Letter 39053

How much gap between anode and cathode for plating? [India] 

January 18, 2006

Dear sir,
I always have query abt the gap between the anode and cathode. I have tried alot of experiment. Then I found that with closer gap deposition is good and efficiency is good. wht be the best gap to produce the best cathode and why?
thanks and regards

Jayanta Hota
student in university - Gujarat

Plating solutions have resistance, so the smaller the gap, the less voltage is required. Making the gap as small as practical for the situation is often a good idea. The limitation is that if the anodes do not conform to the cathode, and the cathode has a shape, you will get poorer distribution because of the geometrical ratios.

Let's say you have a sheet to plate that has a bow to it such that if you placed a straitedge against it the ends would touch but there would be a 2-inch gap in the middle. Now you plate that sheet with a single straight and flat anode. If the anode is 12" from the ends of the sheet, it's 14" from the bowed area and you still have a decent current density in the bowed area. But if you reduce the gap so the anode is 1" from the ends of the sheet, it is 3" from the bowed area so the current density ratio is poor.

 
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

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