JPH10130868A - Figuring method for etching of metallic thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute a figuring which does not give rise to an etching defect by immersing a thin metallic sheet which contains Ni and is provided with resist films of prescribed patterns into a facing liquid crystal of a dilute acid soln. of a specific temp. contg. oxalic acid. SOLUTION: Before the thin metallic sheet 10 is subjected to etching, the thin metallic sheet is immersed into the figuring solution 18 housed in a facing vessel 20 and is subjected to a figuring by removing the oxidized films and residual resist films adhered to the surface to be etched. This facing liquid 18 consists of a dilute acid soln. contg. the oxalic acid and sulfuric acid which are cleaning agents and hydrogen peroxide which is a decomposing agent for casein in the resist films. The temp. of the figuring solution 18 is maintained at 10 to 25 deg.C in the figuring described above. As a result, the formation of the nickel oxalate is suppressed and the floating of the resist films is suppressed. Further, the thin metallic sheet 10 after the immersion into the figuring solution 18 is passed through a vessel 26 having sponge rolls 22 and water supply pipes 254 and is washed with water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an etching product such as a shadow mask for a color picture tube, an aperture grill for a Trinitron (registered trademark) tube, and a lead frame for a semiconductor device by using a photo-etching method. In the above, prior to the etching process, a metal thin plate having a resist film having a predetermined pattern formed on a main surface thereof, particularly a metal thin plate made of a material containing nickel, for example, an invar material which is an iron-nickel alloy containing 36% of nickel The present invention relates to a method for removing an oxide film or a resist remaining film attached to a surface to be etched from the surface to be etched.

[0002]

2. Description of the Related Art Etched products such as shadow masks and aperture grills for color picture tubes and lead frames for semiconductor devices are manufactured by processing strip-shaped metal sheets such as low-carbon aluminum-killed steel using a photo-etching method. Is done. Of the series of manufacturing processes for this etching product, the etching process is described in Japanese Patent Application Laid-Open No. 58-21203.
As disclosed in Japanese Unexamined Patent Application Publication No. 3 (Kokai) No. 3 and the like, a metal sheet is exposed before spray etching. The purpose of this surface removal is to remove the oxide film adhering to the surface to be etched of the metal thin plate after the development and hardening treatment and the very thin remaining resist film remaining to cover the surface to be etched from the surface to be etched. Done in As a method of surfacing, the metal sheet is immersed in a surfacing liquid, which is a dilute acid solution, while transporting the strip-shaped metal sheet in the longitudinal direction. The surfacing liquid contains sulfuric acid and oxalic acid as detergents and aqueous hydrogen peroxide as a decomposer for casein in the resist film. Conventionally, the liquid temperature is about 30 ° C. in order to increase the surfacing efficiency. Uses surfacing liquid.

However, in recent years, color picture tubes have tended to become larger, and as a result, a thermal deformation called a doming phenomenon (electron beam emitted from an electron gun in the color picture tube and directed toward a phosphor) has occurred. Many of them collide with the shadow mask and aperture grille as unwanted electron beams and are absorbed, causing the temperature of the shadow mask and aperture grille to rise and causing significant effects of thermal deformation caused by local thermal expansion. Therefore, there is a problem that color shift occurs on the display screen of the color picture tube. In order to solve this problem, recently, as a material for a shadow mask or an aperture grill, an iron-containing steel containing 36% of nickel has been used instead of the conventionally used aluminum killed steel.
Invar materials, which are nickel alloys and have a low coefficient of thermal expansion, have come to be used.

[0004]

However, if a metal sheet made of Invar material is subjected to surface treatment by a method similar to a conventional method, the metal sheet made of low carbon aluminum killed steel may be subjected to surface treatment. The following new problems have arisen.

[0005] Low-carbon aluminum-killed steel contains approximately 100% iron, and iron oxalate (Fe (COO) ₂ ) is produced by the reaction between the iron component of aluminum-killed steel and oxalic acid in the surfacing solution. Since iron oxalate has a relatively high solubility in water (22 mg / 100 g-cold water), most of the iron oxalate is dissolved in the exposed liquid. On the other hand, the components of Invar material
Iron is 64% and nickel is 36%, and in addition to the above-mentioned iron oxalate, nickel oxalate (Ni (COO) ₂ ) is generated by the reaction with oxalic acid in the surface laying solution. This nickel oxalate, unlike iron oxalate, is poorly soluble (0.3 mg / 100 g-
(Cold water), it precipitates on the surface of the metal sheet.

