JP2004037044A - Vacuum heating furnace for flat panel display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum heating furnace for a FPD capable of heat treatment of a board as even as possible and having excellent productivity. <P>SOLUTION: A plurality of plate-like heaters 22 are provided between a plurality of boards 16, which are supported by supports 20, in nearly parallel with the boards 16, and temperature of these plate-like heaters 22 is controlled by a temperature controller 44 to nearly even each temperature. The heat treatment as even as possible thereby can be performed to the board 16 with radiation from the plate-like heaters 22 in a high-vacuum space formed in a furnace body 12, and temperature accuracy, for example a board surface-inside temperature error is restricted within plus and minus 3°C, is obtained. Since the heat treatment can be performed to a plurality of the boards 16 in one batch, the vacuum heating furnace 10 for a FPD can be provided with excellent productivity. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vacuum heating furnace for FPD which is suitably used for heat treatment of an FPD substrate requiring high temperature accuracy, such as EL or FED.
[0002]
[Prior art]
2. Description of the Related Art In recent years, next-generation flat panel displays (FPDs) such as EL (electroluminescence display) or FED (field emission display) have been put into practical use. These ELs or FEDs guarantee a wide viewing angle and excellent resolution even in a relatively thin structure, and particularly in the field of small and medium-sized display devices of 20 inches or less, for example, a display device for a next-generation workstation terminal. High expectations have been placed on this.
[0003]
In the production of such EL or FED, for example, a metal or inorganic material is melted on a glass substrate represented by soda lime glass or a ceramics substrate represented by alumina, or the material itself is softened or melted. Alternatively, the film is fixed by sintering to form a film having a predetermined function. Conventionally, for such heat treatment, a heating furnace such as a roller hearth kiln has been used, but with the progress of the manufacturing process toward practical use, the substrate can be uniformly heated at a relatively high temperature. A heating furnace has been required. In a recent manufacturing process, for example, a temperature accuracy of about 500 ° C. and a temperature difference within a substrate surface within ± 5 ° C. is required.
[0004]
Therefore, a vacuum heating furnace of a type that heat-treats the substrate in a high vacuum space formed in the furnace has been developed. For example, a heat treatment apparatus for a glass substrate described in the specification of Japanese Patent Application Laid-Open No. 2000-161858 and the like is the one. According to such a vacuum heating furnace, since the heat treatment is performed on the substrate in a high vacuum space of, for example, about 1 × 10 ⁻³ Pa, heat convection and conduction hardly occur, and the substrate is only irradiated by radiation. A heat treatment as uniform as possible is provided.
[0005]
[Problems to be solved by the invention]
However, such a conventional vacuum heating furnace is configured to heat only one substrate per batch, and is not practical because of poor productivity. Therefore, as a vacuum heating furnace capable of heating a plurality of substrates per batch, a vacuum heating furnace 50 as shown in a schematic sectional view of FIG. 6 is conceivable. As shown in this figure, such a vacuum heating furnace 50 includes a cylindrical furnace body 52 for forming a high vacuum space, and a heater 54 embedded in the furnace body 52. A plurality of substrates 56 are subjected to a heat treatment by radiating the generated heat from the inner peripheral surface of the furnace body 52. However, with such a configuration, the in-plane temperature difference of the substrate 56 becomes as large as ± 30 ° C. or more, and it is impossible to perform uniform heating. That is, at present, a vacuum heating furnace for FPD which can perform a heat treatment as uniform as possible on a substrate and has excellent productivity has not yet been developed.
[0006]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vacuum heating furnace for FPD which can perform a heat treatment as uniform as possible on a substrate and has excellent productivity. To provide.
