JPH01282A - Shadow mask and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a shadow mask used in a color television cathode ray tube and a method for manufacturing the same.

<Background of the Invention> Low carbon rimmed steel or low carbon A1 killed steel with a plate thickness of 0.1 to 0.25 mm is generally used as a shadow mask for a cathode ray tube for color television.

The manufacturing process of the shadow mask is generally as follows. First, through processes such as melting and casting of the material and appropriate rolling,
Then, a shadow mask material having a predetermined thickness is manufactured by final cold working. The shadow mask material is etched and perforated to form a flat mask. The flat mask is annealed to give it press formability, and then pressed to form a spherical surface.The zero-spherical mask is subjected to a blackening treatment to become a shadow mask. There is also a method in which annealing to impart press formability is performed immediately after final rolling, and this is called a pre-annealing method.

To explain in more detail, first, taking low-carbon Al-killed steel as an example of the manufacturing method for shadow mask material, the steel is melted in a converter, then cast into an ingot, then hot-rolled and cold-rolled after forging, and then opened. The coil is decarburized by annealing, and then final cold rolled to a predetermined thickness. Thereafter, it is slit to obtain a shadow mask material having a predetermined width.

After degreasing, the shadow mask material is coated with photoresist on both sides, a pattern is baked and developed, and then perforated by etching using an etching solution mainly containing ferric chloride.
Cut into individual pieces to make flat masks.

The flat mask is annealed in a non-oxidizing atmosphere to impart press formability (in pre-annealing this annealing is performed on the final cold rolled material before etching). After leveling, it is spherically molded into a mask shape using a press.

Finally, the spherical mask is degreased and then subjected to a blackening treatment in a steam or combustion gas atmosphere to form a black oxide film on the surface. In this way, a shadow mask is produced.

This is a common manufacturing process for shadow masks, but shadow masks made of low carbon rimmed steel or low carbon Al-killed steel that have gone through the above manufacturing process require a small amount of processing after recrystallization annealing. The coercive force He is about 1.00e, and this is not significantly impaired.

However, some color cathode ray tubes do not use the manufacturing process described above, and the flat mask after etching is not formed into a spherical surface by pressing, but is fixed to a frame etc. under tension and then subjected to blackening treatment. There are things that are built into cathode ray tubes.

In this case, since it is necessary to withstand tension, the low carbon rimmed steel or low carbon Al killed steel is left almost in a cold rolled state or subjected to heat treatment that does not recrystallize, such as heat treatment for strain relief, to make it into a shadow mask. It is assembled into a cathode ray tube with a very high coercive force Hc of about 5 to 70e.

If the coercive force of the shadow mask is high in this way, the shadow mask itself becomes magnetic due to the influence of the earth's magnetism and the magnet inside the speaker, and as a result, the trajectory of the electron beam is not properly controlled, resulting in a decrease in the purity of one color. A defect occurred that caused unevenness.

Furthermore, in the case of this type of shadow mask, since it is used under tension as described above, the shadow mask material must have strength to withstand this tension. Although there are differences depending on the type of cathode ray tube, -70 kg/■ inside the shell
A tensile strength of 2 or more is required.

In recent years, there has been an increasing need to drill more holes in shadow masks with high precision in order to achieve higher definition in color televisions. For this reason, the cold-rolled steel plates with a thickness of 0.1m to 0.25III used in conventional shadow masks have a limit in achieving high definition, so the use of ultra-thin plates with a thickness of 50μm or less is being considered. There is. In this case, since the material is thin, new problems arise such as damage during handling and handling during etching, so the above-mentioned requirement for strength is becoming more important from this point of view as well.

Structure> The present invention was made in view of the above points, and the gist thereof is that G is 0.03% or less in weight percent, S11-5
%, Mn 1% or less, S 0.020% or less, balance Fe
and unavoidable impurities, and C0.03% or less by weight percentage, 81
Made of steel with 1 to 5% 1Mn 1% or less, S 0.020% or less, balance Fe and unavoidable impurities, plate thickness 50 μm
The method of manufacturing a shadow mask is characterized in that it is assembled into a cathode ray tube under tension after cold rolling, etching, perforation, heat treatment, and blackening film treatment.

<Detailed description of the invention> Next, the reasons for limiting the components of the present invention will be explained.

C: If C is more than 0.03%, carbides in the steel will increase and the coercive force will be impaired. Therefore, the range of its components is set to 0.03% or less.

Si: If the Si content is less than 1%, the strength will not increase sufficiently and the coercive force will also be poor. Furthermore, if the Si content is more than 5%, it becomes too hard and significantly impairs productivity.

