The plating process used is driven by technologies
     manufactured.  There are definite trade offs with each
     process, nothing is free.  Circuit boards are getting
     thicker and holes getting smaller,  while circuit
     designs are becoming more complex and performance like
     impedance control more critical.  Panel plate yields
     superior copper thickness distribution in the thru
     holes by minimizing current density variations,  yet in
     doing so adds copper thickness to the base foil which
     complicates the etching process for finer line and
     space technologies.  Pattern plated product is much
     easier to maintain tighter line tolerances at etch
     since base foil thickness is very uniform,  however
     copper thickness variations in the holes and on the
     surface features are much larger which can jeopardize
     hole tolerances and impedance.  There are many
     variables which help a manufacturer to define the best
     plating process for their application, things such as
     etch type (cupric vs. ammoniacal), product mix, other
     process capabilities such as image and lamination.

        Flash plating is just a combination of panel and
     pattern plate which attempts to gain some of the
     benefits of each process,  added steps in the
     manufacturing process are never good though and can
     greatly impact cost and capacity.

     Tony King
     Sanmena  Nashua N.H.
     603-886-0066


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Subject: [TN] Plating
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