Dear Phil:

As you indicated, the potential for circumferential voiding exists in any direct
plating process that would remove the underlying copper from the conductive
deposit. This condition is commonly referred to as wedge voiding, as it exhibits
itself as a wedge shaped defect in cross sectional examinations. Further, this
condition manifests itself typically on the oxide treated surface of the foil
only.

Actual production using palladium based direct plating systems can occasionally
exhibit this defect, but the liklihood is not very great. Further, because
palladium systems can modify the process sequence to incorporate microetching
prior to conditioning, the chance of the defect occuring is further reduced.
Finally, substituting double treat foil for oxide treated foil will eliminate
the chance of wedge voiding in all but the most severe cases.

Kevin H. Baranowski
Atotech USA Inc.