Browse Prior Art Database

Preventing the Corrosion of Silver by Sulfur in the Atmosphere

IP.com Disclosure Number: IPCOM000075766D
Original Publication Date: 1971-Nov-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Berenbaum, L: AUTHOR

Abstract

Corrosion products have been seen at the dewetted region on the Ag-Pd lands of integrated circuit modules. Sulfur and chlorine contaminants have been identified by microprobe analysis. Sulfur in the atmosphere in only 0.2 ppb can cause growth of Ag(2)S films. Ag(2)S is black and the corrosion product is black.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 1

Preventing the Corrosion of Silver by Sulfur in the Atmosphere

Corrosion products have been seen at the dewetted region on the Ag-Pd lands of integrated circuit modules. Sulfur and chlorine contaminants have been identified by microprobe analysis. Sulfur in the atmosphere in only 0.2 ppb can cause growth of Ag(2)S films. Ag(2)S is black and the corrosion product is black.

Since it requires only 0.2 ppb of sulfur to cause corrosion of silver, it would be impossible to purify large volumes of the atmosphere in the vicinity of the modules to remove the contaminant. An alternate technique has been used effectively in preventing tarnish layers from forming on silver tableware. The technique is to wrap the tableware in a paper treated with either copper or cadmium acetate. These compounds preferentially absorb sulfur which comes into close proximity to it.

It is proposed that copper acetate (it is lower cost) be used to line the inside of the module cap so that any sulfur diffusing through the barriers (SYLGARD,* RTV, etc.) would be preferentially absorbed. It may be necessary to use some kind of lining material into which the copper acetate could be absorbed.

This may be an effective method for saving modules which are already out in the field, but have not yet begun to show signs of deterioration. * Trademark of Dow Corning Corp.

1