TWI661483B - Etching system - Google Patents

Abstract

Provided is an etching system, which can effectively use a pressurized filter device in a circulation line, and clean the etching solution at a low cost.

The etching system includes an etching device, a circulation circuit, a membrane filter device, and a pressure filter device. The etching apparatus is configured to include at least an etching solution tank, and an etching solution stored in the etching solution tank is brought into contact with a glass substrate to perform an etching process. The circulation circuit is configured to take out the etchant in the etchant bath to the outside, filter it, and return it to the etchant bath at the same time. The membrane filter device is arranged on a circulation line and includes an immersion membrane for filtering an introduced etching solution. The pressure filtration device is configured downstream of the membrane filtration device arranged on the circulation line, and receives the slurry captured by immersing the membrane to perform solid-liquid separation.

Description

Etching system

The present invention relates to an etching system for performing an etching process on a glass substrate for a flat panel display, and more particularly to an etching system in which a pressurizing filter device is efficiently arranged in a circulation line and the etching solution can be circulated at low cost.

Glass substrates used in flat-panel displays such as liquid crystal displays require a reduction in thickness. In terms of a process for reducing the thickness of a glass substrate for a flat panel display, an etching process in which a hydrofluoric acid-containing etching solution is brought into contact with a glass substrate has been generally used. In terms of such an etching process, there are the following methods: immersing the glass substrate to be processed in a tank filled with an etching solution, or blowing the etching solution onto the glass substrate to be processed.

When the above-mentioned etching process is performed on the glass substrate, the process of generating liquid discharge becomes important. In the past, pressurized filtering devices such as a pressure filter are mostly arranged on a liquid discharge line, and solid waste and liquid separation and dehydration of the liquid are appropriately performed to perform industrial waste treatment (for example, refer to Patent Document 1). The reason is that the pressurized filter device generally has a large filtration area, so it has a high processing capacity and can handle a large amount of drainage. water. In addition, it is said that the pressurized filter device has a high filtration pressure, so a filter cake with a low water content can be obtained, and it also has the advantages of reducing production costs and operating costs compared with the immersion membrane method.

Prior art literature Patent literature

Patent Document 1: Japanese Invention Patent No. 5143440

However, although the pressure filter device is suitable for use in the drainage line, it is not suitable for use in the circulation line. The reason for this is to effectively perform solid-liquid separation with a pressure filter device, and generally, a method of adding a coagulant to the used etching solution that has been introduced. When a flocculant is added, solid-liquid separation becomes effective on the one hand, and on the other hand, there is a problem that the possibility of dissolving a component that may adversely affect the etching in the filtered etching solution becomes high, and It is difficult to reuse the filtered etchant. On the other hand, when a pressure filtering device is used in a circulation line without using an aggregating agent, the filtration efficiency may be deteriorated and it may become difficult to perform sufficient filtration in the circulation line.

An object of the present invention is to provide an etching system which can effectively use a pressurized filter device in a circulation circuit and perform cleaning and purification of an etching solution at a low cost.

An etching system according to the present invention is configured to perform an etching process on a glass substrate for a flat panel display. This etching system includes at least an etching device, a circulation circuit, a membrane filter device, and a pressure filter device.

The etching apparatus is configured to include at least an etching solution tank, and an etching solution stored in the etching solution tank is brought into contact with a glass substrate to perform an etching process. The circulation circuit is configured to take out the etchant in the etchant bath to the outside, filter it, and return it to the etchant bath at the same time. The membrane filter device is arranged on a circulation line and includes an immersion membrane for filtering an introduced etching solution. The pressure filtration device is configured downstream of the membrane filtration device arranged on the circulation line, and receives the slurry captured by immersing the membrane to perform solid-liquid separation.

In this configuration, instead of the etching solution being directly introduced into the pressure-type filtering device arranged in the circulation line, the slurry captured by the membrane-type filtering device arranged in the preceding stage is introduced into the pressure-type filtering device. That is, since the pressure filter device is introduced in a state where the concentration of unnecessary materials such as sludge is high, solid-liquid separation can be effectively performed without using a coagulant. In the pressurized filter device, it becomes possible to apply a high filtration pressure. Therefore, since a filter cake having a low water content is obtained, the disposal of waste becomes easy.

In the above-mentioned configuration, it is preferable that the etching solution filtered by the membrane filter device and the pressure filter device is returned to the etching solution tank, respectively. In this configuration, the membrane filter device and the pressure filter device Since both sides of the installation recover a reusable etchant, the use efficiency of the etchant is improved.

In addition, it is also possible to prepare a pre-stage of a membrane filter device in which an etching solution filtered by a pressure filter device is returned to a circulation line. With this configuration, since the etching solution recovered by the pressurized filter device passes through the membrane filter device, the cleaning performance of the etching solution returned from the circulation line to the etching solution tank can be further improved.

