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Method to Control Stress in Laminated Soft Magnetic Films and Structures

IP.com Disclosure Number: IPCOM000110093D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 80K

Publishing Venue

IBM

Related People

Jahnes, C: AUTHOR [+5]

Abstract

A method to control stress in soft magnetic laminated materials is disclosed. It is significant because balancing stress and magnetostriction is critical to obtain thin film recording heads with acceptable stability and performance for magnetic storage systems.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Method to Control Stress in Laminated Soft Magnetic Films and Structures

       A method to control stress in soft magnetic laminated
materials is disclosed.  It is significant because balancing stress
and magnetostriction is critical to obtain thin film recording heads
with acceptable stability and performance for magnetic storage
systems.

      A key to obtaining magnetic thin film heads with acceptable
stability and performance is balancing two factors (1) magnetic film
stress and (2) magnetostriction (gs) in such a manner as to produce a
magnetic domain structure in the head which is conducive to the
efficient propagation of magnetic flux in and out of the head.  The
relationship between film stress and gs is such that if compressive
stress is present, then positive gs is desirable and, conversely, if
tensile stress is present, then negative gs is desirable.  In
producing heads with monolithic magnetic layers, such as plated
permalloy thin film heads, the composition is adjusted to have
slightly negative &ms. because the plating process produces films
which have tensile stress.  On the other hand if the same type of
head is produced by sputtering, the permalloy films would most likely
have compressive stress and a positive gs would be required.

      It has been shown that there are certain performance
advantages, especially at high data rates, which may result from
making inductive heads in which the soft magnetic material is
laminated with dielectric layers (1-3).  A key issue in using these
laminated materials in heads is control of stress to insure
sufficient adhesion to various substrate materials to tolerate the
many processing steps required in the thin film head fabrication
process.

      We have discovered that if the type of dielectric layer used in
the laminated material is varied the stress in that laminated
material may also be controllably varied without any adverse effect
on the magnet...