JPH0373640B2 - - Google Patents

Description

[Detailed description of the invention]

(Object of the Invention) The present invention relates to a thin plate material for a shadow mask used in a color picture tube. (Prior art and problems) Conventionally, mild steel sheets such as low carbon rimmed cold rolled steel sheets and low carbon Al killed cold rolled steel sheets have been used for shadow masks for color picture tubes, but these materials have lower thermal expansion characteristics. The use of Fe--Ni based alloys such as 36Ni-Fe amber, which has a Generally, when a color picture tube is operated, only 1/2% of the electron beam passes through the aperture of the shadow mask.
3 or less, and the remaining electron beam hits the shadow mask, so the shadow mask sometimes
It is heated to the point where it reaches temperatures as high as ℃. At this time, the shadow mask expands due to heat and the distance between the shadow mask and the phosphor screen changes, resulting in a decrease in color purity, but the use of Fe-Ni-based amber alloy reduces this thermal expansion. be. but,
This Fe-Ni-based amber alloy has a problem with etching properties to create a large number of pores compared to conventional mild steel. In the case of the above-mentioned amber alloy, resist adhesion and etching solution corrosion resistance are different from mild steel, so the conventional etching drilling method results in large variations in hole diameter and hole shape, and as a result, the pores drilled by the etching When light is transmitted through the mask, a haze-like unevenness appears on the mask. In particular, in high-definition masks with small pitches and small hole diameters, which have been rapidly increasing in recent years, even slight disturbances in the hole diameter or shape can cause unevenness, significantly reducing the quality of color picture tubes. . In order to prevent this, a method of lowering the temperature of the etching solution to reduce the etching rate has been considered, but this method extremely reduces productivity and is not economically suitable. For this reason, there has been a long-awaited development of a Ni-Fe based alloy thin plate material for shadow masks that has good production efficiency and can yield high-quality shadow masks. (Structure of the Invention) The present invention has been made in view of the above points, and provides a thin plate material for a shadow mask that can reduce variations in the hole diameter and hole shape of the shadow mask, and can efficiently manufacture high-quality shadow masks without unevenness. It is something to do. That is, the present invention provides a method for forming electron beam transmission holes by etching.
The thin plate material for a shadow mask made of an Fe-Ni alloy containing Fe and Ni as main components has the following surface roughness Ra and an average interval Sm of unevenness of the surface roughness Ra 0.2 to 0.7 μm Sm 100μm or less (However, Ra is the surface roughness according to JIS B 0601, and Sm is the average value of the interval between concavities and convexities of the cross-sectional curve indicating the surface roughness within the standard length.) and electron beam transmission holes are formed by etching. The Fe-Ni alloy shadow mask thin sheet material containing Fe and Ni as main components to be formed has the following surface roughness Ra and average spacing Sm of surface roughness irregularities, and the crystal grain size is the grain size number.
8.0 or more Ra: 0.2 to 0.7 μm Sm: 100 μm or less (However, Ra is the surface roughness of JIS B 0601, and Sm is the cross-sectional curve showing the surface roughness within the standard length. ) is the average value of the spacing between the concave and convex portions. (Specific Description of the Invention) Next, limitations on each condition of the thin plate material for a shadow mask of the present invention will be described. First, regarding surface roughness, surface roughness greatly affects the adhesion of the resist. If the adhesion of the resist is not appropriate, the hole shape will be disordered and the accuracy of hole opening will be reduced. In particular, in high-definition masks, irregularities in hole shape due to slight differences in resist adhesion become a fatal defect. Therefore, it is necessary to strictly define the surface roughness as follows. Surface roughness Ra
If the diameter is smaller than 0.2 μm, the adhesion of the resist is too weak and side etching progresses too much, making it impossible to form holes with high accuracy. On the other hand, if the diameter is larger than 0.7 μm, the adhesion is too strong and the resist may remain in the area where the holes should be formed after the formation, which is not preferable. Also,
In order to increase productivity, it is necessary to raise the etching temperature, but in this case, the corrosion reaction becomes more intense, so it is necessary to control the surface roughness even more strictly to obtain good resist adhesion. A more preferable range of Ra is more than 0.4 to 0.6 μm. However, the above-mentioned Ra alone cannot perform sufficient etching to obtain appropriate pores. Therefore, various studies have been conducted on Sm. Sm
As shown in Fig. 1, represents the average value of the interval between concavities and convexities of the cross-sectional curve indicating surface roughness within the standard length Sm = Sm ₁ + Sm ₂ +... + Smn/n, and if Sm is too large, holes will occur. The shape becomes worse. This situation is shown in FIG. Figure 2 a is
This conceptually shows the case where Sm is too large. Because the roughness pitch is large, the adhesion of the resist is locally weakened, and side etching (etching in the direction of the side wall) occurs in that area, as shown by dotted line 4 in the figure. )
The hole shape becomes disordered because of excessive progress. Figure 2b is
This conceptually shows the case where Sm is moderately small, and the resist adhesion is uniform throughout the hole, so the hole shape is not disturbed. In this way, Sm is an important factor for resist adhesion, and if it exceeds 100 μm, the pore shape will be disordered.
must be 100 μm or less. In particular, when etching is performed at high temperatures or in the case of a fine-hole mask with small hole diameters, it is desirable that the Sm be 50 μm or less. Next, regarding crystal grains, if the grain size is coarse grains with a grain size number of less than 8.0, there is a tendency for the edges of the pores to become jagged and the shape of the pores to be poor due to differences in etching properties depending on the crystal plane. Therefore, in order to improve the hole precision, the grain size should be set to 8.0 in terms of grain size number.
It is desirable that it be above. In order to improve the precision of the pores formed by etching as described above, it is necessary to strictly adjust Ra, Sm, and even the crystal grain size to the conditions of the present invention. Next, an example will be described. (Example) 36Ni-Fe as a thin metal plate material for shadow masks
An alloy called amber was used. This material was rolled to a thickness of 0.2 mm, and the surface roughness was adjusted by dull finishing. In addition, the grain size was adjusted by annealing before final rolling. First, degreasing is performed to remove rolling oil and rust preventive oil, and then a photosensitive solution consisting of alkali milk caseinate and ammonium dichromate is applied to both sides of the mask material to form a prescribed resist film. Next, a pattern having a negative image of large and small mask holes is placed in close contact with the photoresist film on both sides, and an image of the mask holes is obtained by exposing with an ultra-high pressure mercury lamp. After that, development,
After drying and burning, proceed to the etching process.
In the etching process, ferric chloride was used as an etching solution. The shadow mask thus produced was observed under transmitted light in a dark room to evaluate the quality of unevenness. Table 1 shows the present invention and comparative examples obtained through the above experiments. In Examples 1 to 5 of the present invention, Ra, Sm, and crystal grain size were all appropriate, so good masks with high unevenness quality were obtained. In particular, in Examples 1 and 2 of the present invention, since Ra and Sm are in more preferable ranges, particularly good masks with no unevenness are obtained. Inventive Examples 6 and 7 have some unevenness because the crystal grain size is less than 8.0, but this is at a level that poses no problem for practical use. Comparative Examples 8 to 11 have Ra and Sm that are out of the range of the present invention, so they are highly uneven and cannot be put to practical use.

