http://www.smtnet.com/express/200005/soldering/soldering.pdf

> I'm going to come right out and make this statement. You can laugh all you
> want, but the data proves that liquid fluxes are terrible!
>
> Not only for BGA rework, but pretty much any type of rework! They form
> particulates in the solder joints, they run all over, and they like to
> penetrate and boil. Many people do not realize that is one of the main
> causes of lifted pads.
>
> Let the screaming and moaning and hysterical laughing begin. I really
> don't care.
>
> I have been training operators in the companies I work for years and years
> to use only tacky fluxes for touchup, for simple rework, and for hot air
> or hot gas rework, as well as for molten solder fountain rework. I have
> qualified the use of tacky fluxes to replace liquid many, many times. The
> cleanliness results of both water soluble and cleaned RMA tacky fluxes are
> several times better than for liquid fluxes. The tacky fluxes seem to
> promote wetting much better than any liquid flux I have ever used, and I
> think I have used them all.
>
> Because the tacky fluxes are developed for worst-case conditions (hot gas
> and solder fountain rework) they actually work much better than any liquid
> flux I have ever tried.
>
> And they typically are much easier to confine to just the solder joint(s)
> you are trying to touchup or solder.
>
> And they don't evaporate or burn off before you even reach liquidus.
>
> And for about 10,000 other reasons, but one of the biggest is that once
> the operators try using tacky flux for all rework and touchup, they never
> go back.
>
> If the REACH folks decreed that there would be no more liquid flux
> allowed, beginning yesterday, it would not mean a thing to me. I would
> say, "Good riddance".
>
> Most liquid fluxes on the market today were developed for wave solder or
> selective solder use; they were never intended to be used as a benchtop
> flux. People adapted them for compatibility reasons.
>
> My feeling is that they should be limited to wave or selective solder
> processes.
>
> Use a good tacky flux of the same chemistry for everything else. Those
> from one particular solder company have always worked best for me.  God is
> the ____ and the Omega.
>
> But always qualify, qualify, qualify.
>
> dean
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bob Wettermann
> Sent: Tuesday, December 15, 2015 10:40 AM
> To: [log in to unmask]
> Subject: [TN] IPC 7095 and Liquid Fluxes for Rework
>
> Dear Technetters:
>
> In reviewing the IPC 7095 BGA guidelines I noticed a mention of liquid
> based fluxes for BGA rework. Has anyone heard of liquid fluxes being
> robust enough for Sn63 or lead-free rework processes?
>
>
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> Thanks
>
> Bob Wettermann/BEST
>
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