Electroplated indium bump arrays and the bonding reliability

A novel electroplating indium bumping process is described,as a result of which indium bump arrays with a pitch of 100μm and a diameter of 40μm were successfully prepared.UBM(under bump metallization)for indium bumping was investigated with an XRD technique.The experimental results indicate that Ti/Pt(300 A / 200 A)has an excellent barrier effect both at room temperature and at 200 ℃.The bonding reliability of the indium bumps was evaluated by a shear test.Results show that the shear strength of the indium bump significantly increases after the first reflow and then changes slowly with increasing reflow times.Such a phenomenon may be caused by the change in textures of the indium after reflow.The corresponding flip-chip process is also discussed in this paper.