Summary for constant current vs constant voltage Discussion
constant current vs. constant voltage is the core issue in this tin-lead strip plating question. Helen T. Buenaobra asked which rectifier type is better, whether anode-to-cathode ratio matters, and how to calculate anode area for round anode balls in baskets. Ted Mooney, P.E. answered that the ideal power supply is actually constant current density. If that is not available, he said constant current is preferable when the strip area stays the same, while constant voltage is better when the area changes. On anode-to-cathode ratio, he advised following the proprietary process supplier’s data sheet, but noted that 2:1 is typical and never less than 1:1. For basket anodes, he said to use the basket area as the anode area, not the total surface area of the individual balls.
Q. Hello Sir,
I am working with an electronic company that does electroplating using tin-lead plating process. We are using strip-to-strip high speed plating machine. Recently, we have a problem of high voltage due to slow dissolution of anodes. We are using constant voltage type of rectifier. My questions are:
1. What is better power supply, constant current or constant voltage?
2. Will anode to cathode ratio be important? What is the normal ratio?
3. How to compute for anode surface area if I am using round anode balls? Appreciate your feedback, Helen
Helen T.Buenaobra
Electronics ,solder plating – Binan, Laguna, Philippines
2004
A. The ideal power supply is actually constant current density. Lacking that, constant current if the strip is always the same area and constant voltage if not.
Your proprietary process supplier should give you a data sheet with the recommended anode to cathode area, but 2:1 is pretty typical, and never less than 1:1. Just use the area of the baskets as the area of the anode, not the total surface area of the individual balls.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
2004
Q. “Constant Current Constant Voltage Linear Power Supply”? I was curious if the power supply listed in my title would be a good one to electroplate with? Does it need to be just constant current? I need some advice please. I just bought one like listed in the title and I need to know if it is good to electroplate with. If not, what should I get? Thanks ahead of time!
Daniel Bonner
Hobbyist – Montgomery, Alabama, USA
August 18, 2012
A. Hi Daniel. A plating power supply must offer the ability to adjust the voltage as necessary (with a knob and meters of some sort). Purpose-built power supplies for plating go further, and also offer constant current density which automatically adjusts the output to match the size of the load; that is for production plating and a hobbyist probably doesn’t need it.
Any power supply must have sufficient capacity to offer the voltage and current you need for the application. Amperage requirement can vary from about 40-50 ASF for nickel plating to 150 ASF for chrome plating.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
August 19, 2012
Thank you for your reply. From what I gather, this one should be fine for small plating jobs.
Daniel Bonner
Hobbyist – Montgomery, Alabama, USA
August 27, 2012