KR20050108465A - A fabricating method of a stamper for light guiding panel(lgp) and an apparatus and a method for lgp using the stamper - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a stamper used for manufacturing a light guide plate used in a light distribution device of a liquid crystal display device, and a method and apparatus for manufacturing a light guide plate using the stamper.

The stamper may include forming an electroforming body on a surface of a conductive metal substrate, applying a photoresist to a surface on which the electroforming body is formed, and placing a mask on which a predetermined scattering pattern is formed, and UV light on the mask. Exposing the photoresist to the predetermined scattering pattern to form a photoresist pattern, and etching the surface of the electroformed body on the substrate on which the photoresist pattern is formed to a predetermined depth. The light guide plate is manufactured by fixing and positioning the stamper produced by the above method inside the mold by vacuum adsorption, and then injecting and solidifying the liquid light guide plate material. Therefore, by applying a semiconductor process it is possible to reduce the process defects and to produce a light guide plate with good scattering pattern uniformity.

Description

  A fabricating method of a stamper for light guiding panel (LGP) and an apparatus and a method for LGP using the stamper}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a stamper used to manufacture a light guide plate used in a backlight of a liquid crystal display device, and to an apparatus and a method of manufacturing a light guide plate using the manufactured stamper.

More particularly, the present invention relates to a method for manufacturing a stamper for manufacturing a light guide plate including a scattering pattern used for a backlight, and an apparatus and method for manufacturing a light guide plate using the manufactured stamper.

Recently, high resolution of notebooks and monitors is required, and in particular, due to the high functionality and high quality of mobile phones, the demand for liquid crystal display devices, which are mainly used as display devices, is increasing. Among these requirements, there is no high luminance, no luminance unevenness, and luminance uniformity is important. In order to improve the above problem, it is easy to increase the initial intensity of the light source, but it can be seen that this is not an appropriate method due to the increase in power consumption. Therefore, improving the performance of the light guide plate among the components constituting the backlight of the liquid crystal display has been suggested as the most basic solution.

The light guide plate is manufactured by applying (1) light scattering particles to the back surface and (2) forming reliefs and reliefs on the back surface so that light incident from the side surface is directed toward the light guide plate with liquid crystal.

The light guide plate of ① is manufactured by injection molding PMMA (PolyMethlMethAcrylate), which is a raw material of the light guide plate, and forming light scattering particles such as barium sulfate (BaSO 4) or titanium oxide (TiO 3) by screen printing on one surface thereof. However, this manufacturing method is difficult to manage the process of printing the light scattering particles uniformly, and impurities in the air are mixed with the particles during the operation to induce the scattering of light, thereby reducing the uniformity of the brightness. In addition, normally scattered light is absorbed by the printed scattering particles to lower the intensity of the luminance.

In the case of ②, the general method is used in consideration of improving the mass productivity of the light guide plate and improving the intensity of luminance. The manufacturing method is illustrated in FIG.

1A is a thick metal (Nak80, Stavax) disc 1 used as a substrate for cores. The metal master plate 1 needs to control the roughness or flatness of the surface on which the scattering pattern is to be formed. This is because the surface properties directly affect the scattering pattern of the light guide plate.

1B shows a photoresist 2 application process. The metal original plate 1 is fixedly mounted on the spin coating apparatus, and the photoresist 2 is dropped onto the upper surface by using an eyedropper or the like. The metal disc 1 is rotated at high speed so that the photoresist 2 has a uniform thickness on the surface. Recently, a film type photoresist that changes into a liquid phase by heat is also used.

1C shows an exposure process. A mask (3) made of a film having a plurality of scattering patterns corresponding to the uneven portion of the light guide plate is placed close to the coated photoresist (2) and exposed to ultraviolet rays from the top to expose the photoresist (2). To be distinguished by the unexposed part 5. The exposed portion 4 is a portion to be removed in the developing operation described later.

