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Flux residue effects on circuit performance?

Tom Van Heuklon


Flux residue effects on circuit performance? | 15 April, 2002

Can anybody explain breifly what some of the effects of flux residue from a no clean process might be on circuit performance? Alternatively, might you tell me where I might find such information?

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Flux residue effects on circuit performance? | 15 April, 2002

Points are: * Seminal study is: "Evaluation of Low Residue Soldering for Military and Commercial Applications: A Report from the Low Residue Soldering Task Force," published by Sandia National Labs in June 1995. Look here for contact information. * This leads on the boarder point. Search the fine SMTnet Archives to get started. Probably 50+% of our discussion here on SMTnet relates to NC flux. As an example, a recent thread ( ) laments on the difficulty of using NC flux in RF circuits. * Other areas of concern about circuit performance are: conformal coating, flip chip under-fill, proper process control so to not over apply flux, customer acceptance, tougher soldering process control, and ladeda.

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Hany A. Salam


Flux residue effects on circuit performance? | 28 April, 2002

Dear Tom :

I hope I �m not too late. We produce PC motherboards with some buses exceeding the speed of 100MHz . we use no clean flux and it is OK even with the residues you can see under a microscope. But according to our own experience through a modification for more than 1000 boards, the flux residues remaining after manual rework are very critical. Tens of faulty boards passed all normal & burn-in tests just by cleaning the residues of the No Clean Flux.

According to what I understand, N.C.F. means it is not harmful to your components & PCB material from the chemical point of view (corrosion for example). But it could be problematic such as in our case.



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Flux residue effects on circuit performance? | 29 April, 2002

You can try using the brand-solvent "Genesolv 2004" in conjunction with a degreaser machine(source for own machine type?).

this all helps to clean off the NC flux. we used it all integrated together, to clean a satellite modular card.

reason we had to use NC flux, is coz the base PCB materials metallized pads oxidized after WS cleaning processes.

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Capillary Underfill process