Dear Mr. Savard,

First of all, be assured that my purpose was not to confront you but just to
clarify the concept of the pulse periodic reverse technology and its
mechanism when applied to electrodeposition of copper onto PCBs.
In fact, for other applications, the use of this technique has actually the
purpose of 'really stripping' the metal already deposited on the cathode
during the reverse cycle and I just wanted to make clear that this is not
what is happening in the case that interests us (PCBs).

As said in a previous e-mail, the pros and cons of this technology are, now,
well known and defined altough I would make an additional comment.
There is a real need for improving the existing pulse periodic reverse (PPR)
technology and this being worked on. The PPR technique, as most of us know
it, is actually a static technique and therefore not fully optimizable for a
complex system as an electrolytic cell designed to plate copper onto a
complex board containing features as small holes, big holes, blind vias,
isolated traces, ground planes areas, etc...
The use of a static technique, in that case, is just a step but not a
satisfactory answer. We need to evolve to a dynamic technique which would be
able to integrate all the pulse characteristics necessary to the optimization
of a such system.
The Complex Wave Form (CWF) technique has been developed to head into this
direction of dynamic technology. Although slightly more complex, the CWF can
propose number of advantages as the use of a much lower reverse current
density.
As I explained it before, the goal is to redistribute the overall
polarization on the board in order to compensate for the primary current
distribution (geometry of the board). There are several ways to achieve this.
Pulse periodic reverse technology, as we described it, is one of them but
certainly not the only one.

This being said, we are currently working on the optimization of such dynamic
technique in order to provide PCB manufacturers with answers on how to answer
their customers requirement on increasing complex board designs without
sacrifying their productivity and producing better quality products.

Best Regards,
Stephan Menard
Electrochemist - Chemical Engineer
Micropulse Plating Concepts

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