1D shows a developing process. The non-exposed portion 5 is chemically different from the exposed portion 4 through the exposure process and is not removed by the developer. Therefore, only the photoresist 6 corresponding to the non-exposed portion 5 remains on the metal substrate 1.

FIG. 1E shows the corrosion process of the metal disc 1 by the corrosion solution. The device 7 capable of carrying out the corrosion process comprises a nozzle 8 into which the corrosion solution is sprayed, the surface being to be corroded being fixed 9 in the direction in which the nozzle 8 is located. When the corrosion solution is injected from the nozzle 8, the portion without the photoresist 6 is corroded to form an intaglio shape, and in order to increase the efficiency of the corrosion, the nozzle 8 may be mounted to be rotated.

1F illustrates the cleaning process. The metal disc 1 subjected to the corrosion process is a core 10 having a shape that matches the scattering pattern to be processed by cleaning with photoresist strip chemicals, acetone, isopropyl alcohol, and the like.

In the conventional method for manufacturing a core for a light guide plate shown in FIGS. 1A to 1F, a problem occurs in uniformity and reproducibility of the scattering pattern by a corrosion method used in processing a desired scattering pattern. That is, the core surface corrosion by spraying method shows the nonuniformity of the position of the scattering pattern in the mask to the core surface, and the reliability of reproducibility is low depending on the corrosion solution and the user's usage method.

The present invention is to solve the above problems, in order to provide a uniform and reproducible light guide plate manufacturing process, using the exposure process and the etching process used in the semiconductor process, the uneven shape processability of the scattering pattern is easy, uniform and reproducible It is an object of the present invention to provide a manufacturing method of a stamper for manufacturing a light guide plate for improving the brightness and uniformity of the light guide plate injected, and a method and apparatus for manufacturing a light guide plate using the stamper.

In order to achieve the above object, the present invention comprises the steps of forming an electroforming body on the surface of the metal substrate, applying a photoresist to the surface on which the electroforming body is formed and positioning a mask having a predetermined scattering pattern, the upper part of the mask Irradiating UV light to form a photoresist pattern by exposing the photoresist to the predetermined scattering pattern, and etching the surface of the electroformed body on the substrate on which the photoresist pattern is formed by a predetermined depth. It relates to a method for producing a stamper for manufacturing a light guide plate, characterized in that.

Here, at least one surface of the metal substrate may be stainless steel or Nak80 polished to a mirror surface, the electroforming body is produced by the electrolytic method, the electroforming body may use Ni and Ni-W. The electroformed body may be heat-treated at 200 degrees Celsius to 600 degrees Celsius to increase its hardness, and an ultrasonic vibration may be applied to the substrate before the etching step to allow etching to proceed more efficiently. The etching depth in the etching step is smaller than the thickness of the electroformed body, and the etching step is carried out by separating the etching step at least two times, after the first etching step to heat the substrate to reflow the photoresist, and then It relates to a method for manufacturing a light guide plate, characterized in that the etching step of proceeding.

In addition, the present invention comprises a metal substrate, an electroformed body formed on at least one surface of the metal substrate in an electroless manner, a groove formed in a predetermined pattern on the electroformed body, the metal substrate is mirror-polished stainless steel Or Nak80, and the electroforming bodies are Ni-P and Ni-W, and the electroforming bodies are related to a light guide plate manufacturing stamper, which is formed by increasing the hardness through heat treatment at 200 to 600 degrees Celsius. The depth of the groove is smaller than the thickness of the electroformed body, and the groove is separated by at least two wet etching processes, and after the primary etching step, the substrate is heat-treated to reflow the photoresist, and then It relates to a stamper for manufacturing a light guide plate, characterized in that produced by performing the etching step of the light guide plate injection process using the same It characterized by that the vacuum close contact with the stamper to the lower side of the mold frame.

