We have been building cards with no-clean for some time now. We have an
Electrovert wave with foam fluxer.  We have experience with a couple of
different no-clean fluxes ( Cobar 390RxHT  and Interflux  IF2005). Both of
these fluxes have provided good soldering results. I imagine any number of
other brands will too. One thing I have noticed is that one has a narrower
control window when using low solids no-clean as opposed to using the higher
solids aqueous fluxes. Also when setting up the wave for no-clean the process
parameters may differ somewhat from those of aqueous fluxes. For our wave I
have found that, to achieve good hole fill, I have to run a slightly higher
preheat and a longer pot dwell time for no-clean. Varying pot temperature can
also have an effect.

 I have run 0.090" cards through with no problems, it just needed careful
setting of the wave parameters. If a card has large areas of copper on topside
getting heat into the card can be a problem without topside preheaters.

Having said all this I have found that for some cards where solderability
issues are present, for either the card or the componentry  (one of the joys of
contract manufacturing with some parts being consigned), we still use the more
active aqueous flux to achieve acceptable results.

Regards Evan

Evan Jones
Manufacturing Engineer
IBM Wangaratta
Ph 61 3 5720 2539       Fax 61 3 5720 2412
Email [log in to unmask]

---------------------- Forwarded by Evan Jones/Australia/IBM on 06/01/98 10:29
---------------------------


[log in to unmask] on 06/01/98 06:20:49
Please respond to [log in to unmask] @ internet
To: [log in to unmask] @ internet
cc:
Subject: [TN] Any No Clean Flux for Thick PCB's?


Has anyone had any success using a no-clean flux on thick (0.090") multi-layered
thru-hole PCB assemblies?

We want to switch to a no-clean flux from our present aqueous system. Our
Electovert currently has a foam fluxer but would get a jet-sprayer if the flux
was right. However, we tried a few demo no-clean fluxes and experienced problems
with our larger and thicker multilayer boards as far as solder wicking up to the
top-side on feed-thru's. We even added extra heated air-knives and to no avail.

If you have had success with any particular no-clean fluxes, please let me know
what they are.

Thank you.
Fred

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