[sdiy] Board Cleaning, Was: Super S/H doc

charlie wallace charlie at finitemonkeys.com
Tue Jul 14 23:16:17 CEST 2015


curious how you deal with excess solder balls from paste in hand
assembly/hot plating without cleaning (at the small scale/hobby level)
?




On Tue, Jul 14, 2015 at 2:03 PM, Neil Johnson <neil.johnson71 at gmail.com> wrote:
> Sorry if the following offends, but I think after years of seeing
> these kinds of threads regularly pop up, I need to say it:
>
> STOP WASHING YOUR BOARDS!!!
>
> Seriously, most folks here don't understand what they're doing, and
> more than likely doing far more harm than good.  Any washing process
> is destructive at some level, and unless you have a washing system
> that completely and safely removes all contaminants all you are really
> doing is spreading the shit all over your boards rather than leaving
> it alone.
>
> And even if you DID clean your boards properly, there are plenty of
> components that you can't wash and so must be fitted after washing
> (pots, switches, wires, some capacitors, etc) leaving flux residues on
> the board.
>
> There are specific cases where cleanliness is important.  For example,
> Ian's S&H, but in this case the alcohol is to remove surface
> contaminants such as finger grease, which will otherwise increase
> surface leakage currents unless removed.
>
> The other thing I still don't "get" - water soluble flux in a hobby
> environment.  It is a highly-corrosive acidic flux.  Fine.  And you
> read the flux datasheet and they go into great detail about how to
> clean boards.  And that's fine for a production environment where the
> soldered boards are then put into a board cleaning machine, operated
> by folks who know what they are doing, regularly checking the cleaning
> process and following the manufacturer's instructions.  For example, a
> popular brand here in the UK is Hydro-X flux, and the datasheet has
> the following to say about cleaning:
>
> --
>
> CLEANING
> It is essential that the residues from soldering with Multicore
> Hydro-X cored solder wires be removed as soon as possible after
> soldering.  The residues from Multicore Hydro-X cored solder wires may
> be readily cleaned in conventional equipment using water. It is
> important that the cleanliness of boards and components is thoroughly
> checked after soldering and cleaning. The usual procedure is to
> continuously check the conductivity of the final rinse water as a
> measure of ionic contamination. Samples of cleaned boards should be
> subjected to a laboratory corrosion test, insulation
> resistance test, or ionic contamination assessment.
>
> --
>
> Simply rinsing a board under a running tap might appear to be ok, but
> how do you know you haven't left any drops of contaminated wash water
> in little corners or traps?  How do you check that you have correctly
> rinsed the board?  Do you check the conductivity of the rinse water?
> Or do you simply hope?
>
> In summary: use no-clean flux, don't clean unless one of the very rare
> cases where it is necessary.  Enjoy life.
>
> Neil
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