JP2015100880A - Manufacturing method for glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a glass substrate where product failure does not occur even if using polishing slurry including a magnetic substance.SOLUTION: A manufacturing method for a glass substrate comprises: a protection film forming step for forming a protection film on at least one of main surfaces of the glass substrate facing each other; and a polishing step for performing mirror polishing by contacting polishing slurry, including a magnetic substance held by a magnetic force body, on an edge face of the glass substrate where a protection film is formed.

Description

  The present invention relates to a method for manufacturing a glass substrate.

  The manufacturing process of a glass substrate includes the process of chamfering the end surface formed by cutting the glass substrate. The end face of the glass substrate is ground by a diamond wheel to remove cracks and sharp edges caused by cutting. Further, as described in Patent Document 1, as a polishing technique for the end face, a technique for polishing the end face into a mirror shape by using a polishing slurry containing a magnetic material for polishing the end face of the glass substrate is known. Yes.

  When the polishing waste generated by the end face processing with the diamond wheel adheres to the glass substrate, the polishing waste can be removed by cleaning the glass substrate with a cleaning liquid or pure water. On the other hand, the polishing slurry contains metals such as Fe, Mn, and Zn, and these metals have high affinity with the glass substrate. Even if it is washed, it is difficult to remove. And since electric circuits, such as a circuit wiring and a touch panel sensor, are formed in the main surface of a glass substrate, it will cause a product defect if these metals remain adhered to the main surface. Therefore, an extremely low contact angle is required for such a glass substrate.

International Publication No. 2012/066757

  Accordingly, an object of the present invention is to provide a method for producing a glass substrate in which product defects do not occur even when a polishing slurry containing a magnetic material is used.

One aspect of the present invention is a method of manufacturing a glass substrate,
A protective film forming step of forming a protective film on at least one of the opposing main surfaces of the glass substrate;
A polishing step of mirror polishing by bringing a polishing slurry containing a magnetic body held by a magnetic body into contact with an end surface of the glass substrate on which the protective film is formed,
It is characterized by that.

  The polishing slurry containing the magnetic material preferably contains at least iron metal.

  It is preferable that an electric circuit is formed on the glass substrate.

  The protective film is preferably made of a nonmagnetic material.

  A removal step of removing the protective film to which the polishing slurry containing the magnetic material adheres with a cleaning liquid may be further provided.

  According to the said aspect, generation | occurrence | production of a product defect can be prevented even if it uses the polishing slurry containing a magnetic body.

It is process drawing explaining the process of the manufacturing method of the glass substrate of this invention. It is a figure which shows the glass substrate in which the protective film was formed. It is a figure which shows the method of grinding the end surface of a glass substrate. It is a figure which shows the structure of a grinding | polishing apparatus. (A) is a figure for demonstrating the end surface processing of a glass substrate, (b) is sectional drawing which follows the II-II line of (a). It is a figure for demonstrating a washing | cleaning process.

(Embodiment 1)
Hereinafter, with reference to drawings, the manufacturing method of the glass substrate of this embodiment is demonstrated.
FIG. 1 is a flowchart of the glass substrate manufacturing method according to the present embodiment.
First, in the protective film forming step ST1, as shown in FIG. 2, a polishing slurry and abrasive grains containing a magnetic material on one surface, both surfaces, and / or end surfaces of the thin glass substrate G are processed later. A protective film F for preventing adhesion by ST3 is formed. Here, the glass substrate G on which the protective film F is formed is a glass substrate for a flat panel display (for example, a glass substrate for a liquid crystal display, a glass substrate for a plasma display, a glass substrate for an organic EL display), a cover glass or a magnetic disk. Examples thereof include a glass substrate for tempered glass such as, a glass substrate wound up in a roll, and a glass substrate on which electronic devices such as a semiconductor wafer are laminated. The glass substrate G is formed by a known forming method such as a down draw method or a float method from glass in which a glass raw material having a composition such as SiO ₂ or Al ₂ O ₃ is melted.

