JPH0344842B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a metal plate for a shadow mask, and more particularly to a method for manufacturing a high-quality metal plate for a shadow mask that has a relatively rough surface roughness and a high density of roughness. Conventionally, metal plates for shadow masks are produced by first cold rolling a low carbon hot rolled steel strip or a high alloy steel strip such as invar, and then subjecting it to strain relief annealing using a box annealing method (including open coil annealing) or a continuous annealing method. conduct,
The basic manufacturing process is to then perform secondary cold rolling, or further secondary cold rolling and temper rolling to form a slit coil. Therefore, the surface finish of the metal plate for a shadow mask, which is a product, is prepared in the secondary cold rolling or temper rolling process, which is finish rolling, and the surface condition affects the performance of the color cathode ray tube, which is the final product. More specifically, the surface finish of the work roll used for the finish rolling is itself transferred to the metal plate with considerable fidelity, so the surface finish of the work roll is the most important requirement. Next, the production of a shadow mask using a metal plate for a shadow mask will be described. Hereinafter, the metal plate for a shadow mask may be simply referred to as a material. FIG. 1 is a diagram showing the manufacturing process of a shadow mask. In Fig. 1, the material is first pretreated by degreasing, etc., then a photoresist is applied to both sides of the material, and then a vacuum is applied to make the original plate adhere to the surface of the material.After the original plate is completely adhered to the surface of the material, The original pattern is printed onto the material by exposing both sides simultaneously. Then, in a developing process, the unexposed areas of the photoresist are removed, and in a burning process, the exposed areas of the photoresist are baked and hardened to form an acid-resistant film. Then, in the etching step, a ferric chloride solution is used to perforate the exposed portion of the material, and the material is sent to a shearing and inspection step. In this way, a flat mask is completed. Next, in order to give workability to this flat mask, the mask is annealed in a dry or wet atmosphere, then passed through a leveler several times to correct the shape and prevent Reuders lines (leveling process), and then press-formed into a spherical shape. Process. Next, blackening treatment is performed in steam and/or gas to prevent rust and scattering of electron beams during the process.
The shadow mask is completed. Note that the above mask annealing and leveling may not be performed. In this case, in the manufacturing process of the metal plate for the shadow mask, the metal plate is pre-annealed after finish rolling, followed by skin pass rolling or leveling. The above is the process of manufacturing a shadow mask from a metal plate (material) for a shadow mask.Next, the vacuum exposure process according to the present invention will be explained in more detail. FIG. 2 is a perspective view showing a state in which the metal plate 1 after the photoresist 2 has been applied is evacuated and the original plate 3 is brought into close contact with the metal plate 1. In Fig. 2, a degassing pipe 4 connected to a vacuum pump is connected to a photoresist 2 in an airtight area.
The air remaining in the space between the surface of the original plate 3 and the surface of the original plate 3 is suctioned and exhausted. FIG. 3 is a cross-sectional view during evacuation showing the state of degassing the air remaining between the photoresist and the original plate on one side. In FIG. 3, the photoresist 2 is attached to the metal plate 1.
Although it is in close contact with the original plate 3, there is a partial space between it and the original plate 3, and air remains inside. When this is vacuumed in the direction of arrow V, the remaining air is removed,
The original plate 3 is pressurized in the direction of arrow A by atmospheric pressure and comes into close contact with the photoresist. It is desirable for this phenomenon to occur uniformly over the entire surface, but in reality it is not possible to uniformly arrange a large number of degassing pipes compared to the area to be degassed (vacuum degassing pipes are only available at a portion of the periphery). ), the deaeration path tends to be blocked and deaeration takes a long time, and complete deaeration is difficult if you try to deaeration in a short period of time. There was an unavoidable tendency for voids (non-adhesive areas) to remain in areas other than the periphery of the area. In other words, it is extremely difficult to perform sufficient degassing in a short period of time with a small number of degassing tubes and to create an efficient vacuum with conventional material roughness. Therefore, the inventors of the present invention were faced with the need to manufacture a metal plate for shadow masks that is dense and has a roughness with a large difference in peak and valley heights in its microscopic cross section, and as a result of various tests and studies, liquid honing was used as a finish rolling work roll. By using rolls,
The inventors have discovered that the above problems can be solved, and have arrived at the present invention. The progress leading to the present invention will be briefly described below. In other words, conventional finish rolling work rolls for manufacturing metal plates for shadow masks require (1) coarse grindstone polishing;
or (2) the surface was finished by shot blasting. However, method (1) was not suitable because the scratch marks of the grinding wheel were transferred to the metal plate and the holes in the shadow mask tended to have irregular shapes after etching. In addition, in method (2), waviness (microscopically large wave-like heights and lows) and protrusions were generated in the cross-sectional shape of the roll surface roughness, which tended to have an adverse effect on the shadow mask hole shape. That is, the undulations particularly make the straight portion of the shadow mask slot hole non-linear, and the protrusion creates a missing portion called a crater in the shadow mask slot hole. Therefore, method (2) was also inappropriate. Therefore (2)
In order to improve this method, we tested a roll whose surface was finished with a soft grindstone such as a vinyl grindstone after shot blasting, but although the occurrence of craters in the shadow mask holes disappeared, the effect of waviness was not improved. . The above is the research progress that led to the present invention, and therefore, the adoption of a liquid honing roll was by no means a mere idea. An object of the present invention is to provide a method for manufacturing a metal plate for a shadow mask that can achieve uniform evacuation in a short period of time in the shadow mask manufacturing process. Another object of the present invention is to provide a method for manufacturing a metal plate for a shadow mask that is dense and has a high Ra roughness. Still another object of the present invention is to provide a method for manufacturing a metal plate for a shadow mask, which is a shadow mask material suitable for high-quality color picture tubes and capable of obtaining accurate hole shapes. According to the present invention, a liquid honed roll having a surface roughness of 0.5 to 4.0 μmRa and a roughness density of 20 to 80 HSC/2.5 mm can be used as a work roll in finish cold rolling or temper rolling. A method for manufacturing a metal plate for a shadow mask is provided. The present invention will be explained in detail below using Examples. Figure 4 is a work roll surface roughness profile (comparative example) measured by the conventional shot blasting method using a stylus type surface roughness meter, and Figure 5 is a diagram of the work roll surface roughness processed by liquid honing on the same scale. It is a surface roughness profile diagram (Example).
In both cases, the horizontal magnification is 50x, and the vertical magnification is
It is 2000 times more. Table 1 shows numerical values for the surface roughness shown in FIGS. 4 and 5.

