Browsing by Author "Obieta, I."
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Item Advanced packaging for GaN high power electronics(2008) Marcos, J.; Cobo, I.; Barcena, J.; Maudes, J.; Amado, R.; Vellvehi, M.; Jorda, X.; Obieta, I.; Guraya, C.; Bilbao, L.; Jiménez, C.; Coleto, J.; Tecnalia Research & Innovation; EXTREMAT; PRINTEX; MercadoDevices based on wide-bandgap semiconductors such as SiC or GaN allow high power densities and elevated working temperatures. Here we present an innovative package for high-power electronics, within the framework of an ESA-contracted project. The housing concept, design study, materials selection, manufacturing method and first test results are the parameters to be followed in order to get this innovative electronic package. Materials are selected for their high thermal conductivity (TC) and low coefficient of thermal expansion (CTE). Several materials were selected: A1N was selected as substrate material, and novel metal-matrix composites (MMCs) based on Cu-Diamond were evaluated as heat-sink materials. Determination of the final dimensions of the housings according to the new design was required to get a complete bonding. This new heat sink geometry has been validated and the new components fabrication has been already started. An improved surface quality has been achieved, which will increase the contact between the heat sink and the aluminum spreader for electrical characterization. Subsequently, a complete bonding study between ceramic materials and the MMCs was performed. Determination of the final dimensions of the housings according to the new design was required to get a complete bonding. This new MMCs heat sink geometry has been validated and the new components fabrication has been selected. An improved surface quality has been achieved, which will increase the contact between the heat sink and the aluminum spreader for high temperature electrical characterization. In order to obtain fully dense materials A1N was manufactured by pressureless sintering, while the MMCs parts were manufactured by hot-pressing. The MMCs powders were obtained by an electroless plating process. Preliminary characterization of the housing and its parts show encouraging results as a solution for high-power devices working at temperatures up to 400 °C. TC near 500W/mK and CTEs of around 10 ppm/K have been obtained. These are comparable to the stateof-the-art materials. Out-gassing, thermal cycling and hermeticity tests of the packages and high temperature electrical characterization of the electronic paths and global package were performed. The presented new packaging solutions are showing great promise for space applications such as high-frequency power amplifiers for satellite communications and for radar transmitters, and have started to generate an interest from commercial space-system manufacturers.Item Biomedical applications of ceramic nanocomposites(Elsevier Inc., 2013-07) Garmendia, N.; Olalde, B.; Obieta, I.; Biomateriales; Tecnalia Research & InnovationBioceramics and bioceramic composites have been widely used for biomedical applications for the last 50 years. This chapter discusses the advantages of using ceramic nanocomposites. The application of both inert and bioactive ceramics for orthopaedic and dental implants, as well as in the novel field of tissue engineering, is discussed and future trends are presented.Item Carbon nanotubes for biological devices(2006-05) García, A.; Bustero, I.; Muñoz, R.; Goikotxea, L.; Obieta, I.; PRINTEX; Biomateriales; Tecnalia Research & InnovationThe unique properties of carbon nanotubes open attractive possibilities in many applications areas, for instance as biological devices. Multi Wall Carbon Nanotubes (MWNT) have been synthesized by Chemical Vapour Deposition (CVD) and the influence of certain process variables in the final product yield have been studied. In addition, purification treatment applied at synthesized carbon nanotubes, has been developed. Biocompatibility tests have demonstrated that purified carbon nanotubes are non-cytotoxic. Finally, a functionalization process is developed to help in carbon nanotubes-biomolecule interaction.Item Direct patterning of polymer optical periodic nanostructures on CYTOP for visible light waveguiding(2018-08) Diez, M.; Raimbault, V.; Joly, S.; Oyhenart, L.; Doucet, J. B.; Obieta, I.; Dejous, C.; Bechou, L.; Tecnalia Research & InnovationOptical waveguides and grating couplers based on polymer nanostructures are now considered as promising technologies for integrated biophotonic sensing