Thermal fatigue effects on the temperature distribution inside IGBT modules for zone engine aeronautical applications T. Lhommeau a,b,c, * , X. Perpin ˜a ` b , C. Martin a , R. Meuret c , M. Mermet-Guyennet b , M. Karama a a E ´ cole National d’Inge ´nieurs de Tarbes, 47 Avenue d’Azereix BP 1629, 65016 Tarbes, France b PEARL, Alstom Transport Tarbes, Rue du Docteur Guinier-BP4, 65600 Semeac, France c Hispano-Suiza, RP Rene ´ Ravaux site de Villaroche-Re ´au, 77550 Re ´au, France Received 9 July 2007 Available online 4 September 2007 Abstract This work examines the thermal fatigue effects on the temperature distribution inside IGBT modules for aeronautical applications. Exactly, they are used in a very different application where temperature cycling due to the working environment is the most limiting fact. In this case, it is concluded that solder delamination does not present any restriction to module lifetime at short term (up to 60% of total delaminated area). In addition, it is proposed only determining the delaminated area behind devices, which is the main responsible of the thermal temperature increase. Ó 2007 Elsevier Ltd. All rights reserved. 1. Introduction The aircraft industry has recently made an important investment to incorporate power electronics technology in their products. Basically, they aim to replace the traditional hydraulic and pneumatic equipment with electric systems, to reduce the weight and operational cost of their products. As for instance it could be the thrust reverser system. Its function consists in activating the temporary diversion of an aircraft engine’s output so that the thrust produced is directed forward, rather than aft. Consequently, it acts against the forward travel of the aircraft, providing decel- eration. Thrust reversers are used by many jet aircraft to help slow down just after touch-down, reducing wear-out on the brakes and enabling shorter landing distances. In this particular application, the thrust reversal system should be basically composed by an electric motor and a power inverter, in which the IGBT module is one of the master pieces. Prior to mount such novel elements in real aircrafts, pre- vious specific studies especially focused on the power switch reliability are required. In contrast to other applica- tions, the IGBT modules adaptation to these harsh envi- ronmental conditions [1], e.g., high temperature cycles, moisture and cosmic ray phenomena, is a real quest. The several criteria already published in previous works [2] con- cerning both the packaging wear out effect on the module failure and their corresponding indicators determination could not apply in this case. Furthermore, the packaging technology has experienced a considerable reliability improvement in the last years, which reinforces the revision of such criteria in the present application. One of the main consequences of the thermal fatigue is the solder delamination between the substrate and base- plate. This phenomenon consists in the solder cracking between the metallised substrate and the baseplate because of the expansion coefficient mismatches between materials. This fact produces an increase in the package thermal resis- tance, eventually inducing a chip failure (device burn-out). 0026-2714/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.microrel.2007.07.093 * Corresponding author. Address: PEARL, Alstom Transport Tarbes, Rue du Docteur Guinier-BP4, 65600 Semeac, France. Tel.: +33 5 62 53 43 41; fax: +33 5 62 53 44 81. E-mail address: tony.lhommeau@lab-pearl.com (T. Lhommeau). www.elsevier.com/locate/microrel Microelectronics Reliability 47 (2007) 1779–1783