Hi Paul,
Thanks for the comment. I just started learning about fluxes, so all this is great content for me. I have one question, If we used an RMA flux, left it one the board, assuming that there are no other contaminants on the board, would it pass a Ion Chromatography Test?
Rigo
Sr. Quality Assurance Engineer
Workmanship Standards, Code 300
NASA, Goddard Space Flight Center
Greenbelt, MD 20771
Phone. (301) 286-6129
Fax. (301) 286-6576
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
Sent: Friday, October 28, 2011 12:28 PM
To: [log in to unmask]
Subject: Re: [TN] Rookie question on RMA fluxes
Ioan,
You have gotten a lot of good answers to the question so far and I will chip in my two cents worth.
Technically, there is no such thing as an RMA flux anymore, though the term continues in use. RMA, Rosin Mildly Activated, was a flux terminology from the good old days of MIL-F-14256, the military flux specification. It was cancelled in 1995 and directed people to J-STD-004, the current predominant flux specification in the industry. The older rosin flux formulations that were termed RMAs, translated into ROL0, ROL1, or ROM0, depending on the flux and who you ask. RMA fluxes are still available, though as the market shrinks for these, they are becoming more expensive, which encourages users to transition to something more modern.
Most people still using "RMA" flux are using the 15% solids, which is still pretty high, compared to low residue fluxes or water soluble fluxes.
Which means there is a significant amount of flux to clean off compared to other fluxes.
Isopropyl alcohol sucks as a cleaner, at least in my opinion. People want to use it because it is cheap, available almost everywhere, does not impact industrial emissions much depending on where you are in the world, and is not a health hazard, if you don't get too wrapped around the axle over flammability. No way, no how would I ever want to clean an RMA flux with alcohol alone. Does not work reliably.
In my experience, high solids rosin fluxes tend to be OK if you leave them alone, or if you totally remove them. If you "kind of" remove them, you have a great deal of problems. You remove the encapsulating effect of the rosin (which you want), but you free up the activators to cause havoc (which you don't want). In my view, you want a really effective heated saponifier in an in-line aqueous cleaner, with a thorough heated deionized water rinse.
Doug Pauls
Ioan Tempea <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
10/28/2011 08:07 AM
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[TN] Rookie question on RMA fluxes
Dear Technos,
Although I've been around in this trade of ours for quite a while now, I
have never had the occasion to work with RMA fluxes. I need to know how
this functions. How can RMA be cleaned, I've heard about alcohol...? Is
regular aqueous wash enough? If alcohol only, do we need a special
equipment? Anything else to know?
And, anyways, are RMA fluxes still available?
Also, I imagine most of you at ease with RMA have tried to talk your
customers into converting to water soluble flux chemistries. How hard was
that? Is it possible?
Thanks,
Ioan Tempea, ing.
Ingénieur Principal de Fabrication / Senior Manufacturing Engineer
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