Browse Prior Art Database

Selective Etching of Nickel and Iron Laminate

IP.com Disclosure Number: IPCOM000088673D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Jaeger, TH: AUTHOR [+2]

Abstract

Electroform screening masks of the composite form described in the IBM Technical Disclosure Bulletin, Vol. 19, No. 5, October 1976, pages 1790, 1791 are differentiated by selective etching of the differently composed layers. Hitherto, copper and nickel have been employed as lamination media because of the availability of known practical processes for selectively etching these materials.

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Selective Etching of Nickel and Iron Laminate

Electroform screening masks of the composite form described in the IBM Technical Disclosure Bulletin, Vol. 19, No. 5, October 1976, pages 1790, 1791 are differentiated by selective etching of the differently composed layers. Hitherto, copper and nickel have been employed as lamination media because of the availability of known practical processes for selectively etching these materials.

However, copper and nickel have dissimilar stress properties and copper, as the basic/core element of the structure, is recognized to be a less than optimum choice in respect to mechanical strength and dimensional stability.

The major drawback in the use of stronger materrals more stress-compatible with nickel has been the lack of practical systems for accomplishing selective etching of the candidate media (without significant removal of nickel).

The accompanying graph indicates that nitric acid in various ranges of aqueous concentration exerts different etching actions on iron (or nickel/iron alloy) and unalloyed (Watts) nickel. In the range 13-20% iron is removed fairly rapidly while the effect on the nickel is insignificant, and in the range above 30% the rate of attack on nickel is at least an order of magnitude greater than the rate of iron (or nickel/iron alloy) removal.

Thus, a composite having a core layer of iron (or nickel/iron alloy) supporting a comparatively thin layer of Watts nickel can be differentially etched into mask...