SHADOW MASK AND METHOD FOR MANUFACTURING THE SAME

Abstract: A shadow mask which is cheaply manufactured by electro-forming technology and a method for manufacturing the same. According to the shadow mask manufacturing method, a master shadow mask is manufactured by using a base plate, and then the master shadow mask is submerged in an electro-forming bath such as a watt bath, and a nickel layer of a high purity is formed to manufacture the shadow mask. The shadow mask according to the present invention comprises a shadow mask frame in which a plurality of minute holes are formed; and a skirt integrally formed with the shadow mask frame along the edge of the shadow mask frame, for reinforcing the shadow mask frame. According to the shadow mask manufacturing method, a cheap and fine shadow mask can be manufactured without using expensive patterning and etching devices.

Description: SHADOW MASK AND METHOD FOR MANUFACTURING THE SAME BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask, and more particularly to a shadow mask which is manufactured by electro-forming a master shadow mask which is manufactured by using a base plate and a method for manufacturing the shadow mask. 2. Description of the Prior Art Generally, a cathode ray tube or a monitor to which a shadow mask is applied comprises a bulb which has a panel, a funnel, and a neck. The electric gun is disposed in the neck, and red, green, and blue phosphorescence layers are distributed on the inner side surface of the panel. The shadow mask is separated from the red, green, and blue phosphorescence layers by a distance. The shadow mask is used by having an electric beam radiated from the electric gun of the cathode ray tube pass through and collide with red, green, and blue pixels on the phosphorescence layers. Conventionally, the shadow mask is manufactured by using a steel sheet on which a corrosion-proof material for protecting a wanted metal portion is coated. The hole pattern is removed by acid spray, and only a very fine and almost transparent metal plate is left. The fine metal plate is formed so as to extend to the front side of the cathode ray tube, and then is annealed to remove the stress. The above-mentioned molding process causes an unexpected result, and destroys the hole patterns. Therefore, the phosphorescence layers are applied to the cathode ray tube through a light activity process, so that the phosphorescent dots are located at a proper location with respect to the shadow mask. The three colors of the phosphorescence layers should be applied respectively, and the process for mounting and separating the shadow mask to and from the cathode ray tube should be repeated three times. If a defect is discovered in the shadow mask, the shadow mask and the surface plate of the cathode ray tube which is manufactured with the shadow mask should be junked. Defects appear in the shadow mask for various reasons. The defects are often generated because the thickness of the used steel plates are not uniform and the luter line is finished after a molding process and an annealing process. Since the etched steel plate is apt to be broken, the etched steel plate is often deformed in the molding process, and displaces the dot patterns in unintended intervals. Further, in many cases, the sizes of the holes and the slots become irregular and the shadow mask can be broken in the molding process. In order to settle the above-mentioned problems, much research has been performed. U. S. Patent No.4,174,264 discloses a method for manufacturing a shadow mask through the electro-forming process. FIG. 1 is a schematic view for showing a device for electro-forming when the shadow mask according to the above-mentioned patent is manufactured. As shown in FIG. 1, a base 10 is submerged in an electro-forming bath 18. An iron anode 20 is disposed above the base 10. A current is supplied through the iron anode 20 from a voltage source 19. Iron ions are moved through a solution in the bath 10, and are deposited on an exposed portion of the base 10. As a result, the shadow mask can-be formed. In the shadow mask manufacturing method according to the above-mentioned patent, before the electro-forming process, the base 10 is coated by a manner pattern, and only an exposed portion is left through the exposure process and the etching process by the manner pattern. The base 10 is molded so as to have a shadow mask shape, and the base 10 is inspected so as to have an accurate size and a suitable shape. Thereafter, the above-mentioned electro-forming process is performed. As above-mentioned, after the iron ions are deposited on the exposed portion of the base 10 and the shadow mask having a predetermined thickness is formed, the shadow mask is cut off from the base 10. According to the above-mentioned patent, stresses are not left during the rolling, the molding, or the annealing. Therefore, problems like oil canning, buckling, and spring back are not generated. However, in the shadow mask manufacturing method of the above-mentioned patent, since the base is coated with anticonosive and the shadow mask is formed so as to have a predetermined size and shape, an expensive exposing and etching device is needed, and a process in which the base is machined so as to have the shadow mask shape is further needed. SUMMARY OF THE INVENTION The present invention has been made to solve the above mentioned problem, and accordingly it is the first object of the present invention to