  The protective film F is a non-magnetic film, preferably further having an alkali-soluble function, and more preferably a water-insoluble film having an acid resistance function of pH 0.2 to less than pH 7. Specifically, the protective film F is composed of an alkali copolymer resin (resin based on acrylic acid ester and methacrylic acid ester, having a sulfonic acid derivative and a carboxy group), ethyl alcohol, n-propyl alcohol (nPA ), Isopropyl alcohol (IPA), ethanol and the like.

  As a forming method for forming the protective film F, a spray method, a screen printing method, a spin coating method, a roll coating method, a flow coating method, an ink jet method, a dip coating method, a casting film forming method, a bar coating method, a gravure printing method. Etc. Here, in the spray method, a masking tape or the like is attached in advance to a portion where the protective film F is not formed in a predetermined pattern, and the liquid for the protective film F is discharged and applied onto the glass substrate G in the same manner as the ink jet. After the protective film F liquid is dried, the masking tape is removed to form the protective film F having a predetermined pattern. Further, the protective film F can be dried and fixed on the surface of the glass substrate G by a known method. The drying temperature and drying time for drying the protective film F can be changed as appropriate depending on the thickness of the protective film F and the concentration of components contained in the protective film F.

  The thickness of the protective film F is, for example, 0.2 to 5 μm, and since the protective film F is removed in a cleaning process ST4 described later, the thinner one is preferable. Further, the cross cut evaluation (JIS-K5600-5-6) of the protective film F is, for example, 2 or less, and the scratch hardness (JIS-K5600-5-4) of the protective film F is, for example, harder than 2H. Since the protective film F protects the glass substrate G from polishing slurry or the like, it is preferable that the protective film F has high adhesion to the glass substrate G and high hardness.

  Next, in the cutting step ST2, the glass substrate G on which the protective film F is formed is cut into a predetermined product size by a cutting device (not shown). In addition, when the glass substrate G is already a predetermined product size, this process can be omitted. Moreover, the protective film F can also be formed in the glass substrate G cut | disconnected by cutting process ST2.

  Next, in the processing step (grinding step, polishing step) ST3, end face processing (grinding, polishing and corner cutting) of the glass substrate G is performed. In the grinding process, the end surface of the glass substrate G is ground while rotating the grinding wheel at a predetermined speed. FIG. 3 is a diagram illustrating a method of grinding the end surface of the glass substrate G. The grinding device 30 moves the glass substrate G so that both end surfaces of the glass substrate G are in contact with the first grinding wheel 31 and the second grinding wheel 32 that rotate by a rotation shaft (not shown). The grinding device 30 rotates the first grinding wheel 31 and the second grinding wheel 32 to process the end surface 33 on the long side of the glass substrate G, and then the end surface 33 on the short side becomes the first grinding wheel 31 and the first side. 2 The glass substrate G is moved and rotated so as to come into contact with the grinding wheel 32, and the end surface 33 on the short side is processed. As the grinding wheel, a known one such as a diamond wheel is used and is not particularly limited.

