Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
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Fabrication and Characteristics of Electroplated Sn-0.7Cu Micro-bumps for Flip-Chip Packaging

플립칩 패키징용 Sn-0.7Cu 전해도금 초미세 솔더 범프의 제조와 특성

  • Roh, Myong-Hoon (Dept. of Materials Science & Engineering, University of Seoul) ;
  • Lee, Hea-Yeol (Dept. of Materials Science & Engineering, University of Seoul) ;
  • Kim, Wonjoong (Dept. of Materials Science & Engineering, University of Seoul) ;
  • Jung, Jae Pil (Dept. of Materials Science & Engineering, University of Seoul)
  • 노명훈 (서울시립대학교 신소재공학과) ;
  • 이희열 (서울시립대학교 신소재공학과) ;
  • 김원중 (서울시립대학교 신소재공학과) ;
  • 정재필 (서울시립대학교 신소재공학과)
  • Received : 2011.02.01
  • Published : 2011.05.25
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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 $10\times10\times6$ ${\mu}m$ 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 $10\times10\times6$ ${\mu}m$. The shear strength of the eutectic Sn-Cu bump was 9.0 gf when the shearing tip height was 50% of the bump height.

Keywords

Acknowledgement

Supported by : 서울시

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