No-clean flux residues are not allowed on most military high-rel contracts, as they can be just as bad as RMA or even OA flux residues. I do agree that RMA flux residues should be cleaned, and that is also a requirement.
For RMA, we clean using a solvent, followed by machine wash with a good saponifier. This is a good method of ensuring all flux residues and other contaminants are removed. We perform ROSE testing daily, and we also perform IC testing periodically to ensure the CCAs are clean. Cleaning with just the solvent method, or just the saponified DI wash, but not both, has never been able to consistently pass. The solvent should be something other than IPA, which is not a good cleaning solvent.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Wednesday, February 16, 2011 10:22 AM
To: [log in to unmask]
Subject: Re: [TN] RMA flux and IPA
For me, the short answer is don't! I'm sure the subject has been touched
upon many times already. As Mike says, all you are doing is diluting the
active components in the alcohol and letting them dry on again exactly
in the places where you want them least.
However, I disagree with Mike on one point and that is that RMA flux did
have to be cleaned off with specific solvents according to the 28 809
standards for military purposes. It was not permitted to use it as a no
clean flux. That having been said, many people did use it as a no clean
flux for non-military applications, with varying degrees of success.
Despite what many people think, these fluxes did contain halide
activators, although the quantity was limited.
In my opinion, if you need the utmost in reliability, you should do a
proper clean with RMA fluxes or use a suitably qualified no clean flux,
which will give you the reliability that you desire.
Brian
On 16/02/2011 17:17, Phillip Bavaro wrote:
> What happens when the RMA liquid flux used to hand solder thru hole components
> is cleaned using an IPA bath and a brush? Most comnponents come out bright and
> shiny but happens underneath the bodies? Ionic testing doesn't pick up
> anything. Thanks in advance.
>
> Phil
>
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