FIG. 2 is a drawing of a cross-sectional photograph of the surface portion of the metal sheet when the metal sheet made of Invar is subjected to surface treatment, and FIG. 3 is a cross-sectional photograph in which a part thereof is enlarged. FIG. 4 is a drawing of an enlarged cross-sectional photograph at an angle different from that of FIG. In this test, a pattern-like resist film was formed on a surface of a 0.1 mm-thick metal sheet (manufactured by Nippon Steel Industry Co., Ltd.) made of Invar material by a conventional method, and the surface was treated for 1 minute by a factory line apparatus. (The composition of the surface liquid is industrial water: 400
ml (97.80% by weight), 98% sulfuric acid: 160 ml
(0.06% by weight), oxalic acid: 8 kg (1.93% by weight), 35% hydrogen peroxide solution: 6 kg (0.51% by weight)
The temperature of the exposing liquid was 30 ° C.). The sample was molded with a resin, the molded product was polished to obtain a cross section, and the cross section was measured using a focused ion beam scanning device (JEOL).
(JIBL-100). 2 to 4, 1 is a thin metal plate, 2 is a resist film, 3 is a mold resin, 4 is a crack caused by shrinkage of the resin, and 5 is nickel oxalate.

As can be seen from FIGS. 2 to 4, the surface to be etched of the metal thin plate 1 is etched by about 2 to 3 μm by surface treatment, and nickel oxalate 5 is deposited on the surface to be etched. Also, the lower portion of the edge portion of the resist film 2 is slightly etched, and nickel oxalate 5 is also deposited on that portion. Then, the edge portion of the resist film 2 is pushed up from below by the raised portion of the nickel oxalate 5, and the invar material is inferior in adhesion to the resist film as compared with the aluminum-killed steel. Therefore, as shown in FIGS. The edge of the resist film 2 rises, and a gap 6 is formed between the lower part of the resist film 2 and the surface of the metal sheet 1. As a result, in the etching process after the surface exposure, the etchant also penetrates into the gap 6 and is etched to the surface of the thin metal plate 1 which should not be etched, so that the electron beam passes through the shadow mask or the aperture grill. Etching defects such as the formation of the desired through-hole in the desired shape may occur.

The present invention has been made in view of the above circumstances, and a metal sheet made of a material containing nickel, such as invar, is subjected to a surface treatment using a surface liquid containing oxalic acid. In this case, a method of controlling the deposition of nickel oxalate on the main surface of a thin metal plate to prevent the resist film from floating due to the deposition of nickel oxalate and to prevent etching defects is provided. The purpose is to do.

[0009]

The invention according to claim 1 is
The temperature of the surfacing solution, which is a dilute solution of an acid containing oxalic acid, is 1
The temperature is set in the range of 0 ° C. to 25 ° C., and the metal sheet is immersed in the surfacing liquid at the liquid temperature to perform surfacing.

According to a second aspect of the present invention, in the surfacing method according to the first aspect, the cleaning liquid is supplied to the main surface of the metal sheet after being immersed in the surfacing liquid, and adheres to the main surface of the metal sheet. It is characterized in that nickel oxalate is removed.

In the surfacing method according to the first aspect of the present invention, since the temperature of the surfacing liquid is set to 25 ° C. or less, Ni → Ni ₂₊ + 2e ₋ Ni + (COO) ₂₂₋ → Ni (COO) ₂ The progress of the reaction is suppressed, and the precipitation of nickel oxalate on the main surface of the metal sheet is suppressed. For this reason, the floating of the resist film caused by the deposition of nickel oxalate is prevented, and etching failure does not occur.

On the other hand, since the temperature of the exposing liquid is set to 10 ° C. or more, the main surface of the metal sheet is sufficiently exposed, and an oxide film and a resist remaining film adhered to the surface to be etched of the metal sheet are covered. It is sufficiently removed from the etched surface.

According to the second aspect of the present invention, a small amount of nickel oxalate precipitates on the main surface of the metal sheet during the surfacing process, and oxalic acid is deposited on the main surface of the metal sheet pulled up from the surfacing solution. Even if nickel is attached, nickel oxalate is supplied by the cleaning liquid supplied to the main surface of the metal sheet,
Before the etching step, the main surface of the metal sheet is washed away, and the metal sheet is completely etched without leaving nickel oxalate adhered to the main surface of the metal sheet.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a schematic diagram showing an example of the configuration of a surface-appearing device used to carry out the surface-appearing method according to the present invention. A metal thin plate having a resist film of a predetermined pattern formed on the main surface after development and hardening treatment in the previous process, for example, a long strip-shaped metal thin plate 10 made of Invar material and having a thickness of about 0.1 mm to 0.3 mm, , For example, 0.5 m / min
It is continuously conveyed at about 3 m / min and is carried into the surfacing device 11. Then, the metal sheet 10 is guided by the transfer rollers 12, 14, 16 into the surfacing tank 20 containing the surfacing liquid 18, and then sent out from the surfacing tank 20 to be carried to an etching chamber (not shown). It is supposed to be.

