JPH101778A - Zinc displacement treatment solution and zinc displacement treatment method - Google Patents

Abstract

(57) Abstract: A zinc-substituted treatment liquid characterized by mixing one or more amines with a zinc-substituted treatment liquid containing a zinc compound and an alkali hydroxide. [Effect] By using the zinc substitution treatment liquid of the present invention, plating unevenness of the subsequent electroless Ni-P film is eliminated, and the surface of the film after the polishing treatment is much smoother than before.
This can contribute to a higher density hard disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc substitution treatment liquid which is suitably used particularly for pretreatment of electroless nickel plating on an aluminum or aluminum alloy substrate for a hard disk, and a zinc substitution treatment using the zinc substitution treatment liquid. About the method.

[0002]

2. Description of the Related Art Conventionally, in the production of a hard disk, an electroless nickel-phosphorous alloy using hypophosphorous acid or a salt thereof as a reducing agent is formed on the surface of a substrate made of aluminum or an aluminum alloy. A plating film (hereinafter, referred to as an electroless Ni-P film) is formed. In this case, the substrate is subjected to zinc substitution before the Ni-P film is formed, and the surface of the substrate is substituted with zinc. It is necessary to form a film.

[0003] Conventionally, a zinc-substituted treatment solution containing a zinc compound and an alkali hydroxide as main components has been used. However, when a zinc-substitution treatment is performed using such a conventional zinc-substitution treatment solution, A thick portion and a thin portion of the zinc-substituted film are generated, and appear as an uneven pattern (hereinafter, referred to as zinc-substituted unevenness). In the electroless Ni-P film after the zinc substitution treatment, a pattern having the same shape as the zinc substitution irregularity appears (hereinafter, referred to as plating irregularity), and the portion is an aggregate of nodules. Such portions may remain as fine projections (20 to 50 nm) even after the subsequent polishing step, and such fine projections are becoming a problem as the density of the hard disk increases.

[0004] Therefore, it is desired to prevent plating unevenness that occurs when an electroless Ni-P film is formed on an aluminum or aluminum alloy substrate, that is, to prevent zinc substitution unevenness that causes plating unevenness. I was

[0005] The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a zinc substitution treatment liquid and a zinc substitution treatment method which are unlikely to cause the above-described zinc substitution unevenness or plating unevenness.

[0006]

Means for Solving the Problems and Embodiments of the Invention The present inventors have made intensive studies to achieve the above object, and as a result, have found that a zinc-substituted treatment solution containing a zinc compound and an alkali hydroxide as main components. On the other hand, by adding amines such as ethylenediamine and triethanolamine, the occurrence of uneven zinc substitution is significantly suppressed, and furthermore, electroless Ni-P
The present inventors have found that when plating is performed, a uniform film without plating unevenness is formed, and the present invention has been accomplished.

[0007] Accordingly, the present invention provides a method for treating a zinc-substituted solution containing a zinc compound and an alkali hydroxide, wherein one or two of amines are contained.
Kind Code: A1 Provided are a zinc substitution treatment solution containing at least one or more species, and a zinc substitution treatment method characterized by immersing an aluminum or aluminum alloy substrate in the zinc substitution treatment solution to form a zinc substitution film.

Hereinafter, the present invention will be described in more detail. The zinc-substituted treating solution of the present invention contains a zinc compound and an alkali hydroxide.

Here, examples of the zinc compound include zinc oxide, zinc nitrate, zinc chloride, zinc sulfate, zinc acetate, and the like.
One or two or more of these are used. Its content is 0.02-0.6 mol / L as zinc, particularly 0.05-0.6 mol / L.
It is preferably 0.4 mol / L.

Examples of the alkali hydroxide include sodium hydroxide and potassium hydroxide. Of these, sodium hydroxide is preferable, and the compounding amount is preferably 1 to 8 mol / L, more preferably 2 to 5 mol / L. L.

The zinc-substituted solution of the present invention further comprises one or more amines, whereby the zinc-substitute unevenness is suppressed, and the uniform and uniform electroless Ni-
A P film can be formed.

In this case, the amines include ethylenediamine, diaminopropane, diaminobutane, N, N,
N, N-tetramethyldiaminomethane, dimethylethylenediamine, diethylenetriamine, 3,3-iminobispropylamine, triethylenetetramine, N, N-
Bis (3-aminopropyl) ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, N-methylhydroxyamine, N, N-diethylhydroxyamine, 3-amino-1-propanol,
N-methylethanolamine and the like.
Species can be used alone or in combination of two or more. Among them, ethylenediamine and triethanolamine are preferable.

