J-STD-001C
7.2.1 Flux Application: When an external flux is used in conjunction
with flux cored solders, the fluxes shall be compatible.
Just a couple of weeks ago Brian Ellis responded to a thread on this
subject. His comments were accurate and important.

> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Vivari, John
> Sent: Tuesday, March 11, 2003 9:11 AM
> To: [log in to unmask]
> Subject: [TN] Mixing fluxes - documentation vacuum
>
>
> Dear TechNetters,
>
> A customer of ours came to us with a request for a reference
> to an IPC document or other industry standard that explicitly
> states the hazards of mixing flux types on an assembly.  He
> asked for this because his contract manufacturer built a set
> of boards using a No-clean solder paste and reworked some
> BGAs with a water soluble solder paste.  The contract
> manufacture states that he cannot find a standard "anywhere"
> that says the flux types should not be mixed or that there
> will be any long term reliability issues.  I know this seems
> naive but that is their position.
>
> We have searched our library of specifications, books, and
> industry periodicals and have come up empty except for vague
> statements about having to clean between soldering operations
> for certain classes of product without explaining why and a
> reference in Ning-Cheng Lee's new book cautioning against
> combining incompatible fluxes between reflow and wave
> soldering.  We are well versed in the hazards of mixing our
> own fluxes (never mind others) but have never been asked to
> provide "industry standard documentation" before (as opposed
> to a letter of explanation).
>
> Can anyone point to a reference that we have missed?
>
> Hopefully yours,
>
> John Vivari
> Technical Service Engineer
> EFD Inc.
> [log in to unmask]
> www.efdsolder.com
> Ph: 401-333-3800
> Fx: 401-333-4954
>
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