Historical specs need to be viewed in their context: different board
designs, materials of construction, components, fluxes, cleaners and
expectations of performance.
It would be possible to argue that a modern semi-aqueous process is
effective and efficient enough that delayed cleaning is of no consequence
with regard to rosin/resin based materials. (usually type L sometimes M ).
Conversely modern cleaning solvent formulations can be very compromised by
environmental requirements, so similar can not be said of them. My
suggestion there would be to clean as soon as work is below the BP of the
solvent in use.
It's different on water washables (M and H). These can have activity after
soldering and thus may continue to interact with the work. Resulting
appearance may not be good and reaction products may not be water washable
in the process times you have, but could still be potentially hazardous.
Some manufacturers can formulate to allow delays for batching, misplacing
and so on but the general best practice rule remains: clean as soon as
possible after soldering.
Regards
Mike Fenner
Indium Corporation
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of - bogert
Sent: Thursday, July 24, 2008 12:09 AM
To: [log in to unmask]
Subject: [TN] Max time allowed between soldering and cleaning
July 23, 2008
J-STD-001 is silent on how long a time span is acceptable between wave or
reflow soldering and post cleaning for instances where cleaning is mandated
because organic Type M or H flux was used.
I believe the historical soldering specs MIL-STD-2000 and MIl-STD-454
requirement 5 mandated no more than one hour between cleaning and
solddering.
Is there a technically necessary maximum limit and if so is there data to
support it? If there is a technical supported limit why should we mandate
it in J-STD-001?
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