The compounding amount is 0.007 to 0.7 mol /
L, particularly preferably 0.02 to 0.4 mol / L, and if the amount is less than 0.007 mol / L, electroless N
Uneven plating remains on the i-P film, and if it exceeds 0.7 mol / L, the entire substrate surface may become white.

The zinc-substituted solution of the present invention may contain, if necessary, one or more of soluble iron, nickel and copper salts in an amount of 0.001 to 0.3 mol / L, sodium tartrate, rossel salt and the like. Of the complexing agent of 0.003 to 0.3 mol / L.

An appropriate component such as pyrocatechol or hydroquinone can be further added to the zinc-substituted treatment liquid according to the present invention, thereby forming an electroless Ni-P film having more excellent uniformity and gloss. be able to.

The conditions for performing the zinc substitution using the zinc substitution treatment solution of the present invention are not particularly limited, but may be from 10 to 40.
It is preferable to carry out at a temperature of 10 ° C., and if it is lower than 10 ° C., the adhesion to the subsequent electroless Ni—P film is reduced, and if it is higher than 40 ° C., the surface of the aluminum or aluminum alloy substrate may be roughened.

Incidentally, the zinc substitution treatment can be carried out twice or more as necessary. In particular, in the production of a hard disk, it is preferable to carry out the zinc substitution treatment two or more times. In this case, the operation can be repeated in accordance with the conventional method. After zinc replacement, washing with water and immersion in an aqueous nitric acid solution may be performed, and zinc replacement may be performed again.

The zinc-substituted substrate of the present invention can be subjected to various plating methods to form a plating film thereon. In this case, either of electroplating and electroless plating may be used. It is particularly suitable when a hard disk is manufactured by forming an electroless Ni-P plating film thereon. The electroless Ni-P plating solution may have a known composition, and plating may be performed under known conditions.

[0019]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

A zinc substitution treatment solution having the following composition (Example 1,
2, Comparative Example), the aluminum substrate was degreased and etched according to a conventional method, and was immersed in a 30% nitric acid aqueous solution at 25 ° C. and 30 ° C.
After immersion for 2 seconds, a zinc substitution treatment is performed, and further immersion in a 30% nitric acid aqueous solution at 25 ° C. for 60 seconds, zinc substitution treatment is performed again, and then electroless Ni—P plating is performed to a thickness of 15 μm.
m of electroless Ni-P plating film was formed.

In this case, the conditions for the primary and secondary zinc substitution treatments were both 25 ° C. and 30 seconds. [Example 1] Sodium hydroxide 3.0 mol / L Zinc oxide 0.25 mol / L Rossel salt 0.25 mol / L Ferric chloride 0.01 mol / L Sodium nitrate 0.01 mol / L Ethylenediamine 0 .20 mol / L pyrocatechol 0.10 mol / L

Example 2 Sodium hydroxide 4.0 mol / L Zinc oxide 0.30 mol / L Rossel salt 0.50 mol / L Ferric chloride 0.02 mol / L Sodium nitrate 0.01 mol / L L Triethanolamine 0.10 mol / L Hydroquinone 0.10 mol / L

COMPARATIVE EXAMPLE Sodium hydroxide 3.0 mol / L Zinc oxide 0.25 mol / L Rossel salt 0.25 mol / L Ferric chloride 0.01 mol / L Sodium nitrate 0.01 mol / L

Electroless Ni-P plating composition and plating conditions Nickel sulfate 0.1 mol / L Sodium malate 0.2 mol / L Sodium acetate 0.2 mol / L Sodium hypophosphite 0.2 mol / L Nitric acid Lead 1.0ppm pH 4.7 Plating temperature 90 ℃

Next, the appearance of the obtained electroless Ni-P plating film was evaluated, and the presence or absence of uneven plating was examined. As a result, no plating unevenness was observed when the zinc-substituted solutions of Examples 1 and 2 were used. However, when the zinc-substituted solution of the comparative example was used, plating unevenness occurred. It was confirmed that the addition of amines such as ethylenediamine, triethanolamine and the like eliminated uneven plating of the electroless Ni-P film and provided a uniform surface. Plating unevenness Example 1 None Example 2 None Comparative example Available

[0026]

By using the zinc-substituted solution of the present invention, the subsequent plating unevenness of the electroless Ni-P film is eliminated, and the surface of the film after the polishing treatment is much smoother than before, and the It can contribute to high density.

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mika Fukutani 1-5-1, Hirakata-shi, Osaka Pref.

Claims (2)

[Claims] 1. A zinc-substituted solution comprising a zinc-substituted solution containing a zinc compound and an alkali hydroxide mixed with one or more amines. 2. A zinc substitution treatment method comprising immersing an aluminum or aluminum alloy substrate in the zinc substitution treatment liquid according to claim 1 to form a zinc substitution film on the substrate surface.