systems. Commonly, structuration and patterning of polymers at the submicron scale requires the use of time and cost-consuming equipments such as electron beam lithography. Direct patterning of high refractive index polymer devices on CYTOP is now achievable and provides symmetric waveguides with top water-like claddings. In addition, transparency of polymers makes them suitable for operation in the visible range, being of major interest for biophotonic applications. In this paper, we report on the fabrication process of polymer submicronic single-mode waveguides on CYTOP for visible light operation. Sub-wavelength grating couplers with a pitch lower than 300 nm were fabricated to couple the input light into a 350 nm square cross-section waveguide. The whole device is imprinted in a single step using soft stamp lithography with a minimal residual layer. Finally, optical characterizations demonstrate a state-of-the-art transmission efficiency (around 1.5%) at the selected operating wavelength of 507 nm for different coupling angles in good agreement with simulations.Item The effect of the addition of carbon nanotubes in the hydrothermal synthesis and in the thermal phase stability of nanozirconia(2010-04) Garmendia, N.; Arteche, A.; García, A.; Bustero, I.; Obieta, I.; Mercado; PRINTEX; Tecnalia Research & InnovationThe yttria partially stabilized zirconia is a very attractive material for orthopaedic applications. It exhibits excellent biocompatibility, high fracture toughness, high strength and low wear rates. But case studies show that delayed failure can occur in vivo due to crack propagation. Carbon nanotubes could avoid the slow crack propagation and enhance the toughness of the ceramic material used for prostheses fabrication. In this work, X-ray diffraction has been used to study the influence of the addition of MWCNT on the hydrothermal synthesis of tetragonal zirconia nanoparticles and on the phase stability of the CNT-nanozirconia nanocomposite with the temperature. First, the influence of the processing variables on the hydrothermal synthesis has been studied. The theoretical mathematical models that relate the percentage of tetragonal zirconia nanocrystals and the relative crystallinity with the processing variables in the range of analyzed values have been obtained. The values that give the maximum percentage and crystallinity of tetragonal phase in the studied range have been established. No significant differences were observed in the crystalline phases obtained when adding MWCNT during the synthesis. Nanozirconia partially coated MWCNT synthesized under the optimized parameters were added to commercially available nanozirconia particles and their influence in the phase stability of the zirconia with the temperature was studied by XRD. It was concluded that the addition of the carbon nanotubes delays both the monoclinic phase decomposition and the grain growth.Item Innovative packaging solution for power and thermal management of wide-bandgap semiconductor devices in space applications(American Institute of Aeronautics and Astronautics Inc., 2006) Barcena, J.; Merveille, C.; Maudes, J.; Vellvehi, M.; Jorda, X.; Obieta, I.; Guraya, C.; Bilbao, L.; Jiménez, C.; Coleto, J.; EXTREMAT; PRINTEX; Tecnalia Research & Innovation; MercadoDevices based on wide-bandgap semiconductors such as SiC or GaN allow high power densities and elevated working temperatures. Here we present an innovative package for high-power electronics, within the framework of an ESA-contracted project. The paper shows the housing concept, design study, materials selection, manufacturing method and first test results. Materials are selected for their high thermal conductivity (TC) and low coefficient of thermal expansion (CTE). Several materials were selected: AlN was selected as substrate material, and novel metal-matrix composites (MMCs) based on Cu-Diamond and CuVapour Grown Carbon Nanofibres (VGCNFs) were evaluated as heat-sink materials. Subsequently, a complete bonding study between ceramic materials and the MMCs was performed. In order to obtain fully dense materials AlN was manufactured by pressureless sintering, while the MMCs parts were manufactured by hot-pressing. The MMCs powders were obtained by an electroless plating process. Preliminary characterisation of the housing and its parts show encouraging results as a solution for high-power devices working at temperatures up to 300 °C. TC near 500W/mK and CTEsof around 10 ppm/K. have been obtained. These are comparable to the state-of-the-art materials. Out-gassing, thermal