Abnormal depletion of Cu metallization pads in line-bump-line solder joints under electron current stressing

作者：Ho C E^*; Yang C H; Chen C T; Chen B Z

来源：Thin Solid Films, 2015, 596: 216-221.

DOI：10.1016/j.tsf.2015.06.062

• Abnormal Cu depletion
• Electromigration
• Line-bump-line solder joint
• Current crowding
• Sn crystallographic orientation

We observed abnormal electromigration-induced Cu depletion in a traditional line-bump-line (Cu/Sn/Cu) solder joint with extremely high Cu depletion away from the current crowding region (CCR). Electron backscatter diffraction analyses showed that the beta-Sn crystallographic orientation of the solder alloy is responsible for this abnormal electromigration phenomenon. A pronounced depletion in Cu occurred when the Cu neighbored the Sn grains with c-axes parallel to electron flow, despite the fact that the current density distributed in this type of area was one order-of-magnitude lower than that of the CCR. This observation indicated that the current stress and beta-Sn crystallographic orientation played dominant roles in Cu depletion during electron current stressing. Finally, a new failure mechanism is proposed for electromigration in solder joints.

• 出版日期2015-12-1