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Sn (Cu) film surface of tin whisker growth

Author: ZhangJunZhao
Tutor: WuPing
School: Tianjin University
Course: Materials Physics and Chemistry
Keywords: Tin whisker Electromigration Intermetallic compounds Current density
CLC: TB383.2
Type: Master's thesis
Year: 2010
Downloads: 104
Quote: 1
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Abstract

Whisker from tin or tin alloy layer grown on the surface of a thin layer of tin single crystals . It has a very high current load capacity, with serious damage to electronic components . Tin whisker growth phenomenon has been the electronic packaging industry is facing a major problem , so tin whisker formation mechanism become the focus of research . This under different conditions whisker growth were studied first by magnetron sputtering was prepared on Cu substrate having a thickness of 1200nm a pure tin film , they are placed in an argon atmosphere annealing at different temperatures , found that 50 ° C is whisker growth optimum temperature , at this temperature for whisker length and density are maximized. At high temperature, the elimination of residual stress within the sample and form intermetallic compounds cause changes in the sample surface to reduce the number of tin . Blech structure and the use of the mask approach , prepared on a glass substrate of pure tin and tin- copper film . By changing the addition amount of copper , tin-copper thin films studied by electromigration . Found that the electron wind and Joule heat of the low current density, the pure tin film will grow out of tin anode to the cathode is apparent atomic consumption area. As the current density increases , the film appears anode solder balls. For the purposes of SnCu film , Cu is added to change the internal and surface structure of the film . When the Cu content is low , the action of the applied current , the migration rate of Cu is greater than Sn, the film will form SnCu anode pellets . Improve the content of Cu , Cu and Sn, interdiffusion of atoms between the interior of the sample will form an intermetallic compound for inhibition of electromigration . We also believe that the diffusion mechanism of the sample to the grain boundary diffusion -based , Sn presence inhibits diffusion of the sample surface . Cu6Sn5 intermetallic compound on electromigration behavior study found that at lower current densities , the electromigration phenomenon is not obvious, but with the current density increase can be observed clearly electromigration phenomenon . By contrast SnCu film electromigration behavior of intermetallic compounds found to be much slower , electromigration in Blech effect led to its surface migration phenomenon .

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