Hi Doug:

You are doing the right thing by using amperage to control your plating.
However it means your amperage is constant and your voltage is variable (at
least last time I've checked Ohm's law, it was like that...).

Your independent controls on your rectifier give you a freedom to set a
limiting voltage (enough to give you the required amperage).  Your amperage
should remain constant regardles of your voltage setting (assuming your
voltage is adequate).  Any increase in amperage will mean an increase in
current density and increase in plating rate in general (up to a limiting
current density, when polarization can do some nasty things to you).
Typically the lower current density (amperage), the better distribution you
get (but you pay for it by slowing the plating rate).

Other means of improving distribution are masking, anode orientation and
distance, plating bath parameters (concentration, agitation, temperature,
using "polarization agents") and pulse or PR plating.

Regards,

Paul


>We are currently using amperage as the sole set up parameter for our
>Electroplating operations.  (constant Voltage).
>
>Our rectifier has variable controls on both voltage and amperage but we
>have the voltage at a fixed position and only change aperage based on
>area being plated, (maintain constant ASF).
>
>Is there any advantage, (or disadvantage) to also adjusting voltage or
>adjusting voltage and amperage in a given situation. Would a reduction
>in voltage and increase in amperage (constant current) help smooth out
>high current density or low current density problems.
>
>Thanks in advance.
>
>
>Douglas Jeffery
>Electrotek, Inc.
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