Problems upon changing solder plating from sn60 to sn96

Hi All,

We recently changed the plating on our substrate material from an electroplated tin-lead sn60 to an electroplated tin-silver sn96. We adhere the substrate to an aluminum chassis plated with nickel then tin. We had great success with the initial lot, about 20 pieces. After that we began to have problems with adhesion. The plater stated that the sn96 bath began to break down over a period of time. We have not had this problem with sn60. Is there something about the combination of metals and chemicals in sn96 that causes the bath to break down over a period of time, assuming there is no contamination?

Hi Bill ,

I really need more info , Is the Nickel Electroless ? is the Sn96 Tin / Silver alkaline ? why the switch , is it just for Pb free status ? Is the pealing back to Al or just Ni ?

Is it patchy or all over ?

Regards

If a solder with over 90% Sn used, I have seen tin dissolve some nickel and peel off the solder. Thicker Ni may help.