The face-out liquid 18 may have the same composition as that conventionally used. One example of the composition is as follows: 2% by weight of oxalic acid, 35% hydrogen peroxide solution. An aqueous solution consisting of 5% by weight, 98% by weight of 98% sulfuric acid and 96.5% by weight of industrial water. Then, the temperature of the surfacing liquid is adjusted to a temperature in the range of 10 ° C. to 25 ° C., preferably a temperature in the range of 18 ° C. to 22 ° C.

Further, the transport rollers 16 in the facing tank 20 are provided.
A pair of sponge rollers 22 are disposed on the front side in the transport direction of the metal sheet 10.
Are rotatably supported so as to be in contact with the main surface of the thin metal plate 10 following the transport of the sheet metal. Above each sponge roller 22, water supply pipes 24 for dropping washing water toward the peripheral surface of the sponge roller 22 are provided, respectively. The washing water is supplied from each water supply pipe 24 to each sponge roller 22. Is supplied through the respective sponge rollers 22, and the washing water is supplied uniformly over the entire both main surfaces of the thin metal plate 10. Further, below the sponge roller 22, a container 26 for receiving the liquid dripping from the sponge roller 22 is provided.

When the metal sheet 10 is exposed using such an apparatus 11, the temperature of the exposure liquid 18 is lower than in the prior art. The amount of nickel oxalate deposited on the main surface can be suppressed to be smaller than before. Even if a small amount of nickel oxalate precipitates and adheres to the main surface of the metal sheet 10 during the surfacing process, the metal sheet 1 pulled up from the surfacing liquid 18 may be removed.
In the case of No. 0, the exposing liquid adhering to both main surfaces is replaced with cleaning water via the sponge roller 22, so that nickel oxalate adhering to both main surfaces is washed away by the cleaning water. Then, the thin metal plate 10 is transported from the surface-apparatus to the next etching chamber in a state where nickel oxalate is not attached to the main surface at all.

[0019]

According to the surfacing method according to the first aspect of the present invention, a metal sheet made of a nickel-containing material such as invar material is subjected to a surfacing treatment using an oxalic acid-containing surfacing liquid. In addition, since precipitation of nickel oxalate on the main surface of the thin metal plate is suppressed, floating of the resist film due to precipitation of nickel oxalate, which has occurred conventionally, does not occur, and poor etching is prevented.

In the surfacing method according to the second aspect of the present invention, a small amount of nickel oxalate precipitates on the main surface of the metal sheet during the surfacing process, and oxalic acid is deposited on the main surface of the metal sheet pulled up from the surfacing solution. Even if nickel is adhered, the nickel oxalate is washed away from the main surface of the metal sheet, so that etching failure due to the adhesion of nickel oxalate to the main surface of the metal sheet is prevented.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a configuration of a surfacing device used to carry out a surfacing method according to the present invention.

FIG. 2 is a cross-sectional view illustrating a photograph of a cross section of a surface portion of a metal thin plate when a metal thin plate made of Invar material is subjected to a surface laying process by a conventional surface laying method.

FIG. 3 is a sectional view in which a sectional photograph in which a part of FIG. 2 is enlarged is illustrated;

FIG. 4 is a sectional view showing an enlarged sectional photograph at an angle different from that of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Metal thin plate 11 Exposure device 18 Exposure liquid 20 Exposure tank 22 Sponge roller 24 Water supply pipe

Claims (2)

[Claims] A metal thin plate made of a material containing nickel and having a main surface on which a resist film having a predetermined pattern is formed is immersed in a face-out solution that is a dilute solution of an acid containing oxalic acid to form a metal thin plate. In a method for exposing a thin metal plate to remove an oxide film or a resist remaining film attached to a surface to be etched from a surface to be etched, the temperature of the exposing liquid is set to a temperature in a range of 10 ° C to 25 ° C. A surfacing method for etching a thin metal plate, characterized in that: 2. The etching of a metal sheet according to claim 1, wherein a cleaning liquid is supplied to the main surface of the metal sheet after being immersed in the surface liquid to remove nickel oxalate adhering to the main surface of the metal sheet. Surface appearance method.