Journal of the Microelectronics and Packaging Society (마이크로전자및패키징학회지)

The Korean Microelectronics and Packaging Society (한국마이크로전자및패키징학회)
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Effect of Reflow Number and Surface Finish on the High Speed Shear Properties of Sn-Ag-Cu Lead-free Solder Bump

리플로우 횟수와 표면처리에 따른 Sn-Ag-Cu계 무연 솔더 범프의 고속전단 특성평가

  • Jang, Im-Nam (Dept. of Materials Eng, Pukyong National University) ;
  • Park, Jai-Hyun (Research Institute of Industrial Science & Technology) ;
  • Ahn, Yong-Sik (Dept. of Materials Eng, Pukyong National University)
  • 장임남 (부경대학교 신소재공학부) ;
  • 박재현 (포항산업과학연구원) ;
  • 안용식 (부경대학교 신소재공학부)
  • Published : 2009.09.30
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Abstract

The drop impact reliability comes to be important for evaluation of the life time of mobile electronic products such as cellular phone. The drop impact reliability of solder joint is generally affected by the kinds of pad and reflow number, therefore, the reliability evaluation is needed. Drop impact test proposed by JEDEC has been used as a standard method, however, which requires high cost and long time. The drop impact reliability can be indirectly evaluated by using high speed shear test of solder joints. Solder joints formed on 3 kinds of surface finishes OSP (Organic Solderability Preservation), ENIG (Electroless Nickel Immersion Gold) and ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) was investigated. The shear strength was analysed with the morphology change of intermetallic compound (IMC) layer according to reflow number. The layer thickness of IMC was increased with the increase of reflow number, which resulted in the decrease of the high speed shear strength and impact energy. The order of the high speed shear strength and impact energy was ENEPIG > ENIG > OSP after the 1st reflow, and ENEPIG > OSP > ENIG after 8th reflow.

휴대폰 및 휴대기기의 낙하 충격에 대한 관심이 증가되고 있는 상황에서 솔더 볼 접합부의 낙하 충격특성은 패드의 종류와 리플로우 횟수에 영향을 받게 되어 이에 따른 신뢰성 평가가 요구된다. 이와 관련한 평 가법으로 일반적으로는 JEDEC에서 제정한 낙하충격 시험법을 사용하고 있으나 이 방법은 고 비용과 장시간이 소모되는 문제가 있어 본 연구에서는 낙하충격 특성을 간접적으로 평가하는 시험항목인 고속 전단시험을 실시하여 리플로우 횟수에 의해 성장하는 금속간 화합물 층과 OSP(Organic Solderability Preservative), ENIG(Electroless Nickel Immersion Gold) 및 ENEPIG(Electroless Nickel Electroless Palladium Immersion Gold) 등 표면처리에 따른 고속 전단특성을 비교, 분석하였다. 그 결과 리플로우 횟수가 증가함에 따라 IMC 층의 성장으로 고속 전단강도와 충격 에너지 값은 점차 감소하였다. 리플로우 횟수가 1회일 때는 ENEPIG, ENIG, OSP 순으로 고속 전단강도와 충격 에너지 값이 높았고 8회일 때는 ENEPIG, OSP, ENIG 순으로 충격 에너지 값이 높게 측정되었다.

Keywords

References

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