A good flux will protect throughout the reflow cycle, [except those that are
designed to disappear to low or no residue when the protection function is
done instead by nitrogen]. Nitrogen can improve some ordinary fluxes also
but should not normally be necessary.

After reflow?
All metals tarnish (except noble metals like gold). The rate at which they
tarnish is dependant on - obviously the metal - and also the ambient
conditions.  Pragmatically in an electronics manufacturing environment
suggest say 80-90% of the oxide that will form will have done so in a 3-4
hours for things like Sn63 solder.

Regards

Mike Fenner
Indium Corporation

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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of SUBSCRIBE Technet Karl
Loh
Sent: 24 June 2004 12:43
To: [log in to unmask]
Subject: [TN] Oxidation of reflowed solder


Hello,

During reflow, flux de-oxidizes solder.  After reflow, does the solder re-
oxidize?  If so, how long does it take?

Thanks
Karl

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