Especially in terms of solder pastes, the old RMA's are rather close to no-cleans. RMA's were supposed to be safe if left on the board un-cleaned.  Key difference is that RMA's were optimized to be cleaned (soft & reactive residues) whereas no -cleans are made to have a hard yet probable residue.  Activity levels are rather similar.

Don't recommend alcohols by themselves to clean  RMA's. Semi -Aqueous processes work rather well. Addresses both the non-polar and polar residual constituents. If any residues are left behind (ie., QFN's) good chance they will not cause much mayhem. Need to test of course as you can't make a blanket statement. 

People uses to use vapor degreaser to clean RMA's but they often left white residues (polymerized rosins) and you were never certain you really got all of the activators off. 

Batch cleaning with some long chain alcohols holds some promise, but requires a final cleaning step in a more polar solvent (like water). Problem is if first step was not efficient then you may be left with encapsulated activators and the polar solvents can't do their job. 

Problem with water soluble residues is that if left behind they tend to be very unforgiving. I tend not to recommend them and more often than not try to switch a process from water soluble to cleaning of no-clean via semi aqueous. 

BTW - not really a rookie question, as you can see from the # of responses you rec'd . 


Rich Kraszewski
(920)969-6075
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Friday, October 28, 2011 8:08 AM
To: [log in to unmask]
Subject: [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
T | 450.967.7100 ext.244
E | [log in to unmask] <mailto:[log in to unmask]>  
W | www.digico.cc <http://www.digico.cc/> 

 
 N'imprimer que si nécessaire - Print only if you must

 


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