Hi Julie,

Pd causes low current density smut on your panels.  You wouldn't see it with
electroless copper.  Some Pd-based direct metallization systems are more prone
to it then others.  The reason you can't re-create the effect on a Hull cell
panel is that it doesn't see the Pd activator.  You will see it however, if you
process a Hull cell panel -- size piece of laminate through your direct plate
sequence and then plate it in the Hull cell.  Did you try talking to your Acid
Copper and/or Direct Metallization supplier about the problem?

Eric Yakobson
Alpha PC Fab




Julie Dixon <[log in to unmask]> on 01/28/2000 05:32:30 AM

To:   [log in to unmask]
cc:
Subject:  [TN] Fwd: TEMPERATURE EFFECTS ON ACID COPPER PLATING



Dear Net,

We've been having a great deal of trouble with smutting in low Asf areas of
our
Pcb's since the cold snap. Our acid copper plating bath is LeaRonal's PCM
Plus.
The bath is room temp.. Last week the bath was at 78 F, this week it is at
74F.
The other big factor is the preplate line. The rinses are normally heated to
85-88 F.
A malfunction caused the temps to be at 58 F. The acid dip must have been
affected
by the cold panels because its room temp is now 64 F. We started applying
35-40
Asf initially to avoid low current area smutting. It helps. We just
discovered the rinse
temp prob. and bath temp variation. Could someone explain cold panel issues
and
the mechanism of this smutting? The panels entered the tank at 64 F. Why
don't
they all smut? Only about 20-30% smut. I adjusted the rectifier as I loaded
each
panel. We use direct metallization-Pd vanillin-.
I can't recreate in the hull cell. Test panels look good.
Thanks,
Julie Dixon

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