Browsing by Author "Seddon, R."
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Item Carbon nanofibers reinforced copper matrix composites: Manufacture, thermal and mechanical characterisation(2010) Barcena, J.; Seddon, R.; Coleto, J.; Lloyd, J. C.; Neubauer, E.; EXTREMAT; POLIMEROS; MercadoThe present work deals with the study of the manufacture and characterization of reinforced copper matrix composites with vapour grown carbon nanofibers. Nanofillers based on carbon such as carbon nanofibers and nanotubes present high mechanical properties and high thermal conductivity. Therefore they are quite attractive reinforcements in composites materials. An overview of the main developments on the Cu/carbon nanofibers composites at Inasmet-Tecnalia and collaborators over recent years is given. This includes the selection and inspection of nanofibers from different manufacturers; strategies followed for disentanglement/dispersion into the copper matrix; comparison among various manufacturing routes (electroless plating, hotpressing, spark plasma sintering, etc.); microstructural observation (Optical, SEM, TEM); interfacial Cu/C design and optimization; and the evaluation of mechanical and thermal properties. Moreover, in view of the results achieved, this study includes the further work and necessary steps for a complete development of this composite material.Item Effect of the incorporation of interfacial elements on the thermophysical properties of Cu/VGCNFs composites(2010-12-31) Barcena, J.; Garcia de Cortazar, M.; Seddon, R.; Lloyd, J. C.; Torregaray, A.; Coleto, J.; Tecnalia Research & Innovation; CIRMETAL; POLIMEROS; MercadoVapour grown carbon nanofibres exhibit high mechanical properties and thermal conductivities. Therefore they are potential reinforcements in composites materials for high strength and high thermal conductivity applications. A problem not yet solved is the promotion of an improved copper/carbon interface. Several strategies have been envisaged for the incorporation of alloying elements (Ni, Co, B and Ti) at the interface. These techniques are based on duplex electroless plating coatings (combination of Cu and Ni or Cu and Co), electroless plating of alloys (Cu-B) and addition of metal nanoparticles (Ti) to Cu matrix deposited by electroless plating. The effect of the incorporation of these metallic elements on the microstructure and thermophysical properties is discussed. B and Ti lead to higher interaction at the Cu/C interface over Ni and Co. This allows the reduction of the coefficient of thermal expansion but regarding the thermal conductivity it was not possible to obtain a value higher than that of copper.Item Enhancement of electrical conductivity of composite structures by integration of cnts via bulk resin and/or buckypaper films(European Conference on Composite Materials, ECCM, 2014) Gaztelumendi, I.; Chapartegui, M.; Seddon, R.; Flórez, S.; Pons, F.; Cinquin, J.; Korzhenko, A.; POLIMEROSThis work describes two approaches for the incorporation of Carbon Nanotubes (CNTs) in CFRP composites by infusion processing methods: firstly through the addition of the CNTs in the bulk resin to improve the electrical properties of the epoxy matrix prior to infusion [1], and secondly by the addition of CNT-based buckypaper (BP) in the CFRP structure for enhanced electrical properties [2]. Several laminates were manufactured with different formulations. A cross check of EC testing was carried out among different laboratories in order to compare different surface preparations and test methods. This characterization was completed with Scanning Electron Microscopy (SEM) analyses, in order to assess the presence of the filtering effect. In addition, ILSS tests were performed, comparing the results of the different formulations.Item Simulation-Based Analysis of Thermo-Mechanical Constraints in Packages for Diamond Power Devices(Institute of Electrical and Electronics Engineers Inc., 2020-07) Fuste, N.; Avino, O.; Vellvehi, M.; Perpina, X.; Godignon, P.; Seddon, R.; Obieta, I.; Maudes, J.; Jorda, X.; POLIMEROS; Tecnalia Research & Innovation; PRINTEXDiamond is one of the best wide band-gap semiconductor materials available for high power devices development in terms of high current capability, high temperature operability, breakdown voltage and switching speed. Unfortunately, fabrication technology for diamond devices is still experimental and immature. Furthermore, one of the most critical fields to be addressed for practical diamond devices implementation concerns the development of power packaging solutions, given that limitations in the device packaging would hinder the performance of the device and act as the limiting factor for a technology that is still in a development state. Of special interest are the induced stresses and deformations caused by the thermo-mechanical mismatch between materials. These stresses and strains will be considerably different than the ones obtained with silicon or SiC dies, and it will be especially noticeable in high temperature applications due to the higher temperature swings and the reliability constraints that arise from the coefficient of thermal expansion mismatch and stiffness difference. In this paper, a Finite Element Method for thermo-mechanical simulation of a high-temperature thermal cycle for a full-stacked diamond die SOT-227 power module is introduced and compared to silicon- and SiC-die modules. Special interest is addressed to the analysis of stress and deformations generated in the die and die-attach solder layer.