Fabrication and Characteristics of Electroplated Sn-0.7Cu Micro-bumps for Flip-Chip Packaging

作者：Roh Myong Hoon; Lee Hea Yeol; Kim Wonjoong; Jung Jae Pil^*

来源：Journal of the Korean Institute of Metals and Materials, 2011, 49(5): 411-418.

DOI：10.3365/KJMM.2011.49.5.411

• electronic materials
• plating
• mechanical properties
• scanning electron microscopy (SEM)
• bonding

The current study investigates the electroplating characteristics of Sn-Cu eutectic micro-bumps electroplated on a Si chip for flip chip application. Under bump metallization (UBM) layers consisting of Cr, Cu, Ni and Au sequentially from bottom to top with the aim of achieving Sn-Cu bumps 10 x 10 x 6 mu m in size, with 20 mu m pitch. In order to determine optimal plating parameters, the polarization curve, current density and plating time were analyzed. Experimental results showed the equilibrium potential from the Sn-Cu polarization curve is -0.465 V, which is attained when Sn-Cu electro-deposition occurred. The thickness of the electroplated bumps increased with rising current density and plating time up to 20 mA/cm(2) and 30 min respectively. The near eutectic composition of the Sn-0.72wt%Cu bump was obtained by plating at 10 mA/cm(2) for 20 min, and the bump size at these conditions was 10 x 10 x 6 mu m. The shear strength of the eutectic Sn-Cu bump was 9.0 gf when the shearing tip height was 50% of the bump height.

• 出版日期2011-5