JP2921269B2 - Shadow mask manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a shadow mask by electroplating. More specifically, the present invention relates to a method for improving mechanical properties of a shadow mask by electroplating.

[0002]

2. Description of the Related Art As a shadow mask to be incorporated in a shadow mask type color picture tube, there are a mask having a circular electron beam passage hole and a mask having a rectangular electron beam passage hole. As shadow mask type color picture tubes, for general household use, for monitors, for displays,
The pitch of the holes in the household shadow mask is 60
It is about 0 to 700 μm, but in the case of a high-definition color television, 300 μm or less is required.

If the cross-sectional shape of the hole of the shadow mask is such that the fluorescent screen is largely opened, the electron beam side is a small hole, and if the cross section has a knife-edge shape, unnecessary portions generated by hitting the side wall of the hole with the electron beam are unnecessary. This is convenient because scattered electrons can be prevented and a decrease in contrast and color purity of the color picture tube can be prevented. In particular, since the electron beam is obliquely incident on the shadow mask at the corner of the screen, it is necessary to shift the large hole side and the small hole side to largely escape the taper on the wall side where the electron beam hits. Shape is required.

As a method of manufacturing a shadow mask, an etching method is conventionally known, but it has problems in dimensional stability and yield. Therefore, Japanese Patent Application Laid-Open Nos. 50-15745 and 51-128648 disclose methods of manufacturing a shadow mask using an electroforming method. According to this, in Japanese Patent Application Laid-Open No. 50-15745, an electroformed substrate having a large number of non-conductive convex portions having a peripheral wall inclined so that the upper surface side is formed as small holes and a concave portion formed of a metal conductor at the bottom, This is a method in which iron electroforming is performed using an iron electrolytic bath that imparts ductility to the electrodeposit, and the resulting electroformed product having the convex portions of the substrate as holes is separated from the substrate. JP-A-51-128648 discloses a method for producing an electroformed product by electroforming using a conductive substrate having a non-conductive portion having a negative planar shape with respect to a desired planar shape. A method in which iron is electrodeposited in a thickness range of 10 to 90 μm on a substrate in which a nonconductor portion is increased by an amount of growth in the direction (side splicing), separated from the substrate, and then heated at 250 to 700 ° C. It is. The dimensional accuracy was improved by these methods.

However, in each of the above methods, the shadow mask is formed by iron electroforming, and the obtained shadow mask is heated to 500 to 700 ° C. by steam or the like during the blackening treatment, so that the shadow mask is softened as a whole. As a result, there is a problem that the mechanical strength is reduced. In particular, when the shadow mask is further thinned for fine-pitch perforations to increase the resolution, such as in a high-definition television, or when manufacturing a shadow mask with a large radius of curvature corresponding to a flat type phosphor screen, As a result, the strength of the shadow mask is greatly reduced. For this reason, there is a problem that the vibration generated by the speaker or the like changes the shadow mask, that is, the position of the aperture, and eventually causes a color shift in the image. To solve this problem, a shadow mask obtained by electroforming as disclosed in JP-A-60-30038 is a single layer of mild steel, iron-nickel alloy, iron-nickel-cobalt alloy,
Alternatively, it is characterized in that it is a composite layer of a mild steel layer and an iron-nickel alloy layer.

[0006]

However, in the above-mentioned method, it is necessary to form an alloy layer by electroforming. Is difficult to obtain uniformly. Further, in such a case, the mechanical strength of the shadow mask is different, and a fluctuation occurs due to vibration, which causes a color shift. In addition, there is a possibility that a difference in color tone based on a difference in alloy composition may be caused by heating in the blackening process, or deformation may occur due to generation of stress. Furthermore, the management of the plating solution is complicated. An object of the present invention is to provide a method of manufacturing a shadow mask which can solve the above-mentioned disadvantages, satisfy dimensional accuracy, obtain a uniform mechanical strength and a black coating, and does not cause deformation during blackening treatment. It is.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method for forming a substrate, comprising a metal body and an insulator, by subjecting the exposed metal surface to electro-nickel plating by patterning the insulator. The method is characterized in that the nickel coating is peeled from the substrate, and an electric iron plating film is formed on the front and back surfaces of the peeled nickel coating.

Further, the thickness of the electric iron plating film is 0.1
It is characterized in that it is set to 10 μm.

[0009]

In order to improve the mechanical strength of the shadow mask, a metal layer having a sufficient tensile strength is sufficient. The electro-nickel plating film is usually 40 kg / mm ² or more, which is a suitable material. The electro-nickel plating method may be a conventional method using a watt bath.

