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Vol.49, No.5, 411 ~ 419, 2011
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| Title |
| Fabrication and Characteristics of Electroplated Sn-0.7Cu Micro-bumps for Flip-Chip Packaging |
| 노명훈 Myong Hoon Roh , 이희열 Hea Yeol Lee , 김원중 Won Joong Kim , 정재필 Jae Pil Jung |
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| 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. |
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| Key Words |
| electronic materials, plating, mechanical properties, scanning electron microscopy, SEM, bonding |
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