JP5144299B2 - Vacuum dryer - Google Patents

Description

  The present invention removes the solvent from the coating solution by drying the substrate coated with the coating solution obtained by mixing the components of the coating film and the solvent, such as a large glass substrate for manufacturing a liquid crystal display panel, under reduced pressure. The present invention relates to a reduced-pressure drying apparatus configured as described above.

  In general, in a vacuum drying apparatus, a substrate is heated while a vacuum container is decompressed by a vacuum pump during a vacuum drying process. Then, the solvent in the coating solution supplied to the substrate to be processed evaporates and is sucked into the vacuum pump through the exhaust pipe.

  Since the exhaust pipe is easily affected by the atmosphere on the clean room side where the temperature is lower than that of the sealed container, a portion having a temperature lower than the surface temperature of the heated coating substrate is formed inside the exhaust pipe and evaporated from the coating substrate. Condensation may occur due to condensation of the solvent inside the exhaust pipe.

As a countermeasure against such condensation, in the prior art, during drying under reduced pressure, a part of the exhaust pipe is heated with a tape heater while supplying a temperature-adjusted nitrogen gas into the exhaust pipe. There is a reduced-pressure drying apparatus configured to control the temperature of the solvent vapor that is dried from (see, for example, Patent Document 1). In this reduced pressure drying apparatus, it is said that the dew condensation of the solvent vapor in the exhaust pipe can be suppressed and the drying process can be performed quickly at a low cost.
JP 2003-264184 A

  However, during the drying process under reduced pressure, not only the exhaust pipe but also the inside of the sealed container, the solvent evaporated from the coated substrate is condensed in the portion of the surface temperature lower than the surface temperature of the coated substrate, which results in condensation. When the processing time for drying is further required, there is a problem that the drying processing time becomes longer as a whole.

  In the technique according to Patent Document 1 described above, it is difficult to effectively heat the movable portion such as the reinforcing rib and the substrate lift-up pin formed on the outer surface of the chamber. It has been revealed that there is still a possibility that a low temperature part that may cause condensation is generated in a part of the interior of the chamber due to heat radiation from the movable part such as the reinforcing rib and the lift-up pin.

  In addition, it is extremely difficult to heat each portion such as the reinforcing rib and the substrate lift-up pin formed on the outer surface of the chamber using the tape heater described in Patent Document 1, and it can be temporarily heated. However, the construction, maintenance and control of the tape heater may be enormous.

  An object of the present invention is to provide a vacuum drying apparatus capable of shortening the processing time by preventing a low temperature portion that may cause condensation in a chamber or an exhaust pipe with a simple configuration and control. It is to be.

  The reduced pressure drying apparatus according to the present invention is configured to remove the solvent from the coating solution by drying the substrate coated with the coating solution containing the components of the coating film and the solvent in a reduced pressure state. The vacuum drying apparatus includes a chamber, an exhaust pipe, a decompression unit, a closed space formation unit, and a hot air supply unit.

  The chamber includes a placement unit for placing the substrate and a heater for heating the substrate at a set temperature, and is configured to be openable and closable. As an example of the chamber, an example in which at least one of the upper part of the chamber and the lower part of the chamber is configured to be movable is given. The exhaust pipe is configured to communicate with the interior of the chamber. The decompression means is configured to decompress the interior of the chamber via the exhaust pipe. An example of the decompression means is a decompression pump such as a vacuum pump.

  The closed space forming means forms a closed space by surrounding at least the connection portion of the chamber with the exhaust pipe, the reinforcing rib, or the substrate lift-up pin and the exhaust pipe. Here, the closed space does not need to be closed to the extent that it has airtightness, and a small window or notch for piping may be provided in the partition member. In addition, the entire exhaust pipe is not necessarily located in the closed space, and a part of the exhaust pipe may be located outside the closed space.

  The closed space forming means preferably defines the closed space by a flexible partition member. In consideration of following the opening / closing operation of the chamber, it is preferable to use a sheet material as the partition member, but it is also possible to use a flexible plate material or a plurality of plate materials configured to be stretchable.

