JPS6026675A - Etching solution - Google Patents

Abstract

PURPOSE:To develop an etching soln. which has short etching time and has long holding time for etching power by using a soln. prepd. by mixing a concd. hydrochloric acid and a concd. nitric acid at a specific ratio for the etching soln. to be used for measuring the thickness of a magnetic recording medium formed of a thin alloy film cnsisting principally of Co and Cr. CONSTITUTION:A magnetic material for a magnetic recording medium consisting of a Co-Cr alloy is etched with solns. 2, 3, 4 prepd. by mixing a concd. hydrochloric acid (10N) and concd. nitric acid (10N) at 50:50-25:75 and the thickness of the magnetic material is measured by a stylus method in the stage of measuring the layer thickness of the Co-Cr alloy powder as the magnetic material when the Co-Cr alloy is used as said magnetic material. The mixed soln. composed of the concd. hydrochloric acid and concd. nitric acid at the above-mentioned ratio has short etching time and maintains etching power for long time without increasing the etching time even if the time elapsed after prepn. of the mixed soln. is long.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is an etching method used during the manufacturing process of recording media for recording computer disks, music, and video information by magnetic recording, and used to easily measure the thickness of metal films. It concerns solutions.

Conventional configurations and their problems Magnetic recording has made great progress in recent years, and media in the form of tapes, sheets, fixed disks, etc. are being used. Generally, magnetic powder (ferrite or iron-based metal powder) that maintains residual magnetization has been applied to a polymer film or metal nonmagnetic disk using a binder such as resin. Recently, due to the demand for higher density recording, media in which a thin metal film is directly laminated on the magnetic layer in a vacuum or the like have been used, and some Co--Ni and Co--P systems are commercially available. or,
co, l! as magnetic materials under development! A medium in which a thin film of a Cr alloy is laminated has been proposed, and due to the demand for high density, the film thickness has become 1 micron or less. In the production of media, it is necessary to accurately measure this film thickness, and stylus measurement is performed using needle contact.As for Co-Cr alloys, because of their strong weather resistance and strong acid and alkali resistance, Etching when measuring the film thickness is very time-consuming with the solution normally used, and it is difficult to obtain a clean dissolution surface, making it difficult to accurately measure the film thickness.

OBJECTS OF THE INVENTION The present invention provides a novel etching solution that allows easy etching of the film surface when using the tactile method, in order to easily and accurately measure the thickness of the C,o-Cr alloy thin film described above. With the goal.

Structure of the Invention The present invention achieves the above object, and uses concentrated hydrochloric acid (1oN).
The mixing ratio of nitric acid and concentrated nitric acid (1oN) was changed from 50% hydrochloric acid to 2
By a solution consisting of a mixture kept in the range of up to 5%
The present invention provides an etching solution that corrodes and dissolves an alloy whose main components are Co and O.

Description of Examples In order to select an acid that is highly corrosive to the Co--Cr alloy system, an etching test was conducted on the following acids and combinations. 1oN-HCl, 1N-HCl.

1oN-HNO3, 1N-HNO3, 1oN-H2SO
4゜1N H2SO2, 150″cHP O4, 1N
Na OH+HCl-HNO3 system, HCl-) (2S
o4 system, HCl-HPO4 system, HNO3-H2SO4 system. Among these tests, the one with the strongest etching effect was hydrochloric acid, especially a mixed solution of hydrochloric acid and nitric acid.

Therefore, in order to investigate the etching effect of the distribution of a mixed solution of hydrochloric acid and nitric acid, the following test was conducted. The test sample was prepared by laminating a C0-Cl alloy containing 10 to 30 weight percent Cr on a polymer film with a flat surface by RF sputtering and DC sputtering, covering a part of the film with vinyl tape or cellophane tape, and applying an etching solution. Impregnate. The melting of the Co-Cr metal surface was visually confirmed by comparing it with the large X-shaped part of the tape, and the elapsed time up to that point is shown in the figure. The vertical axis is the etching time;
The horizontal axis is the elapsed time after mixing. In the figure, 1 is hydrochloric acid:
The mixing ratio of nitric acid is 3:1 (hydrochloric acid 75 parts), below, 2 is 1:1 (50%), 3 is 1:2 (33
%), 4 has a mixing ratio of 1:3 (25 parts), and 5 has a mixing ratio of 1:4 (20%).

As is clear from the figure, the etching time of the mixture with a mixing ratio of 3:1 (1) gradually decreases as time elapses after mixing, but the etching time of the film that was etched in 1 minute or more was longer. The melting edge did not follow the tape edge and the steps on the melting surface were not sharp, so the accuracy of film thickness measurement by the contact method was poor. This mixing ratio has the disadvantage that it takes time to achieve a predetermined etching ability.

The mixture ratio of 1:1 (2) is approximately 8% after the solution is prepared.
The etching time becomes 30 seconds, and the end face of the etched film is sharply cut at this time. This solution is
It was also confirmed that sufficient etching ability was maintained even after 24 hours had passed.

For the mixture ratio 1:2 (3) and the mixture ratio 1:3 (4), the etching time was 9 minutes for 3 and 6 minutes for 4, and the etching time was 30 seconds. The dissolution edge of the film etched with the solution after 9 minutes in case No. 4 and 5 minutes after etching in case No. 4 is sharply cut.

In the case of a mixture ratio of 1:4(5), the etching time is relatively short immediately after mixing compared to other examples, but after that, the etching time remains almost unchanged even after the passage of time.1 The shortest etching time However, if it takes about 35 seconds or more than 10 minutes, the etching ability will decrease.

As mentioned above, the mixed liquid containing concentrated hydrochloric acid (1ON) and concentrated nitric acid (1oN) at a mixing ratio of 1:1 to 1:3 is C0-Or
When etching a thin alloy film, it can be melted 5 minutes after the mixture is prepared, and the melted edge has a clean step.
It is characterized by the ability to accurately measure thin films using the stylus method.

Note that the above example uses Co,! :Although the case of Or gold alloy has been described, the etching solution of the present invention can be used for Co, C
Any alloy containing r as a main component may be used, with a trace amount of Co, Cr, for example 0.1% or less, Cu, Si, AI.
, Ca, Mg.

A similar effect can be obtained even if Mn or the like is added.

Effects of the Invention In short, the present invention provides concentrated hydrochloric acid (1ON) and concentrated nitric acid (1ON).
ON) with a mixing ratio of 1:1 to 1:3.
This product provides an etching solution that corrodes and dissolves alloys whose main component is Cr.If 5 minutes have passed after preparing the mixed solution, a thin film of about 1 μm can be dissolved within 1 minute, and this effect remains for more than 1 hour. Since it lasts about one day and night, data can be collected quickly. In addition, the edge of CoCr whose cross section is made with an etching solution that can be dissolved for about 30 seconds has the effect of clearly forming a step and making it possible to accurately obtain data using the stylus method.

[Brief explanation of the drawing]

The figure shows the etching time of approximately 0.5 μm of a Co-'Cr alloy deposited on a polyester film by RF sputtering as a function of the elapsed time after solution mixing.

Claims (1)

[Claims] The mixing ratio of concentrated hydrochloric acid (1oN) and concentrated nitric acid (1oN) is
An etching solution characterized in that an alloy containing CO and Cr as main components is corroded and dissolved by a solution consisting of a mixture of hydrochloric acid kept in a range of 50% to 25%.