provide a shadow mask manufacturing method in which a cheap and precise shadow mask can be manufactured without using expensive patterning and etching devices. It is the second object of the present to provide a shadow mask which is manufactured by a shadow mask manufacturing method in which a cheap and precise shadow mask can be manufactured without using expensive patterning and etching devices. In order to achieve the first object of the present invention, a shadow mask manufacturing method according to one aspect of the present invention comprises the steps of : manufacturing a master shadow mask by using nickel and a mold release; forming a shadow mask by submerging the master shadow mask composed of the nickel and the mold release in a bath and electro-forming the master shadow mask; and separating a shadow mask from the master shadow mask in which the shadow mask is formed. Accordin -to the first preferred embodiment of the present invention, the master shadow mask manufacturing step comprises the steps of : (1) filling holes of a base plate by coating the base plate with the mold release, (2) removing the mold release from both surfaces of the base plate by using an abradant, and flattening both surfaces of the base plate, (3) forming a nickel layer on one surface of the base plate by submerging the base plate in a bath and electro-forming the base plate, (4) coating the surface of the base plate with the mold release so as to completely cover the nickel layer formed on the surface of the base plate and then solidifying the mold release, after removing the base plate from the bath, and (5) removing the base plate from the mold release and the nickel layer. According to the second embodiment of the present invention, the master shadow mask manufacturing step comprises the steps of : (1) filling holes of a base plate by coating the base plate with the mold release, (2) removing the mold release from one surface of the base plate by using an abradant, and flattening the surface of the base plate, (3) forming a nickel layer on the surface of the base plate by submerging the base plate in a bath and electro-forming the base plate, (4) coating the surface of the base plate with the mold release so as to completely cover the nickel layer formed on the surface of the base plate and then solidifying the mold release, after removing the base plate from the bath, (5) removing the mold release from the other surface of the base plate by using the abradant, and flattening the other surface of the base plate, and (6) removing the base plate from the mold release and the nickel layer. In order to achieve the second object of the present invention, a shadow mask according to the other aspect of the present invention comprises a shadow mask frame in which a plurality of minute holes are formed; and a skirt integrally formed with the shadow mask frame along the edge of the shadow mask frame, for reinforcing the shadow mask frame, wherein the shadow mask frame and the skirt are integrally formed by a manufacturing process comprising the steps of : manufacturing a master shadow mask by using nickel and a mold release; forming a shadow mask by submerging the master shadow mask composed of the nickel and the mold release in a bath and . then electro-forming the master shadow mask; and separating the shadow mask from the master shadow mask in which the shadow mask is formed. The thickness of the frame and the skirt are about 0.1 mm, and the diameter of the holes formed in the frame is about 20 μ . In the first-and second embodiments of the present invention, the mold release is a silicon resin, and the abradant for chemically removing the mold release is thinner, acetone, or toluene. The abradant for chemically removing the mold release can be a mixture of thinner and toluene. The bath used in electro-forming the base plate can be selected from a watt bath, a chloride nickel bath, a brom-fluoride nickel bath, and a sulfamic acid nickel bath. A nickel ingot is further supplied in the bath to expedite the forming of the nickel layer. According to the present invention, a shadow mask of a high accuracy can be manufactured' without using expensive patterning and etching devices. Further, according to the above-mentioned shadow mask manufacturing method, a shadow mask can be manufactured inexpensively. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of the present invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: FIG. 1 is a schematic view for showing a device for electro-forming a shadow mask according to a conventional art when the shadow mask is manufactured; FIGs. 2 to 4 are views for explaining a process for manufacturing a master shadow mask according to the first embodiment of the present invention; FIGs. 5 to 10 are views for explaining a process for manufacturing a master shadow mask according to the second embodiment of the present invention; FIG. 11 is a schematic view for showing a device for electro-forming a shadow mask according to a preferred embodiment of the present invention when the shadow mask is manufactured; FIG. 12 is a perspective view for showing a shadow mask which is manufactured by a shadow mask manufacturing method according to a preferred embodiment of the present invention; and FIG. 13 is a partly enlarged cross-sectional view for showing the shadow mask manufacturing method according to the preferred embodiment of the present invention, which is taken along the line A-A' of FIG. 