520.494/580.495 Microfabrication Laboratory

Homework Assignment

Plating, Packaging and Yield

Reading: Chapter 8 of Jaeger (1st or 2nd edition).

Questions:

Note: When problem number  in the 2nd edition of the book differs from the 1st edition, the corresponding 2nd edition number is shown in parenthesis.

Q1:

Lets consider a laboratory setup (Galvanic cell) with a bar of Copper (Cu) and a bar of Silver (Ag) immersed in an electrolyte solution. The following are the REDOX half reactions and electrochemical potentials. The Gibbs free energy equals to the negative of the number of electrons exchanged, times the electrochemical potential, times the Faraday constant). For a reaction to spontaneous occur the Gibbs free energy must be negative.

Ag⁺ + e^– ->  Ag                                   E°= 0.80 V;

      Cu⁺⁺ + 2e^– ->  Cu                               E°= 0.34 V

(a)   Will Ag react with Cu⁺⁺? I.e. will we be able to plate Copper on the Silver bar

                                                      yes,    no

(b) Will Cu react with Ag⁺? In other words will we be able to plate Silver on the Copper bar

                                                      yes,     no

(c ) If you place a sheet of copper into a AgNO₃ solution what would  you see happen? What is the reaction?

Q2-7: Problems 8.2, 8.3(8.4), 8.4(8.5), 8.5(8.6), 8.11(8.14), 8.12(8.15)