Abstract
A novel electroplating indium bumping process is described, as a result of which indium bump arrays with a pitch of 100 μm and a diameter of 40 μm were successfully prepared. UBM (under bump metallization) for indium bumping was investigated with an XRD technique. The experimental results indicate that Ti/Pt (300 Å / 200 Å) has an excellent barrier effect both at room temperature and at 200 °C. 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.
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