Holes which have been metallized with conductive carbon cause
electrodeposited copper to "grow" across the hole wall surface until the
entire hole has been plated. The reason for the growth effect is simple.
Carbon is relatively high in resistance compared to copper. Thus a voltage
drop will develop a small distance across the carbon surface from the copper
cathode which it is contacting. Current density decays rapidly as distance
increases from the contacting point. The effect is copper starts to grow
longitudinally from the hole ends until meeting half. Once copper has
completely covered the entire hole wall the plating thickness begins to clim
vertically.

The copper cladding foil on the surface will begin to plating immediately
where as the hole wall always lags behind. I am interested in knowing is how
long of a time (or how many mils of electroplated copper) does it take
before the hole wall reaches the point of completely covered with copper
(hole initiation). I understand the answer depends on many variables, such
as plating C.D. and bath additives.

What are the typically hole wall initiation times in a commercial process,
such as BLACKHOLE ?


Adam Seychell

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------