What are the main changes associated with lead-free hand assembly cosmetics?
Lead-free solders flow a little slower than 63/37 using the same activation levels for the fluxes. The contact angles are slightly larger and feathering out of the solder is therefore less pronounced. The solder joints tend to be less reflective than 63/37 solder. Some re-training is required prior to a full transition to lead-free is done. In some cases certain shrinkage effects as described in Section 5 of the IPC-STD-610D occur. The IPC-610 classifies these as soldering anomalies and not necessarily defects. As mentioned on page 5-22 of the above document, it is not a defect for Class 1, 2 and 3 if the tear bottom is visible and the shrink hole does not contact the lead, land or barrel wall. See the photos below for examples taken from the Kester laboratory. What is the best soldering tip temperature for lead-free SAC and SnCu? The temperature of the tip or contact temperature is very important to ease the lead-free hand-soldering operation. When using 63/37 solders temperatures as
