Hi Eric,

     You don't specify whether you are pattern plating or doing a panel
     plate, tent and etch process.  Also, you don't mention what kind of
     racking system you have in your plating line.  Finally, you don't
     really state what the result is, i.e., uneven line width/spacing,
     excessive overplating, inability to etch.  However, some things you
     might look at:

     1) How rigid are the cores held in the plating racks?  .005" core can
     bend and distort quite a bit from both the cathode agetation and
     solution agetation.  This can result in varying the anode to cathode
     distance which will result in uneven plating.  You may need to devise
     a frame that keeps the cores more rigid.

     2) How's your plating distribution in general?  a)across a panel,
     b)cell to cell, c) tank to tank?

     3) What ASF are you plating these at?  Lower ASF can help the
     uniformity across the panel.

     4) If you are pattern plating, how even is the current density across
     the panel?  Can internal thieving be added to level it out?

     We have some designs that require our using a "dot-pattern plate"
     approach, where we only expose the holes (and small annular ring) to
     plating, protecting the base copper.  Then print and etch.  You may
     need to do some light sanding to reduce the bumps around the holes
     prior to the second image.  Definitely a more costly approach, with 2
     image steps, but it works.

     These are only a few of the things you can be looking at.  I'm sure
     other technetters will have more.  Good luck.

     Hope this helps...Andy


______________________________ Reply Separator _________________________________
Subject: [TN] Buried Vias
Author:  "Blazi; Eric - LYPMPA" <[log in to unmask]> at
SMTPLink-Hadco
Date:    09/16/98 11:49 AM


Hi,

We are venturing into buried vias and are having trouble with the
plating and imaging.  The design parameters are five mil lines and
spaces on 1/2 ounce copper layers of five mil core.

Our main trouble seems to be in the plating process.  We are having
trouble applying a smooth layer of copper.

I would appreciate any help from my fellow technetters.

Thanks

Erci Blazi

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