Side effect of lead free solder (RoHS) use - T/F

[frahit]

We would like to switch from lead to non-lead (Rohs compliant) solder. Soldering operation is carried out in a baths made of acid resistant stainless steel. Cca 2 kg of solder is melted in a pot at cca 480 deg C. Composition of new solder we would like to use is Sn99Cu1. I've heard some rumors that use of Sn98Cu2 corrodes SS pot (even make a hole through in a few weeks). Can someone confirm such statement? Any bad experience?
Thanks

 

[cloa]

I can't say about experience but my reference to Corrosion Engineering by Fontana says that for Nickel Chromium austenitic stainless steels (no data for other stainless) , molten tin at 300C gives attack 01 to 10 mpy and 600C gives attack of 10 mpy. Stress Corrosion cracking is common in materials exposed to molten expecially Ni-Cr stainless i.e. when stressed they tend to rupture. Nickel, Monel and cupronickels have best resistance.

 

[frahit]

Cloa, thank you for your reply. I forgot to mention that we already use this technology (pots with solder on 480deg C). We would only like to switch from PbSn5Ag2 to Sn99Cu solder. It means that if the pot material was subject to cracking due to exposure to molten it would already rupture. Thanks again.