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Vol.53, No.10, 735 ~ 745, 2015
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| Title |
| Effects of PCB surface finishes on the Mechanical and Electrical Reliabilities of Sn-0.7Cu Pb-free Solder Bump |
| 김성혁 Sung Hyuk Kim , 이병록 Byeong Rok Lee , 박규태 Gyu Tae Park , 김재명 Jae Myeong Kim , 유세훈 Se Hoon Yoo , 박영배 Young Bae Park |
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| Abstract |
| The effects of electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the interfacial reaction, and the mechanical and electrical reliabilities of a ball grid array (BGA) Sn-0.7Cu lead-free solder bump were systematically investigated. An in-situ annealing test was performed under three different temperatures to obtain the activation energy for the intermetallic compound (IMC) reaction. Additionally, the ball shear test was conducted under various high-speed loading conditions ranging from 10 to 3,000 mm/s. In addition, the electromigration (EM) test was performed at 13 0℃ with a current density of 5.0 × 103 A/cm2. During annealing, (Cu, Ni)6Sn5 IMC formed at the interface of the ENIG surface finish, while at the OSP surface finish, Cu6Sn5 and Cu3Sn IMCs formed. The activation energies for the total IMCs were 0.84 and 0.74 eV for ENIG and OSP, respectively. The maximum shear force increased with increasing shear speed in the ball shear test, while the shear energy decreased. Furthermore, OSP surface finishes have a similar shear strength with the ENIG surface finishes. The EM lifetime of ENIG surface finish was longer than that of the OSP surface finish because the ENIG surface finish acts as an effective diffusion barrier between the Cu substrate and solder. |
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| Key Words |
| electrical/electron materials, soldering, bonding, electromigrtion, strength, scanning electron microscopy, SEM |
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