During the initial installation of a lead-free wave operation,
leaded and lead-free waves may be in operation.
It is important to avoid cross-contamination, lead-free solder
are similar in color to leaded 63/37. Ideally lead-free
solder bars should be supplied with a unique shape, unique
markings and uniquely labeled box to avoid costly errors.
The consensus at the present time is to keep Pb levels at
0.3% maximum in the solder pot, to avoid reliability issues.
It is also worth noting that the maximum lead level to qualify
as a lead-free joint is 0.1% lead. This does not allow for much
contamination of lead in the wave solder pot. Lead-free Wave Bar Packaging
Segregating dross or oxides from solder pots should also be encouraged. In some cases some
companies use red or black buckets for leaded oxides and green or white buckets for lead-free.
The value of lead-free oxides is substantially more then for 63/37, keeping them separate will insure
maximum return when sold for recycling. It is also advisable to label wave solder machines with “leadfree”
inscriptions as avoid confusion. Soldered board identification will also be required to determine
which are lead-free and which are not. This is important in for rework and field servicing operations.
With proper care and a methodical approach lead-free wave soldering can be accomplished reliably.
Resources are available through various published papers and websites on how to achieve this with
confidence.