Therefore, the component range is set to 1 to 5%.

M n ; M n is useful for improving the strength of steel in addition to deoxidizing purposes. It also combines with S in steel and has the effect of preventing red heat embrittlement of steel. However, if Mn is contained in excess of 1%, the coercive force deteriorates. Therefore, its component range is set to 1% or less.

If the SO8 content is more than 0.020%, uneven drilling will occur during etching and drilling, which will significantly reduce the yield. It also harms magnetism. Therefore, its component range is set to 0.020% or less.

Steel consisting of the above-mentioned components is cold rolled to a plate thickness of 0.1 mm to 0.25 mm. Although it can be used for regular shadow masks and aperture grills, it is suitable for use in items that require higher definition. In this case, in particular, by cold-rolling the plate to a thickness of 50 μm or less, it becomes possible to drill holes with higher definition than before, and the shadow mask is installed in a cathode ray tube with tension applied to it. Masks can be manufactured.

The heat treatment of the present invention is carried out at a temperature of 300°C to 700°C. This heat treatment significantly reduces the coercive force.

If the heat treatment temperature is less than 300℃, the reduction in coercive force will not be sufficient and it is likely to cause a decrease in the purity of one color or the occurrence of unevenness, which is undesirable.If the heat treatment temperature exceeds 700℃, the strength will decrease, so shadow It becomes difficult to assemble the mask into a cathode ray tube with tension applied to it. Therefore, the present invention provides the above heat treatment temperature of 300°C to 70°C.
The temperature should be in the range of 0°C.

The starting temperature of recrystallization of the material of this shadow mask is approximately 6
00°C, the above heat treatment temperature range also includes the recrystallization temperature range.

Therefore, the temperature conditions for the heat treatment are appropriately set within the above-mentioned temperature range of the present invention, taking into account the need to reduce the coercive force and maintain the strength.

<Example> After melting and casting in a vacuum melting furnace, a cold rolled steel plate with a thickness of 25 μm was manufactured through the steps of hot rolling → pickling → cold rolling → annealing → cold rolling. The components of this cold rolled steel sheet are shown in Table 1.

This cold-rolled steel plate was heat-treated at various temperatures, and the tensile strength and coercive force were then measured and are also listed in Table 1. In addition, cold rolled steel sheets after heat treatment are degreased → resist coated → exposed and developed →
A high-definition mask with a pitch of 0.2 m is manufactured through the process of etching perforation → resist removal.Furthermore, the mask is fixed to a frame with tension applied to it, and then incorporated into an actual cathode ray tube to eliminate color unevenness caused by the influence of external magnetic fields. We investigated whether or not this occurred. The results are shown in Table 1.

As is clear from Table 1, Invention Examples Nos. 1 to 6 all have a tensile strength of 70 kg/m" or more and have sufficient strength, and all have coercive forces of 3.OOe or less. As a result, no color unevenness was observed when it was actually incorporated into a cathode ray tube, and good results were obtained.

On the other hand, Comparative Example 7 has C, Comparative Example 10 has Mn, Comparative Example 1
1 has a high S content, so the coercive force is 4.0 even after heat treatment.
0e or more, and as a result, the occurrence of color unevenness is remarkable. Comparative Example 8 has insufficient strength and high coercive force due to the small amount of Si. Comparative Example 9 had a large amount of Si and could not be cold rolled. Comparative Example 12.13 is an example of low carbon Al-killed steel, but after heat treatment at 450°C, the coercive force was extremely high, and the coercivity was 60°C.
Heat treatment at 0°C results in insufficient strength and coercive force is still high.

Comparative Examples 14 and 15 are A1 killed steels with increased C content, and although the strength is satisfactory after heat treatment at 450°C, the coercive force is high.

If the heat treatment temperature is increased to 600°C, the strength will decrease and the coercive force will also be high.

<Effects> As described above, the present invention provides a shadow mask that has sufficient strength and low coercive force, and a method for manufacturing the same.

Margin below

Claims (2)

[Claims] (1) C0.03% or less in weight percent, Si1-5
%, Mn 1% or less, S 0.020% or less, the balance being Fe and unavoidable impurities. (2) C0.03% or less in weight percent, Si1-5
%, Mn 1% or less, S 0.020% or less, balance Fe and unavoidable impurities. After cold rolling to a thickness of 50 μm or less, the steel is subjected to etching perforation, heat treatment, and blackening film treatment to reduce tension. A method for manufacturing a shadow mask, characterized in that it is incorporated into a cathode ray tube in a state in which it is attached.