温度循环条件下镀层表面的Sn须生长行为

功能材料, 2007, 38(11): 1837-1840.

温度循环条件下镀层表面的Sn须生长行为

张金松 ^1, , 李娟娟 ^2, , 吴丰顺 ^3, , 朱宇春 ^4, , 安兵 ^5, , 吴懿平 ^6,

1.华中科技大学,武汉光电国家实验室,湖北,武汉,430074

2.华中科技大学,武汉光电国家实验室,湖北,武汉,430074

3.华中科技大学,武汉光电国家实验室,湖北,武汉,430074

4.华中科技大学,武汉光电国家实验室,湖北,武汉,430074

5.华中科技大学,武汉光电国家实验室,湖北,武汉,430074

6.华中科技大学,武汉光电国家实验室,湖北,武汉,430074

基金项目: 国家自然科学基金(10474024) 湖北省自然科学基金(2006ABA091)

关键词：纯Sn镀层 , Sn须 , 温度循环 , 热应力

Behavior of whisker growth from the pure Sn coating under the temperature cycling condition

采用TO220封装的电子元件,研究了在温度循环条件下,元件Cu引脚上纯Sn镀层的Sn须生长行为.研究发现,Sn须在温度循环条件下的生长呈现出较高速率、较高密度、较一致长度的特点.随着温度循环次数的增加,Sn须密度和长度不断增加;与此同时,镀层表面Sn须的附近区域出现凹坑.研究表明,Cu-Sn金属间化合物的生长速率很快,使得镀层内部压应力增大,Sn须生长驱动力增加;同时,不同材料热失配产生的低周疲劳热应力,为Sn须的生长提供了额外的驱动力.此外,交变的热应力更容易破坏表面氧化膜促进Sn须的生长.满足应力条件和取向条件的晶粒首先发生Sn须生长,高密度的Sn须生长诱发部分晶粒发生向内的变形,在镀层表面形成大量的凹坑.

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