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, preferred embodiments of the present invention will be explained in detail with reference to the attached drawings. The shadow mask manufacturing method according to a prefened embodiment of the present invention comprises the steps of : manufacturing a master shadow mask by using nickel and a mold release 120, 140, 220, 230, and 260; forming a shadow mask 300 by submerging the master shadow mask composed of the nickel and the mold release 120, 140, 220, 230, and 260 in a bath 280 and then electro-forming the master shadow mask; and separating a shadow mask from the master shadow mask in which the shadow mask 300 is formed, after removing the master shadow mask from the bath 280. FIGs. 2 to 4 shows a step for manufacturing a master shadow mask 100 in the shadow mask manufacturing process according to the first embodiment of the present invention. As shown in FIGs. 2 to 4, the master shadow mask manufacturing step comprises the steps of : (1) filling holes of a base plate 110 by coating the base plate 110 with the mold release 120, (2) removing the mold release 120 from both surfaces of the base plate 110 by using an abradant, and flattening both surfaces of the base plate 110, (3) forming a nickel layer 130 on one surface of the base plate 110 by submerging the base plate 110 in a bath 280 and electro-forming the base plate 110, (4) coating the surface of the base plate 110 with the mold release 120 so as to completely cover the nickel lay er 130 formed on the surface of the base plate 110 and then solidifying the mold release 120, after removing the base plate 110 from the bath 280, and (5) removing the base plate 110 from the mold release 120 and the nickel layer 130. In the step (1) in which the mold release 120 is filled in the holes of the base plate 110, the base plate 110 is fully coated with the mold release 120, and the mold release 120 is uniformly dispersed so that the holes in the base plate 110 are filled with the mold release 120. A conventional shadow mask is used, as the base plate 110, and a silicon resin is used as the mold release. Thereafter, as shown in FIG. 2, in the step (2), the mold release 120 distributed on both surfaces of the base plate 110 among the mold release 120 which fully covers the base plate 110 is removed by the abradant. Then, the mold release 120 which is filled in the holes remains filled in the holes. And, both apertures of the holes which are filled with the mold release 120 and both surfaces of the base plate 110 are flattened so that they are located on the same planes. Thereafter, the mold release 120 filled in the holes of the base plate 110 is solidified by cooling the base plate 110 in the air. In the step (2), thinner, acetone, or toluene is used as the abradant for removing and flattening the mold release 120. However, it is preferable that a mixture of thirmer and toluene is used as the abradant. After the mold release 120 is removed from both surfaces of the base plate 110 and the base plate 110 and both apertures of the holes are flattened, the cathode of the power source is electrically, connected to the base plate 110. Then, the base plate 110 is fully submerged in an electro-forming bath 280 filled in a bath 270 with the mold release 120 filled in the holes of the base plate 110 to perform the electro-forming process, and the nickel layer 130 is formed on one surface of the base plate 110. (Step (3)) The electro-forming bath 280 used in the electro-forming process can be selected from a watt bath, a chloride nickel bath, a brom-fluoride nickel bath, and a sulfamic acid nickel bath. An example of the electro-forming bath 280 is schematically shown in FIG. 11. As shown in FIG. 11 , a nickel ingot 290 is supplied in the electro-forming bath 280 to expedite the forming of the nickel layer 130. The nickel ingot 290 is electrically connected to the anode of the power source and is completely submerged in the electro-forming bath 280. The base plate 110 is disposed such that one surface of the base plate 110 is opposite to the nickel ingot 290 in the bath 280. Then, if a cmrent is supplied to the base plate 110 and the nickel ingot 290 from the power source, the current is applied to the nickel ingot 290 through the base plate 110 and the bath 280, and nickel ions separated from the nickel ingot 290 and dissolved in the bath are moved towards the base plate 110 through the bath 280. When the electro-forming process is proceeded in the electro-forming bath 280, the nickel ions in the bath 280 and the nickel ions electrolysed from the nickel ingot 290 are deposited on one surface of the base plate 110 to form a dense layer. However, as above-mentioned, since the holes of the base plate 110 are filled with the mold release 120, the nickel ions cannot be deposited in the holes. Therefore, the nickel layer 130 which is deposited on one surface of the base plate to form a layer, is formed so as to have a shape similar to the base plate 110. However, the nickel layer 130 deposited on one surface of the base plate 110 is grown in the directions paralleHo'one surface of the base plate 110 and perpendicular to one surface of the base plate 110 on the boundary surface in which the mold release 120 filled in the holes and the apertures of the holes. As a result, the diameter of the holes formed in the nickel layer 130 is smaller than that of the holes formed in the base plate 110. As above-mentioned, the