Browse Prior Art Database

Method for Laser Surface Modification of Magnetic Glass Disks

IP.com Disclosure Number: IPCOM000010641D
Original Publication Date: 2002-Dec-31
Included in the Prior Art Database: 2002-Dec-31
Document File: 3 page(s) / 200K

Publishing Venue

IBM

Abstract

This publication briefly describes a process for laser surface modification of finished magnetic glass disk by creating bumps with "rippled" surface profile.

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Method for Laser Surface Modification of Magnetic Glass Disks

Laser texture process of NiP-coated AlMg substrates using near-IR laser based systems has been widely used in hard disk drive industry. We have shown that the geometry of laser produced micro size bumps (height, shape, and diameter), on the commonly used AlMg substrates, is governed by laser parameters, i.e., laser spot size, pulse duration, and pulse energy.

We have also previously shown that the near-IR based laser systems can be employed to produce micro size bumps with smooth "dome-shape" or "quasi-dome-shape" on finished (sputtered) magnetic glass disks with given layered magnetic structures. We showed that the bump shape and geometry is governed by laser parameters, and that the height of bumps can be controlled by laser power, or pulse energy, for such applications as laser zone texturing, laser bump for glide calibration, and laser marking.

This publication briefly describes a process for laser surface modification of finished magnetic glass disk by creating bumps with "rippled" surface profile.

This process utilizes a near-IR laser-based texturing tool to deliver focused, pulsed laser energy from a Q-switched laser system (such as Nd:Vanadate, or Nd:YLF, or Nd:YAG). Absorption of the laser energy by the layered structure, and the consequent increase of surface temperature would result in localized modification of surface topography at the exposed area. In general, the effect of laser exposure on a finished magnetic disks (lubed or unlubed) depends not only on the laser parameters (i.e., laser spot size, pulse energy, and pulse duration), but also on the material structure of the layered sputtered magnetic coating. Structure of layered magnetic coating and laser parameters can be chosen so that to produce bumps with smooth dome-shape or with irregular rippled profile at the laser-exposed spot.

Figure-1 shows the image of few bumps (about 3-micron diameter) with rippled structure produced by pulsed Nd:Vanadate laser on a sputtered magnetic glass disks.

A bump with rippled-surface profile scatters more light than a bump, of comparable size, with smooth dome-shape profile. Therefore,...