Thermal fatigue and failure of electronic power device substrates

S. Pietranico, S. Pommier, S. Lefebvre, S. Pattofatto

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Electronic power devices used for transportation applications (automotive and avionics) experience severe temperature variations, which promote their thermal fatigue and failure. For example, for power modules mounted on the engine of an aircraft, temperature variations range from -55 °C (in the worst case of storage before takeoff) to +200 °C (flight). Direct bonded copper (DBC) substrates are used to isolate chips (silicon dies) from their base plates. For large thermal amplitudes, the failure occurs in DBC substrates, which are copper/ceramic/copper sandwiches. The Weibull approach was used to model the brittle fracture of the ceramic layer from a natural defect. Furthermore, geometric singularities in the upper ceramic/copper interface are at the origin of cracks that grow by fatigue along the interface and finally bifurcate and break the ceramic layer. It is discussed how the framework of linear elastic fracture mechanics (LEFM) can be used to characterize the stress field around singularities and the associated risk of failure. These two criteria and the finite element method, allow analysing how a thermal loading history may modify the risk of failure of DBC substrates. It was shown, in particular, that three overcooling cycles should produce an "overload retardation effect". Experimentally, applying three "overload cycles" (-70 °C, +180 °C), prior to thermal fatigue cycles (-30 °C, +180 °C), increased very significantly the fatigue life of DBC substrates. This result shows that the fatigue life and the reliability of power electronic devices could be optimized using a thermo-mechanical approach of the problem and suitable failure criteria.

Original languageEnglish
Pages (from-to)1911-1920
Number of pages10
JournalInternational Journal of Fatigue
Volume31
Issue number11-12
DOIs
Publication statusPublished - 1 Nov 2009
Externally publishedYes

Keywords

  • Aluminium nitride
  • Copper
  • Overloads
  • Variable amplitude fatigue
  • Weibull

ASJC Scopus subject areas

  • Modelling and Simulation
  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering

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