Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

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No-Clean Solder

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No-Clean Solder | 2 March, 2007

We are in the early stages of converting al of our customers to No-Clean solder. I expect some customers to have no objections, others I am sure will be concerned about the "residue." I know that chemistries have improved greatly and if the process is solid, residue is not an issue. Is this true for RF assemblies as well? How about if the assembly will be conformal coated afterward? (adhesive issues?) Any white papers or other industry data would be greatly appreciated! Thanks!

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No-Clean Solder | 5 March, 2007

We use (and have for some time) used No-clean on our radio boards with no problems. We also conformally coat with a platinum catalyzed, addition cure silicone coating with occassional problems. These silicones are prone to cure inhibition or retardation (drastic slowing of cure). If the flux residue is not fully activated, it has retarded the cure of this silicone. From an adhesion standpoint though, the residue causes no problems.

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No-Clean Solder | 5 March, 2007

When no-clean flux and no-clean soldering first came out in the late 80's / early 90's, there were lots of White Papers written about conformal coating adhesion and no-clean flux. I'm pretty sure all CC's will adhere to today's chemistries.

To be on the safe side, you may want to have your flux and/or solder paste tested at a lab. Order a couple of comb-up and comb-down coupons from IPC, run them through your screen printer & reflow and/or wave solder process, and have them tested for SIR and ionic contamination.

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