JPS61153259A - High accuracy shadow mask - Google Patents

Abstract

PURPOSE:To prevent defective transmission after piercing and to provide high accuracy to a mask by using a cold-rolled dead-soft Al killed steel sheet specifying the diameter of a single inclusion and the length of a group of inclusions in the lateral direction. CONSTITUTION:A cold-rolled dead-soft Al killed steel sheet having <0.3mum average diameter of the single inclusion such as sulfide in a cross-section perpendicular to the rolling direction is used as a material for a shadow mask. A cold-rolled dead-soft Al killed steel sheet in which a group of inclusions having 0.3-5.0mum average diameter have <2.5mum length in the lateral direction may be used. THe Al killed steel sheet is pierced by etching to form a high accuracy shadow mask having <=0.5mm piercing pitch. Ununiform transmission can be inhibited by using the material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-definition shadow mask material used in color picture tubes for consumer and industrial use, which prevents poor transmission after etching and perforation.

Traditionally, rimmed steel has been used as a material for shadow masks, but in the shadow mask manufacturing process, in which a resist is applied to a cold-rolled steel plate, a pattern is baked, developed, and etched, holes are formed due to oxide inclusions. There is a problem in that many etching defects occur, and furthermore, when annealing is subsequently performed to impart press formability, yield point elongation tends to occur, and defects such as stretcher strain are likely to occur during press forming. Therefore, low carbon Al killed steel that has been decarburized and annealed is increasingly being used. Although the use of decarburized Al-killed steel has reduced etching defects compared to rimmed steel, it still often causes transmission unevenness called streak unevenness parallel to the rolling direction, which is a fatal defect as a shadow mask. ing.

Moreover, there is a rapid movement toward higher definition of shadow masks themselves, and with high-definition shadow masks that have a larger aperture ratio than conventional shadow masks, the problem of uneven transmission is becoming more serious than before. It has been desired to develop a material for high-definition shadow masks that has fewer defects.

In view of this, the inventors of the present invention have endeavored to investigate the cause of poor transmission, and have found that when a shadow mask material is perforated with an etching solution mainly containing ferric chloride, inclusions in the material If there are inclusions larger than a certain size, or if the inclusions form a group larger than a certain size, serious defects will occur on the perforated wall surface after etching, resulting in uneven penetration. It was found that the occurrence rate increases as the aperture ratio of the mask increases.

The present invention was developed as a result of repeated research on the relationship between uneven transmission and inclusions. is [AI less than 13 μm
The length in the width direction of a killed cold-rolled steel plate or a group of inclusions composed of a single inclusion with an average diameter α of 3 μm to 5.0 μm is 2
．． This is a high-definition shadow mask with a perforation pitch of 0.5 square meters or less, which is made of ultra-low carbon Al killed cold-rolled steel sheet with a diameter of less than 5 μm.

Note that the average diameter of the single inclusion is the average value of the cross-sectional dimensions of the inclusion, and means the diameter converted into a right circle.

The ultra-low carbon Al killed cold rolled steel sheet has C; o, o
1% by weight or less (weight omitted hereafter), Mn; toON or less, S; 0.025% or less, 5olAl; 0.010
~0.120X, N: 100 ppm or less, and the balance consists of Fe and unavoidable impurities.

The inclusion group in the present invention is observed in a cross section perpendicular to the rolling direction of a rolled material of processed Enoki, and its form is defined in the JIS method or the undergraduate method for inclusion microscopic observation. Similar to system inclusions.

If the maximum average diameter of a single inclusion in the inclusions forming this group exceeds 5.0 μm, uneven transmission occurs even if the inclusions do not form a group. On the other hand, if it is less than 0.3 μm,
1], the unevenness of transmission after etching holes in a high-definition shadow mask of 5- or less is not a practical problem, and even if the average diameter is Q, 3 μm or more, the length in the width direction of the above inclusion group Similarly, if the thickness is less than 2.5 μm, no problem arises.

Incidentally, this inclusion group of 2.5 μm or more becomes an etching perforation defect unless certain specific conditions are met.

In this case, the components of inclusions are mainly sulfide inclusions mainly composed of Mn-8, but sulfide inclusions such as Ca-8 and silicates such as Mn O-S t O2 The same applies to systems.

Further, the type of shadow mask can be either a slot type or a dot type.

The sample material for the example was produced by tapping low carbon steel in a 150-ton converter, then adding Fe-Mn, AI, etc. to adjust the composition, and then forming a steel billet by continuous casting. This steel piece was manufactured through the steps of hot rolling → pickling → cold rolling → decarburization annealing → skin pass rolling → cold rolling again to obtain a thin steel plate with a thickness of 0.13 . This thin steel plate has C: [LOIX or less, Mn: 100X or less, S: 10
25X or less, 5olAl:l:L010~α120%,
N: 10 G pm) or less, and the remainder consisted of Fe and unavoidable impurities.

Table 1 shows the forms of inclusions in this cold-rolled steel sheet and the occurrence of uneven transmission after etching and perforating various shadow masks.

As shown in Table 1, by defining the size of a single inclusion or a group of inclusions as in the present invention, it is possible to suppress uneven transmission.

Table 1 Procedural Amendment (Method) May 20th, 1985 Patent Counterfeiter Shiga Indication of Number of Characters 1985 Patent Application No. 275750 Title of Invention Person who performs high-definition shadow mask correction

Claims (1)

[Claims] 1) In the cross section perpendicular to the rolling direction of the shadow mask,
Al-killed cold-rolled steel sheet in which the average diameter of a single inclusion is less than 0.3 μm, or a group of inclusions composed of single inclusions with an average diameter of 0.3 μm to 5.0 μm, whose length in the width direction is 2.5 μm
A high-definition shadow mask with a perforation pitch of 0.5 mm or less, which is made of an ultra-low carbon Al-killed cold-rolled steel plate with a carbon diameter of less than 0.5 mm.