SIX SIGMA is the industry leader in hot solder dipping of components.
This method is used to change the termination finish of components from leaded
to lead-free or vice versa. It is currently one of the strategies being used
to mitigate tin whiskers, which can form when pure tin plating is used. Hot
solder dipping of pure tin-finished terminations using tin-lead (Sn-Pb) solder
reduces tin whisker formation by replacing tin with a tin-lead alloy. It is
very important that no pure tin remains on the components. Hot solder dipping
of tin-finished leads with lead-free alloys such as tin-silver-copper (SAC)
also reduces whisker formation. Although not as effective as lead, so far there
is no evidence that these SAC alloys produce whiskers.
Hot solder dip applies to almost all types of packages. There are several reasons why components are solder dipped. The
method is used to change the lead finish, i.e., from lead-free to leaded, or
from leaded to lead-free. It is also used to improve/restore the solderability
of the parts, and can act as the primary finish for the terminations.