Numerical modelling of a high temperature power module technology with SiC devices for high density power electronics

This paper presents the development of a new packaging technology using silicon carbide (SiC) power devices. These devices will be used in the next power electronic converters. They will provide higher densities, switching frequencies and operating temperature than current Si technologies. Thus the new designed packaging has to take into account such new constraints. The presented work tries to demonstrate the importance of packaging designs for the performance and reliability of integrated SiC power modules. In order to increase the integrated density in power modules, packaging technologies consisting of two stacked substrates with power devices and copper bumps soldered between them were proposed into two configurations. Silver sintering technique is used as die-attach material solution. In order to assess the assembling process and robustness of these packaging designs, the thermo-mechanical behaviour is studied using FEM modelling. Finally, some recommendations are made in order to choose the suitable design for reliable power module

Etude du comportement mécanique des joints de brasure Au-Ge pour le report des composants SiC pour l’électronique de puissance haute température

Ce papier contribue à l'étude de nouvelles technologies d’assemblage des puces en SiC utilisées dans les modules de puissance hautes températures (250°C). En effet, parmi tous les matériaux entrant dans l’assemblage de ces modules de puissance, le matériau de report des puces sur les substrats fait partie des matériaux les plus susceptibles aux contraintes thermomécaniques. Ainsi, pour répondre aux problématiques d'assemblage de ces puces en SiC, de nouvelles solutions de brasure doivent être développées. L’alliage de brasure Au-Ge peut être utilisé comme alliage de brasure sans plomb pour la haute température grâce à ses bonnes propriétés thermiques et mécaniques. Dans cet article, l’étude du comportement mécanique des joints formés avec la brasure Au-Ge et les puces en SiC, a été réalisée dans le but d’évaluer la robustesse et la fiabilité de ces jonctions en haute température

Towards a reliability analysis method of wide band gap power electronic components and modules

This study is addressing on the reliability of COTS (Commercial Off-The-Shelf) power electronic components and modules which could be used in high reliability systems such as aerospace systems. This paper details the first followed steps to achieve a reliability assessment of some COTS power devices. These first steps are: - Construction analyses for the determination of the packaging assembly technologies of COTS power devices; - Discussion on the material used in COTS power devices; - Synthesis of the potential failure risk analysis under harsh environments; - Determination of several accelerated ageing tests to check the potential failure modes and mechanisms in power electronic for aerospace systems

Study of packaging reliability of two SiC Schottky diodes of power electronic

This study deals with reliability methods developed for power electronic devices dedicated to the aerospace industry, because the reliability is a key issue for safe aerospace applications. Based on end-user requirements, eight different types of non-hermetic power electronic components in standard plastic package have been selected from the commercial marketplace, in particular Si and SiC power electronic devices. These devices are COTS (Component Off The Shelf). The main failure modes and mechanisms expected have been highlighted in specific environments in accordance with the literature. They will be presented in the final paper

Modeling good field days for hay drying: an adaptation of Luder's method in France

International audienc

A Discrete Fracture Network Model with Stress-Driven Nucleation and Growth

International audienceThe realism of Discrete Fracture Network (DFN) models, beyond the bulk statistical properties, relies on the spatial organization of fractures, which is not issued by classical stochastic DFN models. This can be improved by injecting prior information in DFN from a better knowledge of the geological fracturing processes. We first develop a model using simple kinematic rules for mimicking the growth of fractures from nucleation to stop, in order to evaluate the consequences of realistic DFN on the network connectivity and flow structure. The model generates fracture networks with power-law scaling distributions and a percentage of T-intersections that are consistent with field observations. Nevertheless, a larger complexityrelying on the spatial variability of natural fractures positions cannot be explained by the random nucleation process. We propose to introduce a stress-driven nucleation in the timewise process of this kinematic model to study the correlations between nucleation, growth and existing fracture patterns. The method uses the stress field generated by existing fractures and remote stress as an input for a Monte-Carlo sampling of nuclei centers at each time step. Networks so generated are found to have fractal correlations over a large range of scales, with a dimension that varies with time and with the function that relates the nucleation probability to stress. A sensibility analysis of input parameters has been performed in 3D to quantify the influence of fractures and remote stress field orientations

Purification of Synaptosome Populations Using Fluorescence-Activated Synaptosome Sorting

International audienceFor several decades, neurobiologists have used subcellular fractionation methods to analyze the molecular structure and some functional features of the cells in the central nervous system. Indeed, brain tissue contains a complex intermingled network of neuronal, glial, and vascular cells. To reduce this complexity biochemists have optimized fractionation protocols that enrich in specific compartments such as synapses (called “synaptosomes”) and synaptic vesicles, for example. However, recently, these approaches suffered from a lack of specificity and purity. In a recent effort, we extended the conventional synaptosome preparation to purify fluorescent synaptosomes on a cell sorter. We could prove that our method allows for the steep enrichment in fluorescent excitatory VGLUT1venus synaptosomes containing the presynaptic element and the tip of the post-synaptic element and a strong depletion in neuronal and glial contaminants. Here, we propose a detailed procedure for the implementation of Fluorescence Activated Synaptosome Sorting

A Discrete Fracture Network Model With Stress-Driven Nucleation: Impact on Clustering, Connectivity, and Topology

International audienceThe realism of Discrete Fracture Network (DFN) models relies on the spatial organization of fractures, which is not issued by purely stochastic DFN models. In this study, we introduce correlations between fractures by enhancing the genetic model (UFM) of Davy et al. [1] based on simplified concepts of nucleation, growth and arrest with hierarchical rules. To do so, the nucleation of new fractures is correlated with the elastic strain energy of distortion stored in the matrix, which is a function of preexisting fractures. Discrete Fracture Networks so generated show multi-scale clustering effects with fractal dimensions below the topological dimension over a broad range of scales. The fractal dimension depends on the way one correlates the nucleation occurrence to the strain energy. Fracture clustering entails a spatial variability of the fracture density, which increases with the intensity of the coupling between stress and nucleation. The analysis of connected clusters density and of fracture intersections also highlights the differences between the UFM models and its equivalent Poisson model. We show that our stress-dependent nucleation model introduces some new fracture size-positions correlations, with small fractures tending to connect to the largest ones

The use of process based DFN to account for fracture network geometrical complexity

International audienceThis poster present a new method for DFN generation with stress-driven nucleation and growth, in a time-wise proces