[0007]
[Means for Solving the Problems]
In order to achieve such an object, the gist of the present invention is configured to include a furnace body for forming a high vacuum space therein, and an exhaust device for discharging gas in the furnace body to the outside, What is claimed is: 1. A FPD vacuum heating furnace of a type for performing heat treatment on a substrate in a high vacuum space formed in the furnace, comprising: a support for supporting a plurality of said substrates so as to be substantially parallel to each other; A plurality of plate-shaped heating devices provided between the plurality of substrates supported by the substrate so as to be substantially parallel to the substrates, so that the temperatures of the respective plate-shaped heating devices become substantially uniform. A temperature control device for controlling the temperature of the plate-shaped heating device.
[0008]
【The invention's effect】
With this configuration, a plurality of plate-shaped heating devices are provided between the plurality of substrates supported by the support so as to be substantially parallel to the substrates, and the plate-shaped heating devices are provided. Since the temperature is controlled by the temperature control device so that each temperature becomes substantially uniform, radiation from such a plate-shaped heating device in a high vacuum space formed in the furnace body, The substrate can be subjected to a heat treatment as uniform as possible. In addition, since a plurality of substrates can be subjected to heat treatment per batch, a vacuum heating furnace for FPD with excellent productivity can be provided.
[0009]
Other aspects of the invention
Here, preferably, the plate-shaped heating device is such that a rod-shaped heating element is buried inside a metal plate provided with a radiation layer for improving the efficiency of heat radiation on the surface. With this configuration, since the radiation layer is provided on the surface of the metal plate, the efficiency of heat radiation from the surface of the metal plate is increased, and a rod-shaped heating element is provided inside the metal plate. By being buried, the heat generated from the rod-shaped heating element is quickly transferred to the metal plate by conduction, so that there is an advantage that the temperature of the plate-shaped heating device is substantially uniform. .
[0010]
Further, preferably, the plate-shaped heating device includes a flow passage for flowing a cooling fluid, and the temperature control device adjusts a flow rate of the cooling fluid in the flow passage to adjust the flow rate of the cooling fluid. It controls the temperature of the plate-shaped heating device. With this configuration, the plate heating device can be rapidly cooled by flowing a cooling fluid through the flow passage as needed, and the processing time of one batch by the vacuum heating furnace for FPD is reduced. In addition to this, there is an advantage that the temperature of the plate-shaped heating device can be controlled with a relatively simple configuration.
[0011]
【Example】
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0012]
FIG. 1 is a cross-sectional view illustrating the configuration of a vacuum heating furnace 10 for an FPD according to an embodiment of the present invention. As shown in FIG. 1, the vacuum heating furnace 10 includes a cylindrical furnace body 12 for forming a high vacuum space therein, and an exhaust device 14 for discharging gas in the furnace body 12 to the outside. The FPD substrate 16 is subjected to heat treatment in a high vacuum space formed in the furnace body 12. The furnace body 12 is made of, for example, stainless steel, and has a structural strength capable of applying a high vacuum of about 1 × 10 ⁻⁷ to 1 × 10 ⁻³ Pa inside. The exhaust device 14 is, for example, a turbo molecular pump that mechanically transfers gas molecules in the furnace body 12 to the outside, and an exhaust pipe 18 extending from a through hole 16 provided in a furnace wall of the furnace body 12. It is connected to.
[0013]
In the furnace body 12, a support 20 for supporting a plurality of (four in the figure) substrates 16 so as to be substantially parallel to each other, and a plurality of the substrates 16 supported by the support 20. A plurality of plate heaters 22 (16 in total, four for each substrate in the figure) provided between the substrates so as to be substantially parallel to the substrate 16 are provided. FIG. 2 is a sectional view taken along line II-II of FIG. As shown in FIG. 2, the plate-shaped heating device 22 has, for example, a flat longitudinal shape, and a plurality (four in the figure) is arranged on one surface so that the longitudinal directions are parallel to each other. It is supported by the support body 12 in a state where it is in an upright position. A plurality of (three in the figure) pipes 24 made of, for example, stainless steel are fixed on the plurality of plate-like heating devices 22 arranged on one surface in such a manner, and a plurality of A plurality (three in the figure) of conical pins 26 are provided, and the substrate 16 is supported by the plurality of pins 26 with a contact area as small as possible. That is, the plate-shaped heating device 22 of the present embodiment is configured to perform heat treatment by radiation on the substrate 16 provided exclusively on the upper side thereof.