  In the polishing process, the glass substrate G after finishing the end surfaces 33 of the glass substrates on the long side and the short side is conveyed to a position where polishing is performed by the polishing apparatus, and the end surface of the glass substrate G is mirror-finished using the polishing apparatus. Polishing is performed. FIG. 4 is a diagram showing a schematic diagram of the polishing apparatus 40. The polishing apparatus 40 sucks the magnetic fluid in the magnetic fluid tank 41 with the pump 42 and supplies the sucked magnetic fluid to the polishing wheel 44 that rotates from the supply nozzle 43. Since the end of the grinding wheel 44 is magnetized, the magnetic fluid flows on the grinding wheel 44 with viscoelasticity due to the influence of the magnetic field. The polishing apparatus 40 sucks the magnetic fluid flowing on the rotating polishing wheel 44 from the suction nozzle 45 by operating the pump 46 and collects it in the magnetic fluid tank 41. The polishing apparatus 40 conveys the end surface of the glass substrate G so as to be in contact with the polishing wheel 44 supplied with the magnetic fluid, and makes the rotating polishing wheel 44 and the end surface of the glass substrate G contact to perform mirror surface processing. The polishing apparatus 40 moves and processes the glass substrate G on a stage (not shown). Fig.5 (a) is the figure which looked at the glass substrate G to polish from the main surface. FIG.5 (b) is sectional drawing which follows the II-II line | wire of Fig.5 (a). The polishing apparatus 40 rotates the polishing wheel 36 around the rotation shaft 35. In the rotating wheel 36, magnetic abrasive grains 37 (also referred to as polishing media) are provided in a gap (also referred to as a magnetic field forming portion) between disk-shaped magnetic bodies 36 a and 36 b provided in parallel with the length direction of the rotating shaft 35. Configured. Here, a polishing slurry containing a magnetic material is used and mirror-polished. The polishing slurry containing a magnetic substance includes magnetic abrasive grains in which the magnetic substance mainly acts as polishing abrasive grains, and magnetic fluid that acts as a carrier for the magnetic substance to mainly carry abrasive grains. The end of the glass substrate G bites into the magnetic abrasive grains 37 applied with a magnetic field by the magnetic bodies 36 a and 36 b, and the polishing wheel 36 rotates in a state where the end face of the glass substrate G is in contact with the magnetic abrasive grains 37. . As a result, the magnetic abrasive grains 37 and the end face of the glass substrate G move relatively, and the end face of the glass substrate G is polished by the magnetic abrasive grains 37 constrained by the magnetic field formed by the magnetic field forming unit. . In the polishing step, the end surface of the glass substrate G can be polished by a known method using a polishing slurry containing a magnetic substance, and includes the contents described in Japanese Patent Application No. 2013-066511, Be considered.

  The polishing slurry and abrasive grains containing the magnetic material are scattered by the rotation of the polishing wheel and adhere to the front and back surfaces of the glass substrate G. Since the polishing slurry or the like contains metals such as Fe, Mn, and Zn, it has a high affinity with the glass substrate G, and if it adheres to one surface of the glass substrate G, it is difficult to clean with conventional acid cleaning or alkali cleaning. It is. For this reason, the low contact angle (high cleanliness) is ensured by forming the protective film F before the polishing slurry adheres to the glass substrate G. Since the glass substrate G can be protected by forming the protective film F, the polishing slurry can have various configurations. For example, the polishing slurry can be magnetic particles (carbonyl iron, iron oxide, iron nitride, iron carbide, chromium dioxide, low carbon steel, silicon steel, nickel, cobalt, and / or combinations thereof), non-magnetic abrasive grains (oxidized Cerium, silicon carbide, alumina, zirconia, diamond, and / or combinations thereof), liquid solvents (water, mineral oil, synthetic oil, propylene glycol, and / or ethylene glycol), surfactants, and / or corrosion. An inhibitor may be included. In addition, the viscosity of the polishing slurry can be changed as appropriate. Viscosity suitable for glass materials that vary depending on the glass substrate for liquid crystal display, the glass substrate for tempered glass, and the like In the case where the glass substrate G protected by forming the protective film F is end-polished with the polishing slurry, the polishing slurry does not have a possibility of adhering to the glass substrate G, and therefore can be polished with the polishing slurry having the optimum viscosity. . Further, by increasing the number of rotations of the polishing wheel, there is no possibility that polishing slurry or the like scatters and adheres to the glass substrate G, so that the number of rotations of the polishing wheel can be changed as appropriate.

  Next, the cleaning process (removal process) including the process of removing the polishing film, which is a metal deposit, and the protective film F to which the polishing abrasive grains are adhered in the polishing process of the processing process ST3 will be described. As the cleaning method, a batch type, a single wafer type, a one-bath type, or the like can be applied, but here, a batch type will be described. FIG. 6 is a cross-sectional view conceptually showing one of a plurality of liquid tanks in a batch cleaning system for cleaning the glass substrate G. The batch cleaning system includes a plurality of liquid tanks 60 illustrated in FIG. 6 and a transport mechanism that transports a cassette 50 that stores a plurality of glass substrates G. Each liquid tank 60 includes an ultrasonic cleaning mechanism that cleans the glass substrate G with ultrasonic waves in a state where the glass substrate G is immersed in the liquid L, and a temperature adjustment mechanism that adjusts the temperature of the liquid L as necessary. Further, the batch cleaning system includes a tank for supplying the liquid L to each liquid tank 60.

