank. Experiments with coating solutions have shown that there are optimal dimensional parameters. In the case where the film thickness of the work is several μm, the film thickness tolerance is ± 1 μm or less, the work outer diameter is φ10 to 30 mm, and the work length is 200 to 400 mm, the following requirements are preferably provided.
[1] When the outer diameter of the liquid tank 2 is D1 and the outer diameter of the workpiece W is D2, the relationship of D1-D2 <20 mm is satisfied.
[2] The work and volume element charging / discharging speed satisfy 0.1 to 30 mm / Sec.
[3] The distance between the upper surface of the liquid tank and the liquid surface (the width of the vapor layer) satisfies 20 mm or less.

Next, a coating apparatus according to another embodiment of the present invention will be described with reference to FIGS.
First, FIG. 5 shows an example in which a volume element 20 having the same outer diameter as the workpiece W protrudes from an airtight hole 3 a provided in the bottom 3 of the liquid tank 2. The liquid tank 2 is filled with the coating liquid 10 whose concentration and viscosity are adjusted in advance up to the liquid level 10a. There are various coating liquids as described above, but here, it is assumed that a volatile resist is filled. A support rod 21, which is a volume element 20, protrudes into the liquid tank through an airtight hole 3 a (with a leak-proof seal 3 b) provided in the bottom 3 of the liquid tank 2. The leak-proof seal 3b is determined by the compatibility with the resist 10, but generally a fluorine-based oil seal is often used.
Further, the support rod 21 extends upward through the liquid surface 10a of the coating liquid, and a male screw-like connection screw 21a for fixing the work projects from the tip of the support rod. Between the liquid surface 10a of the coating liquid and the upper end of the liquid tank is called a vapor layer 22, and the solvent of the resist 10 is vaporized and stays there. Since the solvent of the resist 10 is often heavier than air, it maintains a substantially constant concentration if convection does not occur due to external blowing. Further, if there is no change in the liquid level, the distance between the liquid level and the upper end of the liquid tank does not change, so the thickness of the vapor layer 22 is constant. Since the vapor layer is constant, the drying conditions of the coating film are also constant, and even when a long workpiece is inserted, fluctuations in film thickness and occurrence of coating film unevenness are suppressed, and the film can be pulled up at high speed. In order to further stabilize the vapor layer, a lid may be installed on the upper part of the liquid tank.

FIGS. 6A to 6F show examples in which dipping is performed using the liquid tank 2 having the configuration of FIG. Initially, as shown in FIG. 6A, the upper portion of the support rod 21 protrudes on the liquid surface 10a, and the workpiece W is outside the liquid tank. Next, as shown in (b), the workpiece W is fixed by the support rod 21 and the connection screw 21a, and there is no gap between the workpiece W and the support rod 21. At this time, since the workpiece and the support rod have the same diameter, they appear to be one cylinder in appearance. Next, as shown in (c), the support rod 21 is pulled down at a desired speed, the workpiece W is put into the coating solution 10, and the coating solution is dipped on the workpiece surface. At this time, in order to stabilize the disturbance of the liquid level due to the input of the workpiece, the sample is stopped for about 10 seconds.
Next, as shown in FIG. 6D, the support rod 21 is pulled up to form a coating liquid film on the work surface. At this time, since the outer diameters of the workpiece and the support rod are the same, the volume of the workpiece and the support rod that are charged into and discharged from the coating solution per unit time is equal, and the liquid level is maintained at a constant height without moving up and down. . However, since the coating liquid is applied to the surface of the workpiece, the liquid level is slightly lowered by that amount, but the film formation by dipping is not affected. Further, in the case of the coating apparatus having the configuration as shown in FIG. 1, even if the liquid level is constant, turbulence is generated in the coating liquid by taking in and out the volume elements 3, 4, and 5, and the liquid level In the configuration of FIG. 6, since the support rod 21 as the volume element and the workpiece W are connected, there is no gap for the coating liquid to enter between the workpiece and the support rod, and the outer diameter Therefore, even if the workpiece is pulled up, turbulent flow is unlikely to occur and a stable liquid level can be secured.

Next, as shown in FIG. 6 (e), when the lower end of the workpiece W located above the support rod 21 reaches the liquid level 10a, the workpiece W is stopped for a while, and at a slight joint (step) between the workpiece and the support rod. The accumulated coating liquid is returned to the liquid tank by surface tension to obtain a uniform film. If this step is omitted, the coating liquid may accumulate in the coating film and be fooled.
Next, as shown in FIG. 6 (f), the upper end portion of the support rod 21 protrudes above the liquid surface 10a to remove the workpiece W from the support rod 21, and is dried in the workpiece drying step to form a resist coating film. obtain. As this process is repeated, the resist gradually decreases. Therefore, an additional resist is added from the application liquid inlet / outlet (not shown) to keep the liquid level constant. Also, if dust is mixed into the resist, remove the resist dust with an external filter (not shown) via a pipe (not shown), and re-apply the resist from the inlet / outlet to always apply it. Stabilize liquid properties.

