JP2007205592A - Baking device for substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a baking device capable of baking a substrate without cracking even if the substrate is conveyed in a state of being directly loaded on a roller without using a setter. <P>SOLUTION: In this baking device 1 for the substrate, having an oven 2 composed of a plurality of furnace chambers, and a plurality of conveying rollers 5 disposed in the furnace chambers and conveying the substrate 4 having a glass plate as its base material in a state of directly loading the same, the oven has at least three zones of a temperature rising zone 2A for heating the substrate to a baking temperature, a baking zone 2B for keeping the substrate at a baking temperature, and a cooling zone 2C for cooling the substrate from the baking temperature, and the conveying roller having a heating means is disposed in the furnace chamber of the cooling zone, so that the cracking of the substrate can be effectively prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a baking apparatus for baking a substrate used in a plasma display panel (hereinafter referred to as PDP).

  Conventionally, a so-called cathode ray tube (CRT) has been a representative display, but a liquid crystal display (LCD) and a plasma display panel (PDP) are rapidly increasing in demand as thin flat panel displays. In particular, PDPs are capable of high-speed display compared to LCDs and are easy to increase in size, and therefore are expected to make progress in the field of high-definition television. There is a strong demand for technology that enables stable production at low cost.

  When manufacturing a PDP, a display electrode made of a transparent electrode and a bus electrode is formed on a substrate, a dielectric layer and a protective layer made of MgO are formed to cover the display electrode, and a front plate is produced. An address electrode is formed on the substrate, a dielectric layer, a partition wall and a phosphor layer are formed on the data electrode to produce a back plate, and the front substrate and the back substrate are bonded together. In each step of forming the display electrode, dielectric layer, address electrode, barrier rib, and phosphor layer, a paste layer is formed on the substrate, and then the paste layer is heated and fired.

  There are two types of firing methods: a batch-type firing device and a continuous-type firing device, but the method using a continuous firing device is superior in terms of production efficiency. Many are used.

  In a continuous firing apparatus, a plate-like object to be heated such as a glass substrate is heated in a tunnel-type furnace to a temperature rising zone where the temperature is raised to a predetermined temperature, a firing zone maintained at the firing temperature, and a cooling zone where cooling is performed. Heat treatment is performed while being sequentially conveyed.

  This continuous firing apparatus is provided with a plurality of rollers for transporting the substrate below the inside of a tunnel type furnace through which the substrate passes. The roller is rotated by a motor, and the substrate placed on the roller is conveyed by this rotation. At this time, the substrate is not placed directly on the roller for the purpose of transporting in a stable state so that the substrate does not distort, and for preventing scratches when the substrate contacts the roller. It is placed on a setter such as glass and is conveyed by placing this setter on a roller.

  However, in the conventional method in which the substrate is placed on the setter and transported, the substrate and the setter are heated at the same time during firing, and thus the power for heating the setter, which does not need to be heated, is consumed. However, there is a problem that the total power consumption increases. Further, the setter needs to be surface-polished after firing a predetermined number of times in order to eliminate the scratches generated in the firing step, and this polishing is very expensive.

  However, with a conventional continuous firing apparatus, when a substrate having a glass plate as a base material is placed directly on a roller and transported, the temperature difference between the furnace chambers is large especially in the cooling zone when transporting the substrate. As a result, the substrate comes into contact with the conveying roller whose temperature is extremely lower than the substrate temperature, and there is a problem that the substrate is cracked due to thermal stress.

  In a firing apparatus using a setter, it has been proposed to control the firing temperature profile in order to obtain substrate cracking suppression and good sintered film quality (Patent Document 1). However, since this method uses a setter, the above problem is solved. In addition, the control of the furnace chamber atmosphere temperature alone is inefficient because the entire furnace chamber is heated.

The present invention has been proposed in view of the above circumstances, and firing that can suppress the generation of cracks in a substrate even if the substrate is directly placed on a roller and transported without using a setter. An object is to provide an apparatus.
JP 2002-373572 A (Claim 1)

  The objective of this invention is providing the baking apparatus which can suppress that a board | substrate cracks even if it mounts and conveys a board | substrate directly on a roller, without using a setter.

