Length-Dependent Electromigration Behavior of Sn58Bi Solder and Critical Length of Electromigration
Length-Dependent Electromigration Behavior of Sn58Bi Solder and Critical Length of Electromigration
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DOI：
10.1007/s11664-016-5093-1
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发表时间：
2017-02
影响因子：
2.1
通讯作者：
Xu Zhao;M. Muraoka;M. Saka
中科院分区：
文献类型：
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作者：
Xu Zhao;M. Muraoka;M. Saka
在设计的测试结构基础上，对长度为50μm、100μm和150μm的Sn58Bi焊锡带在373 K电流密度为27 kA/cm2at下同时进行了电迁移（EM）测试。检测了长度相关的电磁行为，并讨论了机制。随着条带长度的增加，Bi原子更容易向阳极侧偏析，形成较厚的富Bi层或Sn-Bi混合丘。结果表明，回流的存在与焊点长度有关。回流很可能是由Sn58Bi焊料上形成的氧化层引起的。通过测量富Bi层的厚度，得到了Bi的漂移速度。焊点的临界长度为16μm，焊点长度与电流密度的临界乘积为43 A/cm。这一观察将有助于先进电子设备的设计，以预测电磁可靠性。
On the basis of a developed test structure, electromigration (EM) tests of Sn58Bi solder strips with lengths of 50μm, 100μm, and 150μm were simultaneously conducted at a current density of 27 kA/cm2at 373 K. Length-dependent EM behavior was detected, and the mechanism is discussed. Bi atoms were segregated to the anode side more easily as the strip length increased, which resulted in the formation of a thicker Bi-rich layer or Sn-Bi mixed hillocks. The results reveal the existence of back flow that depends on the solder joint length. The back flow is most likely caused by an oxide layer formed on the Sn58Bi solder. By measuring the thicknesses of the Bi-rich layers, the Bi drift velocities were obtained. The critical length of the solder joint and the critical product of the length and the current density were estimated to be 16μm and 43 A/cm, respectively. This observation will assist design of advanced electronic devices to anticipate EM reliability.