Next, another embodiment will be described with reference to FIGS. 7, 8, and 9.
In the coating apparatus 1 according to this embodiment, the bottom portions 3 of two cylindrical liquid tanks 2 are connected in communication by a tube 25, and the coating liquid 10 in one liquid tank is connected to the other liquid via the tube 25. It is configured to be able to flow into the tank. Then, by setting one liquid tank at a predetermined position higher than the other liquid tank, the position of the liquid surface of the coating liquid in the other liquid tank is set to a predetermined value, while the workpiece is placed in the other liquid tank. When the liquid is put into the liquid tank, one liquid tank is lowered to move the coating liquid from the other liquid tank into the one liquid tank. This embodiment is characterized in that a coating liquid (or an auxiliary tank) is used as a volume element instead of a solid member.
In the present embodiment, the liquid tank 2 on the side where the workpiece W is introduced is referred to as a liquid tank 26, and the liquid tank 2 on the side where the workpiece W is not input is referred to as an auxiliary tank 27. First, by putting the workpiece W into the liquid tank 26 filled with the coating liquid 10, the liquid level in the liquid tank 26 rises. At this time, the auxiliary tank 27 previously disposed at the upper retracted position is lowered by a predetermined distance from the retracted position, so that the coating liquid 10 corresponding to the volume of the workpiece charged into the liquid tank 26 via the tube 25 is retained in the auxiliary tank. It flows into the 27 side. As a result, the height position of the liquid level 10a in the liquid tank 26 is kept constant.

Next, in the embodiment of FIG. 8, the inner shape of the auxiliary tank 27 is set to be equal to the outer shape of the workpiece W. Similarly to the case of FIG. 7, the liquid tank 26 and the auxiliary tank 27 are connected by the tube 25. When the workpiece W is introduced into the liquid tank 26, the liquid level 10a of the coating liquid rises. At this time, the auxiliary tank 27 is lowered from the upper retracted position, so that the work is introduced into the liquid tank 26 through the tube 25. The volume of coating liquid flows into the auxiliary tank 27. As a result, the liquid level on the liquid tank 26 side is kept constant.
By the way, when the cross-sectional area of the auxiliary tank 27 and the cross-sectional area of the work W are the same in a plane (horizontal plane) orthogonal to the direction in which the gravity acts, the work input / discharge speed and the auxiliary tank ascent / descent speed Since the liquid level of the liquid tank 26 can be made constant, there is an advantage that controllability is improved. If the internal shape of the auxiliary tank 27 is equal to the external shape of the work, the work loading / unloading speed and the lifting / lowering speed of the auxiliary tank can be made the same, and controllability is improved.

Next, an apparatus configuration for realizing the embodiment of FIG. 8 will be described with reference to FIG.
A workpiece W is fixed to a moving table 32 of a linearly-moving stage 31 arranged vertically via a holding mechanism (not shown). An auxiliary tank 27 having the same internal shape as that of the workpiece W is fixed to the moving table 32. The auxiliary tank 27 and the liquid tank 26 are connected via the tube 25, and the coating liquid 10 can flow into each other. At this time, when the linear motion stage 31 is driven and the moving table 32 is lowered, the workpiece W is immersed in the coating liquid 10. Similarly to the workpiece W, the auxiliary tank 27 is fixed to the moving table 32 and moves up and down integrally, so that the coating solution 10 in the liquid tank 26 flows into the auxiliary tank 27 through the tube 25. Since the inflow amount is the same as the volume in which the work is immersed in the coating liquid, the liquid level 10a is maintained constant as a result. When the moving table 32 is raised and the work is discharged from the coating liquid, the situation is reversed, and as a result, the height of the liquid level is kept the same.
The linear motion stage 31 provided with the moving table 32 and the holding mechanism constitute a workpiece input / discharge mechanism.
Since the auxiliary tank 27 is fixed to the work input / output mechanism and moves up and down simultaneously with the work, the liquid level can be stabilized by using the auxiliary tank or the application liquid as a volume element.
In addition, a liquid level sensor (not shown) that detects the liquid level of the coating liquid is provided, and either or both of the work input / discharge mechanism and the volume element input / discharge mechanism are selected according to the output of the liquid level sensor. By providing a control means (CPU) for controlling the operation, the liquid level can be stabilized by automatic control.

Next, FIG. 10 shows a configuration example in the case where the coating apparatus according to the present invention shown in FIG. 2 has a configuration suitable for mass production.
The coating apparatus 40 includes an A row composed of a plurality of liquid tanks A, a B row composed of a plurality of liquid tanks B, and a base 41 that supports these bottoms. The liquid tanks A and B that are adjacent to each other in the front-rear positional relationship are connected to each other between the bottoms by pipes installed inside the base 21. As described with reference to FIG. 2, the work W <b> 2 is first placed in each liquid tank B of the B row on the front side, and the work W <b> 1 in each liquid tank A of the A set is taken out from the liquid tank A. Next, the workpieces W2 of the group B are pulled up from the liquid tanks B, and at the same time, the workpieces W1 of the group A are put into the liquid tank A at the same speed as the group B. And the vapor layer width is also constant. By adopting such a configuration, it is possible to minimize the area in contact with air and use up the resist that is easily oxidized. Moreover, by stabilizing the liquid surface, it is possible to reduce the film thickness unevenness at the coating film unevenness and the upper and lower ends of the workpiece, and to raise the vapor layer at a high speed by making the width of the vapor layer constant.
In addition, by providing a replenishing means (not shown) for replenishing a new coating liquid in the liquid tank, it is possible to replenish the consumed coating liquid and make the liquid level constant.
In addition, by having a coating solution filtration means (not shown), even for long workpieces, a uniform thin coating on the order of several μm can be formed at high speed, and the thin film can be made uniform efficiently without degrading the resist. Can be formed.

