2024

Vol.31 No.2

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  • Journal of the Microelectronics and Packaging Society
  • Volume 29(3); 2022
  • Article

Review

Journal of the Microelectronics and Packaging Society 2022;29(3):55-61. Published online: Nov, 21, 2022

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DOI : 10.6117/kmeps.2022.29.3.055

A Study on Properties of Pb-free Solder Joints Combined Sn-Bi-Ag with Sn-Ag-Cu by Conditions of Reflow Soldering Processes

  • Jahyeon Kim1,2, Gyeongyeong Cheon1,2, Dongjin Kim1, Young-Bae Park2, Yong-Ho Ko1,3,†
    1Advanced Joining & Additive Manufacturing R&D Department, Korea Institute of Industrial Technology(KITECH), 156, Gaetbeol-ro, Yeonsu-gu, Incheon 21999, Korea, 2School of Materials Science and Engineering, Andong National University, 1375, Gyeongdong-ro, Andong-si, Gyeongsangbuk-do, 36729, Korea, 3Industrial Materials and Smart Manufacturing Engineering, University of Science and Technology(UST), Gajeong-ro, Yuseong-gu, Dajeon 34113, Korea
Corresponding author E-mail: yonghoko@kitech.re.kr
Abstract

본 연구에서는 용융온도가 중온계 무연 솔더인 Sn-3.0Ag-0.5Cu(SAC305)와 저온계 무연 솔더인 Sn-57Bi-1Ag 를 사용하여 형성된 복합 무연 솔더 접합부의 특성에 대하여 보고 하였다. SAC305 솔더볼이 형성된 ball grid array(BGA) 패키지와 Sn-57Bi-1Ag 솔더 페이스트가 도포된 flame retardant-4(FR-4) 인쇄회로기판(printed circuit board, PCB)을 리 플로우 솔더링 공정을 이용하여 복합 무연 솔더 접합부를 형성 하였다. 공정 온도 프로파일을 두 가지 형태로 달리하여 리플로우 솔더링 공정을 진행하였으며 리플로우 솔더링 공정 조건에 따른 계면 반응, 금속간화합물(intermetallic compound, IMC)의 형성, Bi의 확산 거동 등 복합 무연 솔더 접합부 계면 특성을 비교 분석 하였다. 또한, 열 충격 시험 을 통하여 리플로우 솔더링 공정에 따른 복합 무연 솔더 접합부의 신뢰성 특성을 비교하고 열 충격 시험 전후 전단 시험 을 진행하여 접합부의 기계적 특성 변화를 분석하였다.
In this study, properties of Pb-free solder joints which were combined using Sn-3.0Ag-0.5Cu (SAC305) Pbfree solder with a mid-temperature type of melting temperature and Sn-57Bi-1Ag Pb-free solder with a low-temperature type of melting temperature were reported. Combined Pb-free solder joints were formed by reflow soldering processes with ball grid array (BGA) packages which have SAC305 solder balls and flame retardant-4 (FR-4) printed circuit boards (PCBs) which printed Sn-57Bi-1Ag solder paste. The reflow soldering processes were performed with two types of temperature profiles and interfacial properties of combined Pb-free solder joints such as interfacial reactions, formations of intermetallic compounds (IMCs), diffusion mechanisms of Bi, and so on were analyzed with the reflow process conditions. In order to compare reliability characteristics of combined Pb-free solder joints, we also conducted thermal shock test and analyzed changes of mechanical properties for joints from a shear test during the thermal shock test.

Keywords SAC305, Sn-57Bi-1Ag, reflow soldering, combined Pb-free solder joint, interfacial reaction, intermetallic compound, reliability