  The above-mentioned problem is a substrate baking apparatus having an oven composed of a plurality of furnace chambers and a plurality of transport rollers that are provided in the furnace chambers and directly load and transport a substrate having a glass plate as a base material, The oven has at least three zones: a temperature raising zone for raising the temperature of the substrate to the firing temperature, a firing zone for holding the substrate at the firing temperature, and a cooling zone for cooling the substrate from the firing temperature. This can be solved by using a substrate baking apparatus provided with a transport roller having heating means.

  By using the baking apparatus of this invention, generation | occurrence | production of a substrate crack can be suppressed even if it is a case where a board | substrate is directly conveyed on a roller and baking is performed.

  The substrate baking apparatus of the present invention is an oven composed of a plurality of furnace chambers, and a substrate having a plurality of transfer rollers that are provided in the furnace chambers and directly load and transfer substrates based on glass plates. The oven has at least three zones: a temperature raising zone for raising the substrate to a firing temperature, a firing zone for holding the substrate at the firing temperature, and a cooling zone for cooling the substrate from the firing temperature, It is a board | substrate baking apparatus provided with the conveyance roller which has a heating means in the furnace chamber of a cooling zone.

  By directly transporting the substrate on the roller without using a setter, the power consumption can be reduced, and a maintenance process such as polishing of the setter can be omitted.

  Moreover, in this invention, the conveyance roller which has a heating means is provided in the furnace chamber of a cooling area, It is characterized by the above-mentioned. When transporting substrates directly on rollers, if there is no transport roller with heating means in the furnace chamber of the cooling zone, if there is a large temperature difference between adjacent furnace chambers in the cooling zone, the substrate with high temperature will be sufficiently cooled Before it is done, it comes into contact with a low-temperature roller, and the substrate is cracked due to thermal stress caused by a local temperature difference in the base slope.

  In the present invention, by providing a transport roller having a heating means in the furnace chamber of the cooling zone, even if there is a large difference in ambient temperature between adjacent furnace chambers in the cooling zone, the substrate does not crack and is efficient. Can be cooled to.

  Moreover, in the baking apparatus of this invention, it is preferable to provide the conveyance roller which has a lifter part which conveys a board | substrate to a height direction after a cooling zone, and has a heating means in this lifter part.

  By providing the lifter unit and transporting the substrate in the height direction, the transport to the next process can be performed smoothly. In particular, a return conveyor is provided under the oven of the baking apparatus to convey the substrate in the direction opposite to the direction of travel in the oven, and the substrate exiting the cooling zone is conveyed to the return conveyor using the lifter unit, thereby firing. The plane position of the entrance and the exit of the apparatus can be made the same so that the carry-in from the previous stroke and the carry-out to the subsequent process can be performed efficiently, and the substrate can be sufficiently cooled to room temperature.

  In the present invention, by providing the above-mentioned lifter unit with a transport roller having a heating means, it is possible to suppress cracking of the substrate even when the substrate is not cooled to near room temperature in the cooling zone.

  Hereinafter, a PDP substrate which is a preferred application of the present invention will be described.

  The PDP generates a plasma discharge between electrodes facing each other in a discharge space provided between a front glass substrate and a back glass substrate, and emits ultraviolet rays generated from a gas enclosed in the discharge space in the discharge space. The display is performed by touching the phosphor provided in.

  A typical configuration example will be described. A display electrode composed of a transparent electrode and a bus electrode is formed on the glass substrate on the front plate side serving as a display surface. Further, a dielectric layer mainly composed of glass is formed by covering the display electrode, and a protective layer made of magnesium oxide (MgO) is formed by covering the dielectric layer.

  On the other hand, on the glass substrate on the back plate side, a plurality of address electrodes are usually formed in stripes, and a dielectric layer mainly composed of glass is formed by covering the address electrodes. A partition for partitioning the discharge cells is formed on the dielectric layer, and a phosphor layer is formed in a discharge space formed by the partition and the dielectric layer. In a PDP capable of full color display, the phosphor layer is composed of materials that emit light in red, green, and blue colors. The front plate and the back plate are sealed so that the display electrode of the glass substrate on the front plate side and the address electrode on the back plate side are orthogonal to each other, and after thermal vacuum exhaust, helium, neon, A rare gas composed of xenon or the like is enclosed to form a plasma display. Since the pixel cell is formed around the intersection of the display electrode and the address electrode, the plasma display has a plurality of pixel cells and can display an image.

