Hi Ed,

        I can offer some guidelines from past experience at TI. We utilized
Titanium basket anodes with Copper nuggets of ca. 1.5" dia, and calculated the
entire area of the nuggets and then utilized an area of ca. 60% of that. The
copper will be plated from not only line of sight,  but also from the sides of
the baskets and I suppose to a minimun from the back. This figure seemed to
work well for us. If you are using Bar anodes, I would suggest that you use the
surface area facing the cathode Plus at least the sides of the bar as well.
Basket anodes seem to me the better choice, since you can always add nuggets as
the copper is depleted. The bars will finnally erode away decreasing the area.

The Anode to Cathode ratio we maintained was at least 2::1. If you get the
ratio too low this will result in anode polarization (stripping the film off
the anode and eventually resulting in Current loss and Voltage increase)

Anode bars or baskets should be shorter than the cathodes as the edges of
panels act as a hi current density area and naturally want to overplate. This
can compensate somwhat for this problem. The same holds true for the horizontal
position of the anode as well. Keep anodes within the geometric confines of the
cathode in as much as is possible.

I hope this is of some help, If I can be of more help Contact me off line.

Regards and lots of luck,

Les Connally

[log in to unmask]

>  From: Ed Cosper <[log in to unmask]>, on 9/23/97 10:41 AM:
>  We are currently doing some studies on our copper baths. Recently I have
>  been given some conflicting information/guidelines regarding cathode to
>  anode surface area ratios and distances. Could someone please provide me
>  with their preferences/experience to the following questions.
>
>  Q1. When calculating anode area, is only the surface facing the panels to
>  the calculated or
>         do you calculate the entire circumference?
>
>  Q2.  How much anode area should you have facing the panel surface area. The
>  most recent
>         information I have been given indicates you should have at least an
>  equal or 1/1 ration.
>         This would result in having at least  7- 21/2" anodes on each 42" bar
>  or 3 anodes facing
>         each panel with one anode in the middle.
>
>  Q3.  I have been told by some suppliers that you never want your anodes
>  shorter than your
>         panels yet I have recently been advised that my anodes should be
>  about 2 inches
>         shorter than my panels. I'm interested in getting feed back on this
>  matter.
>
>  All responses will be appreciated.
>
>  Ed Cosper
>
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