Marvin,
There are a LOT of factors to look at when you are trying to obtain and
maintain good plating distribution. Here's a few quick ones to be going
on with.  I'm sure there'll be more.

Solution agitation, espescially if the filtration uses the same pump.
Air agitation
Board movement
Anode:cathode area ratio
Anode;cathode distance
Acid:copper ratio
Anode dimensions relative to the board
Connections
Cleanliness of dry film developer solution
Conductivity of direct metalisation if used.
Pulse plating
"Baffle plates" between anode & cathode
Precleaning chemistry

I guess none of the above will give you a big improvement on their own,
but by improving and controlling each of them you should see a good
overall improvement.
Depending on your particular set-up I would go for solution agitation
first.

Hope this helps

Geoff Layhe
www.lamar-uk.co.uk
> ----------
> From:         marvin v. picardal[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;marvin v. picardal
> Sent:         31 August 1999 22:24
> To:   [log in to unmask]
> Subject:      [TN] how to improve plating distribution
>
> TECHnet'rs,
> Greetings!!! PCB Geniuses
>
> I want to gather suggestions regarding items to be considered to
> maintain even distribution for copper plating. So far I have already
> evaluated the effect of board spacing, organic chemical dosage
> control, tank design modification. But the result shows only few
> developments.
>
> Other related principles such as that of mass transfer would be of
> great help.
>
> thank you.
>
>
> Marvin
> Chemical Engineer
> PWB
>
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