Journal of the Microelectronics and Packaging Society (마이크로전자및패키징학회지)

The Korean Microelectronics and Packaging Society (한국마이크로전자및패키징학회)
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A Study on the Microstructure Formation of Sn Solder Bumps by Organic Additives and Current Density

유기첨가제 및 전류밀도에 의한 Sn 솔더 범프의 미세조직 형성 연구

  • Kim, Sang-Hyeok (Department of Materials Science and Engineering, Dong-A University) ;
  • Kim, Seong-Jin (Department of Materials Science and Engineering, Dong-A University) ;
  • Shin, Han-Kyun (Department of Materials Science and Engineering, Dong-A University) ;
  • Heo, Cheol-Ho (Substrate Solution, Samsung Electro-Mechanics) ;
  • Moon, Seongjae (Substrate Solution, Samsung Electro-Mechanics) ;
  • Lee, Hyo-Jong (Department of Materials Science and Engineering, Dong-A University)
  • 김상혁 (동아대학교 공과대학 신소재공학과) ;
  • 김성진 (동아대학교 공과대학 신소재공학과) ;
  • 신한균 (동아대학교 공과대학 신소재공학과) ;
  • 허철호 (삼성전기, 기판사업부) ;
  • 문성재 (삼성전기, 기판사업부) ;
  • 이효종 (동아대학교 공과대학 신소재공학과)
  • Received : 2021.03.17
  • Accepted : 2021.03.30
  • Published : 2021.03.30
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Abstract

For the bonding of smaller PCB solder bumps of less than 100 microns, an experiment was performed to make up a tin plating solution and find plating conditions in order to produce a bump pattern through tin electroplating, replacing the previous PCB solder bumps process by microballs. After SR patterning, a Cu seed layer was formed, and then, through DFR patterning, a pattern in which Sn can be selectively plated only within the SR pattern was formed on the PCB substrate. The tin plating solution was made based on methanesulfonic acid, and hydroquinone was used as an antioxidant to prevent oxidation of divalent tin ions. Triton X-100 was used as a surfactant, and gelatin was used as a grain refiner. By measuring the electrochemical polarization curve, the characteristics of organic additives in Triton X-100 and gelatin were compared. It was confirmed that the addition of Triton X-100 suppressed hydrogen generation up to -1 V vs. NHE, whereas gelatin inhibited hydrogen generation up to -0.7 V vs. NHE. As the current density increased, there was a general tendency that the grain size became finer, and it was observed that it became finer when gelatin was added.

미세화 되고 있는 PCB 솔더 범프 접합을 위해 종래 마이크로 볼에 의한 PCB 솔더 범프의 제조를 대신하여 주석 전기도금을 통한 패턴을 제작하기 위한 도금액을 제작하고 도금공정 조건을 찾는 실험을 진행하였다. SR 패터닝 후에 Cu 씨드층을 형성하고, 다시 DFR 패터닝을 통해 PCB 기판상에 선택성장이 가능한 패턴을 제작하였다. 도금액은 메탄술폰산을 기본액으로 하는 주석도금액을 사용하였으며, 2가의 주석이온의 산화를 방지하기 위해 hydroquinone을 첨가하였다. 표면활성제로는 Triton X-100를 사용하고, 결정립 미세화를 위해 gelatin을 첨가하여 시료를 제작하였다. 전기화학적 분극곡선을 측정함으로써, Triton X-100 및 gelatin 첨가제의 작용 특성을 비교하였으며, gelatin이 -0.7 V vs. NHE까지 수소발생을 억제하는 것에 비해 Triton X-100을 첨가하게 되면 -1 V vs. NHE까지 수소발생이 억제되는 것을 확인할 수 있었다. 결정립의 크기는 전류밀도가 증가하면서 미세화되는 일반적 경향을 나타내었으며, gelatin을 첨가하는 경우에 보다 더 미세해지는 것이 관찰되었다.