[0014]
3A and 3B are diagrams showing a configuration of the plate-shaped heating device 22, wherein FIG. 3A is a plan view and FIG. 3B is a cross-sectional view taken along line III-III of FIG. As shown in this figure, the plate-shaped heating device 22 is preferably made of a metal plate 24 provided on the surface with a radiation layer 26 for increasing the efficiency of heat radiation, for example, t15 mm × 140 mm × It is made of aluminum alloy or stainless steel having a size of about 600 mm. The thickness of the metal plate 24 is preferably, for example, t15 mm or more for an aluminum alloy and t25 mm or more for stainless steel. According to the metal plate 24 having such a thickness, the temperature of the metal plate 24 itself during heating increases. Unevenness is less likely to occur. The radiation layer 26 is, for example, a ceramic film formed by paint baking or the like, or a metal film formed by thermal spraying or the like. As expected, a Ni-Co-Cr-Y-Al alloy coating or the like is preferably used.
[0015]
As shown in FIG. 3B, the metal plate 24 has a plurality of (two in the figure) rod-shaped heating elements 28 embedded therein and a plurality of metal heating plates 28 for flowing a cooling fluid. In this figure, two (two) passages 30 are formed. The rod-shaped heating element 28 is, for example, a tubular sheathed heater in which a heating wire is accommodated in an electrically insulated state. The rod-shaped heating element 28 is inserted into a through hole 32 formed in the longitudinal direction of the metal plate 24 so that Since it is provided in close contact with the peripheral surface, it has high thermal conductivity between itself and the metal plate 24. Further, the flow passage 30 is formed so as to penetrate in the longitudinal direction of the metal plate 24 similarly to the through hole 32, and has the same diameter as the through hole 32, for example, about 8 mmφ. It is. That is, the flow passage 30 and the through hole 32 are interchangeable. In FIG. 3, the two inner through holes are the flow passages 30 and the two outer through holes 32 are the rod-shaped heat generating holes. Although the body 28 is inserted, these combinations can be appropriately changed.
[0016]
FIG. 4 is a diagram illustrating the rod-shaped heating element 28 in detail. As shown in this figure, the rod-shaped heating element 28 is provided with a gradient in the heating value in the longitudinal direction in order to heat the substrate 16 more uniformly. For example, the heating wire buried inside the sheathed heater is relatively sparse at the center portion 28c and relatively dense at both end portions 28c so as to be smaller than the calorific value of both side portions 28s.
[0017]
The two flow passages 30 are connected to each other at one end, and are connected to the inflow pipe 34 and the outflow pipe 36 at the other end. The inflow pipe 34 and the outflow pipe 36 are connected to a fluid control device 38 for adjusting the flow rate of the cooling fluid in the flow passage 30, and the cooling fluid sent from the fluid control device 38 is supplied to the inflow pipe 34. Flows through the flow passage 30 through the flow passage 30, and is returned to the fluid control device 38 through the outflow pipe 36 after flowing through the flow passage 30. Thus, the cooling fluid circulates in the plate-shaped heating device 22.
[0018]
FIG. 5 is a diagram illustrating a control system of the vacuum heating furnace 10. As shown in the figure, the vacuum heating furnace 10 includes a heating element control device 40 for controlling the temperature of the rod-shaped heating element 28, a temperature sensor 42 for detecting the temperature of the plate-shaped heating device 22, and a temperature sensor And a temperature controller 44 for controlling the operations of the fluid controller 38 and the heating element controller 40 based on the temperature detected by the controller 42. Here, the temperature sensor 42 is, for example, a thermocouple, and is disposed at a plurality of locations on the metal plate 24 to detect the temperature distribution.