  The hot air supply means is configured to supply hot air into the space closed by the closed space forming means. As an example of the configuration of the hot air supply means, a hot air generator that generates hot air and a hot air introduction pipe configured to blow hot air generated by the hot air generator to an edge of a surface of the chamber to which the exhaust pipe is connected are provided. The structure which has is mentioned.

  When the hot air supply means supplies hot air having a predetermined temperature to the closed space, the inside of the closed space is heated substantially uniformly, and hot air is blown to a portion or an exhaust pipe disposed in the closed space in the chamber. In particular, hot air is blown to places that are difficult to heat uniformly, such as reinforcing ribs, lift-up pins, and other movable parts, so it is easy to heat those places uniformly. Become. As a result, it is possible to prevent the generation of a low temperature portion that can cause condensation.

  The hot air supply means preferably keeps the inner wall of the chamber and the inner wall of the exhaust pipe at a temperature between the evaporation temperature of the solvent to be removed and the dew condensation temperature. This is because the condensation temperature is generally lower than the evaporation temperature.

  According to the present invention, it is possible to prevent the occurrence of a low temperature portion that may cause condensation in the chamber or the exhaust pipe with a simple configuration and control, and it is possible to greatly reduce the processing time. Become.

  A vacuum drying apparatus 10 according to an embodiment of the present invention will be described with reference to FIG. Here, the reduced-pressure drying apparatus 10 is used in a manufacturing process of a liquid crystal display and is provided in a clean room. The vacuum drying apparatus 10 includes an upper chamber portion 12 and a lower chamber portion 14 that form a sealed container. The chamber upper portion 12 and the chamber lower portion 14 are configured to be freely opened and closed when one of them moves. In this embodiment, an example will be described in which the chamber lower portion 14 moves with respect to the chamber upper portion 12, but the present invention can be applied even in a configuration in which the chamber upper portion 12 moves with respect to the chamber lower portion 14. It is.

  The chamber upper portion 12 includes an upper plate heater 36 inside. The upper plate heater 36 is configured to heat the inside of the sealed container at a set temperature.

  The chamber lower part 14 includes a substrate support pin 42 and a lower plate heater 38 inside. The substrate support pins 42 are configured to support the substrate 40 during the drying process. In this embodiment, the substrate 40 is a glass substrate on which a coating liquid is supplied and a pigment resist film is formed. The lower plate heater 38 is configured to heat the inside of the sealed container at a set temperature. A plurality of lift-up pins 44 are provided at the bottom of the chamber lower portion 14. The lift-up pins 44 are configured to be freely extendable and configured to raise and lower the substrate 40 when the substrate 40 is moved. In this embodiment, 16 lift-up pins 44 are used, but the number of lift-up pins 44 is not limited to this.

  The lower chamber portion 14 is supported by an air cylinder 30 so as to be movable up and down. An opening connected to the exhaust pipe 32 connected to the vacuum pump 28 is provided at the bottom of the chamber lower part 14. The exhaust pipe 32 is provided with a flexible pipe at a portion extending in the vertical direction so as to correspond to the raising / lowering operation of the chamber lower portion 14.

  The reduced-pressure drying apparatus 10 according to this embodiment further includes a partition sheet material 16, a hot air generator 20, and a hot air introduction pipe 34. The partition sheet material 16 is disposed so as to cover the outer peripheral surface of the chamber lower portion 14, the lift-up pins 44, the exhaust pipe 32, and other components. As shown in FIG. 2, the partition sheet material 16 is attached to the outer peripheral surface of the chamber lower portion 14 via a plurality of sheet material fixing plates 162 and bolts 164. In this embodiment, the partition sheet material 16, the sheet material fixing plate 162, and the bolt 164 correspond to the closed space forming means of the present invention.

  The partition sheet material 16 has a thickness of about 150 μm and is made of a transparent material. The partition sheet material 16 includes an intermediate layer (for example, metallocene polyethylene) having flexible physical properties suitable for the partition material, and a surface layer (polyethylene containing a conductive agent) disposed so as to cover the intermediate layer and having antistatic properties. However, the configuration of the partition sheet material 16 is not limited to this, and partition materials made of other substances can be applied. Further, the partition sheet material 16 includes a window hole or notch through which the hot air introduction pipe 34 and the exhaust pipe 32 can pass.

