Of all the  non HASL surface finishes ENIG is the most durable and has  the
longest shelf life.
ENIG will survive standard storage conditions (exposed to ambient air) for
periods exceeding 12 months.
The same cannot be said about silver or tin.
Immersion silver will require resealing (not necessarily vacuum and all)
wrapping the boards in saram wrap to minimize prolonged exposure to sulfur
bearing air is all that is needed.
Immersion Tin has intermetallic issues that are formed over time sealed or
not.


Best  regards

George Milad
[log in to unmask]
National Accounts Manager  for Technology
Uyemura International Corporation
Technical Center
240  Town LIne Rd
Southington CT 06489
(516) 901 3874 (mobile)
(860)  793-4011 (office)
(860) 793-4020 (fax)

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