Browse Prior Art Database

Improved Overcoat Technique for Thin Heads

IP.com Disclosure Number: IPCOM000040904D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

McCaffrey, PM: AUTHOR

Abstract

The current method of depositing protective overcoat on thin heads requires many hours of sputter deposition of alumina to a required depth of about 25 micrometers, the substrates are then lapped back to expose the conductive pads. Disclosed herein is a method of depositing a thin overcoat (approximately 8 micrometers) of alumina. Then a selectively etchable pad and its coating of alumina would be chemically removed exposing the gold contact pad. This process eliminates both the need for thick alumina overcoats with their long sputter deposition times and the need for mechanically lapping back to the conductive contact studs.

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Improved Overcoat Technique for Thin Heads

The current method of depositing protective overcoat on thin heads requires many hours of sputter deposition of alumina to a required depth of about 25 micrometers, the substrates are then lapped back to expose the conductive pads. Disclosed herein is a method of depositing a thin overcoat (approximately 8 micrometers) of alumina. Then a selectively etchable pad and its coating of alumina would be chemically removed exposing the gold contact pad. This process eliminates both the need for thick alumina overcoats with their long sputter deposition times and the need for mechanically lapping back to the conductive contact studs.

The steps of the process are: 1.Coat resist unto finished head (approximately 8 micro meters). 2.Expose wide stud pattern and develop. 3.Plate gold approximately 7 micrometers. 4.Remove resist. 5.Reapply approximately 8 micrometers of fresh resist. 6.Expose smaller stud pattern and develop. 7.Plate copper approximately 12 micrometers. 8.Remove resist. 9.Deposit approximately 8 micrometers of alumina. 10.Etch copper.

The process operates as follows: After the construction of the head is completed, a gold stud 10 is plated onto the leads. On top of this gold stud is plated a smaller stud 12 (see Fig. 1) of copper which overplates the previously applied resist, so that an overhang 14 is produced. Overhang 14 protects the sides of the copper studs during the subsequent alumina deposition. This allows a...