Metal plate

Abstract

The object of the present invention is to provide a metal plate capable of manufacturing a deposition mask in which dispersion of positions of through-holes is restrained. A thermal recovery rate is defined as parts per million of a difference a distance between to measurement points on a sample before a heat treatment and a distance therebetween after the heat treatment, relative to the distance therebetween before the heat treatment. In this case, an average value of the thermal recovery rates of the respective samples is not less than −10 ppm and not more than +10 ppm, and (2) a dispersion of the thermal recovery rates of the respective samples is not more than 20 ppm.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. application Ser. No. 15 / 026,009, filed Mar. 30, 2016, which in turn is the National Stage of International Application No. PCT / 3P2014 / 075168, filed Sep. 24, 2014, the entireties of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to a metal plate for use in manufacturing a deposition mask with a plurality of through-holes formed therein. In addition, the present invention relates to a method of manufacturing the metal plate. In addition, the present invention relates to a method of manufacturing the mask with a plurality of through-holes formed therein, by use of the metal plate.BACKGROUND OF THE INVENTION[0003]A display device used in a portable device such as a smart phone and a tablet PC is required to have high fineness, e.g., an image density not less than 300 ppi. In addition, there is increasing demand that the portable device is applicab...

AI Technical Summary

Benefits of technology

[0006]When a film of a deposition material is formed on a substrate with the use of a deposition mask, the deposition material adheres not only to the substrate but also to the deposition mask. For example, some of the deposition material moves toward the substrate along a direction largely inclined with respect to a normal direction of the deposition mask. Such a deposition material reaches a wall surface of a through-hole of the deposition mask and adheres thereto, before it reaches the substrate. In this case, the deposition material is not likely to adhere to an area of the substrate, which is located near the wall surface of the through-hole of the deposition mask, so that a thickness of the deposition material adhered to this area may be smaller than a thickness of another part and / or there may be a part to which no deposition material adheres. Namely, the deposition near the wall surface of the through-hole of the deposition mask may become unstable. Thus, when this deposition mask is used for forming pixels of an organic EL display device, dimensional precision of each pixel and positional precision thereof lower, which lowers luminous efficiency of the organic EL display device.

[0007]One of possible solutions to this problem is to reduce a thickness of a metal plate used for manufacturing a deposition mask. This is because, since the thickness of the metal plate is reduced, a height of a wall surface of a through-hole of a deposition mask can be reduced, whereby a rate of a deposition material, which adheres to the wall surface of the through-hole, can be lowered. However, in order to obtain a metal plate with a reduced thickness, it is necessary to increase a reduction ratio upon manufacture of the metal plate by rolling a base metal. The reduction ratio herein means a value obtained by a calculation of (thickness of base metal minus thickness of metal plate) / (thickness of base metal). When a metal is rolled, strain occurs in the rolled metal. Even if the metal is heat-treated such as annealed after being rolled, it is not easy to completely remove the strain for a short period of time. Thus, a metal plate used for manufacturing a deposition mask generally has a strain that remains inside the metal plate, i.e., a remaining strain.

[0008]A step using a metal plate to manufacture a deposition mask and a deposition step using the deposition mask respectively include a step of applying heat to the metal plate constituting the deposition mask. At this time, because of the heat, there is a possibility that a remaining stress in the metal plate is removed and / or that a crystalline orientation changes. When the remaining stress is removed and / or the crystalline orientation changes, the dimension of the metal plate may reduce. For example, when the remaining stress is removed, since the material shape held by the remaining stress changes such that there is no strain as much as possible, the dimension of the metal plate may reduce. On the other hand, when the crystalline orientation changes, the crystalline density changes to higher the density, the dimension of the metal plate may reduce.

[0053]wherein the developing step includes a resist heat treatment step of increasing a hardness of the resist film.

[0055]According to the present invention, a deposition mask having a restrained dispersion of positions of through-holes can be obtained. Thus, positioning precision of a deposition material adhered to a substrate can be improved.

Problems solved by technology

Namely, the deposition near the wall surface of the through-hole of the deposition mask may become unstable.

Thus, when this deposition mask is used for forming pixels of an organic EL display device, dimensional precision of each pixel and positional precision thereof lower, which lowers luminous efficiency of the organic EL display device.

When a metal is rolled, strain occurs in the rolled metal.

Even if the metal is heat-treated such as annealed after being rolled, it is not easy to completely remove the strain for a short period of time.

In addition, there is a possibility that the degree of remaining strain inside the metal plate changes in the width direction of the metal plate.

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