cycling and hermeticity tests of the packages were performed. The presented new packaging solutions are showing great prorrise for space applications such as high -frequency power amplifiers for satellite communications and for radar transmitters, and have started to generate an interest from commercial space-systemmanufacturers.Item Innovative packaging solution for power and thermal management of wide-bandgap semiconductor devices in space applications(2008-03) Barcena, J.; Maudes, J.; Vellvehi, M.; Jorda, X.; Obieta, I.; Guraya, C.; Bilbao, L.; Jiménez, C.; Merveille, C.; Coleto, J.; EXTREMAT; PRINTEX; Tecnalia Research & Innovation; MercadoDevices based on wide-bandgap semiconductors such as SiC or GaN allow high power densities and elevated working temperatures. Here we present an innovative package for high-power electronics, within the framework of an ESA-contracted project. The paper shows the housing concept, design study, materials selection, manufacturing method and first test results. Materials are selected for their high thermal conductivity (TC) and low coefficient of thermal expansion (CTE). Several materials were selected: AlN was selected as substrate material, and novel metal-matrix composites (MMCs) based on Cu-diamond and Cu-vapour grown carbon nanofibres (VGCNFs) were evaluated as heat-sink materials. Subsequently, a complete bonding study between ceramic materials and MMCs was performed. In order to obtain fully dense materials AlN was manufactured by pressureless sintering, while the MMC parts were manufactured by hot-pressing. The MMC powders were obtained by an electroless plating process. Preliminary characterisation of the housing and its parts show encouraging results as a solution for high-power devices working at temperatures up to 300 °C. TC near 500 W/mK and CTEs of around 10 ppm/K have been obtained. These are comparable to the state-of-the-art materials. Out-gassing, thermal cycling and hermeticity tests of the packages were performed. The presented new packaging solutions show great promise for space applications such as high-frequency power amplifiers for satellite communications and for radar transmitters, and have started to generate an interest from commercial space-system manufacturers.Item Nanozirconia partially coated MWNT: Nanostructural characerization and cytotoxicity and lixivation study(2008) Garmendia, N.; Bilbao, L.; Muñoz, R.; Goikoetxea, L.; García, A.; Bustero, I.; Olalde, B.; Garagorri, N.; Obieta, I.; PRINTEX; Biomateriales; Tecnalia Research & InnovationCarbon nanotubes could avoid the crack propagation and enhance the toughness of the ceramic material used for prostheses applications. So nanozirconia partially coated carbon nanotubes have been obtained via hydrothermal synthesis of zirconia nanoparticles in presence of multiwall carbon nanotubes. The as covered nanotubes should have a better wettability in the ceramic matrix and improve the dispersion of the CNTs in the nanocomposite, which results in a new ceramic biomaterial with a longer lifetime and better reliability. The obtained product has been structurally characterized by several techniques such as FTIR, XRD, SEM, AFM, EELS, XPS and TGA. The citotoxicity of the sintered product was studied by the change in the pH and ICP-AES in in-vitro biocompatibility tests.Item New sensitive layers for surface acoustic wave gas sensors based on polymer and carbon nanotube composites(2012-12) Sayago, I.; Fernández, M. J.; Fontecha, J. L.; Horrillo, M. C.; Vera, C.; Obieta, I.; Bustero, I.; Biomateriales; Tecnalia Research & Innovation; PRINTEXSurface acoustic wave (SAW) gas sensors based on polymers and carbon nanotube composites as sensitive layers were investigated for the detection of low concentrations of volatile organic compounds as octane and toluene. Several nanocomposites based on polyepichlorohydrin (PECH) and polyetherurethane (PEUT) with different percentage of multiwalled carbon nanotubes (MWCNT) were tested to study the effect of MWCNTs in the response of sensors. The sensors exhibited at room temperature high response to volatile gases (toluene and octane) but did not detect other gases tested as H2, NH3, NO2 and CO.Item New sensitive layers for surface acoustic wave gas sensors based on polymer and carbon nanotube composites(2011) Sayago, I.; Fernández, M. J.; Fontecha, J. L.; Horrillo, M. C.; Vera, C.; Obieta, I.; Bustero, I.; Biomateriales; Tecnalia Research & Innovation; PRINTEXSurface acoustic wave (SAW) gas sensors based on carbon nanotube polymer composites as sensitive layers were investigated for the detection of low concentrations of volatile organic compounds as octane and toluene. Several nanocomposites based on polyepichlorohydrin (PECH) and polyetherurethane (PEUT) with different percentage of multiwalled carbon nanotubes (MWCNT) were tested to study the effect of MWCNTs in the response of sensors.