The stamper manufactured by the above method improves the reproducibility of the injection molded product when the light guide plate is injected, and the light guide plate having high brightness and high uniformity can be manufactured due to the excellent workability of the shape by the wet etching method.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

2A to 2H are manufacturing process diagrams for explaining one embodiment of a method for manufacturing a stamper of the present invention. 2A is an austenitic stainless steel metal substrate 100 used as the substrate of the present invention in consideration of production cost and ease of operation. In one embodiment of the present invention, the 304 soft series is used, and 304 hard or 301 series may be used. The reason for selecting the metal substrate 100 is that the hardness of the substrate is similar to or better than that of the electroforming body, which is the next process, so that there is no deformation of the electroforming body and the metal substrate in heat and pressure during light guide plate injection. Since the surface state of the metal substrate may affect the surface state of the electroforming body, which is the next process, one surface of the metal substrate 100 should be polished. The nearer the degree of polishing, the better the surface of the electroformed body. Silicon substrates and glass substrates are not suitable for use as substrates because they are sensitive to the pressure applied during the mold and injection process. The overall shape of the metal substrate 100 is suitable for the equipment of the processes described below using a circle or a square.

2B illustrates a process of applying the photoresist 110 by spin coating to the opposite surface of the front surface on which the scattering pattern is formed. Since the metal substrate 100 is a conductor, the electroforming metal is simultaneously formed on the front surface and the opposite surface during the plating process. But the electroforming body on the other side is unnecessary. The undesired part of the electroformed body may degrade the flatness of the substrate, and in particular, serves to reduce the reproducibility and stability of etching in the wet etching process. For this reason, a photoresist is applied as a prevention layer in order to prevent the formation of the electroformed body. You can also use Teflon tape or Kapton tape.

2C shows a process of forming the electroforming body 120 on the front surface. In the electroforming body 120 to be formed, Ni is most commonly used in consideration of hardness and workability, but Ni-W alloy is used for the purpose of increasing hardness. In general, electroless Ni is known to have 20% better hardness than electrolytic Ni, and the hardness can be improved by two times through heat treatment at 200 to 600 degrees Celsius. At this time, it should be noted that the bending of the metal substrate 100 due to mechanical stress such as Ni formed on the surface of the metal substrate 100.

The thickness of the electroform 120 is made to be at least 30% thicker than the vertical depth of the groove for the scattering pattern formed on the stamper. Since the height of the light guide plate scattering pattern is directly proportional to the depth of the scattering pattern on the stamper, the thickness of the electroforming body 120 formed on the metal substrate 100 determines the height of the scattering pattern of the light guide plate. Another reason for thickening the depth of the electroforming body 120 by 30% or more may be etched from the front surface of the metal substrate 100 to the surface of the metal substrate 100 due to excessive etching and uneven etching in the subsequent process of wet etching. To prevent that. If the metal substrate 100 is etched, the adhesive force is weakened between the electroforming body 120 and the metal substrate 100, thereby causing a phenomenon of falling. In addition, the uniformity and roughness of the surface of the electroforming body 120 are also important. Uniformity and roughness may affect the surface state and thickness of the light guide plate when the light guide plate is ejected.

After forming the electroform 120, the photoresist on the opposite side is removed using acetone or photoresist strip chemicals in FIG. 2B.

2D illustrates a photoresist 140 application and exposure process. The stainless metal substrate 100 is vacuum-adsorbed to the spin coating apparatus and applies the photoresist 140. Since the metal substrate 100 is heavier than a general silicon wafer, care must be taken in adjusting the pressure during vacuum adsorption. Then, heat treatment is performed in an electric oven or a hot plate at a temperature of 80 to 100 degrees Celsius. Next, the mask 150 in which the scattering pattern is depicted is brought close to the surface of the photoresist 140. The portion 170 through which the UV light passes is a portion that disappears during the developing operation in FIG. 2F described later.