The thickness of the electric iron plating film is 0.1 μm or more.
It must be 10 μm, and if it is less than 0.1 μm, the mechanical strength is insufficient and peeling occurs during the blackening treatment. If the thickness exceeds 10 μm, not only the high tensile strength of the nickel film cannot be fully utilized, but also the dimensional accuracy may be deteriorated because the iron film is formed by electroplating.

The metal plate has no particular problem as long as it has plating bath resistance. Further, the patterning of the insulator performed in the present invention,
Patterning may be performed by a photoetching method using a resin as an insulator, or patterning may be performed directly through a mask using a photoresist. The electric iron plating method is not particularly limited, and a liquid having a basic composition of iron chloride and calcium chloride may be used.

[0012]

【Example】

[Examples 1-2 and Comparative Examples 1-2] A nickel plating film having a thickness of 1.0 μm was formed on one surface of a polyimide resin “Kapton 300 H” manufactured by Toray DuPont by an electroless plating method.
Further, a nickel plating film having a thickness of 100 μm was formed by an electroplating method. On the polyimide resin surface of the obtained substrate, a negative photoresist "FSR-S" manufactured by Fuji Pharmaceutical Co., Ltd. was uniformly applied to a thickness of 10 μm and dried, and then a slit-shaped mask having a width of 180 μm and an interval of 70 μm was provided. Developed and dried. Thereafter, the exposed polyimide resin portion was dissolved and removed at 50 ° C. for 8 minutes using hydrazine monohydrate, and FS
RS was peeled off. The thickness 100
220 μm wide at the nickel ground plane on a nickel layer of μm
μm, spacing 30 μm, width 7 on polyimide resin surface
A base material of a shadow mask having a 75 μm thick polyimide resin layer patterned into a tapered slit having a thickness of 0 μm and an interval of 180 μm was prepared. The obtained base material was immersed in selenous acid at 25 ° C. for 2 minutes to make the nickel surface nonconductive. Thereafter, nickel electroplating was performed on the nickel layer under the following conditions and for a predetermined time shown in Table 1.

(Liquid composition) Nickel sulfamate: 400 g / L Nickel chloride: 20 g / L Boric acid: 40 g / L Sodium dodecyl sulfate: 0.5 g / L (Plating conditions) Temperature: 50 ° C. Cathode current density: 3 A / dm ² pH: 4 Then, a very weak stress was applied to the base material, whereby the shadow mask was separated from the interface with the nickel layer of the base material. After the above treatment, the surface of the electro-nickel plating film was subjected to electro-iron plating for the conditions shown below and for a predetermined time shown in Table 1.

(Liquid composition) Ferrous chloride: 400 g / L Calcium chloride: 150 g / L (Plating conditions) Temperature: 90 ° C. Cathode current density: ² Adm ² pH: 1

After that, the obtained shadow mask is heated at 450 ° C. and 30 ° C. in a mixed gas atmosphere of water vapor and carbon monoxide.
A blackening treatment was performed by applying a heat treatment for a minute to form a triiron tetroxide coating on the shadow mask surface. Table 1 shows the dimensions, appearance, and tensile strength of the obtained shadow mask. The conditions under which there is no problem in the dimensional accuracy and appearance of the shadow mask obtained from Table 1 and the tensile strength of 40 kg / mm ² or more conventionally required for the shadow mask are obtained.
It can be seen that this is the case where the thickness of the electric iron plating film is 0.1 μm or more and 10 μm or less.

In this embodiment, after the shadow mask is peeled off from the base material, electroplating is further performed on the base material, the shadow mask is peeled off, and the steps of blackening are repeated, whereby a shadow mask having the same shape as the above shape is obtained. Was accurately and stably obtained.

[0017]

[Table 1]

[0018]

According to the present invention, a fine shadow mask can be manufactured with high dimensional accuracy, has a uniform mechanical strength, is not deformed by the blackening treatment, and has excellent economic efficiency.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) C25D 1/08 311 C25D 5/26 C25D 7/00 H01J 9/14

Claims (2)

(57) [Claims] An electric metal plating is applied to an exposed metal surface by patterning an insulator of a substrate formed of a metal body and an insulator, and the formed nickel film is peeled off from the substrate. A method for producing a shadow mask, comprising forming an electric iron plating film on the front and back surfaces of the film. 2. The thickness of the electric iron plating film is 0.1 to
2. The method for manufacturing a shadow mask according to claim 1, wherein the thickness is 10 [mu] m.