nickel layer 130 is grown to have a predetermined thickness, preferably about 0.05 mm, the electro forming process is completed. The time needed to grow the nickel layer 130 to have about 0.05 mm of thickness is about 1 to 2 hours in a normal electro- forming bath 280 and under a normal electro-forming condition. If the step (3) in which the nickel layer 130 is formed in the base plate 110 through the electro-forming process is completed, the base plate 110 in which the nickel layer 130 is formed is drawn out from the electro-forming bath 280. Thereafter, as shown in FIG. 3, one surface of the base plate 110 is coated so that the mold release 140 completely covers the nickel layer 130 formed on the surface of the base plate 110. A same material as the mold release 120, i.e., a silicon resin, is used as the mold release 140. After the base plate 110 is coated with the mold release 140, the base plate 110 is cooled again in the air and then solidified, so that the mold release 140 and the mold release 120 filled in the holes of the base plate 110 are integrally formed. Referring to FIG. 3, the mold release 120 is filled in the holes in the base plate 110, and the nickel layer 130 formed on one surface of the base plate 110 is covered by the mold release 140. As above-mentioned, the step (4) in which the base plate 110 is coated with the mold release 140, the mold releases 120 and 140 are separated from the base plate 110. When the mold rele 120 filled in the holes of the base plate 110 is drawn out from the holes, the nickel layer 130 wh is formed on one surface of the base plate 110 is separated from the base plate (Step (5)). In the s (5), the nickel layer 130 is easily separated from the base plate 110 if a force is applied to the nic layer 130. Therefore, the nickel layer 130 is surrounded by the mold releases 120 and 130. The manufacturing of the master shadow mask 100 is completed through the abo mentioned processes. FIG. 4 is a cross-sectional view for showing a master shadow mask 100 manufactured by master shadow mask manufacturing process according to the first embodiment of the pres invention. The master shadow mask 100 shown in FIG. 4 is finished, a shadow 300 is manufactu by using the master shadow mask 100. The master shadow mask 100 in which the cathode of the power source is connected to nickel layer 300 is submerged in a bath which has been explained in relation to the process manufacturing the master shadow mask 100. The nickel ingot 290 together with the master shad mask 100 is submerged in the electro-forming bath 280 shown in FIG. 11, and the nickel ingot 1 and the master shadow mask 100 is disposed such that the nickel ingot 290 is opposite to the nic layer 130 of the master shadow mask 100. Then, if a current is supplied to the master shadow mask 100 and the nickel ingot 290 fr< the power source, the current is applied to the nickel ingot 290 through the nickel layer 130 of master shadow mask 100 and the bath 280, and nickel ions separated from the nickel ingot 290 . dissolved in the bath are moved towards the nickel layer 130 of the master shadow mask 100 throi the bath 280. When the electro-forming is proceeded in the electro-forming bath 280, the nickel ions in bath 280 and the nickel ions electrolyzed from the nickel ingot 290 are deposited on the nickel la; 130 of the master shadow mask 100 to form a dense layer. A new nickel layer created and growr the nickel layer 130 is grown to a tip end of the mold release 120 along the peripheral portion of mold release 120. Therefore, a shadow mask 300 having the same shape as the base plate 1 separated from the master shadow mask 100 is formed. As above-mentioned, if the new nickel layer is grown to finish the shadow mask 300 havi a predetermined thickness, preferably about 0.1 mm, the electro-forming process is completed. 1 time needed to grow the shadow mask 300 to have about 0.1 mm of thickness is about 2 to 3 hours in a normal electro-forming bath 280 and under a normal electro-forming condition. If the step in which the shadow mask 300 is formed by using the master shadow mask 300 through the electro-forming process is completed, the master shadow mask 100 in which the shadow mask 300 is formed is drawn out from the electro-forming bath 280. The master shadow mask 100 drawn out from the electro-forming bath 280 is washed by pure water, and then the shadow mask 300 is separated from the master shadow mask 100. Then, if a force is applied to the shadow mask 300 and the master shadow mask 100, the shadow mask 300 is easily separated from the nickel layer 130 of the master shadow mask 100. By using the shadow mask manufacturing method according to the first embodiment of the present invention,~the shadow mask 300 having the same size as a conventional shadow mask used as the base plate 110 can be easily manufactured, and the shadow mask 300 can be mass-produced by repeatedly using the master shadow mask 100. As above-described, the overall shape, the size, the thickness, and the numerical aperture of the shadow mask 300 are identical with those of a conventional shadow mask. And, the physical characteristics of the shadow mask 300, such as the conductivity, deformation rate, or the like, is similar to or identical with that of a conventional shadow mask. FIGs. 5 to 10 show a process for manufacturing a master shadow mask 200 according to the second embodiment of the present invention. The shadow mask manufacturing process according