For reflow IPC recommends SAC 305, but for wave soldering there is no specific recommendation except SnAgCu(SACX®) and SnCu(Sn100C) based alloys. [...]
Lead-Free Soldering Alloys (3)
Please see all questions concerning Lead-free soldering alloys.
No, copper is the element that must be controlled the most. For all lead-free alloys, by using SAC0300 alloy the bath must be observed and controlled. [...]
This phenomenon is often seen with all lead-free alloys. Outward escape of gas causes the formation of surface bubbles in solder compositions. No definite cause for this phenomenon, although some suspected causes may include :
In Europe, except those included in the RoHS directive at the moment there is no indication of the substance to be added to the banned list. JEITA, recommends lead-free alloys contain silver. Because of the need to complete the desired wetting characteristics, silver is a critical additive. [...]