[Table] In addition, in the above examples, 36Ni-Fe alloy was used as the material for the shadow mask, but the present invention is not limited to this, and 42Ni-Fe alloy, 36Ni-4Cr
−Fe alloy, 32Ni−5Co−Fe alloy, 32Ni−4Co−
Needless to say, any alloy containing Fe and Ni as main components, such as 2Cr-Fe alloy, can be similarly applied. (Effects of the Invention) As described above, according to the present invention, a high-quality shadow mask with small and uniform pore diameter and shape variations can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the surface roughness Sm, and FIGS. 2a and 2b are explanatory diagrams for conceptually explaining the influence of Sm on the pore shape. l: Average line, Sm ₁ , Sm ₂ : ... Distance between unevenness, 1:
Convex portion with rough roughness, 2: Convex portion with dense roughness, 3:
Hole 4: Side etching progresses and the hole shape swells as shown by the dotted line.

Claims (1)

[Claims] 1. A thin plate material for an Fe-Ni alloy shadow mask mainly composed of Fe and Ni for forming an electron beam transmission hole by etching has the following surface roughness Ra and the average unevenness of the surface roughness. The thin plate material for a shadow mask characterized by having an interval Sm Ra 0.2 to 0.7 μm Sm 100 μm or less (However, Ra is the surface roughness of JIS B 0601, and Sm is the cross-sectional curve showing the surface roughness within the standard length. ) 2 A Fe-Ni alloy shadow mask thin plate material mainly composed of Fe and Ni for forming electron beam transmission holes by etching has the following surface roughness Ra and average spacing Sm of surface roughness irregularities, The thin plate material for a shadow mask, characterized in that the crystal grain size is 8.0 or more in terms of grain size number. It is the average value of the interval between concavities and convexities in a cross-sectional curve that indicates roughness).