  The hot air generator 20 is configured to generate hot air having a set temperature and air volume. A temperature sensor 22 including a thermocouple for detecting the temperature of the hot air is disposed near the outlet of the hot air generator 20. In this embodiment, the temperature is set so that the set temperature of the hot air generator 20 is about 5 to 6 ° C. lower than the set temperature of the upper plate heater 36 (for example, 68 ° C.). It is not limited to.

  The hot air introduction pipe 34 is configured to uniformly feed the hot air generated by the hot air generator 20 into the space surrounded by the partition sheet material 16. The hot air introduction pipe 34 is provided with an air filter 24 for maintaining the cleanliness of the hot air. In this embodiment, a HEPA filter is used as the air filter 24, but the air filter 24 is not limited to this. Further, the hot air introduction pipe 34 is provided with a fine differential pressure gauge 18. The fine differential pressure gauge 18 is configured to monitor and control the air flow. Here, the fine differential pressure gauge 18 is provided for the purpose of blocking the entry of dirty air.

  The configuration of the hot air introduction pipe 34 will be described with reference to FIG. The hot air introduction pipe 34 includes a hot air duct 346 and a hot air ejection part 342. The hot air duct 346 is configured to guide the hot air from the hot air generator 20 to the hot air ejecting portion 342 through a plurality of paths while branching the hot air from the hot air generator 20. In order to correspond to the raising and lowering operation of the chamber lower portion 14, flexible piping is applied to a vertically extending portion of the hot air duct 346. Moreover, it is preferable that the hot air duct length which comprises each path | route is uniform from a viewpoint of preventing the deviation of the flow volume of the hot air in a some path | route.

  The hot air ejection part 342 includes a plurality of hot air ejection holes 344. The hot air ejection part 342 is formed in an annular shape along the outer periphery of the chamber lower part 14, and blows hot air against the outer edge of the bottom surface of the chamber lower part 14. The reason why the hot air ejection part 342 is configured in this manner is that the heat radiation from the outer periphery of the chamber lower part 14 is considered to be the largest.

  The hot air blown from the hot air blowing portion 342 to the chamber lower portion 14 circulates in the closed space and is then exhausted from the exhaust port 26 provided in the lower portion. Here, hot air is not circulated with an emphasis on the degree of cleaning of hot air, but a configuration in which hot air is circulated may be employed. In this embodiment, the hot air generator 20 and the hot air introduction pipe 34 correspond to the hot air supply means of the present invention.

  In the above-described configuration, the vacuum drying apparatus 10 decompresses the inside of the sealed container constituted by the chamber upper portion 12 and the chamber lower portion 14 by the vacuum pump 28 during the vacuum drying process. In this embodiment, evacuation is performed with the upper plate heater 36 set to 68 ° C. and the lower plate heater 38 turned off. As a result, the solvent in the coating solution supplied to the substrate 40 evaporates and is sucked to the decompression pump 28 side through the exhaust pipe 32.

  Further, at the time of drying under reduced pressure, the hot air generator 20 is operated to distribute the hot air into the partition sheet material 16. Since the outer surface of the exhaust pipe 32 and the chamber lower part 14 is heated by circulating hot air through the partition sheet material 16, the inner surface temperature of the chamber lower part 14 and the temperature in the exhaust pipe 32 are in the range of 66 to 68 ° C. It can be suppressed. For this reason, there is almost no difference between the surface temperature of the substrate 40 and the inner surface temperature of the chamber lower part 14 or the temperature in the exhaust pipe 32, so that dew condensation hardly occurs in the chamber lower part 14 or the exhaust pipe 32.

  Further, as shown in FIG. 4, the partition sheet material 16 bends in response to the raising / lowering operation of the chamber lower portion 14, and hence the closed space is formed below the chamber lower portion 14, thereby hindering the raising / lowering operation of the chamber lower portion 14. Never come.