Keywords

References

  1. S. Joseph, and G. J. Phatak, "Effect of surfactant on the bath stability and electrodeposition of Sn-Ag-Cu films", Surface & Coatings Technology 202, 3023 (2008). https://doi.org/10.1016/j.surfcoat.2007.11.002
  2. Y. Qin, C. Liu, G. D. Wilcox, K. Zhao and C. Wang, "Electrodeposition of Sn-Cu Solder Alloy for Electronics Interconnection", 2009 11th Electronics Packaging Technology Conference, Singapore, 278 (2009).
  3. N. M. Martyak, and R. Seefeldt, "Additive-effects during plating in acid tin methanesulfonate electrolytes", Electrochimica Acta 49(25), 4303 (2004). https://doi.org/10.1016/j.electacta.2004.03.039
  4. Y. Goh, and A. S. M. A. Haseeb, "Studies on electrodeposition behavior of Sn-Bi alloys in plating baths modified by hydroquinone and gelatin", J. Mater Sci. 51, 5823 (2016). https://doi.org/10.1007/s10853-016-9883-x
  5. C. T. J. Low, and F. C. Walsh, "The stability of an acidic tin methanesulfonate electrolyte in the presence of a hydroquinone antioxidant", Electrochimica Acta 53, 5280 (2008). https://doi.org/10.1016/j.electacta.2008.01.093
  6. S. Joseph, and G. J. Phatak, "Effect of additives on the co-electrodeposition of Sn-Ag-Cu lead-free solder composition", Materials Science and Engineering B 168, 219 (2010). https://doi.org/10.1016/j.mseb.2010.01.017
  7. P. A. Kohl, "The High Speed Electrodeposition of SnPb Alloys", J. Electrochem. Soc. 129, 1196 (1982). https://doi.org/10.1149/1.2124086
  8. A. Sharma, S. Bhattacharya, S. Das, and K. Das, Applied Surface Science 290, 373 (2014).
  9. S.-H. Kim, S.-K. Hong, H.-H. Yim, H.-J. Lee, "Characterization of the SnAg Electrodeposits according to the Current Density and Cross-sectional Microstructure Analysis in the Cu Pillar Solder Bump", J. Kor. Inst. Surf. Eng. 48(4), 131 (2015). https://doi.org/10.5695/JKISE.2015.48.4.131
  10. Y.-N. Kim, J.-M. Koo, S.-K. Park, and S.-B. Jung, "Effect of Under Bump Metallization (UBM) on Interfacial Reaction and Shear Strength of Electroplated Pure Tin Solder Bump", J. Kor. Inst. Met. & Mater. 46(1), 33 (2008).
  11. S.-H. Kim, H.-K. Shin, C.-M. Park, D.-U. Kim, P.-R. Cha, U.-H. Lee, and H.-J. Lee, "Shape Change of Cu Pillar Solder Bump During Reflow Process and Its Modeling", Korean. J. Met. Mater. 53, 495 (2015). https://doi.org/10.3365/kjmm.2015.53.7.495
  12. I.-N. Jang, J.-H. Park, and Y.-S. Ahn, "Effect of reflow number and surface finish on the high speed shear properties of Sn-Ag-Cu lead-free solder bump", J. Microelectron. Packag. Soc. 16(3), 11 (2009).
  13. J.-M. Koo, C.-Y. Lee, and S.-B. Jung, "Effect of reflow number on mechanical and electrical properties of ball grid array solder joint", J. Microelectron. Packag. Soc. 14(4), 71 (2007).
  14. S.-H. Kim, B.-R. Lee, G.-T. Park, J.-M. Kim, S.-H. Yoo, and Y.-B. Park, "Effects of PCB surface finishes on the Mechanical and Electrical Reliabilities of Sn-0.7Cu Pb-free Solder Bump", Korean J. Met. Mater, 53(10), 735 (2015). https://doi.org/10.3365/kjmm.2015.53.10.735
  15. G. Kim, K. Son, G.-T. Park, and Y.-B. Park, "Effect of Current Densities on the Electromigration Failure Mechanisms of Flip-Chip Sn-Ag Solder Bump", Korean J. Met. Mater. 55(11), 798 (2017). https://doi.org/10.3365/KJMM.2017.55.11.798
  16. D.-H. Shin, J.-K. Cho1, and S.-G. Kang, "Study on Thermal Stability of the Interface between Electroless Ni-W-P Deposits and BGA Lead-Free Solder", J. Microelectron. Packag. Soc. 17(1), 25 (2010).
  17. J.-G. Lee, K.-S. Kim, J.-W. Yoon, and S.-B. Jung, "Analysis of Void Effects on Mechanical Property of BGA Solder Joint", J. Microelectron. Packag. Soc. 18(4), 1 (2011). https://doi.org/10.6117/KMEPS.2011.18.4.001
  18. L. Yin, P. Borgesen, "On the root cause of Kirkendall voiding in Cu3Sn", J. Mater. Res. 26(3), 455 (2011). https://doi.org/10.1557/jmr.2010.47
  19. C. Park, B. Yoo, and J. Lee, "Characteristics of Electroless Sn Plating Electrolyte using a Choline Chloride-Based Ionic Liquid", Korean. J. Met. Mater. 56, 645 (2018). https://doi.org/10.3365/KJMM.2018.56.9.645
  20. S.-H. Kim, H.-J. Lee, D. Josell, and T. P. Moffat, "Bottom-up Cu filling of annular through silicon vias microstructure and texture", Electrochim Acta 335, 135612 (2020). https://doi.org/10.1016/j.electacta.2020.135612
  21. C. S. Chen, C. C. Wan, and Y. Y. Wang, "Electrodepostion of Tin-Lead Alloy on a Rotating Disk Electrode in Methane Sulphonic Acid Solutions", Trans. IMF, 76(2), 54 (1998). https://doi.org/10.1080/00202967.1998.11871195
  22. W.-P Dow, M.-Y. Yena, S.-Z. Liaoa, Y.-D. Chiua, and H.-C. Huang, "Filling mechanism in microvia metallization by copper electroplating", Electrochimica Acta 53, 8228 (2008). https://doi.org/10.1016/j.electacta.2008.06.042
  23. W.-P. Dow, C.-C. Li, M.-W. Lin, G.-W. Su, and C.-C. Huang, "Copper Fill of Microvia Using a Thiol-Modified Cu Seed Layer and Various Levelers", J. Electrochem. Soc. 156(8), D314 (2009). https://doi.org/10.1149/1.3147273