[josey.mathew]

Hi
I need to find the time taken to deposit a given volume of Cu on a metal. I got this formula in the web

The calculations for the time and desired thickness are done prior to the electroplating as shown below. Alternatively, the graphs may be used.

Find the exposed seed layer area A (the area which is not covered by the resist)
Choose the desired current density J in mA/m2. Smaller current densities give better quality films but take more time.
Calculate the amount of current needed I.
I=J*A

Calculate the time it will take using the equation:
Time = (t*r *F*n)/(J*M)


Where t = Film Thickness in μm

r = Density of Ni = 8.9g/cm3

F = Faraday constant = 96488 C/mol

n = No. of electrons available in Nickel = 2

J = Current Density in mA/cm2

M = Molecular weight of Nickel Electroplating solution = 58.71g/mol

Substituting the above values:


Time = (48.756217 *t)/ J

Where Time = Time measured in min



Is the formula correct
if so doesnt rate of deposition depend on conc. of electrolyte

 
as a sample calculation
If i need to deposit a 100um of Cu on a metal of dimensions 5*5*.1 cm^3 at J = 1.923mA/cm^2 (100mA by 52 cm^2) the time will be 40.16s

it means that deposition of 4.6436g of Cu will take place in 40s . Is it so fast

Thanks a lot for your replies

[Borek]

Time = (t*r *F*n)/(J*M)

Seems OK, just remember to use copper density and copper molar mass. You will also need to convert everything to the same units - you can't use μm and cm³ in the same equation without using some conversion factor. Use meters or cm in all places (surface, thickness and density).

if so doesnt rate of deposition depend on conc. of electrolyte

No, it depends only on the charge transferred. That's assuming 100% efficiency, as long as you use correct bath and correct voltage (whatever it means in your case) there should be no side reactions and 100% efficiency is a good approximation.

Edit: note that if the concentration of electryte is low you will be not able to reach high current densities, so in a way rate of deposition depends on the concentration - but amount of deposited metal is always directly proportional to charge transferred, that's the base of all electroplating - Faraday's law.

it means that deposition of 4.6436g of Cu will take place in 40s . Is it so fast

Check units, at 100 mA you will need around 40 hours to deposit this mass of copper.