Kathy, we went through the same (selective plating of fingers under
contacts and switch pads under carbon pills mounted on silicon) cycle.
Than we switched to flash gold ; the plate was too costly, and laborious
, with 0 gain .
The telecom life cycling showed no deterioration on flash gold within 1M
cycles on switching (telephones) , adequate ( no det.within 1K)
insertion on fingers (the gold smudges , rather than flakes, on Ni) .
That way you save on gold, and process steps, and problems with too much
gold as well .
We've got now the full boards with flash gold , with fingers ( similar
insertions statistics to yours) , and switch pads ;
and it's much easier and cheaper for everybody .
The Asian shops will give you NiAu actually cheaper than HASL , for a
lot of reasons .
In the end , get samples, realistic statistical assessment (majority
single insertion ?), accelerated life test (Jack or Werner can help you
with that) , and see it yourself .
We are actually discovering here that even the new AlphaLevel silver
with organic over (does not insulate) can be pushed quite far on fingers
(100) and switch pads (100K) , with miles better solderability on rest
of board. But the silver would not be for you .
The flash gold would .
See you Paul Klasek ; ResMed
>----------
>From: Kathy Palumbo[SMTP:[log in to unmask]]
>Sent: Wednesday, 11 March 1998 10:23
>To: [log in to unmask]
>Subject: [TN] Gold Flash vs Gold Plate on PCB connector Fingers
>
>Hey everyone. Can anyone help me out here? Our board vendor is trying
>to convince our purchasing department to use gold flash (about 7u"
>thick) on the PCB connector fingers instead of gold plate (about 30u"
>thick). We make memory boards. These boards will most likely be
>plugged in to a system one time, however there could be instances where
>they are installed and removed many times. We guarantee our boards for
>life. Won't the gold flake off, exposing the nickel and eventually
>cause opens if the nickel surface starts to oxidize? Could anyone tell
>me where I can find documented proof which supports this theory?
>
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