Browse Prior Art Database

High Performance Write Head for Server Applications

IP.com Disclosure Number: IPCOM000014225D
Original Publication Date: 2001-Aug-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Abstract

Today’s server class disk file application requires extremely high data rate capability which today reaches over 600 megabits per second. This requirement is most difficult to achieve in the write head design. Traditionally with magnetoresistive heads where the inductive, write transducer was built atop the read sensor, the emphasis was upon simplicity of design with a high yielding process. With the rapid growth of data rate coupled with the sustenance of over 60% per year growth in capacity per disk, designing a write head for the server application has become most challenging. In answer the industry has shifted quickly to multiple coil layer heads with ion mill, trimmed pole structures. This article describes a straightforward design for achieving high data rates, and high d.c. head efficiency, while very amenable to a high yielding, manufacturing process. The general teaching on how to design the write head for sustenance of high data rates is with multiple coil layers in order to shorten the magnetic yoke length. This in turn leads to complexity and difficulty in manufacturing. The design proposed here goes counter to that teaching by providing a highly efficient write head with a single, pancake coil layer. The distinguishing design features are: 1. Low unsaturated inductance of 30 nanohenries or less, typically, by eliminating one half of the first magnetic pole layer, and replacing it with a planarization layer of metal, typically copper. 2. Pancake, electroplated, single coil layer with pitch of 2.0 to 2.25 micrometers leading to an overall yoke length of 33 micrometers in this configuration.

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High Performance Write Head for Server Applications

  Today's server class disk file application requires extremely high data rate capability which today reaches over 600 megabits per second. This requirement is most difficult to achieve in the write head design. Traditionally with magnetoresistive heads where the inductive, write transducer was built atop the read sensor, the emphasis was upon simplicity of design with a high yielding process. With the rapid growth of data rate coupled with the sustenance of over 60% per year growth in capacity per disk, designing a write head for the server application has become most challenging. In answer the industry has shifted quickly to multiple coil layer heads with ion mill, trimmed pole structures. This article describes a straightforward design for achieving high data rates, and high d.c. head efficiency, while very amenable to a high yielding, manufacturing process.

  The general teaching on how to design the write head for sustenance of high data rates is with multiple coil layers in order to shorten the magnetic yoke length. This in turn leads to complexity and difficulty in manufacturing. The design proposed here goes counter to that teaching by providing a highly efficient write head with a single, pancake coil layer. The distinguishing design features are:

  1. Low unsaturated inductance of 30 nanohenries or less, typically, by eliminating one half of the first magnetic pole layer, and replacing it with a planarizatio...