Effect of Reflow Time on Mechanical and Electrical Properties of Sn-3.5Ag Solder Joints

Sn-3.5Ag 솔더 접합부의 기계적.전기적 특성에 미치는 리플로우 시간의 효과

  • 구자명 (성균관대학교 신소재공학부) ;
  • 문정훈 (수원과학대학 일렉트로닉스패키징과) ;
  • 정승부 (성균관대학교 신소재공학부)
  • Published : 2006.05.01

Abstract

We investigated that the metallurgical, mechanical and electrical properties of the Sn-3.SAg/Cu ball grid array (BGA) solder joints at a reflow temperature of $255^{\circ}C$ for different reflow times of 10, 60, 300 and 1800 s. Two different intermetallic compound (IMC) layers, consisting of scallop-shaped $Cu_6Sn_5$ and very thin $Cu_3Sn$, formed at the solder/substrate interface, and their thicknesses increased with increasing reflow time. The shear force peaked after reflow for 60 s, and then significantly decreased with increasing reflow time. The fracture occurred along the solder ball in the initial reflow, but the fraction of the brittle fracture increased with increasing reflow time. The IMC growth and the volume of Cu dissolved in the solder balls affected the electrical property.

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