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Pt plating: surface finish versus allowable strain

I am trying to selectively, electroplate a stent (i.e. medical implant) with 5-microns of platinum. The surface area to be plated is approximately .008 sq. inches. The substrate is MP-35N cobalt-chrome. Areas where plating is not desired are masked with a butyl-rubber stop-off lacquer (Tolber Miccro XP-2000)

A mirror-like surface is desired, but the plating also must survive at least 15% strain imparted by the substrate. Some postings/responses here indicate that this desired combination of characteristics is somewhat unattainable.

I have had luck with a local vendor on getting the desired surface finish. The vendor maintains that by lowering the current, he was able to get from a matte grey to a shiny silver finish. Unfortunately, the improved finish is not strain friendly.

The vendor uses a Technic Pt-plating solution. The surface is prepped with a series of alkaline etchant and acid baths. A gold strike is laid down prior to plating. The parts are in the bath for 2 hours.

Are there any optimistic individuals out there that can give me hope and/or advice?

David Lowe
Medical Device Mfg. - Menlo Park, California, USA
2006

Why not use pure soft gold(99.99) to stand the strain. Pure gold is also as inert as Pt for stent application?

Hamilton Solidum
- Mays Landing, NJ
2006

Type III soft gold was something considered. Gold has been used in dental work for its bio-inertness, but the surface characteristics after plating brings up other concerns - some speculative, but others proven.

David Lowe
Medical Device Mfg. - Menlo Park, California, USA
2006

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