2E shows a developing process. 2D, the exposed portion 170 and the unexposed portion 160 are distinguished from each other. Proceed with setting the temperature and developing time of the developing solution. After the development work, the heat treatment is performed at 90 to 120 degrees Celsius to cure the remaining photoresist 140. At this time, the temperature and time of the heat treatment are important. If the heat treatment is performed at a temperature higher than 90 to 120 degrees Celsius or an excessive time, the unstable etching rate and the accuracy of etching may be affected in the etching process described later.

Accordingly, in the present invention, the wet etching is performed to stabilize the etching rate and the etching rate of the entire metal substrate 100, and the remaining photoresist 140 is narrow (several to several tens of micrometers) for tens of thousands to hundreds of thousands of times. For the scattering patterns, in order to improve the fact that the etching rate does not come out from the front surface of the metal substrate 100, the heat-treated metal substrate 100 is soaked in a few seconds for several seconds. Through this process, the surface between the photoresist 140, ie, the exposed portion 170, is activated by ultrasonic energy, thereby causing an active chemical reaction with the etchant during the subsequent wet etching, thereby preventing the non-uniform etching.

2F illustrates a wet etching process of the electroform 120. After the process of FIG. 2E, the metal substrate 100 is dipped in the wet etch bath 210 containing the wet etch chemical 200. As a precaution, the etch rate for the electroforming body 120 of this etching chemical 200 is examined with a test metal substrate. The etching time is adjusted according to a predetermined etching rate to wet-etch the metal substrate 100 after the process of FIG. 2E. Depending on the production method of the electro-casting body 120, that is, whether the electrolytic or electroless and also the electroless method is different depending on the concentration of phosphorus etching characteristics will be considered to apply differently to the manufacturing method of the etching chemicals 200 do.

Types of chemicals constituting the etching chemical 200 are nitric acid, acetic acid, acetic acid, deionized water, and the like. To increase the etching rate, the ratio of nitric acid must be increased. In addition, the higher the ratio of nitric acid, the photoresist 140 may be subjected to chemical damage (damage), so the etching chemicals 200 should be manufactured at least 30 minutes before the wet etching process, 90 ~ 120 degrees Celsius after the development process The heat treatment process in between is essential.

When the actual wet etching is performed, a scattering pattern having a desired depth and width can be made at a time, and the shape of the scattering pattern can be adjusted by changing the composition of the etching chemical 200 by dividing it in two to three times. During the wet etching process, it is necessary to circulate the etching chemical 200 in the wet etching bath 210 by the stirring device or the operator to obtain a uniform etching rate and scattering pattern shape on the entire surface of the metal substrate.

Figures 3a, 3b, 3c and 3d is a cross-sectional view showing a step-by-step shape of the groove formed when the wet etching is divided into several times. Figure 3a shows the shape of the groove when the first wet etching. FIG. 3b shows that after wet etching once, the substrate on which the formed photoresist is formed is heat-treated in an oven at about 90 to 150 degrees Celsius, and the photoresist is reflowed to cover the grooves slightly downward compared to the originally formed pattern. It shows the state. FIG. 3C is a cross-sectional view of the groove when the wet etching of FIG. 3B is performed once. The groove may be formed by performing one or more of the above reflow processes. Figure 3d shows the shape of the groove resulting from dividing the etching twice. As the scattering protrusions of the light guide plate formed of the stamper including the grooves are formed in the same manner as in FIG. 3D, light scattering may be more efficiently performed.

When the groove is formed by the above method, the groove has a shape in which the groove is not formed with many bendings, as shown in FIG. 3D, and as a result, the shape of the scattering pattern formed on the light guide plate is changed. Thus, more efficient scattering can be generated.

After the wet etching process is completed, the photoresist 140 is removed with acetic acid or photoresist strip chemicals, washed with isopropyl alcohol, naturally dried in air or further washed with deionized water, and then dried using a rinse dryer equipment. You will complete the stamper.