(A) (b) And (c) is a figure which shows the principle of the coating device of this invention, and is the figure which showed the injection | throwing-in state of the volume element in the solution. (A) thru | or (e) is a figure which shows the coating procedure by the coating device which concerns on other embodiment. (A) And (b) is a figure which shows the structural example of a volume element injection | throwing-in / out mechanism. (A) thru | or (d) is a figure which shows the structural example of a liquid tank. (A) And (b) is a structure and operation | movement explanatory drawing of the coating device which concerns on other embodiment of this invention. (A) thru | or (f) is the figure which showed the example which dipped using the liquid tank provided with the structure of FIG. It is a figure which shows the structure of the coating device which concerns on other embodiment. It is a figure which shows the modification of FIG. (A) And (b) is a figure explaining the apparatus structure for implement | achieving embodiment of FIG. It is a figure which shows the structural example in the case of setting the coating device concerning this invention shown in FIG. 2 as a structure suitable for mass production. (A) And (b) is a conceptual diagram of the dipping method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Coating apparatus, 2 ... Liquid tank, 2a ... Airtight hole, 3 ... Bottom plate, 3a ... Airtight hole, 3b ... Seal, 4 ... Solid member, 5 ... Solid member, 10 ... Coating liquid, 10a ... Liquid surface, 15 ... Piping, 16 ... wire, 17 ... pulley, 18 ... link mechanism, 18a ... fulcrum, 18b ... balance rod, 19 ... lid, 20 ... volume element, 21 ... base, 21 ... support rod, 22 ... vapor layer, 25 ... tube, 26 ... Liquid tank, 27 ... Auxiliary tank, 31 ... Linear motion stage, 32 ... Moving table, 40 ... Application device, 41 ... Base

Claims (14)

In a coating device that applies a coating solution to a workpiece by dipping,
A liquid tank containing the coating liquid;
A workpiece loading / unloading mechanism for loading / unloading the workpiece into / from the coating liquid;
A volume element charging / discharging mechanism for charging / discharging a volume element different from the workpiece into the coating liquid,
By operating the volume element input / discharge mechanism in synchronization with the work input / discharge operation by the work input / discharge mechanism, the liquid level of the coating liquid in the liquid tank is maintained constant. An applicator characterized by comprising.   2. The coating apparatus according to claim 1, wherein the volume element is a solid member.   3. The coating apparatus according to claim 2, wherein the solid member has the same cross-sectional area as the workpiece in a plane orthogonal to a lifting direction of the workpiece.   4. The coating apparatus according to claim 2, wherein the solid member has the same outer shape as the workpiece.   5. The operation according to claim 1, wherein the work input / discharge mechanism is used to input / discharge the work into / from the liquid tank, and the volume element input / discharge mechanism is used to move the volume element into the liquid tank. A coating apparatus comprising an interlocking mechanism that interlocks the operation of loading and unloading to a container.   The coating apparatus according to claim 1, wherein the volume element is a coating liquid.   2. The coating apparatus according to claim 1, wherein the volume element is an auxiliary tank, and the application liquid is charged into and discharged from the liquid tank by moving the auxiliary tank up and down.   8. The coating apparatus according to claim 7, wherein a cross-sectional area of the auxiliary tank and a cross-sectional area of the workpiece are the same in a plane orthogonal to a direction in which gravity acts.   9. The coating apparatus according to claim 7, wherein an internal shape of the auxiliary tank is the same as an external shape of the workpiece.   10. The coating apparatus according to claim 7, wherein the auxiliary tank is fixed to the workpiece loading / unloading mechanism and moves up and down simultaneously with the workpiece.   11. The liquid level sensor for detecting the liquid level height of the coating liquid according to claim 1, and a workpiece input / discharge mechanism or a volume element input / discharge mechanism according to the output of the liquid level sensor. And a control means for controlling the operation of either one or both.   12. The coating apparatus according to claim 1, further comprising a replenishing unit that replenishes the liquid tank with a new coating liquid.   13. The coating apparatus according to claim 1, further comprising a filtering unit for the coating liquid. In the method of applying the coating liquid to the workpiece by charging and discharging the workpiece into and from the coating liquid stored in the liquid tank,
A step of storing the coating liquid in the liquid tank; and a step of performing a charging / discharging operation of a volume element different from the workpiece into the coating liquid while synchronizing with the charging / discharging operation of the workpiece. A coating method characterized by maintaining the liquid level of the liquid constant.

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