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Etching Copper Coated With Permalloy

IP.com Disclosure Number: IPCOM000078212D
Original Publication Date: 1972-Nov-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Jones, AS: AUTHOR [+2]

Abstract

A selected area of a copper layer underlying a layer of permalloy is removed by first etching away an area of the permalloy layer, corresponding to the selected area of copper, and then etching the copper with an aqueous solution of sodium polysulphide. Use of the sodium polysulphide etchant avoids undercutting of the permalloy, which occurs when conventional copper etchants, such as ferric chloride solution are used.

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Etching Copper Coated With Permalloy

A selected area of a copper layer underlying a layer of permalloy is removed by first etching away an area of the permalloy layer, corresponding to the selected area of copper, and then etching the copper with an aqueous solution of sodium polysulphide. Use of the sodium polysulphide etchant avoids undercutting of the permalloy, which occurs when conventional copper etchants, such as ferric chloride solution are used.

This technique is particularly useful in the manufacture of a single-turn magnetic transducer. Principal steps in making such a transducer from a ferrite/copper/permalloy sandwich are:
1) Mask the permalloy to leave a "U" shaped area covered;
2) Etch away the unmasked area of permalloy;
3) Etch the copper exposed by step 2 with sodium polysulphide

solution;
4) Remove any remaining portions of the original mask and remask

the permalloy layer to leave an area over the base of the

"U" unprotected; and
5) Etch away the unmasked area of permalloy.

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