2g illustrates a process of injecting a light guide plate after mounting a stamper on a mold. The stamper is fixed to the lower surface of the lower mold frame 220 by vacuum suction through the vacuum hole 230. The upper mold 240 is assembled to the lower mold 220. The reason why the vacuum is fixed is that the stainless metal substrate 100 may be bent in the injection process, so that the vacuum hole 230 is disposed to uniformly pull the stamper as a whole. After injecting a liquid light guide plate raw material into the mold, injection molding the light guide plate and separating the light guide plate from the mold die.

2H illustrates an injection molded light guide plate 250. The injection molded light guide plate 250 has a shape having an embossed scattering pattern 260. In the manufacture of the light guide plate 250, it is preferable to make only one or two in one raw material injection for accurate shape of the light guide plate, and the size of the light guide plate is preferably manufactured by manufacturing a light guide plate according to its size.

The present invention is not limited to the above-described embodiments and the accompanying drawings, and it is common knowledge in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those who have

According to the present invention, there is an effect that a light guide plate having a shape having excellent scattering properties and having a uniform width and height of a scattering pattern than a conventional light scattering particle printing method or core corrosion type light guide plate can be produced.

In addition, since the manufacturing process of the product is manufactured by a high precision process by using a semiconductor process, there is an effect that the quality and yield of the product is improved.

Figure 1a to 1f is a process diagram showing a corrosion process for producing a core used in a mold for manufacturing a conventional injection-type light guide plate.

2A to 2H are process drawings showing a manufacturing method of the stamper of the present invention and light guide plate injection.

3A, 3B, 3C, and 3D are cross-sectional views of steps in the case where etching for groove formation is divided into several times.

<Symbol description for main parts of drawing>

1: Metal Disc 2: Photoresist

3: mask 4: exposure part

5 non-exposed part 6 patterned photoresist

7: etching bucket 8: nozzle

10 core formed with scattering pattern 100 metal substrate

110 and 140 photoresist 120 electroforming

150: mask 160: non-exposed part

170: exposed portion 200: wet etching chemicals

210: etching bath 220: lower mold

240: upper mold 250: light guide plate

260: embossed scattering pattern

Claims (9)

Forming an electroforming body on the surface of the metal substrate, Applying a photoresist to a surface on which the electroformed body is formed and placing a mask on which a predetermined scattering pattern is formed; Irradiating UV light from the upper portion of the mask to expose the photoresist to the predetermined scattering pattern to form a photoresist pattern; And etching the surface of the electroformed body on the substrate on which the photoresist pattern is formed by a predetermined depth. The method of claim 1, wherein at least one surface of the metal substrate is stainless steel or Nak80 polished to a mirror surface. The method of claim 2, wherein the electroforming body is manufactured by an electrolytic or electroless method, and the electroforming body is Ni and Ni-W. The method of claim 3, wherein the electroforming body is heat-treated at 200 to 600 degrees Celsius. The method according to any one of claims 1 to 4, wherein ultrasonic vibration is applied to the substrate before the etching step. The method of claim 5, wherein the etching depth in the etching step is less than the thickness of the electroforming, The etching step is performed by separating at least two times, After the first etching step to heat the substrate to reflow the photoresist, the etching step for producing a light guide plate, characterized in that to proceed to the next etching step. Metal substrate, An electroformed body formed on at least one surface of the metal substrate in an electroless manner, Comprising a groove formed in a predetermined pattern on the electroforming body, The metal substrate is mirror polished stainless steel or Nak80, The electroforming bodies are Ni and Ni-W, Light stamping plate manufacturing stamper, characterized in that the electroform was formed by increasing the hardness through heat treatment at 200 to 600 degrees Celsius. The method of claim 7, wherein The depth of the groove is smaller than the thickness of the electroformed body, The groove is separated by at least two wet etching proceeds, A stamper for manufacturing a light guide plate according to claim 1, wherein the substrate is heat-treated after the first etching step to reflow the photoresist, and then the next etching step is performed. The method according to claim 7 or 8, The stamper is a light guide plate manufacturing stamper, characterized in that fixed to the lower side of the mold mold by vacuum compression when mounted to the mold for manufacturing the light guide plate injection.