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edfas.org 9 ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 19 NO. 4 assuming that the location to be opened is precisely known. Superimposition with an x-ray CT virtual slice of the PCB was useful for correctly placing the laser on top of the areas to be opened. Understanding the root cause of the failure is another challenge. This article showed that thermomechanical Fig. 12 Local misorientation mapping and associated histogram repartition for a thick solder joint Fig. 13 Local misorientation mapping and associated histogram repartition for a thin solder joint stresses applied to a solder joint generate the cracks. Those stresses originate from different phenomena: the resin CTE, the thickness of the solder joint, and its inter- nal ability to withstand shear stress. All three parameters have been optimized to enhance the reliability of the DC/ DC converter. ABOUT THE AUTHOR Jérémie Dhennin received his Master’s degree in micro- and nanophysics from the University of Paul Sabatier in Toulouse, France, in 2005. He joined NOVA MEMS as a research engineer working on multiphysical characterization and modeling of MEMS switches failure mechanisms. His research activities focused on radio-frequency MEMS switches reliability, failure analysis, and modeling, especially dealing with microcontact issues. Since 2012, Mr. Dhennin’s technical scope has evolved to more generic reliability issues, dealing with other types of MEMS or electronic components. His managerial experience and broad technical scope allowed him to assume the Chief Executive Officer position at NOVA MEMS (now ELEMCA) in early 2013. He is still involved in many failure analysis pro- cesses, dealing with both electronic devices and MEMS components.