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.Item Surface acoustic wave gas sensors based on polyisobutylene and carbon nanotube composites(2011-08-10) Sayago, I.; Fernández, M. J.; Fontecha, J. L.; Horrillo, M. C.; Vera, C.; Obieta, I.; Bustero, I.; Biomateriales; Tecnalia Research & Innovation; PRINTEXSurface acoustic wave (SAW) gas sensors based on polyisobutylene (PIB) and composites (PIB and carbon nanotubes) as sensitive layers were investigated for the detection of octane and toluene (volatile organic compounds) and other atmospheric pollutants (H2, CO, NO2 and NH3) at room temperature. In order to study the effect of nanotubes in the response of SAW sensors, several composites based on PIB with different percentages of multiwalled carbon nanotubes (MWNTs) were tested and compared to the response obtained from PIB SAW sensors. Sensors exhibit high responses and selectivity to volatile organic compounds (VOCs) with fast response and recovery times as well as good repeatability and reproducibility. Experimental results show as small percentages of nanotubes improve the response to octane.Item Surface energy and frictional / adhesive properties of polymeric resist films(2011) Koszewski, A.; Jarzabek, D.; Rymuza, Z.; Obieta, I.; Tecnalia Research & InnovationThe effect of plasma treatment on surface properties of resist films devoted for nanoimprint lithography (NIL) was studied. The Atomic Force Microscope was used to identify surface topography, pull-off force and lateral (friction ) force of the resist film before and after plasma treatment with the presence of nitrogen and hydrogen gases. The wettability was studied to estimate surface energy of the films both with polar and dispersion components. The AFM-based microtribometer enabled to study the frictional behavior of the resist films. The results of these extended studies have shown that the used plasma functionalization is effective to modify dramatically the surface properties of the resist films.Item Toxicogenomics study of nanomaterials on the model organism zebrafish(2007) Rojo, I.; Uriarte, M.; Obieta, I.; Bustero, I.; Egizabal, A.; Pardo, M. A.; De Martínez Ilárduya, O.; Tecnalia Research & Innovation; PRINTEX; BiomaterialesWe have adapted an "in vitro" toxicity test using zebrafish embryos for a toxicogenomics approach. Our goal is to develop a rapid toxicity assay for nanoparticles to be used in food and other applications. We incubated fertilized fish eggs for 48 h in the presence of a solution of purified MWCNT (1 ppb to 10 ppm) or with nanosilver solutions (1 ppb to 5 ppm). We could not detect effects on development or timing. We have used quantitative RT-PCR to analyze the expression patterns of Cyp1A1, Ahr2, Cpt1, iNOS, Ncf1, NudT1, c/EBP-a and MafT. These genes are involved in detoxification patterns, in the protection against oxidative stress or code for regulatory factors involved in the immune response. At these concentrations, nanosilver had clear effects on the expression of most of the genes in a dose dependant manner. Induction was maximum in the case of regulatory factors. On the contrary, changes in gene expression induced by MWCNTs were much lower, suggesting a reduced toxicity at the tested concentrations.Item XRD study of the effect of the processing variables on the synthesis of nanozirconia in the presence of MWCNT(2009-02) Garmendia, N.; Arteche, A.; García, A.; Bustero, I.; Obieta, I.; Mercado; PRINTEX; Tecnalia Research & InnovationSeveral challenges must be solved to obtain an effective introduction of carbon nanotubes in a ceramic matrix. Dispersion, good load transfer, and wettability are the major issues to be overcome to obtain good final properties of a zirconia nanocomposite. We have developed a process to coat multi-wall carbon nanotubes with nanozirconia to deal with these challenges. The process is based on the hydrothermal synthesis of tetragonal zirconia nanoparticles in the presence of multi-wall carbon nanotubes (MWCNT). In this work, X-ray diffraction has been used to study the influence of the processing variables in order to optimize this process. The theoretical mathematical models that relate the percentage of tetragonal zirconia and their crystallinity in relation