JPH0434721A - Method for recovering hard disk board - 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 method for reclaiming a hard disk substrate, which involves removing a coating layer formed on the substrate and reclaiming the hard disk substrate.

[Summary of the invention]

The present invention provides a hard disk in which a magnetic layer and a protective film layer are sequentially formed on a substrate with an underlayer interposed therebetween, by lapping the removed surface after removing the magnetic layer and protective film layer. It is possible to reliably remove residual elements of
The aim is to improve the yield of recycled products.

[Prior Art] For example, disc-shaped magnetic disks that can be randomly accessed are widely used as storage media in computers, etc. Among them, substrates are used because of their excellent responsiveness and large storage capacity. In recent years, magnetic disks made of hard materials such as A1 alloy plates, glass plates, plastic plates, etc., so-called hard disks, have come to be used as fixed disks or external disks.

The above-mentioned hard disk has, for example, an N1-P plating layer or an alumite treatment layer formed on an A1 alloy substrate for magnetic disks, a magnetic layer involved in recording and reproduction, and a protective film layer that protects the magnetic layer. A carbon film layer is sequentially deposited by sputtering, and if necessary, a lubricant layer for improving the running properties of the magnetic disk is formed thereon by a technique such as spin coating. This hard disk rotates at high speed in the circumferential direction to record and reproduce information on a large number of concentric tracks.

By the way, in the above-mentioned hard disks, defective hard disks with peeling or cracking of the magnetic layer due to poor sputtering or the like, non-standard hard disks, or used hard disks are often recycled. In order to reproduce a hard disk, it is necessary to remove the above-mentioned lubricant layer, carbon coating layer, and magnetic layer that are involved in recording and reproduction, and then expose the underlayer such as the N1-P plating coating layer or the alumite treatment layer again.

An example of this method is to remove the lubricant layer, the highly hard carbon coating layer, and the magnetic layer using a chemical reaction with aqua regia, and then polish the removed surface. In the polishing process, a slurry-like polishing liquid made by mixing abrasive with water or oil, etc. is liquefied, and the polishing liquid is supplied to the substrate sandwiched between upper and lower surface plates with flat surfaces.
This is a processing method in which the required amount of machining allowance is removed from the substrate with an abrasive cutting edge using the rotational movement of the upper and lower surface plates while applying processing pressure.

The reason why the removed surface from which the magnetic layer and the like have been removed is then polished is because the presence of residual elements on the removed surface adversely affects the magnetic properties after film formation and reduces reliability. Therefore, it is necessary to reliably remove the elements remaining on the removed surface by polishing the removed surface.

[Problems to be Solved by the Invention] However, in the above-mentioned polishing process, it is necessary to wrap a considerable amount of approximately 3 μm to completely remove the elements remaining on the removed surface, so lapping takes time. Since large-scale recycling is not possible, and a considerable amount of polishing liquid is required for the second processing, the cost of the polishing liquid increases, and it is not possible to reduce the cost of recycling the substrate.

Furthermore, polishing processing equipment is difficult to automate due to its mechanical structure and requires manual operation, which inevitably increases costs for recycling substrates. Even if the equipment were automated, it would be impossible to obtain productivity commensurate with the cost of automation.

Therefore, the present invention has been proposed in view of the above-mentioned conventional situation, and it is possible to reliably remove residual elements on the removed surface, and to regenerate high-quality hard disk substrates without deterioration of magnetic properties with a high yield. Another object of the present invention is to provide a method for reproducing a hard disk substrate, which has a simple structure and can be regenerated automatically.

[Means for solving problems]

The method for reproducing a hard disk substrate of the present invention includes the above-mentioned m
This method was proposed to solve the problem of e.g., for a hard disk in which a magnetic layer and a protective film layer are sequentially formed on a substrate via an underlayer, after removing the magnetic layer and protective film layer, It is characterized by wrapping the surface.

[Function] In the present invention, after removing the highly hard protective film layer and magnetic layer, the removed surface is lapped, so that the elements remaining on the removed surface are reliably removed. Therefore, after wrapping,
If a magnetic layer or the like is formed on the removed surface to form a hard disk, the magnetic properties will not deteriorate due to residual elements.

Further, in the present invention, since the process is performed by wrapping, automation is desired, and a large amount of substrates can be recycled without any cost.

〔Example〕

Hereinafter, a specific example of a method for reproducing a hard disk substrate to which the present invention is applied will be described in the order of its steps.

First, the lubricant layer, protective 111JI layer, and magnetic layer of a hard disk that is out of specification or defective is removed.

To the hard disk to play! A conventionally known method is one in which a base layer such as an N1-P coating layer or an alumite treatment layer, a magnetic layer, a protective film layer, and a lubricant layer are sequentially laminated on a substrate made of alloy, Al-Mg alloy, etc., or glass. In this example, a hard disk having a diameter of 5.25 inches was used, in which an N1-P plating film, a Co-Cr film, a carbon film, and a lubricant layer were sequentially laminated on an aluminum substrate.

These lubricant layers, protective film layers, and magnetic layers can be removed using, for example, an inorganic acid solution or a solution containing an organic substance added to an inorganic acid, or an ion etching method that removes these films by oxidizing them at a low temperature. A plasma ashing method, which is a type of method, can be adopted. Note that in consideration of cost, a method using an inorganic acid solution is more desirable than a plasma ashing method.

Examples of inorganic acids include phosphoric acid, sulfuric acid, and nitric acid.

