Application of Kriging and radial basis function in power electronic module wire bond structure reliability under various amplitude loading Pushparajah Rajaguru ⇑ , Hua Lu, Chris Bailey Computational Mechanics and Reliability Group, University of Greenwich, London, United Kingdom article info Article history: Received 13 February 2012 Received in revised form 12 June 2012 Accepted 15 June 2012 Available online 29 June 2012 Keywords: Reduced order models Power electronic module Life prediction Kriging Radial basis Microsystems abstract This paper discusses life time prediction of wire bond structure in a power electronic module based on computational approach that integrates methods for high fidelity analysis, reduced order modelling, and life time prediction using reduced order model. This methodology is demonstrated for the design of a wire bond structure in a power electronic module with aim of reducing the chance of failure due to the wire bond lift off in power electronic module when a random load is applied to the aluminium wire. In particular, wire bond reliability of the power module related to the thermal fatigue material deg- radation of aluminium wire is one of the main concerns. In the power electronic module reliability, understanding the performance, reliability and robustness of wire bond is a key factor for the future development and success of the power electronic module technology, because wire bond lift off failure ignites other catastrophic failures. The main focus in this study is on the application of reduced order modelling techniques and the devel- opment of the associated models for fast evaluation and analysis. The discussion is on methods for approximate response surface modelling based on interpolation techniques using Kriging and radial basis functions. The reduced order modelling approach uses prediction data for the electro-thermo-mechanical behaviour of the power module wirebond design obtained through non-linear transient finite element simulations, in particular for the fatigue life-time of the aluminium wire attached to the silicon chip of the wire in the module. The reduced order models are used for the analysis of predicting the life time of the wire bond structure under random load. One of the widely used cycle counting algorithm, so called rainflow counting algorithm is utilised to count the cycles of temperature profile at the a specific point of the wire bond structure in a power electronic module. Using the cycle results from rainflow algorithm mean life time of the wire bond structure is predicted by a linear cumulative damage model such as Palmgren–Miner rule. This model is utilised to predict the mean fatigue life of the wire bond structure. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Power electronic modules (PEM) are self contained power electronics components that are widely used in various industries such as aerospace, automotive, alternative energy generation and distribution application for conversion and control of electrical power. PEMs have highly inhomogeneous structure, which consists of several layers of insulator or ceramic, conductor and semiconduc- tor, some metal wires, and other materials. These materials are assembled in the packaging process to form the power electronic circuit as in Fig. 1. The technology used during the packaging and manufacturing processes of the power electronic circuits are solder- ing, direct bond copper (DBC), wire bond, and pressure contact interconnect [1]. Power electronic modules usually dissipate large amount of heat and operate in harsh environment such as engines compartment of automobiles. Therefore today’s power electronic modules require far greater reliability with respect to electric per- formance, insulation efficiency, thermal performance, and strength. The development of power electronic technology is driven by huge demand to control electrical power for wide range of applica- tions. The power devices turn on turn off time has decreased from milliseconds to microseconds and even nanoseconds, depending on power level. The power range commanded by converters now ranges from micro-VA to several hundreds of mega VA. A volt–am- pere (VA) is the unit used for apparent power in electronics. Among the new power devices, insulated gate bipolar transistor (IGBT) de- vices are widely accepted and more and more are increasingly used in traction application such as locomotive, elevator, tram and sub- way. IGBT modules have become important devices for static power conversion, variable speed drives and uninterruptable power supplies. They have replaced bipolar transistors and metal oxide semiconductor field effect transistor (MOSFET) in many applications owing to suitable combination of frequency range 0142-1123/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijfatigue.2012.06.013 ⇑ Corresponding author. Tel.: +44 20 8331 8761; fax: +44 20 8331 8665. E-mail address: p.r.rajaguru@gre.ac.uk (P. Rajaguru). International Journal of Fatigue 45 (2012) 61–70 Contents lists available at SciVerse ScienceDirect International Journal of Fatigue journal homepage: www.elsevier.com/locate/ijfatigue