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From [log in to unmask] Thu Oct 31 16: |
43:13 1996 |
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Was soldermask on the board when it was run through electroless
Nickel/Immersion Gold?
If so, is the soldermask proven to be compatible with the electroless
Nickel bath?
If not, there was probably a lot of soldermask curing going on after
plating which will oxidize nickel through the porous immersion gold.
Thicker gold and/or an acid cleaner (to remove Nickel oxides) after the
curing will help.
Steve Sparkowich
Plating Engr.
[log in to unmask]
VIC BELDAVS <[log in to unmask]> Wrote:
|
| I sent this message earlier. At the same time, lost contact
| with Tech Net.
| I'm not sure if this message got through. If it did, I
| apologize for the
| duplication.
|
| We purchase some pc boards with immersion gold over nickel to
| obtain
| flat pads for better stenciling of solder paste. Our spec is
| 5-8
| microinches of immersion gold over 150-200 microinches of
| electroless
| nickel. We have generally been successful. The indications
| are that
| about one year ago when this was first implemented, the gold
| plating
| was coming in per the spec.
|
| At this point, however, we are seeing the gold thickness to
| be more in
| the range of 2-4 microinches. We are still doing OK except
| for one batch
| of boards that came in recently. There are solderability
| problems with
| these boards. This batch is also associated with a solder
| mask change.
| But we also have other immersion gold boards with the same
| solder
| mask change and no solderability problems.
|
| Could it be that 2-4 microinches is at the ragged edge where
| the gold is
| insufficiently robust to withstand further processing at the
| fabricator and
| in assembly?
|
| Does anyone else have similar experiences with immersion gold
| in the
| 2-4 microinch range?
|
| Is anyone consistently doing well with about 2-4 microinches
| of gold?
|
| Thanking you in advance.
|
| Vic
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