  In the above PDP substrate, when forming functional layers such as bus electrodes on the front plate, dielectric layers, address electrodes on the back plate, dielectric layers, barrier ribs, phosphor layers, and sealing members, inorganic components and In general, a paste made of an organic component is applied, dried and patterned as necessary, and then baked to remove the organic component to form a functional layer made only of an inorganic component. The baking apparatus of this invention can be preferably used for the baking process for formation of the said functional layer.

  Next, a baking apparatus used in the above baking process will be described.

  FIG. 1 shows a substrate baking apparatus according to an embodiment of the present invention. The baking apparatus 1 includes a transport roller 5, an oven 2, a return conveyor 3 provided under the oven 2, and a lifter unit 8 that transports a substrate from the oven 2 to the return conveyor 3.

  In the oven 2, a transport roller 5 is installed as a transport means for transporting the substrate 4. On the ceiling surface and floor surface of the oven 2, a heater 6 made of, for example, an electric heater or an infrared heater is used as a heating means. Is installed. Each heater 6 is divided into a plurality of directions in the traveling direction and the width direction according to the size of the furnace chamber, and is configured to be able to individually control the amount of heat generated so as to obtain a target temperature distribution.

  Here, the oven 2 includes at least three heating zones 2A for raising the temperature of the substrate 4 to a set temperature, a firing zone 2B for heat-treating at a constant temperature, and a cooling zone 2C for cooling to a predetermined temperature. Provide the area along the transport direction. The cooling zone 2C includes a furnace chamber that does not have heating means. In particular, in order to shorten the firing time, it is preferable that the last furnace chamber in the cooling zone is the quenching chamber 7 in which the substrate is rapidly cooled.

  In the present invention, a transport roller having heating means is provided in the furnace chamber of the cooling zone. Thereby, the crack of a board | substrate can be prevented effectively as mentioned above.

  The method of heating the transport roller is not particularly limited, but a heating source such as an electric heater, a halogen heater, an IR heater, etc. is arranged at the center of a cylindrical object having a thickness of several millimeters, and is heated by radiant heat. A method of heating with a heating medium such as is preferably used.

  The material of the transport roller must be able to withstand the processing temperature in each furnace chamber according to the desired firing temperature profile. For example, in a furnace room at a high temperature range of 200 ° C. or higher, it is made of ceramic such as alumina, mullite, SiC, etc. However, for example, in a furnace room in a low temperature region below 200 ° C., a cylindrical roller made of metal such as stainless steel is preferably used.

  In the transport roller of the present invention, the surface that contacts the substrate with a metal as an axis may be coated with ceramics, resin, or the like according to a desired temperature. In the case of resin, silicon rubber, fluororesin, polyethersulfone, nylon, urethane rubber and the like are used, and silicon rubber, fluororesin, polyethersulfone and the like are preferable from the viewpoint of heat resistance.

  In the firing furnace of the present invention, in order to efficiently control the temperature of the substrate and to reduce the temperature difference between the front and rear in the substrate being transported, the substrate is transported between the furnace chambers and the furnace every predetermined time particularly in the cooling zone A tact conveyance system that repeatedly stops in the room is preferably used. Substrate cracking suppression in the present invention is particularly effective when the substrate moves quickly between furnace chambers using the tact method, and the difference between the substrate temperature and the transport roller temperature becomes significant.

  The temperature of the transport roller to be heated is preferably set so that the temperature difference from the immediately preceding furnace chamber is within 200 ° C., more preferably within 150 ° C., in order to increase the effect of suppressing cracking. It is preferable that a plurality of transport rollers having heating means are provided in the furnace chamber constituting the cooling zone. Moreover, the furnace chamber provided with the conveyance roller which has a heating means may be single, or plural according to need.

  When the furnace chamber immediately before the lifter unit is particularly higher than room temperature, it is preferable to provide a transport roller having heating means in the lifter unit 8 in order to suppress the occurrence of substrate cracking in the lifter unit.

  The method for heating the transport roller in the lifter is not particularly limited, and the same heating means for the transport roller in the cooling zone described above can be used.

