Question: What type of impact would it have if the wires were tin-dipped in lead-free solder then were soldered to a board with 63/37 solder? Are there problems that may occur that would cause difficulty in soldering?
Answer: In regards to mixing 63/37 (tin lead) and lead free solder, the difficulty of the soldering process is not the complete issue or concern. The lead free may have been soldered with a higher temperature as well as a flux that may not be compatible with the materials utilized at the board surface. Check the flux content data from the manufacturer for compatibility. Depending on the customer and what Class product, there may be defect conditions related to solderability and traceability. You may be required to separate the wires per the process for the customer.