JPS6016010B2 - Manufacturing method of high recording density magnetic disk - Google Patents

Description

Detailed Description of the Invention The present invention provides a high recording density magnetic disk with excellent mechanical dimensional accuracy and stability of magnetic properties when manufacturing a high recording density magnetic disk using a magnetic plated film as a recording medium. The present invention relates to a method of manufacturing a disc.

The most promising high-density magnetic disk is a so-called plated disk.

As shown in the figure, this plated disk is made by forming a pretreatment layer 2 on a magnetic disk material 1 (in this case, an AI material), then forming a strike plating layer 3 on this, and further forming a base plating layer on top of this. A layer 4 was formed, this base plating layer was subjected to rough processing and finishing to make it smooth, a magnetic plating layer 5 was formed thereon, and a protective film 6 was formed on this. It is something. Co is currently used as the magnetic plating layer.
-Ni alloy coatings and Co-Ni-P alloy coatings are often used. In addition, the properties required for the protective film include head crush resistance against collision between the head and the disk;
If the head is of the Contact Staple Stop (CSS) type, CSS resistance, corrosion resistance to protect the plating medium from moisture, gas, etc., defect-free property, smoothness, etc. are required.

A protective film satisfying these required properties can be obtained by heating at about 300 oo. However, this heat-fitted disk has a disadvantage in that the flatness, smoothness, and corner-perfectness of the surface of the disk are reduced. That is, the warpage of the disk increases and the straightness of the disk increases. The surface roughness also deteriorates, causing undulations, bulges, and protrusions. As a result, the flatness and smoothness achieved on the base plated surface was impaired, resulting in the problem that the surface of the plated disk could not meet the target mechanical specifications. In addition to the above problems, the reproducibility of the magnetic properties of the magnetic plated layer may be poor. The magnetic properties are controlled by the magnetic plating conditions (plating composition, current density, temperature, etc.), but there is also the influence of the substrate. The crystal structure and composition of the base metal affect the structure and composition of the nutritious plating layer, thereby changing the magnetic properties. In the conventional technology, the influence of this base is large, and it is difficult to control. The reproducibility and stability of the magnetic properties obtained were poor due to the inability to conduct a magnetic field. The purpose of the present invention is to solve the above-mentioned problems in manufacturing high-density magnetic disks using a magnetic plated layer as a recording medium, and to provide a plated disk surface that is highly flat and smooth, and in addition, the surface of the plated disk is highly flat and smooth. An object of the present invention is to provide a method for manufacturing a high recording density magnetic disk with stable magnetic properties and excellent reproducibility. In order to achieve the above object, the inventor investigated various methods of manufacturing high-density magnetic disks, and found that
Strike plating is applied to the magnetic disk material, then base plating is applied to this, then this is rough processed, the rough processed material is finished, and then the finished material is given rock-like plating. In a method for producing a high-density magnetic disk, which consists of a step of coating the magnetic disk, then heating it to form a protective film, if the heat treatment is performed at a temperature higher than the heating temperature at which the protective film is formed between the base plating step and the finishing step. I saw and brought out good things.

This heat treatment stabilizes the base plating layer, increases the adhesion of the pre-treatment layer, and relieves the internal stress of the base plating layer, making it difficult for surface roughness, blistering, warping, etc. to occur, resulting in a highly flat and smooth surface. It is possible to obtain a magnetic disk with a high recording density. In addition, since the structure of the base plating layer is stabilized by heat treatment, the influence of the base on the magnetic plating layer is stabilized, and the reproducibility of magnetic properties is improved.

The present invention will be explained below with reference to Examples. Super zincate solution (Nippon Kagaku Kizai K.
A zinc-substituted film was formed using the following method.

Next, five copper strike platings were formed to improve adhesion, and then three copper-tin alloy platings were formed as a base plating. Next, heat treatment was performed. The heat treatment conditions are as follows. Heat treatment conditions Temperature...320qo (heating 10q0/min, cooling 2
C/min) Holding time: 6 and 1 Method: This heat treatment was carried out in air while applying a load (40k9), and then the base plated surface was polished.

Next, a magnetic plating layer of Co--Ni--P alloy was formed as a medium to a thickness of 0.1 mm, and a special polymeric protective film was formed thereon. Thereafter, an air heat treatment of 300 qo was performed to strengthen the magnetic plating layer and the protective film. Finally, when we measured the electrical characteristics, we found that the output and resolution were improved over the previous model, and the envelope (uniformity of output within the plane) was also improved. And target record characteristics 15 00 fertilizer P1,5
I was able to achieve 00TPI. The heat treatment temperature after base plating was determined based on the following experimental results.

The table shows the results of observing the effect of heat treatment temperature on surface roughness and amount of warpage change. For samples that are not heat treated before top processing, such as the sample in 1 in the table, the surface roughness is 0.
．． The target value (below 0.04 French m) cannot be satisfied because the value becomes 0.078 French mRmax. In addition, in sample 1, the warp of the disk changed significantly by 32 degrees after the finishing process and the heat treatment in the final process, and did not satisfy the target value (5r or less). However, as shown in 2.3 and 4 in the table, as the heat treatment temperature is increased, the changes in surface roughness and warpage become smaller, and at heat treatment temperatures of 300° C. or higher, the target values are satisfied. The magnetic reluctance (Hc) of the magnetic plating layer varies within the disk surface due to the influence of the underlying layer. Target value 1,000 12 melons
On the other hand, in sample 2 in the table, the variation width is large, but as the heat treatment temperature increases, the variation width becomes smaller and the target value is achieved and stabilized, and the reproducibility is improved. From these facts, it can be seen that when the heat treatment temperature in the final step is 30 to 0, the heat treatment temperature performed after base plating must be 300°C or higher. Effects of Heat Treatment Temperature As stated above, it has been revealed that the present invention has the following effects.

1. The magnetic disk surface is highly smoothed.

2. The magnetic disk surface is highly flattened.

3. Since defects will not occur in the surface treatment applied to the magnetic disk material, the production yield will be improved.

4. The magnetic properties of the magnetic plating layer are stabilized and reproducibility is improved.

[Brief explanation of the drawing]

The figure shows a cross section of a high recording density magnetic disk. 1... Magnetic disk material, 2... Pretreatment layer, 3... Strike plating layer, 4... Base plating layer, 5... Magnetic plating Layer 6...Protective film.

Claims (1)

[Claims] 1. A first step of pre-treating the magnetic disk material for strike plating, a second step of applying strike plating to the magnetic disk material pre-treated in the first step, and a second step of pre-treating the magnetic disk material for strike plating.
A third step of applying base plating to the magnetic disk material that has been subjected to strike plating in the process, a fourth step of performing rough processing to the magnetic disk material that has been subjected to base plating in the third step, and The fifth step is to apply finishing to the material that has been rough processed in the fourth step, and the sixth step is to apply magnetic plating to the magnetic disk material that has been finished in the fifth step. A method for manufacturing a high recording density magnetic disk comprising a seventh step of forming a protective film on a magnetic disk material subjected to magnetic plating, a third step of applying base plating and a fifth step of performing finishing processing. A method for manufacturing a high recording density magnetic disk, characterized in that heat treatment is performed at a temperature higher than the heating temperature for forming a protective film in the seventh step.