  Since the baking apparatus controls the position of the substrate, it is preferable that an optical position sensor including a light projecting unit and a light receiving unit is provided in at least a part of the furnace chamber. The optical position sensor detects light projected from the light projecting unit across a predetermined position through which the substrate passes. When the substrate comes to the predetermined position and the light is blocked, It detects that it is in the predetermined position.

  Although not shown, in the baking apparatus of this example, in order to carry the substrate in a tact manner, it is preferable that the same optical position sensor as described above is provided at each position as a position sensor for determining each stop position.

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these.
(Example 1) In the apparatus shown in FIG. 1, the length of one furnace chamber was 1500 mm, the number of furnace chambers was 20, and the length of the entire oven was 30 m. In addition, 7 furnace chambers in the temperature raising zone, 4 furnace chambers in the firing zone, and 9 furnace chambers in the cooling zone. In the 11 rooms of the temperature raising zone and the firing zone, the continuous conveyance system was used, and in the 9 rooms of the cooling zone, the tact conveyance was adopted. In the continuous conveyance area, the baking time was 6 minutes, the processing time per room was 4 minutes in the tact conveyance area, and the entire oven passage time was 102 minutes. Table 1 shows the temperature conditions and processing conditions of each furnace chamber.

  The transport rollers in the first to 19th furnace chambers are made of ceramic, and the transport rollers have no heating means. The conveying roller had a diameter of 45 mm, a length of 2400 m, a roller pitch of 150 mm, and the number of rollers per chamber was 10.

Note that the last furnace chamber (20th chamber) in the cooling zone did not heat the entire furnace chamber. The temperature in the furnace chamber just before the quenching chamber (19th chamber) was 310 ° C., and the temperature in the quenching chamber was 35 ° C.
The conveying roller in the quenching chamber had a heating means and was heated to 180 ° C. The moving speed between the tact conveying areas was 4 m / min.

  The conveyance roller in the quenching chamber was a stainless steel roller coated with silicon rubber, and a stainless steel roller with an electric heater at the center was used. The conveying roller in the quenching chamber had a diameter of 50 mm, a length of 2400 m, a roller pitch of 200 mm, and the number of rollers per chamber was 8.

  Moreover, as a conveyance roller of a lifter part, what has the same heating means with the same material as the conveyance roller of a quenching chamber was heated at 80 degreeC. The transport roller of the lifter unit had a diameter of 50 mm, a length of 2400 m, a roller pitch of 200 mm, and the number of rollers per room was 8.

A high strain point glass (PD200 manufactured by Asahi Glass) having a thickness of 964 mm × 570 mm and a thickness of 1.8 mm was used as the processing substrate. With respect to the treated substrate after firing, the generation of cracks was not particularly observed, and a good fired substrate was obtained.
(Comparative example)
The quenching chamber and the lifter part were not provided with a transport roller having heating means, and the same baking apparatus as in the example was provided except that the first to 19th chambers and the same transport roller were provided. A substrate crack occurred in the quenching chamber when heat treatment was carried out under the same conditions as in the example except that the heating rollers in the quenching chamber and the lifter chamber were not heated.

1 is a schematic diagram showing an overall configuration of a substrate baking apparatus according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Baking apparatus 2 Oven 2A Temperature rising zone 2B Firing zone 2C Cooling zone 3 Return conveyor 4 Substrate 5 Transfer roller 6 Heater 7 Rapid cooling chamber 8 Lifter part 9 Transfer direction

Claims (2)

A substrate baking apparatus having an oven composed of a plurality of furnace chambers, and a plurality of transport rollers that are provided in the furnace chambers and directly transport a substrate having a glass plate as a base material, the oven being a substrate At least three zones: a temperature raising zone for raising the temperature to the firing temperature, a firing zone for holding the substrate at the firing temperature, and a cooling zone for cooling the substrate from the firing temperature, and heating means is provided in the furnace chamber of the cooling zone. The baking apparatus of a board | substrate provided with the conveyance roller which has. The substrate baking apparatus according to claim 1, further comprising a transfer roller having a lifter unit that transfers the substrate in a height direction after the cooling zone, and having a heating unit in the lifter unit.

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