Two Laws to Know about Wafer Plating

To do a good job in wafer plating, two basic laws must be introduced, namely Faraday's first law of electrolysis and Faraday's second law of electrolysis.

0020-27113 CLAMP RING 6 SMF TI

Faraday's law of electrolysis is an empirical law derived by Michael Faraday through numerous experiments in the first half of the 19th century and published in 1834. Faraday's law of electrolysis is applicable to the redox process of all electrode reactions, and is the basic law of quantification in electrochemical reactions.

Faraday's first law of electrolysis
During electrolysis, the mass of the material precipitated on the electrode is directly proportional to the amount of electricity passing through the electrolyte.Mathematical Expressions:

m: mass of precipitated or dissolved substance (g); k: Electrolysis equivalent (g/C); Q: Electricity (Coulomb, C); I: Current (A); t: Power-on time (s).

In layman's terms:

The thicker the coating, the greater the amount of electricity that needs to pass through; If the current is stable, the longer the plating time, the thicker the coating; It can be used to control plating thickness, deposition rate, etc.

0020-21361 CLAMPING RING 6" AL JAPAN MAJOR

Faraday's second law of electrolysis
Under the action of the same electricity, the precipitation mass of different substances is directly proportional to their chemical equivalent.
Mathematical Expressions:

m1, m2: mass of different substances; E1, E2: The corresponding chemical equivalent (i.e. molar mass / number of charges).

To sum up the above two laws, we can get:

n = number of moles of the resulting substance [mol]; Q= Total Charge [C]; z= number of electron transfers in the product; F= Faraday constant 96 485 [C mol−1].

0020-25279 8"CLAMP RING

What is Faraday's law of electrolysis used for?
1. Calculate the mass of the material precipitated or dissolved on the electrode;

Predict plating thickness;

Design plating time and current;

Calculate the plating efficiency.