Journal of the Microelectronics and Packaging Society (마이크로전자및패키징학회지)

The Korean Microelectronics and Packaging Society (한국마이크로전자및패키징학회)
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Shearing Characteristics of Sn3.0AgO.5Cu Solder Ball for Standardization of High Speed Shear Test

고속전단시험의 표준화를 위한 Sn3.0Ag0.5Cu 솔더볼의 전단특성

  • 정도현 (서울시립대학교 신소재공학과) ;
  • 이영곤 (서울시립대학교 신소재공학과) ;
  • 정재필 (서울시립대학교 신소재공학과)
  • Received : 2011.02.16
  • Accepted : 2011.03.22
  • Published : 2011.03.31
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Abstract

Shearing characteristics of Sn-3.0wt%Ag-0.5wt%Cu ball for standardization of high speed shear test were investigated. The solder ball of 450 ${\mu}m$ in diameter was reflowed at $245^{\circ}C$ on FR4 PCB (Printed Circuit Board) to prepare a sample for the high-speed shear test. The metal pads on the PCB were OSP (Organic Solderability Preservative, Cu pad) and ENIG (Electroless Nickel/Immersion Gold, i.e CulNi/Au). Shearing speed was varied from 0.5 to 3.0 m/s, and tip height from 10 to 135 ${\mu}m$. As experimental results, for the OSP pad, a ductile fracture increased with tip height, and it decreased with shearing speed. In the case of ENIG pad, the ductile fracture increased with the tip height. The tip height of 10 ${\mu}m$ (2% of solder ball diameter) was unsuitable since the fracture mode was mostly pad lift. Shear energy increased with increasing shearing tip height from 10 to 135 ${\mu}m$ for both of OSP and ENIG pads.

고속전단시힘의 표준화를 위한 기초 연구의 일부로 Sn-3.0wt%Ag-0.5wt%Cu 솔더 볼의 고속전단특성에 대한 연구를 수행 하였다. 고속전단 시험편 제작을 위해 직경 450 ${\mu}m$의 솔더 볼을 FR4 PCB (Printed Circuit Board) 위에 장착한 후 $245^{\circ}C$ 온도에서 리플로 솔더링을 행하였다. PCB 상의 금속 패드로는 ENIG (Electroless Nickel/mmersion Gold, i.e Cu/Ni/Au)와 OSP (Organic Solderability Preservative, Cu 패드)를 사용하였다. 고속전단 속도는 0.5~3.0 m/s 범위, 전단 팁의 높이는 10~135 ${\mu}m$ 범위에서 변화시켰다. 실험결과로서, OSP 패드의 경우 전단 팁 높이 증가에 따라 연성 파괴가 증가하였으며, 전단속도 증가에 따라 연성파괴는 감소되었다. ENIG 패드의 경우에도 전단 팁 높이 증가에 따라 연성 파괴가 증가하였다. 전단 팁 높이 10 ${\mu}m$(볼 직경의 2%)는 패드 박리 파괴가 대부분이어서 전단파면 관찰에는 부적절한 높이였다. 고속전단에너지는 OSP 및 ENIG 패드 모두 전단 팁 높이 증가에 따라 증가하는 경향을 보였다.

Keywords

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