It is preferable to use an MF membrane filter in terms of a membrane filter device, and it is preferable to use a pressure filter in terms of a pressure filter device. According to this structure, it becomes possible to suppress the filtration cost on a circulation line with the addition effect of an MF membrane filtration device and a filter press, and to improve filtration efficiency at the same time.

According to the present invention, it becomes possible to effectively use a pressurized filter device in a circulation circuit, and to perform cleaning and cleaning of an etching solution at a low cost.

10‧‧‧ Etching System

14‧‧‧ Etching device

16‧‧‧ Filtration Department

18‧‧‧MF filter device

20‧‧‧Press Filter

22‧‧‧Sludge holding tank

100‧‧‧ glass substrate

142‧‧‧Etching Department

144‧‧‧Etchant supply department

182‧‧‧MF filter tank

184‧‧‧microfilter

186‧‧‧ diffuser device

188‧‧‧ Mud Containment Tank

[FIG. 1] A diagram showing an outline of an etching system according to an embodiment of the present invention.

[FIG. 2] A diagram illustrating an example of a filtering process in an etching system.

[Fig. 3] A schematic diagram of an MF filter device used in an etching system.

[FIG. 4] A diagram showing an outline of an etching system according to another embodiment of the present invention.

An etching system 10 according to an embodiment of the etching system of the present invention will be described with reference to FIGS. 1 (A) and 1 (B). The etching system 10 is configured to perform an etching process on a glass substrate for a flat panel display such as a liquid crystal display or an organic EL display. The etching system 10 includes at least an etching device 14, a circulation line 15, and a filter processing unit 16. The etching device 14 includes an etching solution supply unit 144 including an etching solution tank 145 and an etching processing unit 142 configured to perform an etching process by contacting an etching solution with a glass substrate. The etching solution tank 145 is configured to receive an etching solution used in the etching device 14. In this embodiment, although an etching solution containing 5 to 25% by weight of hydrofluoric acid is used, the composition of the etching solution is not limited to this.

The etching solution supply unit 144 is configured to supply the etching solution in the etching solution tank 145 to the etching processing unit 142. With regard to the etching device 14, in this embodiment, a single-chip etching device 14 configured as follows is used: The glass substrate 100 is continuously conveyed one at a time to one or a plurality of etching processing units 142, and the etching processing is performed simultaneously. The part 142 sprays an etching liquid on the glass substrate 100. In this etching apparatus 14, an etching solution is supplied from the etching solution tank 145 to the etching processing unit 142 by a well-known liquid feeding means such as a pump. In the etching processing part 142, an etching solution is sprayed onto the upper surface, the lower surface, or both the upper and lower surfaces of the glass substrate 100.

The etching solution sprayed onto the glass substrate 100 and brought into contact with the glass substrate is flowed down to the bottom of the etching treatment section 142 and recovered in the etching solution tank 145. The recovered etching solution contains a silicon-based compound, an aluminum-based compound, and the like dissolved from the glass substrate 100. For this purpose, the etching system 10 includes a circulation line 15 configured to take out the etching solution from the etching solution tank 145 to the outside, and simultaneously filter and return the etching solution to the etching solution tank 145. In the etching system 10, the etching solution is sent from the etching solution tank 145 to the filter processing unit 16 via the circulation line 15 at any time, and the filtered etching solution is returned to the etching solution tank 145 to maintain the quality of the etching solution.

Next, an example of processing in the filtering processing unit 16 will be described using FIG. 2 (A). The filtration processing unit 16 includes: an MF filter device 18 disposed on the circulation line 15 and provided with an immersion membrane for filtering the introduced etching solution; and a downstream of the MF filter device 18 disposed on the circulation line 15, The filter press 20 receiving solid-liquid separation by immersing the slurry captured by the membrane is received. The MF filter device 18 corresponds to the membrane filter device of the present invention, and the pressure filter 20 corresponds to the pressure filter device of the present invention. Among them, in the membrane filter device, a device using an immersion membrane other than an MF membrane such as a RO membrane, a NF membrane, and a UF membrane can be applied. In the pressure filter device, a closed leaf filter, a closed type Devices other than filter presses such as stage filters.

The filtration processing unit 16 is configured to purify an etching solution used in the etching device 14. The filtration processing unit 16 is connected to the sludge storage tank 22. The sludge storage tank 22 is configured to store a cake that has been dehydrated by applying pressure to the filter press 20. Contained in sludge The filter cake of the storage tank 22 is appropriately treated as industrial waste.