to the second embodiment of the present invention is identical with the shadow mask manufacturing process according to the first embodiment of the present invention except a process for manufacturing the mask shadow mask 200. As shown in FIGs. 5 to 10, the master shadow mask manufacturing step comprises the steps of : (1) filling holes of a base plate 210 by coating the base plate 210 with the mold release 220 and 230, (2) removing the mold release 230 from one surface of the base plate 210 by using an abradant, and flattening the surface of the base plate 210, (3) forming a nickel layer 240 on the surface of the base plate 210 by submerging the base plate 210 in a bath 280 and electro-forming the base plate 210, (4) coating the surface of the base plate 210 with the mold release 260 so as to completely cover the nickel layer 240 formed on the surface of the base plate 210 and then solidifying the mold release 230, after removing the base plate 210 from the bath 280, (5) removing the mold release 230 from the other surface of the base plate 210 by using the abradant, and flattening the other surface of the base plate 210, and (6) removing the base plate 210 from the mold release 220 and 260 and the nickel layer 240. In the step (1) in which the mold release 220 is filled in the holes of the base plate 210, as shown in FIG. 5, the base plate 210 is fully coated with the mold release 230, and the mold release 220 is uniformly dispersed so that the holes in the base plate 210 are filled with the mold release 220. As explained in relation to the first embodiment of the present invention, a conventional shadow mask is used as the base plate 210, and a silicon resin is used as the mold release 220, 230, and 260. Thereafter, as shown in FIG. 6, in the step (2), the mold release 230 distributed on one surface of the base plate 210 among the mold release 230 which fully covers the base plate 210 is removed by the abradant. Then, apertures of the holes which are filled with the mold release 220 and one surface of the base plate 210 are flattened so that they are located on the same planes. Thereafter, the mold release 220 and 230 which filled in the holes of the base plate 210 and which covers the base plate 210 is solidified by cooling the base plate 210 in the air. Thinner, acetone, or toluene is used as the abradant for removing the mold release 230 and flattening the base plate 210. However, it is preferable that a mixture of thinner and toluene is used as the abradant. After the mold release 230 is removed from the surface of the base plate 210 and the base plate 210 and the apertures of the holes are flattened, the cathode of the power source is electrically connected to the base plate 210. Then, the base plate 210 is fully submerged in an electro-forming bath 280 filled in a bath 270 with the mold release 220 and 230 filled in the holes of the base plate 210 to perform the electro-forming process, and the nickel layer 240 is formed on one surface of the base plate 210. (Step (3)) The electro-forming bath 280 used in the electro-forming process can be one used in the shadow mask manufacturing process according to the first embodiment of the present invention and can be selected from a watt bath, a chloride nickel bath, a brom-fluoride nickel bath, and a sulfamic acid nickel bath. An example of the electro-forming bath 280 is schematically shown in FIG. 11. As shown in FIG. 11, a nickel ingot 290 is supplied in the electro-forming bath 280 to expedite the forming of the nickel layer 240. The nickel ingot 290 is electrically connected to the anode of the power source and is completely submerged in the electro-forming bath 280. The base plate 110 is disposed such that one surface of the base plate 110 in which the mold release is removed is opposite to the nickel ingot 290 in the bath 280. Then, if a current is supplied to the base plate 210 and the nickel ingot 290 from the power source, the current is applied to the nickel ingot 290 through the base plate 210 and the bath 280, and nickel ions separated from the nickel ingot 290 and dissolved in the bath are moved towards the base plate 210 through the bath 280. When the electro-forming is proceeded in the electro-forming bath 280, the nickel ions in the bath 280 and the nickel ions electrolyzed from the nickel ingot 290 are deposited on one surface of the base plate 210 to form a dense layer. However, as above-mentioned, since the holes of the base plate 210 are filled with the mold release 220, the nickel ions cannot be deposited in the holes. Therefore, the nickel layer 240 which is deposited on one surface of the base plate to form a layer, is formed so as to have a shape similar to the base plate 210. (Refer to FIG. 7) However, the nickel layer 24 deposited on one surface of the base plate 20 is grown in the directions parallel to one surface of the base plate 210 and perpendicular to one surface of the base plate 210 on the boundary surface in which the mold release 220 filled in the holes and the apertures of the holes. As a result, the diameter of the holes formed in the nickel layer 240 is smaller than that of the holes formed in the base plate 210. As above-mentioned, the nickel layer 240 is grown to have a predetermined thickness, preferably about 0.05 mm, the electro forming process is completed. The time needed to grow the nickel layer 240 to have about 0.05 mm of thickness is about 1 to 2 hours in a normal electro- forming bath 280 and under