Reworking Pb-Free PCBs

摘要

Hand soldering, paste reflow and wave soldering are the dominant methods used to apply solder in electronics assembly. They predate the shift toward Pb-free processes now making their way into the mainstream. The transition process (Table 1) presents a daunting number of possible permutations of board finishes, component finishes and solder alloys that may manifest in an assembly operation, often when inconvenient. Engineers, operators and technicians must be cognizant of the different manufacturing parameters for producing Pb-free assemblies and any subsequent rework. Hand soldering. One more common, yet oft-overlooked, problem in reworking a Pb-free solder joint is preheating substrates prior to applying the soldering iron to the joint area. Preheating will reduce the contact time of the soldering tip to the joint, which will mitigate localized overheating of the underlying pad.