  A cassette 50 containing a plurality of glass substrates G is transported by a transport facility, and is sequentially immersed and cleaned in a liquid L such as an acidic cleaning liquid, an alkaline cleaning liquid, pure water, or ultrapure water stored in a liquid tank 60. The As the acidic cleaning liquid stored in each liquid tank 60, for example, a solution of oxalic acid, tartaric acid, and hydrogen fluoride (HF) can be used. As the alkaline cleaning liquid, for example, a potassium hydroxide (KOH) solution can be used.

  The acidic cleaning solution is obtained by adding one or more acidic components selected from polyhydric organic acids such as oxalic acid, tartaric acid, citric acid and hydrogen fluoride to a diluted solution obtained by diluting a glass substrate cleaning agent with water. To produce an acidic cleaning solution. The acid cleaning solution containing organic acid should lower the pH to 1.6 or less to remove the polishing slurry and abrasive grains by making the zeta potential on the glass surface positive, and prevent re-adhesion by the chelating effect of the acid cleaning solution component Thus, the polishing slurry and the abrasive grains can be effectively cleaned. Moreover, an alkaline cleaning liquid produces | generates an alkaline cleaning liquid by adding alkaline components, such as potassium hydroxide, to the dilution liquid which diluted the cleaning agent with water. Further, a surfactant can be added to the alkaline cleaning liquid. Since the alkaline cleaning liquid containing the surfactant has an effect of reducing the surface tension, the alkaline cleaning liquid easily penetrates between the protective film F and the glass substrate G, and the protective film F can be effectively removed.

  In the batch cleaning system, the type and sequence of the liquid L in which the glass substrate G is immersed use an acidic cleaning liquid, and then use an alkaline cleaning liquid. As an example, the glass substrate G can be cleaned using an acidic cleaning solution from the first to the second, a pure water from the third to a fourth, an alkaline cleaning solution from the fifth, and a pure water from the sixth to the seventh.

  In the cleaning process, the glass substrate G on which the protective film F is formed is cleaned using an acidic cleaning solution. For the cleaning with the acidic cleaning liquid, a known cleaning method can be used, and the number of times of cleaning is arbitrary. Adhesive foreign matter derived from recycled paper, adhesive foreign matter that has changed in quality over time, and polishing slurry and abrasive grains scattered in the polishing step of the processing step ST3 adhere to the front and back surfaces and end surfaces of the glass substrate G. Here, the polishing slurry and the abrasive grains adhere to the protective film F formed before the polishing step as described above. If it is a normal adhesive substance, it can be removed by an acidic cleaning solution, but it is difficult to completely remove the polishing slurry and abrasive grains. However, since the polishing slurry and the abrasive grains are attached due to the chelating effect of the protective film F formed on the glass substrate G, it is not necessary to completely remove them with the acidic cleaning liquid. Since the protective film F is water-insoluble and has acid resistance, the protective film F is not removed by the acidic cleaning liquid and remains on the glass substrate G to protect one surface of the glass substrate G. For this reason, it is possible to remove a normal adhesive substance while cleaning with an acidic cleaning liquid while protecting the one surface of the glass substrate G while leaving the protective film F.

  Next, the glass substrate G is cleaned using pure water. For cleaning with pure water, a known cleaning method can be used, and the number of times of cleaning is arbitrary.

