Palladium silver surface finish

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Hello Everyone, We are having some problem with Palladium-... - Jul 04, 2004 by

Sounds like your Si plalladium finish has oxide on it from t... - Jul 13, 2004 by

May I ask what component types you are using and who the sup... - Aug 12, 2004 by

Indy, We use Palladium silver surface finish parts for silve... - Aug 12, 2004 by usdmain

If the terminations on your components are not barrier plate... - Aug 13, 2004 by davef

indy

#29371

Palladium silver surface finish | 4 July, 2004

Hello Everyone, We are having some problem with Palladium-Silver surface finish. We have ceramic components with the above surface finish. When we try to assemble these on Sn/Pb solder, we are observing open joints. If we reflow the compt for more times the open joints keep increasing.Basically the surface finish is not catching on to the solder paste.

Does anyone know anything abt reliability Palladium-silver and its ability to hold on to solder paste.

Your help is appreciated.

regards Indy

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Richard

#29486

Palladium silver surface finish | 13 July, 2004

Sounds like your Si plalladium finish has oxide on it from the firing or sitting around too long. I used to assemble LTCC and have had plenty of dealings with this matter. The best and easiest is to get an active type flux and solder paste. AIM makes a good OA flux that I have had good luck with. The other thing you need to do is keep the ceramic in a dessicator and have the surface touching silver saver paper which will keep the tarnish down. The other alternative is to burnish the surface with a red pencil type eraser be very careful as you do not want to take off too much metalization. If you need anymore details e-mail at ryabuki@canram.com

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#30013

Palladium silver surface finish | 12 August, 2004

May I ask what component types you are using and who the suppliers are?

FYI - If the components have exceeded their shelf life, they may have oxidized too much for soldering using low activity fluxes.

Thanks and best regards, SR

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usdmain

#30014

Palladium silver surface finish | 12 August, 2004

Indy, We use Palladium silver surface finish parts for silver epoxy attached parts only. It is our understanding that this finish is not for solder, but only silver epoxy attach. I expect that is you problem. Dave

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davef

#30020

Palladium silver surface finish | 13 August, 2004

If the terminations on your components are not barrier plated, you must be very careful about the amount of time you stay above liquidous. As you'd expect, longer is not better. The longer you stay at liquidous, the more of the component termination plating that leaches into the solder. If you stay too long, this leaching process consumes the termination plating and makes it look like the termination has dewetted.

As a tent stake in the sand, with barrier plated terminations, you can stay at temperature about ~4X the time you can stay with non-barrier plated terminations.

Beyond the barrier plating, some shops use a silver loaded solder to help reduce the degree to which the silver plating is leached from the termination. [We don't really know if this is true or not, but we do it. Probably one of those urban soldering myths. We used to believe that Ag2 would help reduce embrittlement caused by gold in solder connections, but at least we don't bite on that one any longer. We're making progress!!! ;-)]

For more, check with your component supplier. For instance: http://www.microcapacitors.com/pdf/multipart3.pdf

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