JPH0620270A - Production of aluminum board for magnetic disc - Google Patents

Abstract

PURPOSE:To increase yield by arranging glass boards at the opposite ends of boards arranged at same intervals by means of a suspender when the board is subjected to underlying electroless Ni-P plating. CONSTITUTION:When an aluminum board 1 for magnetic disc is subjected to underlying electrless Ni-P plating, dummy boards 3 comprising glass boards are arranged at the opposite ends of a shaft at predetermined pitches through the use of a cassette container. Since the boards 3 are arranged at the opposite ends of a shaft suspender 2, flatness of the board 1 is enhanced. Since the board 3 is a nonconductor stable against strong acid, strong alkali, and high temperature plating liquid, it can be used repeatedly resulting in high yield plating.

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 improvements in the Ni-P plating process.

[0002]

2. Description of the Related Art Aluminum (including aluminum alloys, the same applies below) substrates for magnetic disks are blanked by punching a rolled material into a donut shape.
The surface of this is finished by turning or grinding to obtain a substrate, which is further electroless Ni-P plated and polished to obtain a substrate-treated product.

In the electroless Ni-P plating process in these magnetic disk substrate manufacturing processes, as shown in FIG. 1, a plurality of magnetic disk substrates 1 are arranged on a shaft suspension jig 2 at equal intervals (for example, 10 mm pitch). Then, this is immersed in a plating solution for plating treatment. In such a plating process, in a substrate in which the flow of the plating solution is particularly arranged at both ends, the plating film thickness differs between the substrate adjacent side and the plating solution open side, and the plating solution open side 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 deteriorates. In particular, as the thickness of the substrate has recently been reduced (from 1.27 t to 0.8 t), the strain of the substrate is likely to occur.

The present invention prevents the flatness of the substrate from deteriorating at both ends of the hanging jig during the electroless Ni-P plating treatment and improves the yield of the electroless Ni-P plating treatment step. It is an object to provide a method for manufacturing a substrate.

[0005]

According to the method of the present invention, when an aluminum substrate for a magnetic disk is plated with an electroless Ni-P underlayer, a glass substrate is provided on both ends of a plurality of substrates arranged at equal intervals by a hanging jig. Alternatively, it is characterized by disposing a stainless steel substrate, which solves the above problems.

FIG. 2 shows an example in which the present invention is carried out. In FIG. 2, 1 is a magnetic disk substrate and 2 is a shaft hanging jig, which is similar to FIG. In such an arrangement, dummy substrates 3 made of a glass substrate, a stainless steel substrate, or the like are arranged at both ends of the hanging jig 2.

The dummy substrate 3 is stable to a strong acid and a strong alkali, stable in a high temperature plating solution at 100 ° C., is hard to be coated with an electroless Ni-P plating film, and is made of a non-conductor. That can be used repeatedly for plating
Alternatively, it is preferably inexpensive, and from this point, a glass substrate or a stainless steel substrate is particularly preferably applicable as described above. The thickness and dimensions of the dummy substrate 3 need not be the same as those of the magnetic disk substrate 1,
It can be set arbitrarily.

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

[0009]

As described above, according to the present invention, the flatness defects that have occurred in the magnetic disk substrates arranged at both ends of the shaft suspension jig are eliminated, the yield is good, and the electroless Ni-
P plating process can be performed.

[0010]

EXAMPLES A5052 as an aluminum disc material
As shown in FIG. 2, a 3.5-inch doughnut-shaped substrate (thickness: 0.8 t) made of -H _{34 is set} to 10 mm pitch using a cassette type container containing 25 pieces, and 50 pieces are hung by one shaft. As a conventional example, when all the substrates are magnetic disk substrates 1, and when 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, the four magnetic disk substrates 1 arranged at both ends all had poor flatness and the yield was 92%. When the dummy substrates were arranged on both ends, the magnetic disk substrate 1 had no flatness defect.

[Brief description of 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 of performing electroless Ni—P plating according to the method of the present invention.

[Explanation of symbols]

 1 magnetic disk substrate 2 shaft hanging jig 3 dummy substrate

Claims (1)

[Claims] 1. A glass substrate or a stainless steel substrate is arranged at both ends of a plurality of substrates arranged at equal intervals by a hanging jig when an underlayer electroless Ni-P plating is performed on an aluminum substrate for a magnetic disk. Method for manufacturing aluminum substrate for magnetic disk.