  In the above-described configuration, when the outer surface of the sealed container is not heated by the hot air generator 20, the drying process per coating substrate took about 800 seconds, whereas the hot air generator 20 Thus, when the outer surface of the sealed container is heated, the drying processing time per coated substrate is shortened to about 600 seconds.

  In this embodiment, the configuration in which the chamber lower portion 14 moves with respect to the chamber upper portion 12 is adopted. The invention can be applied. When the closed space is formed on the chamber upper portion 12, a frame member for supporting the partition sheet material 16 may be provided on the chamber upper portion 12.

  Moreover, although the above-mentioned embodiment demonstrated the drying process with respect to the glass substrate in the manufacturing process of a liquid crystal display, the application range of this invention is not limited to this. For example, for heat insulation heating of airtight containers and vacuum tubes for vacuum drying equipment used in the field of semiconductor devices, heat insulation heating of airtight containers and tubes of CVD equipment in the field of semiconductor devices, and heat insulation heating of airtight containers of sputtering equipment in the field of FPD However, the present invention can be applied.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

It is a figure which shows the outline of the reduced pressure drying apparatus which concerns on embodiment of this invention. It is a figure which shows the example of installation of a partition sheet material. It is a figure which shows the outline of a hot air introduction pipe | tube. It is a figure which shows the reduced pressure drying apparatus at the time of board | substrate transfer.

Explanation of symbols

10-Vacuum drying apparatus 12-Upper part of chamber 14-Lower part of chamber 16-Partition sheet material 20-Hot air generator 34-Hot air introduction pipe 40-Substrate

Claims (6)

A vacuum drying apparatus configured to remove the solvent from the coating solution by drying the substrate coated with the coating solution containing the component of the coating film and the solvent in a reduced pressure state,
An openable and closable chamber having therein a placement unit for placing the substrate and a heater for heating the substrate at a set temperature;
An exhaust pipe configured to communicate with the interior of the chamber;
Decompression means configured to decompress the interior of the chamber via the exhaust pipe;
A closed space forming means for forming a closed space surrounding at least the connection portion of the chamber with the exhaust pipe and the exhaust pipe;
Hot air supply means configured to supply hot air of a predetermined temperature into the space closed by the closed space forming means;
A vacuum drying apparatus comprising: A vacuum drying apparatus configured to remove the solvent from the coating solution by drying the substrate coated with the coating solution containing the component of the coating film and the solvent in a reduced pressure state,
An openable and closable chamber having therein a placement unit for placing the substrate and a heater for heating the substrate at a set temperature;
An exhaust pipe configured to communicate with the interior of the chamber;
Decompression means configured to decompress the interior of the chamber via the exhaust pipe;
Closed space forming means for forming a closed space surrounding at least a substrate lift-up pin in the chamber;
Hot air supply means configured to supply hot air of a predetermined temperature into the space closed by the closed space forming means;
A vacuum drying apparatus comprising: A vacuum drying apparatus configured to remove the solvent from the coating solution by drying the substrate coated with the coating solution containing the component of the coating film and the solvent in a reduced pressure state,
An openable and closable chamber having therein a placement unit for placing the substrate and a heater for heating the substrate at a set temperature;
An exhaust pipe configured to communicate with the interior of the chamber;
Decompression means configured to decompress the interior of the chamber via the exhaust pipe;
A closed space forming means for forming a closed space surrounding at least the reinforcing rib in the chamber;
Hot air supply means configured to supply hot air of a predetermined temperature into the space closed by the closed space forming means;
A vacuum drying apparatus comprising:   The reduced-pressure drying apparatus according to any one of claims 1 to 3, wherein the closed space forming unit includes a flexible partition member. The hot air supply means includes
A hot air generator for generating hot air of a predetermined temperature;
A hot air introduction pipe configured to blow hot air generated by the hot air generator to an edge of a surface of the chamber to which the exhaust pipe is connected;
The reduced-pressure drying apparatus according to claim 1, comprising:   The vacuum drying apparatus according to claim 4 or 5, wherein the partition member is a transparent member.

Images