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Fine Surface Finish for Magnetic Disk

IP.com Disclosure Number: IPCOM000084122D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Kirkman, DH: AUTHOR [+2]

Abstract

A disk substrate is described which is suitable for thin magnetic film deposition. The disk substrate consists of a glass or metallic base laminated with plastics overlay. The plastics overlay is "polished" by using a heated, highly polished platen to give a superfine finish.

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Fine Surface Finish for Magnetic Disk

A disk substrate is described which is suitable for thin magnetic film deposition. The disk substrate consists of a glass or metallic base laminated with plastics overlay. The plastics overlay is "polished" by using a heated, highly polished platen to give a superfine finish.

Present methods employ very complex mechanical polishing. The superfinish is required due to the low-flight height of floating magnetic heads and to reduce surface defects to obtain uniform magnetic properties.

Example: An aluminium alloy base is prepared with a semifinished surface having no protrusion or scratch greater than 5 microns. An overlay consisting of a polyimide film of thickness 0.005'' to 0.0025'' is laminated on to the base using an adhesive. A laminating temperature of 150 degrees C and a pressure of 150 psi are used.

After curing, the substrate is "polished" by contact with a highly polished stainless steel platen at a temperature of 200 - 250 degrees C and a pressure of 200 - 300 psi. This causes the polyimide to flow and take the surface finish off the platen.

The substrate is cooled under platen pressure to below 35 degrees C when the platen is removed. The disk substrate having a superfinished surface may then receive a thin magnetic film deposited by an evaporation or plating technique.

An alternative to a metallic base is a glass base, but for all base materials the semifinished surface should be treated to give maximum adhesion.

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