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Low-Inductance, Low-Resistance, Write Head for High Data Rate Application

IP.com Disclosure Number: IPCOM000116025D
Original Publication Date: 1995-Jul-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 98K

Publishing Venue

IBM

Related People

Anderson, NC: AUTHOR

Abstract

A design of a low inductance/low resistance thin film write head for high data rate applications is described.

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Low-Inductance, Low-Resistance, Write Head for High Data Rate Application

      A design of a low inductance/low resistance thin film write
head for high data rate applications is described.

      The trend in Direct Access Storage Device (DASD) areal density,
Bits Per Inch (BPI) times Tracks Per Inch (TPI), requires achieving,
in products, about 1 Gb/in2 by mid 1995, 2 Gb/in2 in late 1996 to
early 1997, and 5 Gb/in 2 in early 1998.  The trend in media data
rate shows applications of these areal densities requiring about 20,
35, and 50 MB/sec respectively in the same timeframes.

      The conventional "pancake" coil thin film head in use today has
several flaws that will limit its high-speed writing capability.
One, the extraneous volume occupied by the portion of the coil that
does not contribute to the write function (or the read for that
matter), contributes half or more of the inductance of the structure.
As data rates increase, it will be necessary to significantly reduce
the inductance of the write head to maintain a risetime commensurate
with the frequencies in use.  Two, this same extraneous volume
contributes to reduced write efficiency for the structure relative to
a solenoid winding.

      The inductance is a function of N*2, reducing N to reduce the
inductance of the conventional coil, while it would contribute to
improved risetime, would also require an increase in Iw (write
current)
to a level probably unacceptable for small low power DASD devices.

      To meet the recording performance requirements of the future, a
significant structural change in...