Shorted magnetoresistive head elements for electrical overstress and electrostatic discharge protection

• US 5,491,605 A
• Filed: 12/23/1994
• Issued: 02/13/1996
• Est. Priority Date: 12/23/1994
• Status: Expired due to Term

• Current Assignee: HGST Netherlands B.V. (Western Digital Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Phipps, Peter B. P., Hughbanks, Timothy S., Lee, Hin Pong E., Wallash, Albert J., Robertson, Neil L.
• Primary Examiner(s): WOLFF, JOHN H
• Application Number:
  US08/363,460
• Time in Patent Office: 417 Days
• Field of Search: 360/113, 360/104, 360/126, 360/128
• US Class Current: 360/323
• CPC Class Codes: G11B 5/11 Shielding of head against electric or magnetic fields
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: G11B 5/3967 Composite structural arrangements of transducers, e.g. inductive write and magnetoresistive read G11B5/3906 takes precedence
• CPC Class Codes: G11B 5/40 Protective measures on heads, e.g. against excessive temperature G11B5/31 takes precedence; protection against wear G11B5/255 ; protective structure of the head: see under structures, e.g. G11B5/3106

Abstract

In a magnetic read/write transducer, the elements of the magnetoresistive (MR) and inductive heads are shorted together and to the slider substrate to provide a low resistance, conductive path bypassing the MR sensor element and minimizing electrical current through the MR sensor element during discharge of static electric charge. The MR sensor element, the MR conductive leads, the MR magnetic shield elements and inductive pole tips exposed at the slider air bearing surface are shorted together and to the slider substrate by a layer of conductive material, such as tungsten, formed over the slider air bearing surface. The conductive layer shorts the head elements together and to the slider substrate thus protecting the head against ESD/EOS damage during subsequent handling and assembly. The conductive layer is removed by wet etching prior to placing the magnetic head into operation in a magnetic storage system.

Claims

1. A method for protecting a magnetoresistive sensor element in a magnetic head assembly from damage caused by electrostatic discharge, said magnetic head assembly supported on a substrate and including at least a magnetoresistive sensor element disposed in spaced relationship between a pair of magnetic shield elements, a pair of electrical lead conductors, each of said electrical lead conductors attached to said magnetoresistive sensor element at opposite ends thereof, said magnetoresistive sensor element, said magnetic shield elements and said lead conductors being exposed at an air bearing surface of said magnetic head assembly, said method comprising the step of coating at least a portion of said air bearing surface with a layer of conductive material shorting said magnetoresistive sensor element, said magnetic shield elements and said conductive leads together and to said substrate.

2. A method as in claim 1 including the additional step of removing said conductive layer prior to said magnetic head assembly being assembled in a head disk assembly.

3. A method as in claim 1 wherein said conductive material comprises a material dissolvable in a basic solution.

4. A method as in claim 3 wherein said basic solution has a pH less than 10.0.

5. A method as in claim 4 wherein said basic solution comprises a solution of ferric cyanide.

6. A method as in claim 4 wherein said basic solution comprises a solution of sodium persulfate, dipotassium hydrogen phosphate and a surfactant.

7. A method as in claim 6 wherein said surfactant comprises octylphenoxypolyethoxy ethanol.

8. A method as in claim 3 wherein said conductive material comprises tungsten.

9. A method as in claim 1 wherein said conductive material comprises tungsten.