If the electroplating current density is 100 mA/cm2 What will be the (deposition

Question

If the electroplating current density is 100 mA/cm2

What will be the (deposition) rate?

Hints: This is similar to the above problem, but the deposition method is electroplating instead of PECVD. The electroplating current tells us the amount of electric charge associated with the plating process. Q [coulombs]=I (Amps)×t [sec] Actually, they gave us the current density (100 mA/cm2), so every cm2 of the substrate is associated with 100 mA = 0.1 A of plating current. To relate the amount of charge to the amount of metal plated, we need Faraday’s constant F F = 96,485.3 Coulomb/mole. Also, nickel has a charge of +2 (this actually depends on the chemistry of the electroplating bath, but +2 is common.) Accordingly, every mole of nickel plated is associated with the 2 x 96,485.3 coulombs of charge of the plating current. The atomic mass of nickel = 56.7 grams/mole. The density of solid nickel is 8.912 grams/cm3. From all of this, you can figure out the electroplating deposition rate (microns/minute). The arguments above lead to equation 5.15 in text = mass = ItM/nF

Explanation / Answer

The amount of nickel deposited at the cathode and the amount dissolved at the anode are directly proportional to the product of the current and time and may be calculated from the expression m ¼ 1:095 aIt ð3:1Þ where m is the amount of nickel deposited at the cathode (or dissolved at the anode) in grams, I is the current that flows through the plating tank in amperes, t is the time that the current flows in hours, and a is the current efficiency ratio (see Chapter 1 for the definition of current efficiency). The proportionality constant (1.095) in grams per ampere hour equals M/nF, where M is the atomic weight of nickel (58.69), n is the number of electrons in the electrochemical reaction (2), and F is Faraday’s constant, equal to 26.799 A-h (more commonly given as 96,500 C). The proportionality constant must be multiplied by the actual electrode efficiency ratio if precise values are required. The anode efficiency for nickel dissolution is almost always 100% under practical electroplating conditions; that is, a ¼ 1 when estimating anode weight loss. I

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