To reduce the slivering of gold plated circuits in alkaline etchants, keep
the pH as low as you dare without sludging.  That means 8.0 or less if
possible.  The gold helps cause a  galvanic cell interaction between the
nickel and the copper so that the copper touching the nickel etches very
fast.  Solder and dry film don't form galvanic reactions, so the copper under
those etch resists is only removed by physical splashing or immersion etching
(very slow with alkaline.)

The use of thick nickel helps support the gold, and half ounce foil means
less time in the etchant.   In any case, the cross section of the trace may
look something like the letter "T".  

By the way, why do you need electroplated gold?  Combinations of electroless
nickel, electroless palladium, and immersion gold have been demonstrated to
solder, wire bond, and serve as touch contacts.  About the only thing I
haven't seen is edge connector contacts and someone has probably done that.
 Immersion metals cover the trace sidewalls, and don't have a chance of
slivers.

Dennis Fritz
MacDermid

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************