Abstract
The effects of Sn layer orientation on the evolution of Cu/Sn joint interfaces were investigated. Three Sn layers possessing (112), (321) and (420) orientations were electroplated on polycrystalline Cu substrates respectively. The orientations of Sn layer preserved during reflowing at 250 °C for 10 s. After aging at 150 °C for different time, the interfacial microstructures were observed from the cross-section and top-view. The alignment between the c-axis of Sn and Cu diffusion direction significantly sped up the Cu diffusion, leading to the thickest intermetallic compound layer formed in (112) joint. Two types of voids, namely, intracrystalline voids and grain islanding caused intercrystalline voids generated at Cu/Cu3Sn interfaces due to the different interdiffusion coefficients of Cu and Sn (112) oriented Sn/Cu joint produced many more voids than (321) joint, and no voids were detected in (420) joint. Therefore, to enhance the reliability of solder joints, using (420) oriented Sn as solder layer could be an efficient way.
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This work is sponsored by National Nature Science foundation of China (61376107) and the National Basic Research Program of China (973 Program, 2015CB057200). We also thank the Instrumental Analysis Center of Shanghai Jiaotong University for the use of SEM/EDX equipment.
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Sun, M., Zhao, Z., Hu, F. et al. Effects of Sn Layer Orientation on the Evolution of Cu/Sn Interfaces. Electron. Mater. Lett. 14, 526–532 (2018). https://doi.org/10.1007/s13391-018-0048-8
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DOI: https://doi.org/10.1007/s13391-018-0048-8