Characteristics of lead-free solders during flow soldering (selective and wave soldering)

The use of lead-free solders requires new fundamental information for flow soldering. Parameters, approved for many years with the solder SnPb, for wave height, flow speed and also the tear-off angle must be defined again for lead-free solders. In addition, the corrosion of substrate metallization and especially of machines (crucible and other parts in liquid solder) is under discussion for lead-free soldering today. A new combined measurement method for analyzing the characteristics of new solder in a relatively short time was developed at IZM. Therefore, the surface energy as a value for tear-off behavior, the viscosity as a value for the flow behavior and also the corrosion rate were measured. A comparison between different solders or solder alloys provides the solder manufacturers as well as the solder machine manufacturer with important data for the application and further development of new technologies.