Hi Cory,
As a manufacturer of aqueous cleaning systems, my advise is somewhat biased, however I believe it to be accurate.
We have hundreds of customers who have implemented no-clean programs. The programs have been successful when measuring the reduction of the quantity of boards requiring cleaning. Very rarely however, has a contract manufacturer been 100% successful in the complete elimination of a cleaning process. It seems true that at least some boards require cleaning. The most popular reasons as stated by our customers�?
1. Customer requirements dictate cleaning. 2. Elimination of slight visual residue (even if it is considered �harmless�) 3. Bed-of-nails tester probes get �gooey�. 4. Superior adhesion of conformal coating.
Handling a board carefully after reflow will not address preexisting contamination from fabrication.
Anecdotally, we have a customer that manufactures flight data recorders. Everything is conformal coated. The customer switched from one type of cleaning process to another and experienced a marked improvement in adhesion.
I am aware that there are companies that conformal coat no-clean boards wihtout cleaning. They have great ovens or waves with very good spray fluxers and very tight process control. Profiles are very tight.
Conclusion� Clean a board a little, get fairly good adhesion results. Clean a board thoroughly, get excellent adhesion. Skip the cleaning process, iffy.
Good Luck Mike
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