Electromigration에 의한 Sn-0.7Cu 솔더 금속간화합물 성장 예측 |
허민혁1,3, 강남현1,2, 박성훈3, 김준기4, 홍원식5 |
1부산대학교 차세대전자기판회로학과 2부산대학교 재료공학과 3부산대학교 기계공학부 4한국생산기술연구원 용접접합그룹/마이크로조이닝센터 5전자부품연구원 융복합전자소재연구센터 |
Kinetics of Intermetallic Compounds Growth Induced by Electromigration of Sn-0.7Cu Solder |
Min-Hyeok Heo1,3, Namhyun Kang1,2, Seonghun Park3, Jun-Ki Kim4, Won Sik Hong5 |
1Education Program for SAMSUNG Advanced Integrated Circuit, Pusan National University, Busan 46241, Republic of Korea 2Department of Materials Science & Engineering, Pusan National University, Busan 46241, Republic of Korea 3Department of Mechanical Engineering, Pusan National University, Busan 46241, Republic of Korea 4Welding & Joining R&D Group/Micro-Joining Center, Korea Institute of Industrial Technology, Incheon 21999, Republic of Korea 5Electronic Convergence Materials & Device Research Center, Korea Electronics Technology Institute, Gyeonggi-do 13509, Republic of Korea |
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Received: 7 April 2016; Accepted: 17 June 2016. Published online: 5 December 2016. |
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ABSTRACT |
The reliability of printed circuit boards (PCB) has emerged as a critical concern as the size of solder bump decreases and current density to solder bump increases by fine pitch formation. The main failure mode of solder bumps is open-circuits due to void formation as intermetallic compounds (IMC) grow, mainly due to electromigration. This study modeled IMC growth by electromigration in Sn-0.7Cu solder bumps. The IMC produced in the reflow process grew again significantly due to electromigration upon application of electric current. The thickness of the IMC under electromigration increased as the current increased from 1 A (current density: 1.3 × 104 A/cm2) to 1.5 A (current density: 1.9 × 104 A/cm2). For the current density applied in the study, IMC growth of Cu6Sn5 was faster than that of Cu3Sn. The Nernst-Einstein relation was used to model the IMC growth induced by electromigration. The modeling results of Cu3Sn and Cu6Sn5 thickness showed good agreement with the experimental observations of IMC growth under electromigration. Specifically, a good prediction for Cu3Sn growth was derived for the current density of 1.3 × 104 A/cm2. However, the modeling values of 1.9 × 104 A/cm2 and Cu6Sn5 thickness showed a minor difference as compared with the experimental IMC thickness results. As the current density increased from 1.3 × 104 A/cm2 to 1.9 × 104 A/cm2, the solder bump probably evolved under heat generation, and the further effects of aging and thermomigration should be incorporated in the IMC growth. |
Keywords:
electromigration, Sn-0.7Cu solder, intermetallic compounds, current density, modeling |
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