RMA flux Based Solder Paste

Same query:

Do we really need to clean the board with when using RMA ? I've been told that aqeous is not needed to clean the board, what cleaner is suitable and how?

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Talk about bucking the trend!!! OK, OK, I know some US military work still requires RMA.

You�re both correct. Cleaning decisions for RMA fluxed boards are based on customers requirements. [Some do (clean) and some don�t.] Older US military specifications defined the process the assembler should use [in addition to the end result], rather than simply specifying the end result.

The two primary methods for cleaning RMA, if you�re a doer, are:

1 Semiaqueous Cleaning. A cleaning process using a solvent wash section followed by a "standard" aqueous wash cycle.

2 Saponifier. Alkaline chemicals, added to water, that convert rosin/resin flux residues in the water to soluble soaps. This saponified wash section is followed by a "standard" aqueous wash cycle.

Either way you add about four feet to the length of you aqueous cleaner and attendant materials, energy, and waste control considerations. Umm, um.

The benefits of using RMA over NC depend on the particular fluxes selected and the processes, but primarily your customer will like [and pay] you a lot more.

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Hi Dave, If my solder paste is RMA based and my Wave Solder flux is NC Based, will there be incompatibility problem that might arise during the process? thanks

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Hi Dave, If my solder paste is RMA based and my Wave Solder flux is NC Based, will there be incompatibility problem that might arise during the process? And if i don't clean my boards what will be the possible effects of the residues left? thanks

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If you do not have one of the big in-line aqueous cleaners, then there is an easier way that is a lot less expensive. I suggest you try Asahi's AK-225T vapor degreasing solvent which has been around for 10 years now. And it is legal. If you have not been using RMA flux, then you would not have heard about it.

Works in a standard vapor degreaser and works great on RMA residue with no white residue problem. Lots of the big aerospace and military companies doing hi-rel and using RMA for SMT use it. It is non-flammable, non-VOC (i.e., Exempt) and US EPA 'SNAP' approved. It is even legal in Los Angeles (SCAQMD)where they are really strict. Asahi's website is http://www.AK-225.com. Good luck.

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DO NOT Mix Technologies....

If you are using a no clean solder paste use a no clean wave solder process. I have direct experience with using a no clean paste and a RA water-soluble wave solder process. When cleaning with the water wash system your �NO-Clean� joints will hydrate and become white. I will challenge the best cleaners on the market to remove a no-clean residue that has hydrated.

I will buck the system and contend that a water-soluble system works very well in all circumstances. The process has a very wide window so optimization is not as crucial for good results.

Whatever you chose DO NOT MIX....

Good luck,

Kevin

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