a normal electro-forming condition. If the step (3) in which the nickel layer 240 is formed in the base plate 210 through the electro-forming process is completed, the base plate 210 in which the nickel layer 240 is formed is drawn out from the electro-forming bath 280. Thereafter, as shown in FIG. 8, one surface of the base plate 210 is coated so that the mold release 260 completely covers the nickel layer 240 formed on the surface of the base plate 210. A same material as the mold release 220, i.e., a silicon resin, is used as the mold release 260. When one surface of the base plate 210 is coated, a material such as a screen 250 is inserted into the mold release 260 to reinforce the mold release 260. After the base plate 210 is coated with the mold release 260, the base plate 210 is cooled again in the air and then solidified, so that the mold release 260 and the mold release 220 filled in the holes of the base plate 110 are integrally formed.(Step 4). Referring to FIG. 8, the mold release 220 is filled in the holes of the base plate 210, and the both surfaces of the base plate 210 is covered with the mold release 230 and 260. Therefore, the nickel layer 240 formed on one surface of the base plate 210 is fully covered with the mold release 260. If the step (4) in which the base plate 210 is coated with the mold release 260, the mold release 230 which covers the other surface of the base plate 210 is removed by using an abradant such as a mixture of thinner and toluene, and the other surface of the base plate 210 is flattened. As shown in FIG. 9, the other apertures of the holes of the base plate 210 and the other surface of the base plate 210 are flattened so as to locate in a same plane. If the step (5) in which the mold release 230 is removed from the other surface of the base plate 210 and the base plate 210 is flattened, the nickel layer 240 formed on the surface of the base plate 210 is separated from the base plate 210 by drawing out the mold release 220 filled in the holes of the base plate 210 from the holes. (Step 6) In the step (6), if a force is applied to the nickel layer 240, the nickel layer 240 is easily separated from the base plate 210. Therefore, the nickel layer becomes surrounded by the mold releases 220 and 260. Through the above-mentioned process, the manufacturing of the master shadow mask 200 as shown in FIG. 10 is completed. After the manufacturing of the master shadow mask 200 is completed, the shadow mask 300 is manufactured by using the master shadow mask 200. In the electro-forming bath 280 which has been explained in relation to the process for manufacturing the master shadow mask 200, the master shadow mask 200 in which the cathode of the power source is electrically connected to the nickel layer 240 is submerged. The nickel ingot 290 together with the master shadow mask 200 is submerged in the electro-forming bath 280 shown in FIG. 11, the nickel ingot 290 and the master shadow mask 200 are disposed such that the nickel ingot 290 is opposite to the nickel layer 240 of the master shadow mask 200. Then, if a current is supplied to the master shadow mask 200 and the nickel ingot 290 from the power source, the current is applied to the nickel ingot 290 through the nickel layer 240 of the master shadow mask 200 and the bath, and nickel ions separated from the nickel ingot 290 and dissolved in the bath are moved towards the nickel layer 240 of the master shadow mask 200 through the bath. When the electro-forming process for manufacturing the shadow mask 300 in the electro- forming bath 280 is proceeded, the nickel ions in the bath 280 and the nickel ions electrolyzed from the nickel ingot 290 are deposited on the nickel layer 240 of the master shadow mask 200 to form a dense layer. A new nickel layer created and grown in the nickel layer 240 is grown to a tip end of the mold release 220 along the peripheral portion of the mold release 220. Therefore, a shadow mask 300 having the same shape as the base plate 210 separated from the master shadow mask 200 is formed. As above-mentioned, if the new nickel layer is grown to finish the shadow mask 300 having a predetermined thickness, preferably about 0.1 mm, the electro-forming process is completed. The time needed to grow the shadow mask 300 to have about 0.1 mm of thickness is about 2 to 3 hours in a normal electro-forming bath 280 and under a normal electro-forming condition. If the step in which the shadow mask 300 is formed by using the master shadow mask 300 through the electro-forming process is completed, the master shadow mask 200 in which the shadow mask 300 is formed is drawn out from the electro-forming bath 280. The master shadow mask 200 drawn out from the electro-forming bath 280 is washed by pure water, and then the shadow mask 300 is separated from the master shadow mask 200. Then, if a force is applied to the shadow mask 300 and the master shadow mask 200, the shadow mask 300 is easily separated from the nickel layer 130 of the master shadow mask 200. By using the shadow mask manufacturing method according to the second embodiment of the present invention, the shadow mask 300 having the same size as a conventional shadow mask used as the base plate 210 can be easily manufactured, and the shadow mask 300 can be mass- produced by repeatedly using the master shadow mask 200. As above-described, the overall shape, the size, the thickness, and the numerical aperture of the shadow mask 300 are identical with those