Examples include hydrochloric acid, chromic anhydride, pyrophosphoric acid, aqua regia, and the like. In this example, the hard disk described above was immersed for 10 minutes in an inorganic acid solution consisting of water and aqua regia, where the aqua regia accounted for 20% of the entire solution.

As a result, an electrochemical reaction (ii. depolishing) occurred between the hard disk and the inorganic acid solution, and the lubricating sublayer, protective film layer, and magnetic layer of the hard disk were removed, and the underlying layer formed on the substrate was exposed. . Note that it was observed that some Cr element remained on the removed surface at this time.

Next, the removed surface from which the above-mentioned coating layer was removed, that is, the exposed surface of the base layer, is lapped, and the carbon remaining on the surface of the base layer is lapped.
Remove r element.

As shown in Fig. 1, wrapping is carried out by rotating a hard disk substrate (2) with a center hole (1) clamped in the direction of the arrow in the figure, and rolling a cylindrical roll (3) which also rotates in the direction of the arrow in the figure. Wrapping tape (5
) is pressed against the surface (base layer surface) of the hard disk substrate (2).

The roll (3) is a cylindrical hard rubber roll attached to a rotating shaft (4) driven by a motor or the like, and has a length that can cover at least the area that requires wrapping.For example, The roll length l of the roll (3) is defined as l≧(ψ2−ψ
, )/2 is satisfied.

On the other hand, as the lapping tape (5), a tape such as sand vapor or the like is used, in which abrasive grains are fixed to a sheet-like base. Here is the roughing tape (5
) is the same as the length l of the previous roll (3), W≧
The relationship (φ2−ψ1)/2 is satisfied. In addition, the roughening tape (5) is designed to ensure the removal of elements remaining on the surface of the underlayer of the hard disk substrate (2) and ensure the surface roughness of the underlayer before forming the magnetic layer. In this example, the surface roughness of the underlayer surface before the magnetic layer is formed is defined as the centerline surface roughness Ra.
To make the particle size about 8.5 to 11.5 nm, the particle size is #3000.
A lapping tape of WA abrasive grains (white fused alumina abrasive grains) of ~#4000 was used. In addition, when the wrapping tape with the above particle size is used, the processing time is set to 30 seconds to 60 seconds in order to satisfy the above surface roughness.

In this example, a wrapping tape (5) made of WA abrasive grains with a grain size of #3000 is wrapped around the circumferential surface of a roll (3) and run at a speed of 500 m/min.
was rotated at a rotational speed of 300 rpm and wrapped for 30 seconds. During this lapping, pressure P1P2 is applied to the rotary wheel (4) that rotates the roll (3), and the hard disk base is removed. Wrapping tape (5) was pressed onto the surface of (2).

In addition, the pressure at this time is the hard disk substrate (2)
P+-0.8kg on the inner peripheral edge side, P2-1. on the outer side.
The weight was 2 kg.

As a result, the underlayer of the hard disk substrate (2) was lapped, and the Cr element remaining in the previous step was reliably removed. Actually, when the surface of the underlayer of the hard disk substrate (2) was observed, residual elements were not removed.

Then, the surface roughness of the underlayer of the hard disk substrate (2) was confirmed using a Talystep surface roughness meter, and the surface roughness was found to be 9.8 to 11 nm in Ra. Therefore, by reproducing a node λ-node disk through the above-described steps, the hard disk substrate can be regenerated to such an extent that a magnetic layer can be immediately formed. Also, the rap fee at this time was relatively small with 500 to 600 people.
Therefore, a reduction in processing time can be expected.

Although one embodiment of the method for reproducing a node disk substrate to which the present invention is applied has been described above, the present invention is not limited to the above-described embodiment and can be modified in various ways.

For example, in the above embodiment, after removing the magnetic layer, etc., the removed surface of the node disk substrate was wrapped with a wrapping tape. may be brought into direct contact with the removed surface of the hard disk substrate.

Alternatively, the lapping tape may be removed and the rubber roll itself brought into direct contact with the removed surface of the node disk substrate, and a polishing liquid containing a slurry of free abrasive grains may be dropped onto the substrate before lapping. .

[Effects of the Invention] As is clear from the above explanation, in the method of the present invention, after removing the hard magnetic layer, protective film layer, etc., the removed surface is wrapped, so that the removal of the magnetic layer, etc. Elements that remain on the removed surface afterward can be reliably removed. Furthermore, by lapping the underlayer so that it has a predetermined surface roughness, it is possible to reproduce the state between the hard disk substrate and the track before forming the magnetic layer.

Therefore, by sequentially forming a magnetic layer, a protective film layer, a lubricant layer, etc. on a recycled hard disk substrate, a highly reliable hard disk without deterioration in magnetic properties can be obtained.

Further, in the method of the present invention, residual elements are removed by lapping, so the apparatus configuration is extremely simple and automation can be easily performed. Therefore, according to the method of the present invention, a large number of hard disk substrates can be recycled in a short period of time with a high yield.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of the loading device used in this example, and FIG. 2 is a partially cutaway front view showing how the rolls are arranged with respect to the node disk substrate. . 2... Hard disk substrate 3... Roll 5... Wrapping tape

Claims (1)

[Claims] A hard disk substrate in which a magnetic layer and a protective film layer are sequentially formed on a substrate with an underlayer interposed therebetween, the removed surface being wrapped after the magnetic layer and protective film layer are removed. How to play.