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Purifying and Recycling Palladosammine Chloride Plate Baths

IP.com Disclosure Number: IPCOM000078928D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Caricchio, JJ: AUTHOR [+2]

Abstract

In plating palladium from a palladosammine chloride bath, the buildup of chloride is inherent. Thus, for every addition of palladium salt to the bath to replace metal plated out, chloride is also added as the anion portion of the salt and is not depleted during normal bath operation. As the chloride concentration builds up to an intolerable level, bath operation and control becomes increasingly difficult.

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Purifying and Recycling Palladosammine Chloride Plate Baths

In plating palladium from a palladosammine chloride bath, the buildup of chloride is inherent. Thus, for every addition of palladium salt to the bath to replace metal plated out, chloride is also added as the anion portion of the salt and is not depleted during normal bath operation. As the chloride concentration builds up to an intolerable level, bath operation and control becomes increasingly difficult.

This is a process for purifying and restoring high-chloride palladosammine chloride plating baths to a normal operational mode. The restoration concept is simple, highly economical and very efficient.

The operational sequence is as follows:
1. With agitation, add concentrated HCl to the "spent" bath

to lower

pH to 1-3.0. Precipitation of palladosammine chloride

occurs rapidly throughout the bath and settles to the bottom

of tank once agitation is off.
2. Allow solution to stand overnight to permit a distinct

separation between liquid and solid layers.
3. Siphon off carefully the upper liquid layer down to

within

1 inch of the precipitate cake.
4. Add back an equivalent amount of deionized water and stir

mixture rapidly for one-half hour to wash the precipitate,

to free it from further chloride or contaminants.
5. Again let settle overnight to achieve complete separation

of layers.
6. Repeat siphoning off upper liquid layer down to about 0.5

inch

of cake.
7. At this point, there is an option of building...