Effect of Sn crystallographic orientation on solder electromigration and Ni diffusion in Cu/Ni plating/Sn–0.7Cu joint at low current density

• Published in: Journal of materials science. Materials in electronics Vol. 28; no. 17; pp. 12630 - 12639
• Main Authors: Kadoguchi, Takuya, Sakai, Tsubasa, Sei, Tsubasa, Take, Naoya, Yamanaka, Kimihiro, Nagao, Shijo, Suganuma, Katsuaki
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2017; Springer Nature B.V
• Subjects: Automobiles; Automotive engineering; Characterization and Evaluation of Materials; Chemistry and Materials Science; Copper; Crystallography; Current density; Detaching; Diffusion plating; Electrodes; Electromigration; Materials Science; Modules; Nickel plating; Optical and Electronic Materials; Orientation; Semiconductors; Solders; Tin; Parallel Region; Enlarge Scanning Electron Microscope Image; Power Module; Solder Joint; Electron Flow
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-017-7087-z

Electromigration (EM) in solder joints has recently been recognized as a serious reliability issue in the field of car electronics. EM in power modules is also of concern for next-generation environmentally-friendly vehicles. The current density of 10 kA/cm 2 is well-known as the threshold for EM failure. Few researches have studied the EM behavior of solders at realistic current densities lower than 10 kA/cm 2 . In the present study, EM in a Cu/Ni plating/Sn–0.7Cu joint was investigated at low current densities of 2.5 and 5.0 kA/cm². It was found that even at a low current density of 2.5 kA/cm 2 , severe EM damage can be induced depending on Sn crystallographic orientation. When the c -axis of Sn crystals was parallel to the direction of electron flow, the solder detached at the cathode of the joint operated at 2.5 kA/cm 2 for 2520 h. Conversely, when the c -axis of Sn crystals was perpendicular to the direction of electron flow, the solder did not detach in the joint until after a much longer time of 8200 h. Thus, it was clarified that the EM lifetime in a Cu/Ni plating/Sn–0.7Cu joint when the c -axis of Sn crystals was parallel to the direction of electron flow at a low current density of 2.5 kA/cm 2 was about one-third that of the perpendicular orientation.