JP2741312B2 - Method of manufacturing aluminum substrate for magnetic disk - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum substrate for a magnetic disk, and more particularly to an improvement in a Ni-P plating process.

[0002]

2. Description of the Related Art Aluminum (including an aluminum alloy, the same applies hereinafter) substrate for a magnetic disk is used as a blank material by punching a rolled material into a donut shape.
This is surface-finished by turning or grinding to form a substrate, which is further subjected to electroless Ni-P plating, and polished to obtain a ground-treated product.

In the electroless Ni-P plating step in the magnetic disk substrate manufacturing step, as shown in FIG. 1, a plurality of magnetic disk substrates 1 are arranged at equal intervals (for example, 10 mm pitch) on a shaft suspending jig 2. This is immersed in a plating solution for plating. In such a plating process, a plating film thickness is different between a side adjacent to the substrate and a side where the plating solution is opened, particularly in a substrate where the flow direction of the plating solution is disposed at both ends, and the side where the plating solution is opened is adjacent to the substrate. Thicker than the side. As a result, a difference in film stress occurs, and the flatness of the substrates at both ends is deteriorated. In particular, with recent thinning of the substrate (from 1.27 t to 0.8 t), distortion of the substrate is likely to occur.

SUMMARY OF THE INVENTION The present invention relates to an aluminum for a magnetic disk capable of preventing the flatness of a substrate at both ends of a suspending jig from being deteriorated during electroless Ni-P plating and improving the yield of the electroless Ni-P plating process. An object of the present invention is to provide a method for manufacturing a substrate.

According to the method of the present invention, when an aluminum substrate for a magnetic disk is subjected to base electroless Ni-P plating, electroless N is applied to both ends of a plurality of substrates arranged at equal intervals by a suspending jig.
It is preferable that a dummy substrate made of a glass substrate or a stainless steel substrate which is difficult to be subjected to i-P plating and formed to have substantially the same inner and outer diameters as the magnetic disk substrate is disposed at equal intervals with the magnetic disk substrate on a hanging jig and subjected to plating. The present invention has solved the above-mentioned problem.

FIG. 2 shows an example in which the present invention is implemented. In FIG. 2, reference numeral 1 denotes a magnetic disk substrate and 2 denotes a shaft suspension jig, as in FIG. In such an arrangement, a dummy substrate 3 made of a glass substrate, a stainless steel substrate or the like is disposed at both ends of the hanging jig 2.

The dummy substrate 3 is stable to strong acids and strong alkalis, stable in a high-temperature plating solution at 100 ° C., hardly provided with an electroless Ni—P plating film, and made of a nonconductor. Can be used repeatedly for plating
Alternatively, it is preferably inexpensive, and from this point, a glass substrate or a stainless steel substrate can be particularly preferably applied as described above. The inner and outer diameters of the dummy substrate 3 are substantially the same as the magnetic disk substrate as shown in FIG.

As shown in FIG. 2, when dummy substrates 3 are arranged at both ends of a shaft suspension jig and subjected to electroless Ni-P plating, plating is performed on the open side of the dummy substrate 3 and on the adjacent side of the magnetic disk substrate 1. Even if there is a difference in the flow of the liquid and, as a result, a difference in the plating film thickness on both sides of the dummy substrate 3, the dummy substrate 3 does not become a product and does not pose any problem. This dummy substrate 3 can be used repeatedly.

[0009]

According to the present invention as described above, the flatness defects which have occurred on the magnetic disk substrates disposed at both ends of the shaft suspension jig are eliminated, the yield is improved, and the electroless Ni-
P plating can be performed.

[0010]

EXAMPLE A5052 was used as an aluminum disk material.
A 3.5-inch donut-shaped substrate made of -H ₃₄ (thickness 0.8 t) as shown in FIG. 2, a 10mm pitch by using 25 pieces cassette type containers, hanging Shi 50 sheets at one shaft As a conventional example, a case where all the substrates are magnetic disk substrates 1 and a case where four dummy substrates 3 made of glass substrates are arranged at both ends of the shaft according to the present invention,
The substrate after the electroless Ni-P plating treatment was inspected. As a result, in the case of the conventional method, all of the four magnetic disk substrates 1 disposed at both ends became poor in flatness, and the yield was 92%. When the dummy substrates were arranged at both ends, there was no flatness defect of the magnetic disk substrate 1.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a case where an electroless Ni—P plating process is performed by a conventional method.

FIG. 2 is an explanatory diagram showing an example of a case where an electroless Ni—P plating process is performed by the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic disk board 2 Shaft suspension jig 3 Dummy board

Claims (1)

(57) [Claims] When an aluminum substrate for a magnetic disk is subjected to electroless Ni-P plating on a base, a glass substrate or a glass substrate which is difficult to have electroless Ni-P plating on both ends of a plurality of substrates arranged at equal intervals by a suspending jig. Manufacturing a dummy substrate made of a stainless steel substrate and having the same inner and outer diameters as that of the magnetic disk substrate, arranged on a hanging jig at equal intervals to the magnetic disk substrate and plated. Method.