  Next, the glass substrate G is cleaned using an alkaline cleaning solution. For cleaning with an alkaline cleaning solution, a known cleaning method can be used, and the number of cleanings is arbitrary. The conventional adhesive foreign matter adhering to the glass substrate G is removed by the alkaline cleaning liquid, and the protective film F to which the polishing slurry and abrasive grains are attached is further removed. Since the protective film F has alkali solubility, the protective film F is removed by being dissolved by the alkaline cleaning liquid and penetrating between the protective film F and the glass substrate G. Polishing slurry and abrasive grains are attached on the protective film F. By removing the protective film F, the polishing slurry and abrasive grains are simultaneously removed. By washing with an alkaline cleaning liquid, in addition to removing a normal adhesive substance, the protective film F to which the polishing slurry and the abrasive grains are attached can be removed, and at the same time, the polishing slurry and the abrasive grains can be removed. For this reason, the glass substrate G to which the polishing slurry and the abrasive grains are not attached can be manufactured.

  After the cleaning using the alkaline cleaning liquid, in order to remove (volatilize) ethanol (boiling point 78 ° C.) contained in the protective film F, the glass substrate G is dried by heating, and the glass substrate G is further cleaned using pure water. Thereby, the cleaning degree of the glass substrate G is increased, and the contact angle of the glass substrate G with pure water is, for example, 4 degrees or less. After the cleaning process ST4, in the inspection process, the end face and the main surface of the glass substrate G are inspected, and then shipped to a panel manufacturer or the like as a display glass substrate or a tempered glass substrate.

  As described above, according to the method for manufacturing the glass substrate G of the present embodiment, it is possible to prevent the polishing slurry from adhering to one surface of the glass substrate G during polishing using the polishing slurry containing the magnetic material. Even if the polishing slurry is used, the occurrence of product defects can be prevented. Further, by protecting the glass substrate G with the protective film F, the contact angle of the glass substrate G can be lowered.

(Embodiment 2)
Next, the case where the protective film F is a non-magnetic acid-soluble film will be described. In addition, description is abbreviate | omitted about the structure which is common in the above-mentioned embodiment.

  The protective film F is a water-insoluble film having alkali resistance of pH 7 to pH 12. Specifically, the protective film F includes an acidic copolymer resin, ethyl alcohol, n-propyl alcohol (nPA), isopropyl alcohol (IPA), ethanol, and the like.

  In the protective film forming step ST1, an alkali-resistant protective film F is formed on the glass substrate G as in the first embodiment. In the cleaning step ST4, the protective film F is removed using an acidic cleaning liquid. As the acidic cleaning liquid, the same cleaning liquid as in the first embodiment can be used. Thereby, in cleaning process ST4, the protective film F can be removed only by cleaning using the acidic cleaning liquid, and the polishing slurry adhering to the protective film F can be removed.

  According to the manufacturing method of the glass substrate G of this embodiment, since the protective film F can be removed only by cleaning using an acidic cleaning liquid, the cleaning process can be simplified. Further, by protecting the glass substrate G with the protective film F, it is possible to prevent the occurrence of product defects even when a polishing slurry containing a magnetic material is used.

G Glass substrate F Protective film 35 Rotating shaft 36 (36a, 36b) Magnetic body 37 Magnetic body abrasive grain 40 Polishing device

Claims (5)

A protective film forming step of forming a protective film on at least one of the opposing main surfaces of the glass substrate;
A polishing step of mirror polishing by bringing a polishing slurry containing a magnetic body held by a magnetic body into contact with an end surface of the glass substrate on which the protective film is formed,
A method for producing a glass substrate, comprising: The polishing slurry containing the magnetic material contains at least iron metal,
The method for producing a glass substrate according to claim 1. An electrical circuit is formed on the glass substrate.
The manufacturing method of the glass substrate of Claim 1 or 2 characterized by the above-mentioned. The protective film is made of a nonmagnetic material.
The manufacturing method of the glass substrate of any one of Claim 1 to 3 characterized by the above-mentioned. A removal step of removing the protective film to which the polishing slurry containing the magnetic material adheres with a cleaning liquid;
The manufacturing method of the glass substrate of any one of Claim 1 to 4 characterized by the above-mentioned.

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