JPS6112875A - Electroless plating bath - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plating bath for producing a magnetic recording medium (magnetic film) used in a magnetic recording medium such as a magnetic disk.

[Conventional technology]

2. Description of the Related Art In recent years, magnetic disks in which magnetic recording media are formed by plating have begun to be used as high-density magnetic recording materials.

However, in conventional electroless plating baths f for forming magnetic recording media, citrate, tartrate rR salt, malonate, birophosphate, etc. are used as complexing agents. The problem with the accumulating bath is that the nickel ions added to adjust the magnetic properties make the bath extremely unstable, and bath decomposition is likely to occur.

Furthermore, in order to change the magnetic properties of the magnetic film formed by electroless plating, it is necessary to change the plating conditions such as the pT1 bath temperature, and these operations promote bath decomposition of the plating bath. [Objective of the Invention] The object of the present invention is to improve the problems of the conventional plating bath as described above and to improve the performance of the plating bath. si! enables stable production of magnetic recording media with magnetic properties. The purpose is to provide a relaxing bath.

[Structure of the invention]

The gist of the present invention is that the electroless polishing bath contains cobalt ions,
An electroless method characterized in that an aqueous solution containing nickel ions, a reducing agent for these metal ions, a pH buffer, and a pH adjuster has seven diglycolic acid groups or citraconic acid groups as a complexing agent for the ions. Exists in plating bath. This diglycolic acid group or citraconic acid group and free metal ions in the plating bath form a lead body, which prevents metal ions in the plating solution from changing into floating substances such as nickel hydroxide and prevents them from decomposing in the bath. Prevention, plating bath becomes feminine.

Cobalt ions and nickel ions used as metal ions in the present invention are supplied by dissolving soluble salts of cobalt and nickel such as sulfates, hydrochlorides, and acetates in an electroless plating bath.

Cobalt ion once is usually 0.002~/m o 1
/t range is used, preferably 0.0/t.
~0. /'! It is in the range of mO1/L. The concentration of nickel ions is usually in the range Q~θJmO1/l, but preferably O1θθko~0.0/m01/l.
The range is 1.

Hypophosphites are commonly used as reducing agents, but borohydrides of human disine salts and the like can also be used.

Ammonium salts and ash salts are used as pH buffers.

Organic acid salts are used, usually 0°O/~2 mol/
A fineness in the range of l is used.

As a pH adjuster, an alkali such as ammonia or sodium hydroxide is used to increase bp'', and an acid such as phosphoric acid or hydrochloric acid is used to decrease p'II.

Diglycol lJ groups as complexing agents are provided by diglycolic acid or soluble salts of diglycolic acid, and concentrations in the range o,i-coj mol/L are usually used. In the case of a citraconic acid group, citraconic acid or a soluble salt of citraconic acid is used. The present invention is not limited to the following examples.

Example/ An Oo-Ni-P film was formed on a polyimide film substrate for attaching manufactured by Bunshishi (1) under the following plating bath composition and plating conditions.

Plating bath composition 4A Cobalt acid: 0-Ot mo1/l-Nickel sulfate: 0.0 da Sodium hypophosphite 20, -0 Ammonium sulfate 20, j O Diglycolic acid: 0. ! 0 Plating conditions pH of plating bath: ? A (pH adjusted with NH and OH at room temperature) Temperature of plating bath: ♂O℃ Plating time: Depending on film thickness / j seconds to 10 minutes Magnetic properties of the cobalt-nickel-phosphorus film thus obtained Rounded vibrating sample play magnetometer (VBM-
The measurement results obtained by JB') are shown in the following table.

As the film thickness increased, the coercive force decreased from lS 00θ to 2OOθ. As the film thickness increases, the squareness ratio becomes θ,!
6 to 0. ．． It decreased to 2/.

The stability of plating γi was extremely good, with no floating matter and no precipitates.

A cobalt-nickel-phosphorous film was plated in the same manner as Hiyoka/Execution row/, but the plating bath had the following composition: □ Plating bath composition Cobalt sulfate: 0.06m01/L nickel sulfate
20, θg Sodium hypophosphite 20-2 Ammonium sulfate 20,! Sodium tartrate 20! Plating was discontinued because bath decomposition occurred shortly after plating started. Plating has started again! After a few minutes, a film with a thickness of 3 μm was obtained, and the magnetic properties were evaluated as t-value.

Coercive force (0θ): /30 Saturation magnetization (emu/cc): t Decocagonal ratio
20. Co-Ni was applied to Koda using the following plating bath composition and plating conditions.
-p film was formed.

Plating bath composition Cobalt sulfate = θθ6m01/L Nickel sulfate: OO4 is replaced with sodium hypophosphite 20・λθ Ammonium sulfate: O, jθ Citraconic acid 20, SO Plating conditions Plating bath pH: TA・O (N residual at room temperature) (pH adjusted with OH) Plating bath temperature: ro℃ Plating time: Depending on the film thickness! min to λθ min To clarify the magnetic properties of the cobalt-nickel-phosphorus film thus obtained, a vibrating sample magnetometer (Toei Kogyo HVSM-is) was used.
) is used to apply a magnetic field of l0KOθ in the in-plane direction, and the measurement results are shown in the following table.

Although the film thickness was changed to / ~ da μm, the coercive force was 1i4
It had a constant value of too θ and had a high coercive force.

The stability of the plating bath was extremely good with no floating matter or precipitate formation.

Comparative Example A cobalt-nickel-phosphorous film was plated in the same manner as in Example, but the following composition was used as the plating bath.

Plating bath composition Cobalt sulfate: 0.06 mob/L Nickel sulfate: o, o4, sodium hypophosphite 20, - Ammonium sulfate: OJ Sodium tartrate: 0. ! Approximately 2 minutes after the start of plating, bath decomposition occurred, so plating was stopped. Plating has started again! After a few minutes, a film with a thickness of 3 μm was obtained, so the magnetic properties were evaluated.

Coercive force (0θ) = /3° Saturation magnetization (emu7cc): 420 square ratio
:0.2g [Effects of the Invention] According to the present invention, a magnetic film having cobalt ions, nickel ions, a reducing agent for these metal ions, a pH value, and good magnetic properties can be obtained.

Candidate Mitsubishi Chemical Industries, Ltd. Agent Patent Attorney Hase - (7 people)

Claims (1)

[Claims] (1) An aqueous solution containing cobalt ions, nickel ions, a reducing agent for these metal ions, a pH buffer, and a pH adjuster contains a diglycolic acid group or a citraconic acid group as a complexing agent for the metal ions. Characteristic electroless plating bath.