|Ask the Experts|
November 17, 2017
Leaded to Lead-Free Wave Solder Pallets
We have many assemblies moving from leaded to lead free solder. The design change is not changing the PCB layout. Our wave solder pallets are made from Durostone material which can take the increased heat. Can we use the same wave solder pallets, or should they be replaced? Our concern is contamination from residue on the pallets from earlier builds using leaded solder.
|Expert Panel Responses|
I would recommend that you use separate pallets and identify them as such. Tin/lead solder particles and dross can be picked up by the pallet and transferred to your lead free pot or even to the lead free product. Lead can then build up in the solder pot and there wouldbe considerable cost in relpacing the contents of the pot. In addition, it would also be wise to have two sets of maintenance tools to avoid any other potential sources ofcross-contamination.
Principal Engineer - CMA Lab
Without a doubt, re-use the pallets. Save yourself some money. I'm sure there are some pallet manufacturers who will suggest that there may be some chance of cross-contamination, but the quantity is so small as to be negligible, if any. If in doubt, clean the pallets with any of the very good pallet and oven cleaners on the market today, like the Reflow Oven Cleaner from MicroCare.
If the high temperature (350c) Durostone pallets are in good shape and can be cleaned thoroughly, they should be able to go from the lead, to lead free solder with little or no issues. The material does resist solder contamination. You should not, however, continue to go back and forth between the two. This eventually might cause cross contamination. In the case of a single switchover, they should be ok if cleaned properly. I appreciate the opportunity to reply to your question. Please feel free to contact me at any time.
Global Director of Sales
I have polled a few folks who did the change over and I also contacted a well known tooling company that supplies pallets throughout the industry. The response overwhelmingly is that "Only you can make that determination". However a few technical notes of interest did surface in my investigation.
Technical Expert Sales Support
I do not see an issue with using the samepallets, as long as you've clean them thoroughly. Washing them after each usewill also help with the regular maintenance of the pallets (removing the fluxand solder residues). It has to be said that sharing the pallets for bothleaded and lead free processes is not a healthy practice - so continuingswitching the process has to be avoided.Do not forget to mark them accordingly too.
Engineering and Operations Management
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