科研之友
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摘要
In order to investigate the microstructure and mechanical properties of small sized Sn-Bi bump, the eutectic Sn-Bi bumps with a diameter of 25 gm and a height of less than 20 mu m after reflow were fabricated by electroplating and reflow. The reflow temperature of the Sn-Bi bumps was 170 degrees C, and the reflow times were varied from 5 to 20 min. The experimental results showed that a eutectic Sn-Bi composition was obtained by plating at a current density of 30 mA/cm(2) for 15 min. The average height and diameter of the bumps reflowed for 5 min were 16.1 +/- 0.7 mu m and 25.2 +/- 0.7 mu m, respectively. The microstructure of the reflowed bumps consisted of Sn- and Bi-rich phases. The thickness of the IMC of Cu6Sn5 increased from 1.17 to 2.25 mu m with increasing reflow time from 5 to 20 min. The shear strength of the reflowed Sn-Bi bump increased with increasing reflow time, and reached approximately 11 gf at 15 and 20 min. The elastic modulus and hardness of eutectic Sn-Bi bump by nanoindentation were 53.5 and 0.43 GPa. Those of Cu6Sn5 were found to be 121.1 and 6.67 GPa.
- 出版日期2014-1
