| Title |
Fabrication and Characteristics of Electroplated Sn-0.7Cu Micro-bumps for Flip-Chip Packaging |
| Authors |
노명훈(Myong Hoon Roh); 이희열(Hea Yeol Lee); 김원중(Won Joong Kim); 정재필(Jae Pil Jung) |
| DOI |
https://doi.org/10.3365/KJMM.2011.49.5.411 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
electronic materials; plating; mechanical properties; scanning electron microscopy; SEM; bonding |
| Abstract |
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 10×10×6 ㎛in size, with 20㎛ 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/cm2 and 30 min respectively. The near eutectic composition of the Sn-0.72wt%Cu bump was obtained by plating at 10 mA/cm2 for 20 min, and the bump size at these conditions was 10×10×6 ㎛. The shear strength of the eutectic Sn-Cu bump was 9.0 gf when the shearing tip height was 50% of the bump height. |