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Ceramic subtrate with silver/palladium surface finish

C.W

#29609

Ceramic subtrate with silver/palladium surface finish | 22 July, 2004

hi All, i have recently running a Ceramic board with silver/palladium surface finish, using Alpha Metal 63/37 WS solder paste, soldering meet IPC standard after reflow, however, the solder joint look grainy, not sure if there could be too much intermetallic formed. Any one has any experience on ceramic brd with silver/palladium surface finish? do you still get the smooth and shinny looking solder joints as usual? what's your process then? paste used? profile etc.

pls advise!! thanks!

Chester

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#29628

Ceramic subtrate with silver/palladium surface finish | 23 July, 2004

We have run not AgPd [that we know of]. We can comment on PdNi. [But you're probably have Ni under the AgPd]

In general, palladium solution rate is much slower than other sacrificial finish materials that we use for the purpose. The key then is to extend the duration of the reflow zone to accommodate the slower rate and it should improve the wetting results.

We refer to solder joints made to PdNi plated parts as having an "alligator" surface texture, rather than a smooth shiny surface. Metallurgical evaluations indicated that the surface texture was due to concentrations of Pd near the surface.

If we increased reflow recipe 5 to 10*C hotter, the "alligator" texture would be less pronounced. What we wound up doing was: * Retraining operators. * Providing visual aids for inspectors.

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C.W

#29638

Ceramic subtrate with silver/palladium surface finish | 24 July, 2004

thanks Dave!!

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#29772

Ceramic subtrate with silver/palladium surface finish | 31 July, 2004

Your liquidus time is too long. 63/37 is a eutectic so leave at liquid state a very short time

SF

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