[Table] Here, Ra is the center line average roughness, and from the low-frequency cut-off roughness curve, extract a part of measurement length L in the direction of the center line, and set the center line of that part on the x-axis, When the direction of vertical magnification is taken as the y-axis and the roughness curve is expressed as y=f(x), it is expressed in units of μm given by the following formula. Ra=1/L∫ ^L ₀ |f(x)|dx (according to JIS B 0601) HSC is the number of peaks per unit length (High Spot
Count), and a certain measurement length L from the cross-sectional curve (L = 2.5 in this case)
mm. ) is extracted and the peaks and valleys are distinguished based on whether they are above the average line.It is expressed as the number of peaks. Therefore, in Table 1, Ra is almost the same in both the comparative example and the inventive example, but when compared with HSC, the example is about three times as large as the comparative example, which means that the density of roughness is extremely high. It shows something high.
This fact is also clear by comparing Figures 4 and 5. Example of the present invention (Fig. 5)
The roughness of the shadow mask metal plate transferred during finish rolling shows almost the same roughness profile, so as mentioned above, an exhaust passage is secured during vacuuming, and the original plate can be coated with resist even during short-time vacuuming. Closely adheres to the metal plate. Therefore, a shadow mask with good pore shape in terms of performance can be obtained. The surface roughness of the work roll should be 0.5 to 4.0μmRa.
The reason for this is that if Ra is smaller than 0.5 μm, the exhaust passage will be blocked during evacuation.
This is because if the diameter is larger than 4.0 μm, the hole shape of the shadow mask will be warped and become inaccurate. In addition, the density of the work roll surface roughness is 20~
The reason for setting 80HSC/2.5mm is that if HSC is less than 20, the roughness will be plain with few irregularities as in the conventional example (see Figure 4), resulting in poor shadow mask hole shape, and if HSC exceeds 80. This is because it is difficult to implement industrially with the current liquid honing technology. The reason for limiting the surface roughness of the product metal plate is the same as that of the work roll surface roughness. However, due to the transfer rate, only Ra was set to 0.2 to 2.4 μm empirically. Note that the transfer rate of the work roll surface roughness (Ra) to the product metal plate is usually about 40 to 60%. In addition to mild steel, the material of the metal plate is amber, 42%
Examples include Ni-Fe alloy, Kovar (Fe-Ni-Co alloy), permalloy, etc., but it goes without saying that it can also be applied to materials other than these. By carrying out the present invention as described above, all of the above objectives have been achieved and it has become possible to industrially produce high quality shadow masks.

[Brief explanation of drawings]

Fig. 1 is a manufacturing process diagram of a shadow mask, Fig. 2 is a perspective view of the evacuation process, Fig. 3 is a sectional view of the evacuation process, and Figs. 4 and 5 are workpieces of a comparative example and an example of the present invention, respectively. It is a roll surface roughness profile diagram. 1...Metal plate, 2...Photoresist, 3...
Original version, 4... Degassing pipe.

Claims (1)

[Claims] 1. In finish cold rolling or temper rolling,
A method for manufacturing a metal plate for a shadow mask, characterized in that a liquid honed roll having a surface roughness of 0.5 to 4.0 μm Ra and a roughness density of 20 to 80 HSC/2.5 mm is used as a work roll. 2. The manufacturing method according to claim 1, wherein the product metal plate has a surface roughness of 0.2 to 2.4 μm Ra and a roughness density of 20 to 80 HSC/2.5 mm.