Here, the MF filter device 18 will be described using FIG. 3. The MF filter device 18 is configured such that an etching solution in use is supplied by the etching supply unit 144 and stored in the MF filter device filter tank 182. The supplied etching solution is suction-filtered by the microfilter 184, and the filtrate is returned to the etching supply unit 144. On the other hand, the slurry is captured on the surface of the microfilter 184. The trapped slurry is peeled from the surface of the filter by the pressure caused by the bubbling caused by the air diffuser device 186 disposed at the bottom to prevent clogging of the filter, and precipitates into the slurry storage tank 188. The mud storage tank 188 is configured such that the bottom surface is inclined toward the center, and the mud is efficiently recovered. The slurry collected on the bottom surface of the slurry storage tank 188 is sent to the pressure filter 20 through a well-known slurry pump (Warman Pump, etc.), piping, and the like.

The MF filter device 18 is configured to permeate a plurality of microfilters 184 for suction, thereby filtering, and it is easy to increase or decrease the number of the microfilters 184 according to the amount of liquid discharged to adjust the processing efficiency.

The slurry conveyed by the slurry storage tank 188 is filtered by the pressure filter 20. Generally speaking, the filter 20 is added with a coagulant to the liquid to be filtered to effectively perform solid-liquid separation. For this reason, it is not conventionally arranged in the circulation line 15 for cleaning and cleaning the etching solution in use as in this embodiment, but in the drainage line for discharging the used etching solution. The reason for this is that when a flocculant is used in the circulation line 15, there is a high possibility that a component that adversely affects the etching process (such as protrusions of the glass substrate 100, whitening, and the like) is dissolved in the filtered etchant after filtration. In this embodiment, it is captured by the MF filter device 18 Since the slurry is introduced into the filter press 20, solid-liquid separation can be effectively performed without using a flocculant. Therefore, the filter press 20 can be effectively operated in the circulation line 15.

In this embodiment, the etching solution filtered by the MF filter device 18 and the pressure filter 20 is as shown in FIG. 2 (A). Although the etching solution tank 145 is returned to the etching solution supply unit 144, it is not limited. Make up here. For example, as shown in FIG. 2 (B), the etching liquid filtered by the filter 20 is returned to the front stage of the MF filter device 18 on the circulation line 15. With this configuration, the etching solution recovered by the filter 20 is further filtered by the MF filter device 18 and returned to the etching solution tank 145 of the etching solution supply unit 144, so that the cleaning performance of the etching solution can be further improved. .

The more the slurry and sludge contained in the chemical solution introduced into the filter press 20, the more efficiently the filtration can be performed. Although the method of adding a coagulant to the pre-filtration tank was originally used, the sludge-based sludge that was captured by the microfilter 184 was collected and the best sludge for the filter press 20 was recovered without adding the coagulant. Therefore, as described above, it is possible to perform highly efficient filtration in the circulation line 15 without using the coagulant. In addition, since the filter pressure 20 has a high filtration pressure, a filter cake having a low water content can be obtained. For this reason, in addition to more reusable etching solutions, the cost of industrial waste such as sludge can be reduced.

In addition, in the case where the cleaning of the etching solution and the treatment of the sludge are performed using only the membrane filter device, it is necessary to configure a multi-stage membrane filter device or the like in multiple stages. However, in this embodiment, the membrane filter device is used. It is effectively combined with the pressure filter device and is arranged, so that the cost can be significantly reduced compared to a case where the filter filter device is configured only.

In the above-mentioned embodiment, although the example of the etching device 14 is described in the form of a single-piece conveying type and the etchant is sprayed on the glass substrate, the example of the etching device 14 is not limited to this. For example, as shown in FIG. 4 (A) and FIG. 4 (B), the present invention can also be applied to a batch-type immersion type etching apparatus that processes a plurality of glass substrates 100 and immerses them in an etching solution to perform etching.

The description of the above-mentioned embodiment is an example in all aspects and should be considered as a non-limiting person. The scope of the present invention is not shown in the foregoing embodiment, but is expressed by the scope of patent application. The scope of the present invention is intended to include all changes within the meaning and scope equivalent to the scope of patent application.

Claims (1)

An etching system for performing an etching process on a glass substrate for a flat panel display. The etching system includes a single-piece and spray-type etching device configured to include at least an etching solution tank, and the etching solution stored in the etching solution tank is aligned once. One continuous conveyed glass substrate is sprayed to perform an etching process; a circulation line that does not use an aggregating agent is configured to take out the etching solution of the etching solution tank to the outside, and at the same time, to capture compounds dissolved from the glass substrate and the glass The etching solution in contact with the substrate is filtered and returned to the etching solution tank. The membrane filter device is disposed on the circulation line and is provided with an immersion membrane that filters the introduced etching solution. A solid-liquid separation is efficiently performed downstream; and a pressure filtration device configured to be disposed downstream of the membrane filtration device disposed on the circulation line, and receives the slurry captured by the impregnated membrane to perform solid-liquid separation. ; Wherein, the etching solution filtered by the membrane filter device and the pressure filter device is sent back separately The etching tank and the membrane filtration device as MF membrane filtration apparatus, the filtration device is a pressure filter press.