to the processing variables have been extracted.Item Zirconia coating of carbon nanotubes by a hydrothermal method(2008-11) Garmendia, N.; Bilbao, L.; Muñoz, R.; Imbuluzqueta, G.; García, A.; Bustero, I.; Calvo-Barrio, L.; Arbiol, J.; Obieta, I.; PRINTEX; SISTEMAS FOTOVOLTAICOS; Tecnalia Research & InnovationCarbon nanotubes have unique mechanical properties that open attractive possibilities in many fields, such as the biomedical one. Currently, zirconia ceramics are widely used as femoral heads, but case studies show that delayed failure can occur in vivo due to crack propagation. Nanotubes could avoid the slow crack propagation and enhance the toughness of the ceramic material used for prostheses fabrication. In this work, single-wall carbon nanotubes and multi-wall carbon nanotubes have been partially coated with nanozirconia via hydrothermal synthesis and characterized by several techniques: X-ray diffraction, infrared spectroscopy, scanning electron microscope, transmission electron microscope, electron energy loss spectra, X-ray photoelectronic spectroscopy and atomic force microscopy. By means of these techniques, the existence of bonds between zirconium and the carbon nanotube has been proved. The as covered nanotubes should offer a better wettability in the ceramic matrix and improve the dispersion of the carbon nanotubes, to obtain the desired new ceramic biomaterial with a longer lifetime and better reliability.Item Zirconia-multiwall carbon nanotubes dense nano-composites with an unusual balance between crack and ageing resistance(2011-06) Garmendia, N.; Grandjean, S.; Chevalier, J.; Diaz, L. A.; Torrecillas, R.; Obieta, I.; Tecnalia Research & InnovationYttria stabilized zirconia (Y-TZP) ceramics are used in a wide variety of applications, such as orthopaedic and dental implants. Y-TZP offers indeed a unique combination of biocompatibility and mechanical properties (high crack resistance for a ceramic). However, the major drawback of Y-TZP is their lack of stability: zirconia is prone to ageing, especially under humid atmosphere. Increasing the ageing resistance of Y-TZP led so far to a decrease of toughness and crack resistance. Here we show that the addition of a small volume fraction of multiwall carbon nanotubes (MWCNT) in a polycrystalline nano-structured Y-TZP sintered under specific conditions (Spark Plasma Sintering) leads to a material exhibiting a balance between ageing and crack resistance never reached before.Item Zirconia-MWCNT nanocomposites for biomedical applications obtained by colloidal processing(2010-05) Garmendia, N.; Santacruz, I.; Moreno, R.; Obieta, I.; Tecnalia Research & InnovationZirconia ceramics are widely used as femoral heads, but case studies show that delayed failure can occur in vivo due to crack propagation. The addition of carbon nanotubes (CNT) is aimed to avoid the slow crack propagation and to enhance the toughness of the ceramic material used for prostheses. However, to really enhance the mechanical properties of the material it is necessary to achieve a uniform distribution of the CNT in the zirconia matrix. Colloidal processing has demonstrated to be suitable for obtaining ceramic-based composites with homogeneous distribution of the phases and high green density. This work compares the colloidal behavior of the as-received multi wall carbon nanotubes (ar-MWCNT) and the partially coated MWCNT (pc-MWCNT) when immersed in a nanozirconia matrix. With pc-MWCNT an improvement in the dispersion is proved. Moreover, the sintered samples that contain pc-MWCNT show higher density, lower grain size, improved toughness and enhanced hardness under the same sintering cycle when compared to the samples with ar-MWCNT.Item Zr-metal adhesion on graphenic nanostructures(2008) Sanchez-Paisal, Y.; Sanchez-Portal, D.; Garmendia, N.; Muoz, R.; Obieta, I.; Arbiol, J.; Calvo-Barrio, L.; Ayuela, A.; Tecnalia Research & InnovationOur high resolution transmission electronic microscopy studies of multiwall carbon nanotubes show, after the growth of zirconia nanoparticles by a hydrothermal route, the presence of surface Zr, forming an atomically thin layer. Using first-principles calculations we investigate the nature of the Zr-C interaction, which is neither ionic nor covalent, and the optimal coverage for the Zr metal in a graphene flake. This preferred coverage is in agreement with that deduced from electron energy loss spectra experiments. We show also that the amount of charge transferred to the C layer saturates as the Zr coverage increases and the Zr-C bond becomes weaker.