[0019]
When performing the heat treatment on the substrate 16 by the vacuum heating furnace 10 configured as described above, first, a door (not shown) provided on the furnace body 12 is opened, and the plurality of substrates 16 are respectively placed at predetermined positions. Install. Subsequently, the door is closed and the exhaust device 14 is operated to form a high vacuum space in the furnace body 12. The substrate 16 is subjected to a heat treatment by the plate-like heating device 22 in the vacuum space thus formed. Here, a reflection plate 46 is provided at an upper end portion and four side portions of the support body 14 and a lower side of the plurality of plate-shaped heating devices 22 arranged on one surface, respectively. The divergence is blocked, and the radiation from the plurality of plate-like heating devices 22 provided above each substrate 16 and arranged on one surface does not affect the heat treatment of the substrate 16.
[0020]
As described above, according to the present embodiment, the plurality of plate-shaped heating devices 22 are provided between the plurality of substrates 16 supported by the support body 20 so as to be substantially parallel to the substrates 16. Since the temperatures of the plate-shaped heating devices 22 are controlled by the temperature control device 44 so that the respective temperatures become substantially uniform, a high vacuum formed in the furnace body 12 is used. Due to the radiation from the plate-shaped heating device 22 in the space, the substrate 16 can be subjected to a heat treatment as uniform as possible. Is obtained. In addition, since a plurality of the substrates 16 can be heat-treated per batch, the FPD vacuum heating furnace 10 excellent in productivity can be provided.
[0021]
In addition, since the plate-shaped heating device 22 is a device in which a rod-shaped heating element 28 is embedded inside a metal plate 24 provided with a radiation layer 26 for improving the efficiency of heat radiation on the surface, the metal plate 24 By providing the radiation layer 26 on the surface of the metal plate 24, the efficiency of heat radiation from the surface of the metal plate 24 is increased, and in addition, a rod-shaped heating element 28 is embedded inside the metal plate 24. By doing so, the heat generated from the rod-shaped heating element 28 is quickly transferred to the metal plate 24 by conduction, so that there is an advantage that the temperature of the plate-shaped heating device 22 is substantially uniform. Further, by using such a relatively small plate-shaped heating device 22, there is an advantage that the vacuum heating furnace 10 for FPD can be downsized.
[0022]
Further, the plate-shaped heating device 22 includes a flow passage 30 for flowing a cooling fluid, and the temperature control device 44 adjusts the flow rate of the cooling fluid in the flow passage 30 to adjust the flow rate of the cooling fluid. Since the temperature of the plate-shaped heating device 22 is controlled, a cooling fluid is circulated through the flow passage 30 as needed, so that the plate-shaped heating device 22 can be moved as quickly as possible, for example. Cooling can be performed in about 1/10 of the time without the provision, and the processing time of one batch by the FPD vacuum heating furnace 10 can be reduced to about 1/2 of the conventional vacuum heating furnace. In addition, there is an advantage that the temperature of the plate-shaped heating device 22 can be controlled with a relatively simple configuration.
[0023]
As described above, the preferred embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and may be implemented in other embodiments.
[0024]
For example, the above-described vacuum heating furnace 10 forms a high vacuum space, that is, a space reduced to about 1 × 10 ⁻⁷ to 1 × 10 ⁻³ Pa inside the furnace body 12. Is not limited to this, and if necessary, an ultrahigh vacuum space, that is, a space reduced to 1 × 10 ⁻⁷ Pa or less may be formed inside the furnace body.
[0025]
Although the above-described vacuum heating furnace 10 includes the cylindrical furnace body 12, the vacuum heating furnace 10 may include, for example, a rectangular parallelepiped furnace body. That is, any shape may be used as long as it has a structural strength capable of forming a required high vacuum therein.
