Russ: the reasons, causes and solutions could form a long grocery list of
possibilities. Let me give some inputs.

1. It sound like your bath is destabilizing and plating out. It may already
be gone.
2. The roughness you are seeing is probably copper particles these are
creating plating sites to consume the bath and also plate out on the board.
3. Due you constantly filter the electroless bath to remove particulates? It
would help prevent this from happening.
4.Do you have two electroless tanks so you can pump over to a clean tank on
a routine basis to properly strip and clean the old electroless tank? If not
you should.
5. If possible pump out the bath and inspect for plate out. I would guess
the inside walls/floor and heater have copper build up which will continue
to cause more plate out, chemical consumption and instability. I so the tank
needs to be thoroughly stripped.
6. By now the bath may be so unstable that it's non-recoverable. You can
possibly save it by doing the filtering, tank stripping, 50% decant and
adding stabilizer. Or just bite the bullet and make up a new one.
7. Do you filter the catalyst? I would recommend a constant 10 micron filter
with a slow turn over and a 1 micron over night filter once a month. This
will help prevent particles and plate out in the electroless bath.
8. Are you are using an "accelerator" step after catalyst?
9. I'm assuming you are correctly analyzing maintaining the bath on a
routine basis. If making manual adds, add each component slowly one at a
time in separate areas of the tank with good air agitation.

There's a book full of additional causes and cures.

                                                        Good Luck


Mike Barmuta

Staff Engineer

Fluke Corp.

Everett WA

425-446-6076


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Russell Burdick
Sent: Thursday, January 15, 2004 12:39 PM
To: [log in to unmask]
Subject: [TN] eless copper


Hello everybody,

Today's chemistry question concerns electroless copper plating.

Problem is small nodules of copper deposited on the surface of the board and
in the holes at the electroless copper bath. Noticable differences in bath
operation is more foaming during plating and more foam present after plating
is completed. Also, a noticable black/dark green particulate visible on the
foam surface and eventually on the tank wall and equipment.

Have previously found and corrected excessive EDTA conc. ( indicating higher
than wanted proprietary bath chemicals ). Problem still exists but to a
lesser extent.

Thanks for all help.

Russ

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