First-principles investigation of the structural stability and electronic properties of Pd doped monoclinic Cu6Sn5 intermetallic compounds

作者：Shao Wei Quan^*; Lu Wen Cai; Chen Sha Ou

来源：Materials Science- Poland, 2014, 32(4): 592-596.

DOI：10.2478/s13536-014-0233-x

• intermetallic compounds (IMC)
• thermal stability
• site occupancy
• ab-initio calculations

Tri-layer Au/Pd/Ni(P) films have been widely used as surface finish over the Cu pads in high-end packaging applications. It was found that a thin (Cu,Pd)(6)Sn-5 IMC layer was beneficial in effective reducing inter-diffusion between a Cu substrate and a solder, and therefore the growth of the IMC layer and the EM (electromigration) processes. In this study, the structural properties and phase stability of monoclinic Cu6Sn5-based structures with Pd substitutions were studied by using the first-principles method. The (Cu,Pd)(6)Sn-5 structure with the 4e site substituted by Pd has the lowest heat of formation and is the most stable among (Cu,Pd)(6)Sn-5 structures. Hybridization of Pd-d and Sn-p states is a dominant factor for stability improvement. Moreover, Pd atoms concentration corresponding to the most stable structure of (Cu,Pd)(6)Sn-5 was found to be 1.69 %, which is consistent with the experimental results.

• 出版日期2014-12
• 单位青岛大学