Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C15/00—Surface treatment of glass, not in the form of fibres or filaments, by etching
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
  • B32B3/02—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by features of form at particular places, e.g. in edge regions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
  • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C23/00—Other surface treatment of glass not in the form of fibres or filaments
  • C03C23/0075—Cleaning of glass
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2204/00—Glasses, glazes or enamels with special properties
  • C03C2204/08—Glass having a rough surface

Definitions

• the disclosure generally relates to a method of treating glass substrate surfaces, and more particularly to a method of treating glass substrate surfaces by use of a combination of atmospheric pressure plasma enhancement and wet etching.
• Glass substrates are widely used for flat panel displays.
• a liquid crystal display is made of very thin layer of liquid crystalline sandwiched by two glass backplanes, so-called, thin film transistor (TFT)-backplane and color filter (CF)-backplane.
• TFT thin film transistor
• CF color filter
• One category of glass commonly used in LCD applications is alkali- free glass.
• Alkali-free glass is generally free of alkali metal oxides and is commonly used as the backplanes for LCD and organic light emitting diode (OLED) applications.
• These glasses need to have high strain points because these backplanes are heated up to a temperature of several hundreds of degrees C during the film forming process or annealing, and the change of shape or dimension thereof during the TFT forming process should be minimized.
• LCD backplanes include: (1) inertness of glass, stability against chemicals, such as acidic solutions used during a photolithographic etching process, (2) surface cleanness free of foreign materials or particles on the glass surface and stability of glass during the longtime storage before use, and (3) electrostatic charge (ESC) or electrostatic discharge (ESD) and stickiness on the substrate plate.
• ESC electrostatic charge
• ESD electrostatic discharge
• the B-side glass surface namely the down-facing surface where the glass is conveyed horizontally or the surface processed where the glass is fed vertically, can be roughened to reduce the contact area between the glass sheet and the substrate plate.
• ESC caused by the contact of B-side glass surface with the substrate plate can extend up to A-side glass surface by induction, and can cause ESD within the TFT on the A-side glass surface.
• Such ESC can be minimized by roughening B-side glass surface. It can be achieved by wet chemical etching of B-side glass surface and the surface roughness (Ra) can be obtained by atomic force microscope (AFM).
• the present disclosure provides a method for manufacturing a flat panel display glass substrate having a first surface on one side and a second surface on the other side thereof, the method comprising:
• the method may further include the steps of washing the second surface with deionized water, rinsing the second surface, and drying the second surface.
• advantages may include: i) high line speed in range of 5 meters per minute to 20 meters per minute, such as 10 meters per minute to 20 meters per minute; ii) surface roughness Ra in a range of 0.5 nm to 1.5nm; and iii) variation of Ra of from 0.3 to 2.0 nm.
• the conveyance speed is preferably not less than 5 meters per minute and not more than 20 meters per minute.
• the glass substrate may be produced by a fusion draw process.
• the glass substrate preferably comprises alkali-free glass.
• the glass substrate may be heated to a temperature not less than 25 °C and not more than 70 °C prior to the first step.
• the process gas containing HF gas may contain, as a carrier gas, at least one of nitrogen and argon.
• the step of washing the second surface with deionized water may comprise washing the first surface at the same time, whereby providing the first surface having a surface roughness of not less than 0.15 nm and not more than 0.3 nm.
• the first surface preferably has a surface roughness of not less than 0.2 nm and not more than 0.3 nm.
• FIG. 1 is an exemplary schematic diagram of process step i) contact with dry HF gas enhanced by atmospheric plasma
• FIG. 2 is an exemplary schematic diagram of process step ii) contact with wet aqueous solution containing HF.
• Ranges can be expressed herein as from one particular value, and/or to another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.
• the glass substrate 1 includes first major surface (otherwise referred to herein as upper surface A) and second major surface (otherwise referred to herein as lower surface B).
• Upper surface A (“A-side glass surface”) is a surface ultimately intended to be proximate to components such as electrode wires and various electronic devices
• the lower surface B (“B-side glass surface”) is on the opposite side of glass substrate 1 as upper surface A and, as shown in FIG. 1, is in contact with a conveyance device, specifically conveyer rollers 3.
• B-side glass surface is defined as a down-facing surface where the glass substrate 1 is conveyed horizontally or a processed surface where the glass substrate 1 is fed vertically.
• the conveyer speed may, for example, range from 5 meters per minute to 20 meters per minute.
• a conveyer speed lower than 5 meters per minute may be economically undesirable.
• a conveyer speed higher than 20 meters per minute may increase the risk of damaging the glass sheet.
• B-side glass surface is treated by two continuous process steps:
• the wet etching zone 7 may be located upstream or downstream of the dry etching nozzle unit 5. Performance of the above process steps can achieve an average surface roughness determined by AFM, as described herein, in a range of from 0.5 nm to 1.5nm.
• the substrate is subjected to further treatment that includes deionized (DI) water washing, rinsing and drying of at least lower surface B (not shown).