of a conventional shadow mask. And, the physical characteristics of the shadow mask 300, such as the conductivity, deformation rate, or the like, is similar to or identical with that of a conventional shadow mask. Hereinafter, a shadow mask 300 according to another preferred embodiment of the present invention will be explained in detail. FIG. 12 is a perspective view for showing the shadow mask 300 which is manufactured by using a shadow mask manufacturing method according to a preferred embodiment of the present invention. FIG. 13 is a partly enlarged cross-sectional view for showing the shadow mask manufacturing method according to the preferred embodiment of the present invention, which is taken along the line A-A of FIG. 12. As shown in FIGs. 12 and 13, the shadow mask 300 according to the preferred embodiment of the present invention comprises a shadow mask frame 310 in which a plurality of minute holes 330 are formed; and a skirt 320 integrally formed with the shadow mask frame 310 along the edge of the shadow mask frame 310, for reinforcing the shadow mask frame 310. The shadow mask frame 310 and the skirt 320 are integrally formed by a manufacturing process comprising the steps of : manufacturing a master shadow mask by using nickel and a mold release, forming a shadow mask 300 by submerging the master shadow mask composed of the nickel and the mold release in a bath 280 and then electro-forming the master shadow mask, and separating the shadow mask 300 from the master shadow mask in which the shadow mask is formed, after removing the master shadow mask in which the shadow mask 300 is formed from the bath 280. The master shadow mask 300 is manufactured by using one of the shadow mask manufacturing methods according to the first and second preferred embodiments of the present invention. Referring to FIGs. 12 and 13, a plurality of holes 330 are formed in the frame 310, and the number of the holes 330 of the shadow mask which is applied to a 15 inch cathode ray tube or monitor is eight hundred thousands. The shadow mask 300 can be manufactured so as to be suitable for the size of the cathode ray tube or monitor to be applied thereto, and the thickness of the shadow mask 300 is about 0.1 mm, and the diameter of the holes 330 formed in the frame 310 is about 20 mm. As above-described, if the shadow mask is manufactured by using the shadow mask manufacturing method according to the preferred embodiment of the present invention, a shadow mask of a high accuracy can be manufactured without using expensive patterning and etching - devices. Further, according to the above-mentioned shadow mask manufacturing method, a shadow mask can be manufactured inexpensively. While the preferred embodiments of the present invention have been described, it is understood that the present invention should not be limited to these preferred embodiments but various changes and modifications can be made by one skilled in the art within the spirit and scope of the present invention as hereinafter claimed.

Claims: What is claimed is: 1. A shadow mask manufacturing method comprising the steps of : manufacturing a master shadow mask by using nickel and a mold release; forming a shadow mask by submerging the master shadow mask composed of the nickel and the mold release in a bath and electro-forming the master shadow mask; and separating a shadow mask from the master shadow mask in which the shadow mask is formed. 2. A shadow mask manufacturing method according to claim 1 , wherein the master shadow mask manufacturing step comprises the steps of : (1 ) filling holes of a base plate by coating the base plate with-the mold release, (2) removing the mold release from both surfaces of the base plate by using an abradant, and flattening the both surfaces of the base plate, (3) forming a nickel layer on one surface of the base plate by submerging the base plate in a bath and electro-forming the base plate, (4) coating the surface of the base plate with the mold release so as to completely cover the nickel layer formed on the surface of the base plate and then solidifying the mold release, after removing the base plate from the bath, and (5) removing the base plate from the mold release and the nickel layer. 3. A shadow mask manufacturing method according to claim 2, wherein the mold release is a silicon resin. 4. A shadow mask manufacturing method according to claim 2, wherein in the step (2) , the abradant is thinner, acetone, or toluene. 5. A shadow mask manufacturing method according to claim 3, wherein in the step (2), the abradant is a mixture of thirmer and toluene. 6. A shadow mask manufacturing method according to claim 2, wherein in the step (3), the bath used in electro-forming the base plate is one selected from a watt bath, a chloride nickel bath, a brom-fluoride nickel bath, or a sulfamic acid nickel bath. 7. A shadow mask manufacturing method according to claim 2, wherein a nickel ingot is further supplied in the bath to expedite the forming of the nickel layer. 