Pressureless sintering multi-scale Ag paste by a commercial vacuum reflowing furnace for massive production of power modules

  • Haidong Yan
  • Yun-Hui MeiEmail author
  • Meiyu Wang
  • Xin Li
  • Guo-Quan Lu


Air is critical to Ag sintering. The Cu surface of the non-metallized direct-bonding-copper (DBC) substrate can be oxidized seriously for bonding power devices using Ag paste in air. In this paper, we presented a pressureless sintering approach for a multi-scale Ag paste in the formic acid vapor by a commercial vacuum reflowing furnace. The study found that the activation temperature of the formic acid vapor had an obvious effect on the sintering behavior of the multi-scale Ag paste. The multi-scale Ag paste could obtain much denser sintered Ag when the formic acid vapor was rapidly injected at 180 °C by the vacuum reflowing furnace. The sintered Ag necks larger than 0.4 μm and the porosity lower than 11.3% were achieved in formic acid vapor, which had better sintering behavior than Ag nanoparticles (NPs) paste. The thermal resistance of 1200 V/50 A half-bridge IGBT modules by sintering the multi-scale Ag paste in formic acid vapor was 0.41 °C/W, which was ~ 12% lower than those of the commercial IGBT modules using Pb92.5Sn5Ag2.5. This work could overcome the contradiction between the Ag sintering and the Cu oxidation of the non-metallized DBC substrate by the formic acid vapor in a commercial vacuum reflowing furnace. The method is extremely useful for the traditional manufacturer, who do not have to invest any new facilities for the sintering.



This work was supported by the National Natural Science Foundation of China (No. 51877147), the Science Challenge Project (No. TZ2018003), and the Tianjin Municipal Natural Science Foundation (No. 17JCYBJC19200). Dr. Yunhui Mei is the corresponding author of this work.


  1. 1.
    C. Chen, K. Suganuma, T. Iwashige, K. Sugiura, High-temperature reliability of sintered microporous Ag on electroplated Ag, Au, and sputtered Ag metallization substrates. J. Mater. Sci. 29(3), 1785–1797 (2018). Google Scholar
  2. 2.
    F. Yu, J. Cui, Z. Zhou, K. Fang, W. Johnson, M.C. Hamilton, Reliability of Ag sintering for power semiconductor die attach in high temperature applications. IEEE Trans. Power Electron. 32, 7083–7095 (2017). CrossRefGoogle Scholar
  3. 3.
    S. Noh, C. Choe, C. Chen, H. Zhang, K. Suganuma, Printed wire interconnection using Ag sinter paste for wide band gap power semiconductors. J. Electron. Mater. 29(17), 15223–15232 (2018). CrossRefGoogle Scholar
  4. 4.
    S. Wang, H. Ji, M. Li, C. Wang, Fabrication of interconnects using pressureless low temperature sintered Ag nanoparticles. Mater. Lett. 85, 61–63 (2012). CrossRefGoogle Scholar
  5. 5.
    S.Y. Zhao, X. Li, Y.H. Mei, G.Q. Lu, Study on high temperature bonding reliability of sintered nano-silver joint on bare copper plate. Microelectron. Reliab. 55(12), 2524–2531 (2015). CrossRefGoogle Scholar
  6. 6.
    M.S. Kim, H. Nishikawa, Influence of ENIG defects on shear strength of pressureless Ag nanoparticle sintered joint under isothermal aging. Microelectron. Reliab. 66–67, 420–425 (2017). CrossRefGoogle Scholar
  7. 7.
    G.Q. Lu, W. Li, Y. Mei, G. Chen, X. Li, X. Chen, Characterizations of nanosilver joints by rapid sintering at low temperature for power electronic packaging. IEEE Trans. Devices Mater. Reliab. 14(2), 623–629 (2014). CrossRefGoogle Scholar
  8. 8.
    D. Wakuda, M. Hatamura, K. Suganuma, Novel method for room temperature sintering of Ag nanoparticle paste in air. Chem. Phys. Lett. 441(4–6), 305–308 (2007). CrossRefGoogle Scholar
  9. 9.
    J. Li, X. Li, L. Wang, Y.H. Mei, G.Q. Lu, A novel multiscale silver paste for die bonding on bare copper by low-temperature pressure-free sintering in air. Mater. Des. 140, 64–72 (2018). CrossRefGoogle Scholar
  10. 10.
    R. Khazaka, L. Mendizabal, D. Henry, Review on joint shear strength of nano-silver paste and its long-term high temperature reliability. J. Electron. Mater. 43(7), 2459–2466 (2014). CrossRefGoogle Scholar
  11. 11.
    H. Zheng, D. Berry, K.D.T. Ngo, G.Q. Lu, Chip-bonding on copper by pressureless sintering of nanosilver paste under controlled atmosphere. IEEE Trans. Compon. Packag. Technol. 4(3), 377–384 (2014). Google Scholar
  12. 12.
    A. Hanss, G. Elger, Residual free solder process for fluxless solder pastes. Solder. Surf. Mount Technol. 33(2), 118–128 (2017). CrossRefGoogle Scholar
  13. 13.
    L.A. Navarro, X. Perpina, P. Godignon, J. Montserrat, V. Banu, Thermomechanical assessment of die-attach materials for wide bandgap semiconductor devices and harsh environment applications. IEEE Trans. Power Electron. 29(5), 2261–2271 (2014). CrossRefGoogle Scholar
  14. 14.
    W. Lin, Y.C. Lee, Study of fluxless soldering using formic acid vapor. IEEE Trans. Adv. Packag. 22(4), 592–601 (1999). CrossRefGoogle Scholar
  15. 15.
    M. Hosseinpour, S. Fatemi, S.J. Ahmadi, Y. Oshima, M. Morimoto, M. Akizuki, Isotope tracing study on hydrogen donating capability of supercritical water assisted by formic acid to upgrade heavy oil: computer simulation vs experiment. Fuel 225, 161–173 (2018). CrossRefGoogle Scholar
  16. 16.
    H. Zhang, S. Nagao, K. Suganuma, Addition of SiC particles to Ag die-attach paste to improve high-temperature stability; grain Growth kinetics of sintered porous Ag. J. Electron. Mater. 44(10), 3896–3903 (2015). CrossRefGoogle Scholar
  17. 17.
    H. Zhang, W. Li, Y. Gao, J. Jiu, K. Suganuma, Enhancing low-temperature and pressureless sintering of micron silver paste based on an ether-type solvent. J. Electron. Mater. 46(8), 5201–5208 (2017). CrossRefGoogle Scholar
  18. 18.
    H. Alarifi, A. Hu, M. Yavuz, Y.N. Zhou, Silver nanoparticle paste for low-temperature bonding of copper. J. Electr. Mater. 40(6), 1394–1402 (2011). CrossRefGoogle Scholar
  19. 19.
    S.C. Fu, M. Zhao, H. Shan, Y. Li, Fabrication of large-area interconnects by sintering of micron Ag paste. Mater. Lett. 226, 26–29 (2018). CrossRefGoogle Scholar
  20. 20.
    H. Yan, Y.H. Mei, X. Li, C. Ma, G.Q. Lu, A multichip phase-Leg IGBT module using nanosilver paste by pressure-less sintering in formic acid atmosphere. IEEE Trans. Electron Devices 65(10), 4499–5405 (2018). CrossRefGoogle Scholar
  21. 21.
    S. Fu, Y. Mei, X. Li, C. Ma, G.Q. Lu, A multichip phase-leg IGBT module bonded by pressureless sintering of nanosilver paste. IEEE Trans. Devices Mater. Reliab. 17(1), 146–156 (2017). CrossRefGoogle Scholar
  22. 22.
    E. Deng, Z. Zhao, P. Zhang, J. Li, Y. Huang, Study on the method to measure the junction-to-case thermal resistance of press-pack IGBTs. IEEE Trans. Power Electron. 33(5), 4352–4361 (2018). CrossRefGoogle Scholar
  23. 23.
    G. Bai, Guofeng. Low-temperature sintering of nanoscale silver paste for semiconductor device interconnection. Diss. Virginia Tech, 2005.
  24. 24.
    J. Yan, G. Zou, A. Hu, Y.N. Zhou, Preparation of PVP coated cu NPs and the application for low-temperature bonding. J. Mater. Chem. 21, 15981–15986 (2011). CrossRefGoogle Scholar
  25. 25.
    A. Hu, J.Y. Guo, H. Alarifi, G. Patane, Y. Zhou, G. Compagnini, C.X. Xu, Low temperature sintering of Ag nanoparticles for flexible electronics packaging. J. Appl. Phys. 97(15), 153117-153117-3 (2010). Google Scholar
  26. 26.
    W. Li, L. Li, Y. Gao, D. Hu, C.F. Li, H. Zhang, J. Jiu, S. Nagao, K. Suganuma, Highly conductive copper films based on submicron copper particles/copper complex inks for printed electronics: microstructure, resistivity, oxidation resistance, and long-term stability. J. Alloy. Compd. 732, 240–247 (2014). CrossRefGoogle Scholar
  27. 27.
    S. Inaba, Theoretical study of water cluster catalyzed decomposition of formic acid. J. Phys. Chem. A 118, 3026–3038 (2014). CrossRefGoogle Scholar
  28. 28.
    J. Yan, G. Zou, A. Wu, J. Ren, A. Hu, Y. Zhou, Pressureless bonding process using Ag nanoparticle paste for flexible electronics packaging. Scripta Mater. 66(8), 582–585 (2012). CrossRefGoogle Scholar
  29. 29.
    I. Kim, J. Kim, The effect of reduction atmospheres on the sintering behaviors of inkjet-printed Cu interconnectors. J. Appl. Techno. 108(10), 102807-1–102807-5 (2010). Google Scholar
  30. 30.
    F. Hermerschmidt, D. Burmeister, G. Ligorio, S.M. Pozov, R. Ward, S.A. Choulis, E.J.W. List-Kratochvil, Truly low temperature sintering of printed copper ink using formic acid. Adv. Mater. Phys. 3(12), 1800146 (2018). Google Scholar
  31. 31.
    J. Francl, W.D. Kingery, Thermal conductivity experimental investigation of effect of porosity on thermal conductivity. J. Am. Ceram. Soc 37(2), 99–107 (1954). CrossRefGoogle Scholar
  32. 32.
    H. Yan, Y. Mei, X. Li, P. Zhang, G.Q. Lu, Degradation of high power single emitter laser modules using nanosilver paste in continuous pulse conditions. Microelectron. Reliab. 55(12), 2532–2541 (2015). CrossRefGoogle Scholar
  33. 33.
    J. Feng, Y. Mei, X. Li, G.Q. Lu, Characterizations of a proposed 3300-V press-pack IGBT module using nanosilver paste for high-voltage applications. IEEE J. Em. Sel. Top. 6(4), 2245–2253 (2018). Google Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin UniversityTianjinChina
  2. 2.School of Materials Science and EngineeringTianjin UniversityTianjinChina
  3. 3.Department of Materials Science and EngineeringVirginia TechBlacksburgUSA

Personalised recommendations