• DI deionized
• the dry HF gas 4 moves along the glass substrate 1 while the upper surface A is prevented from being exposed to the HF gas 4 by air flows 14 and 15 flowing into the space over the upper surface A and the dry HF gas 4 and the air flows 14 and 15 are exhausted out of the outlet 16 of the nozzle unit 5.
• the glass substrate 1 is conveyed by sponge conveyer rollers 3 which are wetted by aqueous HF solution 10 spouted from nozzles 12, whereby the lower surface B is wet by the HF solution 10 to perform the wet etching (ii).
• the glass substrate can, for example, be produced by a fusion-draw method.
• the glass substrate may also be produced by other processes such as float processes, slot draw processes, up-draw processes, and press-rolling processes, to name a few.
• the glass substrate can, for example, include alkali-free glass, including, for example, a substrate comprising Corning Eagle ® XG or Lotus ® NXT glass.
• the glass thickness may, for example, be 0.1mm to 1.0mm.
• the glass size may, for example, be 1 square meter or larger.
• the step (i) comprises dry HF gas etching, where the dry HF gas can be generated by atmospheric pressure plasma enhancement.
• Commercially available atmospheric plasma etching enhancement devices can be used with embodiments disclosed herein in order to treat lower surface B.
• Exemplary atmospheric plasma etching enhancing devices include AP-E series devices supplied by Sekisui Chemical Co., Ltd.
• fluorine-containing gas such as CF4can be used with water, H2O vapor .
• the gas mixture will yield process gas comprising gaseous HF 4.
• argon (Ar) or nitrogen (N) may be used.
• the glass substrate 1 may be at first preheated at 25 - 70 degrees C and then treated by the dry HF gas 4, generated by atmospheric plasma device 6. With this heat pretreatment, the Ra variation can be controlled to be within a range of 0.2nm to 0.3nm. In contrast, if the temperature is below 25 degrees C, the Ra variation can be greater.
• the treatment time of glass by the plasma etching process can be, for example, in a range of 0.1 seconds to 5 minutes.
• the line speed can, for example, be in a range of 5 meters per minute to 20 meters per minute, such as 10 meters per minute to 20 meters per minute.
• the step (ii) comprises treatment with wet aqueous solution 10 comprising HF.
• the HF concentration may, for example, be in a range of 0.1 wt% to 5 wt%.
• the glass substrate may, for example, be kept at the temperature range of 25 - 70 degree C during the roller conveyance.
• the aqueous HF solution 10 may comprise other acids, such as, for example, at least one of H2SO4, HC1, and H3PO4. It may also be buffered. That is, a buffer solution such as a mixture of NaF and H3PO4 or acetic acid may be used to maintain HF produced in an equilibrium state.
• a buffer solution such as a mixture of NaF and H3PO4 or acetic acid may be used to maintain HF produced in an equilibrium state.
• Embodiments disclosed herein can achieve an average surface roughness Ra for lower surface B of 0.5 nm to 1.5nm, as measured by AFM, as described herein.
• Embodiments disclosed herein can also achieve an average surface roughness Ra for upper surface A of 0.15 nm to 0.3nm, such as is 0.2 nm to 0.3nm. Such can be achieved by, for example, washing the surface by DI water or alkaline-containing detergent. With the washing and drying, lower surface B can be cleaned to remove some solid particles and etching vapor residues comprising HF from the lower surface B surface treatment process.
• the glass substrate 1 is conveyed horizontally, it may be conveyed partly or entirely in a vertical or inclined path.
• the B-side glass surface B which may not be down facing, is exposed to the dry HF gas 4 in step (i) and to the aqueous HF solution 10 in step (ii).
• step (i) a mixture of gases having a feed rate of 10 liters per minute of Argon, 0.8 liters per minute of CF4, and 180 milligrams per minute of water vapor were used. Atmospheric plasma was applied at 4KW to yield dry HF gas. Air flow was used at about 200 liters per minute to prevent process gas from leaking out of the device together with exhaust gas flow. The resulting dry process gas comprising HF gas was applied to the lower surface B of each sample.
• step (ii) a solution comprising 0.09M NaF and 0.11M H3PO4 was used.
• the solution was applied to the conveyed glass through sponge rollers 3.
• the glass was conveyed to a washing zone and washed with city water. Both upper surface A and lower surface B were washed in the washing zone. After that, the both glass surfaces were rinsed with DI water and dried by air flow.
• Comparative examples 1 and 2 were performed as described above except without step (i).
• Comparative example 3 was performed as described above except without step (ii).
• Glass A Corning Eagle XG
• Glass B Lotus NXT.
• Ra for embodiments disclosed herein was obtained by Hitachi High-Tech AFM5400L.
• Surface morphology image of AFM was scanned with Dynamic Force Mode (DFM).
• Soft X-ray was irradiated onto the glass surface during the measurement for discharging the glass surface.
• Table 2 shows the parameter of the AFM measurement. The average Ra was taken from 18 measurements.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Surface Treatment Of Glass (AREA)
• Liquid Crystal (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (1)

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Citations (4)

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• 2018
  • 2018-06-15 CN CN201880040340.3A patent/CN110831754A/zh active Pending
  • 2018-06-15 WO PCT/US2018/037711 patent/WO2018232213A1/en not_active Ceased
  • 2018-06-15 US US16/622,601 patent/US20210147285A1/en not_active Abandoned
  • 2018-06-15 KR KR1020207001213A patent/KR20200019693A/ko not_active Withdrawn
  • 2018-06-15 TW TW107120617A patent/TW201904906A/zh unknown
  • 2018-06-15 JP JP2019569357A patent/JP2020523277A/ja not_active Abandoned

Patent Citations (4)

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