The glib answer is that most people use RMA because they do..
The longer answer:
If you go back say 50 years when people first started using activated fluxes, RMA type specs
were written to ensure that these newfangled activated fluxes were no more corrosive than if
they weren't activated.

Most people clean because they look so messy, but  by definition there is no need to. [If you
want to probe or coat or have concerns about fly paper effect then you will have to, but this is
due to the mechanical/physical nature of the residues rather than their chemical/electrical
properties.] If you are cleaning  there is no need to put up with the inadequacies of RMA , more
active fluxes are then permitted in MIL applications.
Just as an aside: I recall work done during CFC elimination programs showed that the best SIR
boards were uncleaned RMA (compared to however cleaned RMA).

Mike


----- Original Message -----
From: Stephen R. Gregory <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, June 16, 2000 8:33 PM
Subject: [TN] Generic question about Flux types...


> Hi ya'll!!
>
> I gotta generic question about flux types. We do quite a few boards here that
> still call out that the assembly is to be built to MIL-STD-2000 specs, and as
> has always been here, RMA flux is always used. My question is, what is the
> REAL reason to use an RMA?
>
> I've been under the impression that because a RMA is not as active as an OA,
> any residues that might be left behind from the RMA wouldn't be as harmfull
> as OA residues would be. But if you always ensure that you clean your boards
> thoroughly, what difference does it make whether you use an RMA or an OA?
>
> -Steve Gregory-
>
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