| After RoHS released, the content of Pb element in electronic product is becoming stricter and stricter, and the electronic production is trending to Pb-free. More and more Pb-free materials are used in electronic product lead frame plating, such as pure Sn, Sn-Ag, and Sn-Bi. The Pb-free materials do be good to environment protecting and human health, which however will derivate relative problem. One of the most serious problems brought by Pb-free productin is tin whisker.To investigate the solution of tin whisker growth of pure tin finish, two series of experiment is carried out in this paper. One is contrast experiment, and the other is 5 factors and 2 levels interferential experiment. The samples prepared for these two kinds of experiments are all plating in real product line. And whisker acceleration tests are carried out following JESD22A121.01 tin whisker acceleration test standard. And the whiskers are inspected and measured in Scan Electronic Microscope, and the result will be record respectively.The contrast experiment result shows that, among the 5 factors of plating process which may affect tin whisker growth, only plating chemical and annealing have great effect to tin whisker growth. The other three factors, lead frame material, descale and neutralization, have little effect to whisker growth. The interferential experiment result is almost the same, which shows that plating chemical, neutralization and annealing affect whisker growth significantly while lead frame material and descale have little effect to whisker growth.Finally, the paper can be concluded that plating chemical and annealing are the two factors affect tin whisker growth most. The recommended plating process to mitigate whisker growth is methyl sulfonic acid plating chemical and E-260 neutralization and annealing. |
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