[0026]
Further, the above-mentioned plate-like heating device 22 has a flat long shape, and the plurality of plate-like heating devices 22 are arranged in a state where a plurality of the plate-like heating devices 22 are arranged on one surface so that the longitudinal directions thereof are parallel to each other. The heat treatment is performed on one of the substrates 16. For example, the heat treatment is performed on one of the substrates 16 by forming a shape close to a square in a plan view. No problem.
[0027]
The plate heating device 22 has a flow passage 30 formed therein, and forced cooling can be performed by flowing a cooling fluid through the flow passage 30. For example, such a flow passage is used. 30. A relatively low-reactive cooling gas such as nitrogen is introduced into a furnace of a vacuum heating furnace provided with a plate-shaped heating device not provided with 30 to forcibly cool the plate-shaped heating device. No problem.
[0028]
In addition, the above-described plate-shaped heating device 22 is configured to perform heat treatment by radiation only on the substrate 16 disposed on the upper side. However, for example, heat treatment is performed on the substrate 16 disposed on the lower side. Alternatively, the substrate 16 may be subjected to heat treatment by radiation from both upper and lower directions.
[0029]
Further, the above-described exhaust device 14 is a turbo-molecular pump that mechanically transfers gas molecules to the outside, but this is an oil rotary pump, a dry pump, a diffusion pump, or a combination thereof. No problem. When a relatively high degree of vacuum is required, a getter pump or a sputter ion pump of a type that stores gas is used in combination.
[0030]
Further, the above-described vacuum heating furnace 10 is not limited to the heat treatment of the substrate for EL or FED, but is preferably used for heat treatment of a substrate for a plasma display panel (PDP). .
[0031]
Although not illustrated one by one, the present invention is embodied with various changes without departing from the spirit thereof.
[Brief description of the drawings]
FIG. 1 is a sectional view illustrating a configuration of a vacuum heating furnace for an FPD according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II of FIG.
3A and 3B are diagrams showing a configuration of a plate-shaped heating device provided in the vacuum heating furnace for FPD shown in FIG. 1, wherein FIG. 3A is a plan view and FIG. 3B is a sectional view taken along line III-III of FIG. is there.
FIG. 4 is a view for explaining a rod-shaped heating element inserted into the plate-shaped heating device shown in FIG. 3 in detail.
5 is a diagram illustrating a control system of the vacuum heating furnace for FPD shown in FIG.
FIG. 6 is a schematic sectional view illustrating the configuration of a conventional vacuum heating furnace.
[Explanation of symbols]
10: Vacuum heating furnace for FPD 12: Furnace body 14: Exhaust device 16: Substrate 20: Support body 22: Plate heating device 24: Metal plate 26: Radiation layer 28: Rod heating element 30: Flow path 44: Temperature control device

Claims (3)

A furnace body for forming a high vacuum space therein, and an exhaust device for exhausting gas in the furnace body to the outside are provided, and heat treatment is performed on the substrate in the high vacuum space formed in the furnace body. A type of vacuum heating furnace for FPD,
A support for supporting the plurality of substrates so as to be substantially parallel to each other,
A plurality of plate-shaped heating devices provided so as to be substantially parallel to the substrate between the plurality of substrates supported by the support,
A temperature control device for controlling the temperature of the plate-shaped heating device so that the temperature of each of the plate-shaped heating devices becomes substantially uniform. The vacuum heating furnace for an FPD according to claim 1, wherein the plate-shaped heating device has a rod-shaped heating element embedded in a metal plate having a radiation layer provided on a surface thereof for increasing the efficiency of heat radiation. The plate-shaped heating device has a flow passage for flowing a cooling fluid, and the temperature control device adjusts a temperature of the plate-shaped heating device by adjusting a flow rate of the cooling fluid in the flow passage. The vacuum heating furnace for an FPD according to claim 1 or 2, wherein the furnace is controlled.

Images