Here is my simplified version of what happens during pulse plating:

The biggest advantage of pulse plating is that the process gives more even
plating inside the though hole.
It has basically 2 plating phase:

1- A lower current plating setting that plates the whole part more or less
like conventional plating.
2- A higher current stripping, much shorter, that strips away the copper on
the most exposed areas.

Since conventional plating tend to have thick plating at the knee of the
hole and lower plating inside the hole, the reverse current pulse strips
away the copper at area like the outer traces and the knees, leaving most of
the copper that accumulated inside the hole, this makes the plating more
even all the way though. This is perfect for high differential aspect holes.


Disadvantage, lots of monitoring. Some parameters, mostly current densities
and timing of the pulses, must be carefully selected and closely monitored.
You do not want to strip away the surface copper too much and leave more
plating in the hole then on the surface.

There was an excellent article on in PCFab Magazine of July 1999 called PPR
Rectification (page 22+). PPR stands for periodic pulse reverse.

Alain Savard, B.Sc.
Chemical Process Analyst
CAE Electronics Ltd.
e-mail: [log in to unmask]

-----Original Message-----
From: brian carlson

   Can someone give me an insight on benefits or possible disadvantages to
pulse plating. I am interested to hear some stories of what happens to the
Cu thickness in the hole wall when aspects ratios increase to 15:1. Any
feedback is welcome.

Rgds,
Brian

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