JP2943259B2 - Metal plate etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a method for etching a metal plate.

[Prior art]

2. Description of the Related Art Color filters for liquid crystal displays are currently being actively manufactured by printing techniques such as concave plate offset printing. In order to manufacture a filter by a printing method in this way, a printing plate in which a number of fine stripe-shaped image grooves are repeatedly formed is necessary, and these image grooves are currently engraved mainly by an etching method. .

[Problems to be solved by the invention]

When the resist 2 is left and formed in a desired pattern on the surface of the metal plate 1, for example, when the window-shaped exposed portion 11 is etched to form the image groove 12, the metal plate 1 is brought into contact with the etching solution. Since it is etched vertically, the etching proceeds simultaneously in the width direction along with the etching in the thickness direction,
The etching extends to the lower side covered by the resist 2. Therefore, as the etching progresses, the image grooves 12
Are widened and, for this reason, are formed shallower on both sides. It is difficult to print and form a high-precision image from the image groove having such a shape, and ink unevenness occurs in the width direction, so that only a color filter having high and low density can be manufactured. There was a problem. For this reason, there has been a strong demand for the development of an etching method capable of engraving an image groove as small as possible in width and as uniform as possible in depth.

[Means for Solving the Problems]

The present invention has been made in order to solve the above-mentioned problems of the prior art, and a ferric chloride solution having a concentration exceeding 47 ° Be ′ is applied to the surface of a metal plate on which a resist remains in a pattern.
An object of the present invention is to provide a method for etching a metal plate, which comprises spraying from a distance shorter than 15 cm at a temperature exceeding 60 ° C. and a pressure exceeding ² kgf / cm ² .

[Action]

In the etching method of the present invention, the etching solution is sprayed at a high concentration and a high temperature from a short distance and at a high pressure as compared with the conventional etching method, so that the etching proceeds more in the thickness direction than in the width direction. For this reason, the image groove does not expand so much in the width direction and is formed deep in the plate thickness direction.

[Examples and Comparative Examples]

Next, the present invention will be described in detail with reference to comparative examples. A stainless steel plate having a thickness of 100 μm is used as the metal plate 1, and an appropriate resist (for example, casein) 2 is coated on one surface of the stainless steel plate.
A uniform coating with a thickness of 10 μm is exposed by a mask using a conventionally known photolithography technique.
By removing to a width of μm, a window-shaped exposed portion 11 was formed at the center of the metal plate 1. The metal plate 1 was placed horizontally with the window-shaped exposed portion 11 facing upward, and a ferrous chloride solution 3 of an etching solution was sprayed from above under the conditions shown in Table 1 to spray the window-shaped metal plate 1. Exposed part 11
The shape of the image groove 12 having a depth of 50 μm, which was engraved corresponding to FIG. The superiority of the etching condition is not determined by comparing the depth and width of the image groove alone, but by the window-like exposed portion 11 as shown in FIG.
Is W ₁ , the depth of the actually engraved image groove 12 is D, and the width is
When the W _2, determine the etch factor EF defined by the following equation, and compares this value as a parameter.
As can be seen from the definition, the larger the etch factor EF, the more preferable from the viewpoint of processing accuracy. As is clear from FIG. 1 showing the comparison results, the experiment numbers 15 and 16 of the present invention were different from those of the other experiment numbers in terms of the etch factor EF.
taller than. Therefore, it can be seen that the etching progressed more effectively in the depth direction than in the width direction. This is the cross-sectional shape of the object groove 12 engraved by Experiment No. 16 (Fig. 2a).
And the cross-sectional shape of the object groove 12 obtained by Experiment No. 1 (No.
It is clear from the comparison of FIG. 2b). As described above, according to the etching method of the present invention, the image groove 12 having the same depth as the conventional one is obtained.
Also, when forming, since the increase in groove width is small, if the window-shaped exposed portion 11 is formed in advance to an appropriate width, since it does not greatly expand from this width, it is possible to improve the accuracy of the groove width. I can do it. Also, compared to the prior art, both sides of the image groove 12 have been largely eliminated in the degree of shallowness, so when used for printing such as a color filter, the width accuracy is high, and in the width direction. An image with stable shading is easily formed. Since the present invention is not limited to the above-described embodiment, the metal plate 1 may be made of brass, nickel, iron / nickel alloy, stainless steel such as SUS-304, cupro nickel, or the like, in addition to the copper plate. As long as the resist 2 can expose only a portion to be etched with desired accuracy, the material and the like are not limited, and the shape, size, number, and the like to be exposed are also limited. Not something. In addition, as for the method of spraying the ferric chloride liquid, any method may be used as long as the method can spray the exposed surface of the metal plate 1 at a uniform pressure.

【The invention's effect】

As described above, in the method of etching a metal plate of the present invention in which the etching solution is sprayed at a high concentration and a high temperature from a short distance and at a high pressure as compared with the conventional etching method, the etching proceeds more largely in the thickness direction than in the width direction. Therefore, the object groove does not expand so much in the width direction and is formed deep in the plate thickness direction.
Therefore, since the image groove having a shape in which both sides are almost not shallow is formed with high precision, this is an extremely effective etching method for manufacturing a printing plate such as a color filter for a liquid crystal display.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the experimental results of the embodiment of the present invention and a comparative example, FIGS. 2a and 2b are diagrams showing the cross-sectional shapes of image grooves according to experiment numbers 16 and 1, respectively, and FIG. FIG. 4 is an explanatory diagram showing the outline, and FIG. 4 is an explanatory diagram showing an example of shape measurement. DESCRIPTION OF SYMBOLS 1 ... Metal plate 11 ... Window-like exposed part 12 ... Image groove 2 ... Resist 3 ... Ferric chloride liquid

Claims (1)

(57) [Claims] 1. A ferric chloride solution having a concentration exceeding 47 ° Be 'is applied to the surface of a metal plate on which a resist is left in a pattern.
A method for etching a metal plate, which comprises spraying from a distance shorter than 15 cm at a temperature exceeding ℃ and a pressure exceeding ² kgf / cm ² .