Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Palladium finish and solder balls

David R

#20522

Palladium finish and solder balls | 27 June, 2002

Hi there.

We have had an out of control reflow oven that has allowed its temperature to fluctuate by up to +/- 20 deg C from set point in very short periods of time. We found the root cause of the problem and fixed it, but by then we had already run product through. The solder joints looked acceptable, however we found that the boards had solder balls around the pads of one part and one part only.

The part that exhibited the problem has leads with a Palladium/ Nickel finish. We know that the printing was not an issue, and there are other parts of similar size and pitch on these boards.

My question is... would parts with this Palladium finish for any reason be more prone than normal parts to giving solder balls in an out of control oven.

Cheers, Dave.

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#20525

Palladium finish and solder balls | 27 June, 2002

You're correct that the Ni/Pd termination seems to have something to do with you solder balling. It could be related to the interaction between your paste and the Pd. I assume these are really 'fines' rather than 'balls'. Things that come to mind are: * Exceeding the working time for the solder paste is the most common culprit. * TI has documented that soldering Pd is very flux dependant.

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David R

#20530

Palladium finish and solder balls | 28 June, 2002

Great,

now at least I have an explanation of sorts.

Thanks, Dave.

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