With the introduction of lead-free soldering we are often confronted with joints that look not as good as we were used when soldering with tin-lead.
E.g. in wave soldering we find suddenly through hole joints that will not flow up to the top anymore. As a result we got questions on how to optimize the process, so that the common quality aspects will be met again.
Sometimes however it is not possible to meet the needs of the customer, even when the process is optimized for lead-free soldering.
The reason is that solder quality is related to solderability, however for lead-free soldering the solderability requirements are not the same as for tin-lead soldering as will be explained.
ITW EAE Support Center