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Thin Film Head Process

IP.com Disclosure Number: IPCOM000086826D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Brock, GW: AUTHOR [+13]

Abstract

The manufacture of a simple thin-film head requires many process steps. Each of these steps poses one or more demands or problems which must be resolved in order for the entire head to perform properly.

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Thin Film Head Process

The manufacture of a simple thin-film head requires many process steps. Each of these steps poses one or more demands or problems which must be resolved in order for the entire head to perform properly.

In a thin-film head, there must be some basic substrate to support the structure. Molybdenum substrates have been found useful as substrates for miniature thin-film heads due to their capability of being provided in sections 50 mils thick having a flatness of 50 millionths of an inch which can be surface- finished to a 2 mils center line average (CLA). Surface-finishing of molybdenum substrate material is provided by lapping each section against a hard plate using a silicon carbide slurry with a planetary lapping motion. Subsequent to surface- finishing, the molybdenum substrate is coated with a thin layer of silicon dioxide.

Then, in order to allow electroplating of magnetic and conductive components of the structure on the glass substrate, a conductive substrate of, for example, chromium-copper is provided by vacuum-deposition. In order to provide chromium-copper which does not delaminate from the substrate, the substrate is first heated to about 200 degrees C followed by vacuum deposition in a sequence of chromium first, followed by deposition of a chromium and copper mix, and then completed with only copper deposition. After this conductive portion is provided, details of conductive and magnetic circuitry are provided by electroplating in conjunction with standard lithographic techniques.

In order to avoid the formation of unwanted sedimentary flakes on the substrate surface during plating, which sediment could lead to track or circuit failures, the surfaces of the substrates are maintained in a vertical position during plating. Additionally, in order to provide the desired magnetic and physical characteristics to the plated magnetic material, permalloy is found to provide good characteristics when plated from a bath containing saccharin and sodium laurel sulfate. These bath additives provide stress relief and improved brightness, respectively.

It is also found to be beneficial to plate the magnetic material in a cell surrounded by a helmholtz coil, providing a magnetic field to orient the film in a manner which provides desired magnetic switching characteristics. In the preparation of a multilayered structure of magnetic and conductive...