JPS607708B2 - Etching method for metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an etching method that can prevent side etching and efficiently form barrier holes when forming holes in a metal plate using photolithography.

There are various methods for providing openings in a metal plate, one of which is an etching method using photolithography.

This method will be explained below by taking as an example the case where a checkpoint is provided in a shadow mask. That is, as shown in FIG. 1, the shadow mask has a single metal plate 1 with mask holes 2 formed in a predetermined arrangement, and the mask holes 2 have different diameters on both sides of the metal plate 1. Drilling such a mask hole 2 is normally performed as follows. As shown in FIG. 2, a photocurable resin is applied to both sides of a flat metal plate 1 and dried to form a photoresist film l1 having a constant thickness. Next, a negative original plate 1 having a negative image of a hole with a large diameter on one side of the metal plate 1 is provided.
2 and a negative original plate 13 having a negative image of a hole with a small diameter on the other side are arranged in close contact with each other by adjusting the pitch.
It is then exposed to light to print the negative hole image onto the photosensitive film. Then, the exposed uncured resin of the photoresist film is developed and dissolved away to expose the mask hole perforations 14 and 15 of the metal plate 1. Furthermore, in order to prevent uneven drying, alcohol or the like is used to make the amount of water distributed evenly on the metal slope. Thereafter, the photoresist film is heat-treated, and then an etching solution is sprayed onto the exposed portions 14 and 15 of the metal plate to form holes 16 in the metal plate 1. Providing barrier holes on a metal plate by a chemical method is best from the viewpoint of quality stability and mass production, and this method is often used. When forming barrier holes by etching in this way, the problems are the etching resistance of the photoresist film and the amount of side etching, but for the former, commercially available photocuring resin is used, and high temperature heat treatment after development is optimal. This can be almost satisfied if the conditions are met.

However, there are various problems regarding the latter, that is, side etching. In the etching step for forming an opening, the etching progresses and becomes more severe as the etching depth increases, and at the end of the etching, a hole larger than the desired diameter is formed. (Figure 2 C
). For this reason, when producing a negative master plate, it is necessary to take into account the amount of increase in pore height due to side etching, but it is important to consider the material and thickness of the metal plate used, the concentration and temperature of the etching solution, etc.
Since the amount of side etching varies depending on the spraying conditions, etc., it cannot be adjusted using only the negative master plate, and it is therefore very difficult to obtain holes with a desired diameter over the entire surface of the shadow mask. This variation in the amount of side etching leads to non-uniformity in the hole diameter of the shadow mask, which is a major cause of deterioration in the quality of the shadow mask.Furthermore, as shadow masks with smaller hole diameters have been desired in recent years, the amount of side etching has become even more important. reduction is becoming an important issue. For this reason, various methods have been considered to prevent side etching, including the giraffe blood method, which involves repeatedly applying giraffe blood to the etched side surface during etching, and the use of certain aromatic hydrocarbons in the etching solution. There are methods to form a film that prevents corrosion by adding etching, etc., but the former has poor accuracy and the shape of the line and takes too much time, making it unsuitable for mass production. It takes a long etching time to form, and it is difficult to maintain the amount of additives in the etching solution at a constant level, which causes variations, and both methods have the drawback that a shadow mask with large variations in pore diameter is obtained.

The present invention has been made in consideration of these points, and provides an etching method for forming holes in a metal plate such as a shadow mask while preventing side etching. In other words, a photoresist film that is electrochemically active against corrosion.
Side etching is prevented by inactivating the boundary surface of the metal plate, especially the area where the etching solution, photoresist film, and metal plate coexist, which is the starting point when side etching progresses. As such a means, a corrosion inhibitor is interposed in the photoresist layer. This invention will be further explained below.

As a means of interposing a corrosion inhibitor in the photosensitive film layer, there is a method of adding a certain amount of the corrosion inhibitor to the photocurable resin in advance, but this method depends on the type and concentration of the corrosion inhibitor added. This is undesirable since there is a risk of causing the photoresist film to deteriorate and cause a defective coating of the photoresist film, or a risk of lowering the sensitivity of the resin to light and causing peeling of the photoresist film during development. In this invention, a certain amount of a corrosion inhibitor is added to a water draining agent used for so-called water draining to uniformize the amount of water distribution on the metal plate after completion of development. By doing so, the corrosion inhibitor can be penetrated into the photoresist film layer, and the desired purpose can be achieved without any influence on other processes. When processed by the method of this invention, the surface of the photoresist film that has come into contact with the etching solution is dissolved during the etching process after draining, and the corrosion inhibitor contained therein causes a slow exchange rate of the etching solution. layer·
A protective film of a corrosion inhibitor is formed on the metal plate coexistence area (20 in FIG. 3) to make it inactive against corrosion.

As a result, etching progresses at the interface between the photoresist film layer and the metal plate.
Koku becomes. In the depth direction of the metal plate, even if a protective film of a corrosion inhibitor is formed, it will be destroyed by the mechanical impact of the spray, so the side etching prevention effect of the protective film is weak and there is no problem. An example of the perforation state obtained by the method described above is shown in FIG.
As the hole 22, a hole 23 is provided which has a nearly one-to-one correspondence with the negative original.

Examples of the present invention will be described below.

Add methylamine to alcohol as a draining agent from 0.01 to 0.01
A solution added in a range of 1% is used and applied to the exposed metal plate at the mask hole punched area after hot water development.

Thereafter, etching is performed according to a predetermined process. At this time, methylamine reacts with the ferric chloride solution in the etching solution, and a protective film consisting of a kind of insoluble compound represented by (CH3NH3)・Fec〆40nQO coexists with the etching solution, photoresist layer, and metal plate. It will be formed in the area. Therefore, the above-mentioned coexistence region becomes inactive, and the effect of preventing side etching is exhibited, and the conventional side etching to the metal plate under the photoresist film, that is, the penetration of etching, is almost eliminated, and it is almost 1:1 with the negative master. A shadow mask having well-corresponding openings is obtained. Even if trimethylamine is added in addition to methylamine, ((CH3)3NH) is obtained in the same way as above.
An insoluble compound having an FeC4.n ratio of 0 is generated, and side etching can be prevented in the same way as described above.

In addition to the above, corrosion inhibitors that may be added include amine and aldehyde organic compounds, acetylene alcohols such as propargyl alcohol, sulfur organic compounds such as B-thiodiglycol, arsenic compounds such as potassium arsenate, and potassium antimonate. The same effect as above can be obtained by using a drainage agent containing an antimony compound such as . The above description describes a method for forming holes in a shadow mask for a color picture tube, but the present invention is not limited to this, and can be applied as an etching method for forming holes in metal plates used as tube parts, semiconductor device parts, etc. Of course it can be done.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the hole in the shadow mask, and FIG. 2 is a cross-sectional view showing the process order of forming the hole in the shadow mask.
FIG. 3 is a cross-sectional view of a portion of a shadow mask having barrier holes formed according to the present invention. 1... Metal plate, 20... Etching solution/photosensitive film layer/
Metal plate coexistence part, 23...Sekihole. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. When forming openings in a metal plate by etching, a photoresist film is formed on the metal plate, exposed and developed, and before the film is dried, a solution is applied to the metal plate. A method for etching a metal plate, characterized in that a corrosion inhibitor is added to the solution in order to maintain a constant water distribution amount on the metal plate. 2 As corrosion inhibitors, amine and aldehyde organic compounds, acetylene alcohols, sulfur organic compounds,
2. The method of etching a metal plate according to claim 1, wherein at least one of an antimony compound and an arsenic compound is used.