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New Method of Forming Low Noise, Center Tapped, Magnetoresistive Sensors

IP.com Disclosure Number: IPCOM000122566D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 3 page(s) / 141K

Publishing Venue

IBM

Related People

Denison, EV: AUTHOR [+4]

Abstract

We have found a method of design and fabrication for a ferrite substrate and closure interleaved magnetic recording head which will produce low noise MR elements with thick (Ti) magnetoresistive (MR) contact tabs which do not affect the head gap length. This use of non-Au contact tabs avoids the associated galvanic corrosion reliability problem.

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New Method of Forming Low Noise, Center Tapped, Magnetoresistive
Sensors

      We have found a method of design and fabrication for a
ferrite substrate and closure interleaved magnetic recording head
which will produce low noise MR elements with thick (Ti)
magnetoresistive (MR) contact tabs which do not affect the head gap
length. This use of non-Au contact tabs avoids the associated
galvanic corrosion reliability problem.

      Prior art usually required the use of very low conductivity
material which is very thin to contact a low noise rectangular MR
device. The contact material must be very thin because it added
directly to the head gap when a ferrite MR recording head is being
constructed. An obvious choice of metallurgy would be gold which
unfortunately forms a galvanic couple with the NiFe and will result
in corrosion of the NiFe MR sensor in the presence of moisture. Other
metallurgy solutions have higher resistivity and generally form
corrosive products. A material such as Ti has very high resistance
(i.e., 65 u ohm-cm vs. 2.3 u ohm-cm for Au); however, it is highly
corrosion resistant and does not form a galvanic cell with NiFe.

      Fig. 1(a) shows the MR pattern mask with the use of a
rectangular MR 1 which has been known to produce a lower noise MR
response from prior art. We have formed the MR element into two
separate rectangular elements to isolate the magnetic rotation
associated with the center tapped MR element. The MR legs 2 are
broken advantageously in a manner which will become clear as we
proceed in this article.

      Fig. 1(b) shows a tab mask, MR contac...