8. A shadow mask manufacturing method according to claim 1, wherein the master shadow mask manufacturing step comprises the steps of : (1) filling holes of a base plate by coating the base plate with the mold release, (2) removing the mold release from one surface of the base plate by using an abradant, and flattening the surface of the base plate, (3) forming a nickel layer on the surface of the base plate by submerging the base plate in a bath and electro-forming the base plate, (4) coating the surface of the base plate with the mold release so as to completely cover the nickel layer formed on the surface of the base plate and then solidifying the mold release, after removing the base-plate from the bath, (5) removing the mold release from the other surface of the base plate by using the abradant, and flattening the other surface of the base plate, and (6) removing the base plate from the mold release and the nickel layer. 9. A shadow mask manufacturing method according to claim 8, wherein the mold release is a silicon resin. 10. A shadow mask manufacturing method according to claim 8, wherein in the steps (2) and (5) , the abradant is thinner, acetone, or toluene. 11. A shadow mask manufacturing method according to claim 9, wherein in the steps (2) and (5), the abradant is a mixture of thinner and toluene. 12. A shadow mask manufacturing method according to claim 11 , wherein in the step (3), the bath used in electro-forming the base plate is one selected from a watt bath, a chloride nickel bath, a brom-fluoride nickel bath, or a sulfamic acid nickel bath. 13. A shadow mask manufacturing method according to claim 12, wherein a nickel ingot is further supplied in the bath to expedite the forming of the nickel layer. 14. A shadow mask comprising : a shadow mask frame in which a plurality of minute holes are formed; and a skirt integrally formed with the shadow mask frame along the edge of the shadow mask frame, for reinforcing the shadow mask frame, wherein the shadow mask frame and the skirt being integrally formed by a manufacturing process comprising the steps of : manufacturing a master shadow mask by using nickel and a mold release; forming a shadow mask by submerging the master shadow mask composed of the nickel and the mold release in a bath and then electro-forming the master shadow mask; and separating the shadow mask from the master shadow mask in which the shadow mask is formed. 15. A -shadow mask according to claim 14, wherein the master shadow mask manufacturing step comprises the steps of : (1) filling holes of a base plate by coating the base plate with the mold release, (2) removing the mold release from both surfaces of the base plate, and flattening the both surfaces of the base plate, (3) forming a nickel layer on one surface of the base plate by submerging the base plate in a bath and electro-forming the base plate, (4) coating the surface of the base plate with the mold release so as to completely cover the nickel layer formed on the surface of the base plate and then solidifying the mold release, after removing the base plate from the bath, and (5) removing the base plate from the mold release and the nickel layer. 16. A shadow mask according to claim 15, wherein the mold release is a silicon resin. 17. A shadow mask according to claim 15, wherein in the step (2) , the abradant is thinner, acetone, or toluene. 18. A shadow mask according to claim 17, wherein in the step (2), the abradant is a mixture of thinner and toluene. 19. A shadow mask according to claim 15, wherein in the step (3), the bath used in electro-forming the base plate is one selected from a watt bath, a chloride nickel bath, a bro - fluoride nickel, or a sulfamic acid nickel bath. 20. A shadow mask according to claim 15, wherein a nickel ingot is further supplied in the bath to expedite the forming the nickel layer. 21. A shadow mask according to claim 15, wherein the thicknesses of the shadow mask frame and the skirt are about 0.1 mm and the diameter of the holes formed in the shadow mask frame is about 20 mm. 22. A shadow mask according to claim 14, wherein the master shadow mask manufacturing step comprises the steps of : (1) filling holes of a base plate by coating the base plate with the mold release, (2) removing the mold release from one surface of the base plate by using an abradant, and flattening both surfaces of the base plate, (3) forming a nickel layer on the surface of the base plate by submerging the base plate in a bath and electro-forming the base plate, (4) coating ' the surface of the base plate with the mold release so as to completely cover the nickel layer formed on the surface of the base plate and then solidifying the mold release, after removing the base plate from the bath, (5) removing the mold release from the other surface of the base plate by using the abradant, and flattening the other surface of the base plate, and (6) removing the base plate from the mold release and the nickel layer. 23. A shadow mask according to claim 22, wherein the mold release is a silicon resin. 24. A shadow mask according to claim 22, wherein in the steps (2) and (5) , the abradant is thinner, acetone, or toluene. 25. A shadow mask according to claim 24, wherein in the steps (2) and (5), the abradant is a mixture of thinner and toluene. 26. A shadow mask according to claim 22, wherein in the step (3), the bath used in electro-forming the base plate is one selected from a watt bath, a chloride nickel bath, brom-fluoride nickel bath, or a sulfamic acid nickel bath. 27. A shadow mask according to claim 26, wherein a nickel ingot is further supplied in the bath to expedite the forming of the nickel layer. 28. A shadow mask manufactured by a shadow mask manufacturing method according to one of claims 1 to 13.

Inventors: KIM JEONG SIK, KIM, JEONG, SIK
Applicants: KIM JEONG SIK, KIM, JEONG, SIK
Application year: 2000
Main classification: H01J9
IPC codes: H01J9