2024

Vol.31 No.3

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  • Journal of the Microelectronics and Packaging Society
  • Volume 28(2); 2021
  • Article

Review

Journal of the Microelectronics and Packaging Society 2021;28(2):65-70. Published online: Mar, 18, 2022

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DOI : 10.6117/kmeps.2021.28.2.065

Interfacial and Mechanical Properties of Sn-57Bi-1Ag Solder Joint with Various Conditions of a Laser Bonding Process

  • Byeongjin Ahn1,2, Gyeong-Yeong Cheon1,2, Jahyeon Kim1,2, Jungsoo Kim1, Min-Su Kim1, Sehoon Yoo1, Young-Bae Park1, Yong-Ho Ko1,3,†
    1Korea 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 Technology, University of Science and Technology (UST), Daejeon 34113, Republic of Korea
Corresponding author E-mail: yonghoko@kitech.re.kr
Abstract

본 연구에서는 레이저 접합 공정을 이용하여 flame retardant-4 (FR-4) 인쇄회로기판 (printed circuit board, PCB)의 organic solderability preservative (OSP) 표면처리 된 Cu pad와 전자부품을 Sn-57Bi-1Ag 저온 솔더 페이스트로 접합을 한 후 접합부의 계면 특성과 기계적 특성에 대하여 보고 하였다. 레이저 접합 공정은 레이저 파워 및 시간 등을 다르게 진행하여 접합 공정 조건이 접합부의 계면 및 기계적 특성에 미치는 영향을 살펴보았다. 레이저 접합 공정의 산 업적 적용을 위하여 산업적으로 많이 이용되고 있는 리플로우 접합 공정을 이용한 접합부의 특성과도 비교 하였다. 레이 저 접합 공정 적용 결과 2, 3 s의 짧은 공정 시간에도 계면에 Cu6Sn5 금속간화합물 (intermetallic compound, IMC)를 생 성하여 접합부를 안정적으로 형성함을 확인 하였다. 또한, 리플로우 공정과 비교해 보았을 때 레이저 접합 공정을 적용할 경우 접합부의 보이드 형성이 억제됨을 확인할 수 있었으며 접합부의 전단강도도 리플로우 공정 접합부보다 높은 기계 적 강도를 나타냈다. 따라서, 레이저 접합 공정을 적용할 경우 짧은 접합 공정 시간에도 불구하고 안정적인 접합부 형성 및 높은 기계적 강도를 확보할 수 있는 것으로 기대된다.
In this study, interfacial properties and mechanical properties of joints were reported after Cu pads finished with organic solderability preservative (OSP) on flame retardant-4 (FR-4) printed circuit board (PCB) and electronic components were joined with a Sn-57Bi-1Ag solder paste by using a laser bonding process. The laser bonding process was performed under various bonding conditions with changing a laser power and a bonding time and effects of bonding conditions on interfacial and mechanical properties of joints were analyzed. In order to apply for industry, properties of bonding joints using a reflow bonding process which are widely used were compared. When the laser bonding process were performed, we observed that Cu6Sn5 intermetallic compounds (IMCs) were fully formed at the interface although the bonding times were very short about 2 and 3 s. Furthermore, void formations of the joints by using the laser bonding process were suppressed at the joints with comparing to the reflow bonding process and shear strengths of bonding joints were higher than that by using the reflow bonding process. Therefore, in spite of a very short bonding time, it is expected that joints will be stably formed and have a high mechanical strength by using the laser bonding process.

Keywords interfacial property, mechanical property, Sn-57Bi-1Ag, laser bonding, Cu OSP, intermetallic compound