My 2 cents
No clean fluxes work in different ways, thus (oversimplifying) high solids
rosin based fluxes work by encapsulating ionics and low solids by
inactivating. If you use a low solids flux with a rosin material, you're
thinking flux but chemically what you are doing is adding dirty solvent (IPA
with 1,2,3% whatever ionics) to the rosin. This will tend to
dissolve/disperse and contaminate it, overloading the rosin and reducing its
encapsulation effectiveness. It may be that keeping to the same basic flux
formulation types irrespective of supplier works out OK, but the world is
not oversimplified so it may not. If using multiple fluxes therefore it is
not a good idea to also mix suppliers - at least without testing. If there
are problems a single supplier will know what is being mixed and make
recommendations and is likely to have tested recommended combinations.
Conversely he clearly can not know the formulation details of all other
supplier products and certainly not how multiple different supplier products
will interact with each other and his own material.
Regards
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Thursday, September 15, 2011 1:46 AM
To: [log in to unmask]
Subject: Re: [TN] Flux Compatibility
Cedric,
In some rather rare cases fluxes of different types (core wire vs. solder
paste, wave flux vs. solder paste, etc.) when mixed together fail SIR and/or
electrochemical migration testing, even though they individually pass. I
can't prove it, but I would expect that a failure would be more likely to
happen if the two materials are not made by the same supplier.
That being said, even large companies like Nortel (now deceased :( ) did
NOT test ever combo, not even 10% of the combinations, because, frankly, it
would be too costly and the risk was deemed low enough to live with the
possibility.
So there is some risk, but as far as I know, no one in our industry has ever
quantified what that risk is.
Bev
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Cedric ORAIN
Sent: Wednesday, September 14, 2011 3:10 AM
To: [log in to unmask]
Subject: [TN] Flux Compatibility
Good morning dear Technetters,
I'm asked by one of my customer if I checked the compatibility between in
one hand the no-clean flux from the SMD paste and the other hand the resin
flux from the wires.
The answser was no !
Could you advise which kind of issue could occur if any ?
Thanks for your help,
Regards,
Cedric
www.inovelec-groupe.com
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