Method of plating on a glass base plate, a disk substrate, method for manufacturing the same and a perpendicular magnetic recording medium

Abstract

A method of plating on a glass base plate is disclosed. The method allows a plating film to be formed on a base plate composed of a glass material with excellent adhesivity and homogeneity by means of an electroless plating method, even to a thickness of 1 mum or more. Before forming the plating film by electroless plating, a series of surface treatments are conducted on the surface of the base plate composed of a glass material. The surface treatments comprises at least a glass activation treatment, a silane coupling agent treatment, a palladium catalyst treatment, a palladium bonding treatment, ab electroless plating to form a preliminary plating film having a thickness in the range of 0.02 mum to 0.5 mum, and an annealing at a temperature in the range of 200 DEG C. to 350 DEG C.

Description

technical field [0001] The present invention relates to a method for coating a substrate made of a glass material, a method for manufacturing a magnetic disk substrate for a perpendicular magnetic recording medium using the coating method, a magnetic disk substrate for a perpendicular magnetic recording medium manufactured by the manufacturing method, and using the coating method. The perpendicular magnetic recording medium of the magnetic disk substrate is especially suitable for the perpendicular magnetic recording medium mounted in the hard disk device. Background technique [0002] In recent years, hard disk devices are widely used as storage devices for computers, digital home appliances, and the like. A magnetic disk (hard disk) as a magnetic recording medium mounted in this hard disk device is usually formed on the surface of a disk-shaped non-magnetic substrate by using an electroless plating method in the case of a longitudinal magnetic recording system (longitudina...

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Problems solved by technology

[0036] However, using the above-mentioned known electroless plating before and after treatment methods, the electroless plating method is used to form a Co-Ni-P film on a glass substrate, Ni-P, Ni-Fe-P, Co-Ni-Fe -In the case of a soft magnetic film such as P or a nonmagnetic film such as Ni-P, a sufficient film thickness (film thickness of 1 μm to 3 μm) for obtaining a good magnetic disk and sufficient adhesion at this film thickness cannot be satisfied. , uniformity and smoothness

[0037] That is, according to the research of the inventors, it can be known that: on the glass substrate, silane coupling agent treatment (for example, immersion in 3-aminopropylethoxysilane aqueous solution), Pd catalytic treatment (for example, immersion in chlorinated palladium solution), etc., in the case of the method of forming a coating film by the electroless plating method, when the bonding force at the interface between the glass substrate and the silane coupling agent layer is weak, due to the film stress in the coating reaction, it will occur during the deposition of the coating layer. Film blistering, or even if film blistering is not achieved, adhesion failures such as end film peeling or slight film peeling may sometimes occur in the subsequent polishing process

[0038] In order to improve poor adhesion, there is a method of etching the surface of the glass substrate by acid treatment to increase the surface roughness, but increasing the surface roughness further improves the recording density of the magnetic recording medium, so from the recording and reproduction characteristics From a point of view, it is not preferred

[0039] On the other hand, there is also a method of forming a bottom layer such as Ni-P by sputtering. However, generally, it is difficult to directly form a bottom layer film on a glass substrate due to poor adhesion between glass and metal. A layer containing Ti or Cr, which has relatively good adhesion to glass among metals, is formed on the substrate as an adhesion layer, and an underlying film is formed on it

In this method, the adhesion between Ti or Cr as the adhesive layer and the glass is not good enough. When the film thickness of the bottom layer or the adhesive layer increases, there will be adhesion due to the stress caused by the difference in expansion coefficient. The problem of sexual decline

In addition, as mentioned above, in the perpendicular magnetic recording medium that has been actively developed in recent years, a relatively thick layer with a film thickness of 0.2 μm to 3.0 μm is required as a soft magnetic backing layer. Reduced performance becomes a problem, and there is also a problem of rising costs

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