Here
is a copy of 4 pictures of 7-year real time aging of silver and
copper
The pictures
are:
(1)
Silver Spoon - 10 years in the bag (taken out for trade shows
- no polishing)
(2)
Silver Lead frame - 10 years - unprotected after 9 months
is also in the picture
(3)
Copper Bus Bar (3 feet long in a torn bag - no corrosion
after 7 years) - this bar
is represented in the Bus Bar graph that shows corrosion after 7
days
(4) Integrated Circuit
Chip (IC Chip) -- this is a combination of the silver lead frame
(that forms the "feet" of the chip when bent) and tin
solder attaching the "feet" to the circuitry (the black
box) -- it is this multi metal point (where the tin solder contacts
the silver) where you get the worst corrosion.
This is a combination
of galvanic corrosion and atmospheric corrosion.
Galvanic corrosion occurs when you have two dissimilar metals
in contact with each other. The two metals set up an electrical connection
-- like biting aluminum foil with fillings in your teeth, what you
actually feel is electrical. Intercept,
being electrical in nature, actually blocks this electrical connection
between the two metals and acts as a
sacrificial electrode giving itself up instead of the metals reacting
-- thus stopping or significantly slowing the galvanic corrosion.
Intercept needs to be in intimate contact for this two work
though, but no other material on the market (except using zinc or
an actual sacrificial circuit) can protect against
galvanic corrosion. The unprotected
IC chip corroded to this extent in the picture after 6 months --
the Intercept protected chip was 7 years. Quite a difference.
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