Measurement of Surface Features of Hard Disk Media and Heads

By AZoNano Editors

Table of Contents

Measuring Hard Disk Media
     Introduction
     Metrology
          Textured Landing Zone
          Outside Diameter Defects
          Surface Defects
          Monitoring Media Roughness
Measuring Hard Disk Heads
     Introduction
     Metrology
          Flying Head Height
          Pole Tip Recession
Taylor Hobson

Measuring Hard Disk Media

Introduction

Advancements in hard disk drive technology are increasing the boundaries of media production. With increasing data densities and the anticipation of lower numbers of errors by users, there is a requirement for sophisticated metrology to survey and determine the media surface. Taylor Hobson provides products that are designed specifically to meet high-quality demands. A large field of view and a one million pixel camera provide in-depth analysis of the media surface. Automatic characterization of the media roughness, media surface defects, edge defects, and landing zone laser textures are possible on both aluminum and glass substrates.

Metrology

Textured Landing Zone

Hard disk drives need a textured landing zone that allows the heads to be parked on the media surface when they are not being used. This is achieved by utilizing a laser texturing procedure that can be monitored by using Talysurf CCI devices. Automatic characterization includes the mean diameter, density, height, and volume of whole or individual regions of texturing.

Outside Diameter Defects

Edge defects are mostly referred to as outside diameter defects. These occur due to the problems in media handling. Even a small impact on the edge of the media results in deformation of the media surface, which in turn can generate data errors.

Surface Defects

Surface defects comprise of a variety of errors that are caused in the recorded data because of some form of peak or pit on the media surface. The defects occur due to contact damage, inclusions, and delamination. The Talysurf CCI unit identifies these defects, even at the sub-nanometer scale vertically.

Monitoring Media Roughness

Monitoring the media roughness is critical since it is a key limiting factor on the head’s fly height. Decreasing the media roughness enables a reduced fly height and delivers smaller magnetic spacing, which is needed to sustain high data densities.

Measuring Hard Disk Heads

Introduction

Advancements in hard disk technology have propelled the demand for very high tolerances on the sliders. Controlling the sliders’ shape to a high tolerance enable them to be closer to the disk surface. This decreases the magnetic spacing, thereby allowing higher data density.

Metrology

Flying Head Height

Flying head height plays a crucial role in restricting the hard disk drive’s data storage density. This is substantially affected by the small curvature of the air bearing surface (ABS), which is present on the side of the slider. This increases the requirement to restrict the ABS curvature to the nanometer level. The sliders can be altered and the curvature can be brought within tolerance by measuring the twist, cross curve, and crown parameters. The Talysurf CCI 9150’s large field of view and the 1 million pixel camera corrects dissimilar material errors, making it suitable for flatness measurement.

Pole Tip Recession

The slider’s pole tip recession (PTR) region is a crucial metrology application in the hard disk sector. Each year, features of the PTR have been decreasing in size and have been requiring high manufacturing tolerances. Measurement repeatability, vertical resolution, number of measurement points, and lateral resolution are vital for pole tip recession.

Taylor Hobson

Taylor Hobson is an ultra-precision technology company operating at the highest levels of accuracy within the field of surface and form metrology. They provide contact and non-contact measurement solutions to the most demanding applications on a global basis, with a worldwide infrastructure to support our clients, wherever they may be.

This information has been sourced, reviewed and adapted from materials provided by Taylor Hobson.

For more information on this source, please visit Taylor Hobson.

Date Added: Apr 8, 2011 | Updated: Jun 18, 2013
Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit