The role of nano and micro particles on partial discharge and breakdown strength in epoxy composites

Zhe Li*, Kenji Okamoto, Yoshimichi Ohki, Toshikatsu Tanaka

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

84 Citations (Scopus)


Epoxy composite is expected to become the substrate insulation of gate bipolar transistors (IGBTs) that can replace ceramics if it has high thermal conductivity. Fillers with high thermal conductivity were added to the epoxy resin, while this composite often suffers from lowering in breakdown (BD) strength. In order to reveal the above phenomena and to clarify the breakdown (BD) mechanism, we carried out experiments using several electrode structures, i.e. an MB-PWB (metal-base printed wiring board) insulation simulated structure, a rod-to-plane electrode for PD erosion resistance, and a sphere-to-sphere electrode for BD strength. As a result, it was clarified that the IGBT insulation breaks down after successive partial discharges (PDs), and the BD strength of microcomposite decreases with increasing the content of micro-fillers, while PD resistance of microcomposite is improved with increasing the content of micro-fillers. A trial was made to raise the once-lowered BD strength by adding nano-Al2O3 fillers. Above experiments were carried out for nanocomposites and nano-micro-composites. It was clarified that the nano-fillers can improve the PD resistance of composites obviously, while nano-fillers improve the BD strength of composite slightly. Such a phenomenon was found that the BD strength of composites was increased with the dispersion state of nano-fillers.

Original languageEnglish
Article number5931052
Pages (from-to)675-681
Number of pages7
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Issue number3
Publication statusPublished - 2011 Jun


  • Nano-omposite
  • PD resistance
  • breakdown strength
  • discharge
  • epoxy
  • erosion
  • nano-AlO
  • nano-micro-composite
  • surface

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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