We also ran into the same problem when using photoimageable coverlay
with immersion gold. After verifying venting on oven and cleaning
processes it was determined that the PIC was having an affect on the
copper surface.Our fix was to chanpe the manufacturing routing, by
subjecting Flex panels to immersion gold prior to PIC application.

> -----Original Message-----
> From: [log in to unmask] [SMTP:[log in to unmask]]
> Sent: Monday, March 16, 1998 2:33 PM
> To:   [log in to unmask]
> Subject:      [TN] Immersion gold on flexible circuits
>
> I am manufacturing flexible circuits using immersion gold over
> electroless
> nickel as the finish. If I use a polyimide covercoat there are no
> problems -
> but if I use a photoimageable coverlay the process appears to be hit
> and miss.
> Are dry film photoimageable coverlays subject to outgassing onto the
> copper
> surface leading to problems in the plating process.
>
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