One of the problems with many "no-clean" fluxes is that they sublimate 
and re-condense on cooler parts. I've often seen connector issues, such 
as you describe. Easy cure: have a mating connector in place during 
soldering!

Brian

Phil Nutting wrote:
> Good afternoon,
> 
> A problem has cropped up with a board built by a CM.  The board was
> soldered using a no-clean flux (I don't know which one yet) and
> apparently it got on the fine pitch pins of a micro D-Sub rendering the
> board non-functional because of the insulative layer of flux on some or
> all pins.
> 
> So if you are sending a board to a CM;
>     do you specify the method of cleaning the board?
>     do you specify parts that must be clean after the build?
>     if no-clean is used, but you require a clean board to a specific IPC
> level, isn't it better to use an OA or RMA washable flux?
> 
> Replacing these connectors my be more costly than simply trashing the
> boards due to the time to remove and replace the connectors not to
> mention the possible reliability issues.  I believe the only feasible
> method of removing this connector is with a selective soldering system
> so all 64 pins can be unsoldered at the same time.  Don't have one of
> these systems.
> 
> Assuming I can find out what flux was used is there a way to clean these
> connectors successfully?  Sounds like a call to Zestron.
> 
> Thanks in advance.
> 
> Phil Nutting
>     
> 
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