Thermal resistance analysis by induced transient (TRAIT) method for power electronic devices thermal characterization. I. Fundamentals and theory

• Published in: IEEE transactions on power electronics 1998-11, Vol.13 (6), p.1208-1219
• Main Authors: Bagnoli, P.E., Casarosa, C., Ciampi, M., Dallago, E.
• Format: Article
• Language: English
• Subjects: Assembly; Circuits; Electrical resistance measurement; Electronic packaging thermal management; Power dissipation; Temperature measurement; Thermal management of electronics; Thermal resistance; Transient analysis; Vehicle dynamics
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/63.728348

In this paper, a careful theoretical analysis of the thermal dynamics of an electronic device and its package was carried out in order to study the problem of the equivalent thermal circuit implementation. It was found that the device temperature evolution in time is ruled by an infinite and convergent series of time constants. The knowledge of the first n terms of the time-constant spectrum obtained from the temperature transient measurements allows the complete characterization of a suitable and reliable equivalent thermal circuit structured as a Cauer low-pass network with n cells. The total thermal resistance is therefore evaluated as a sum of several contributions due to given parts of the whole system. The techniques allowing the physical identifications of these contributions are also discussed. Furthermore, the influence of plastic coverage on the device thermal behavior is taken into account. The proposed characterization method is also applied to one-dimensional (1-D) multilayered simulated structures in order to study the influence of the number of time constants used for the analysis and effects of local defects or modifications of the material thermal properties.