###### Abstract  
This paper presents the use of physics of failure (PoF) methodology to infer fast and accurate lifetime predictions for power electronics at the printed circuit board (PCB) level in early design stages. It is shown that the ability to accurately model silicon-metal layers, semiconductor packaging, printed circuit boards (PCBs), and assemblies allows, for instance, the prediction of solder fatigue failure due to thermal, mechanical, and manufacturing conditions. The technique allows a life-cycle prognosis of the PCB, taking into account the environmental stresses it will encounter during the period of operation. Primarily, it involves converting an electronic computer aided design (eCAD) circuit layout into computational fluid dynamic (CFD) and finite element analysis (FEA) models with accurate geometries. From this, stressors, such as thermal cycling, mechanical shock, natural frequency, and harmonic and random vibrations, are applied to understand PCB degradation, and semiconductor and capacitor wear, and accordingly provide a method for high-fidelity power PCB modelling, which can be subsequently used to facilitate virtual testing and digital twinning for aircraft systems and sub-systems. power electronics; physics of failure (PoF); printed circuit board; finite element analysis (FEA) 202115 March 20  
As the design evolves into the manufacturing stage, additional information becomes available to the design in terms of maintenance, repair, and overhaul in-service data which may be fed back into the design process, leading to changes and modifications to the design. This in-service data (ISD) is extremely useful in trend monitoring to track routine airplane performance using the parameters of flight hours and landings, component removals and failures, component no-faults-found (NFFs), airplane schedule reliability, and maintenance action rates. The processed data is also used to understand, in greater detail, what is driving the high-level trend data; for instance, if there is a change in the meantime between unscheduled removal for a particular component. In addition to trend analysis, the ISD may be used for new system development, including system improvements and requirement settings. The huge variety of different materials and components used on an aircraft make product stewardship essential to managing the environmental impacts of different components and materials, and at different stages in their production, use, and disposal. Ensuring compliance is becoming increasingly important to modern designs. This design cycle highlights the need to explore innovative tools to improve the design process, in particular the initial and detailed design and analysis stages. Developing reliability into the design at this stage helps improve the overall availability and maintainability of aircraft systems. Keeping the aforementioned in perspective, this paper presents how modern computer-aided engineering (CAE) tools can be used optimally to evaluate the overall reliability of an electronic system from an initial design, in this case an off-the-shelf power electronic evaluation module. We employ physics of failure (PoF), or reliability physics, which makes use of degradation algorithms that describe how physical, chemical, mechanical, thermal, or electrical mechanisms can decline over time and eventually induce failure. Utilizing PoF allows derivation of accurate predictions of the failure behavior of next-generation components, including silicon transistors, wire bonds, solder bumps, die attach, light-emitting diodes, electrolytic capacitors, plated through-holes, and solder joints. Printed circuit board (PCB) modelling and simulation facilitates design failure mode and effects analysis (DFMEA) and thermal de-rating, for accurate selection of glass and fiber, and informing the overall material properties selection. In addition, identification of mesh copper features within PCB substrate materials helps identify potential risks.