IMECE2002-33859 MANUFACTURING OF ELECTRICALLY CONDUCTIVE MICROSTRUCTURES BY DROPWISE PRINTING AND LASER CURING OF NANOPARTICLE-SUSPENSIONS

ABSTRACT A novel method for the manufacturing of electric microconductors for semiconductor and other devices is presented. The method brings together three technologies: controlled (on demand) printing, laser curing, and the employment of nanoparticles of matter, possessing markedly different properties (here, melting point) than their bulk counterparts. A suspension of gold particles in toluene solvent is employed to print electrically conducting line patterns utilizing a modified on demand ink jet printing process. To this end, microdroplets of 80-100 µm diameters are deposited on a moving substrate such that the droplets form continuous lines. Focused laser irradiation is utilized in order to evaporate the solvent, melt the metal nanoparticles in the suspension, and sinter the suspended particles to form continuous, electrically conducting gold microlines on a substrate. The ultra fine particles in the suspension have a diameter size range of 2 -5 nm. Due to curvature effects of such small particles, the melting point is markedly lower (400°C) than that of bulk gold (1063°C). Thermodynamic aspects of the effect of particle size on the melting and evaporation temperatures of gold and toluene, respectively, are discussed in the paper. The structure and line width of the cured line as a function of the laser irradiation power and stage velocity are reported in detail. Preliminary measurements of the electrical conductivity are represented

Pattern formation during the evaporation of a colloidal nanoliter drop: a numerical and experimental study

An efficient way to precisely pattern particles on solid surfaces is to dispense and evaporate colloidal drops, as for bioassays. The dried deposits often exhibit complex structures exemplified by the coffee ring pattern, where most particles have accumulated at the periphery of the deposit. In this work, the formation of deposits during the drying of nanoliter colloidal drops on a flat substrate is investigated numerically and experimentally. A finite-element numerical model is developed that solves the Navier-Stokes, heat and mass transport equations in a Lagrangian framework. The diffusion of vapor in the atmosphere is solved numerically, providing an exact boundary condition for the evaporative flux at the droplet-air interface. Laplace stresses and thermal Marangoni stresses are accounted for. The particle concentration is tracked by solving a continuum advection-diffusion equation. Wetting line motion and the interaction of the free surface of the drop with the growing deposit are modeled based on criteria on wetting angles. Numerical results for evaporation times and flow field are in very good agreement with published experimental and theoretical results. We also performed transient visualization experiments of water and isopropanol drops loaded with polystyrene microsphere evaporating on respectively glass and polydimethylsiloxane substrates. Measured evaporation times, deposit shape and sizes, and flow fields are in very good agreement with the numerical results. Different flow patterns caused by the competition of Marangoni loops and radial flow are shown to determine the deposit shape to be either a ring-like pattern or a homogeneous bump

Direct fabrication of unsupported inclined aluminum pillars based on uniform micro droplets deposition

In order to investigate forming directly complex parts without support materials or structures by uniform micro droplets deposition technique, the present work focus on fabricating the unsupported inclined aluminum pillars through offset deposition. An experimental system is developed to produce and deposit uniform molten aluminum droplets. A model is introduced to describe the inclined angle of the droplet deposition at different offset ratios. A one dimensional heat transfer model is proposed to help select the initial temperature parameters of the impinging droplet and the previous solidified droplet to ensure that the fusion occurs. No melting, partial melting and excessive melting region at different offset ratios are determined. The correspondence between offset ratio and inclined angle is considered to be a simple cosine function, and the hypothesis is verified by experiments. The influence of deposition error on an inclined angle of pillars is studied. Internal microstructure of droplet fusion is observed in order to ensure good metallurgical bonding. All of these studies show the feasibility of fabricating directly unsupported inclined aluminum pillars in the limited angle range by using uniform micro droplets

Disseny i anàlisi de l'actuador de direcció d'un Formula Student

Els cotxes autònoms són el futur. Com a component de l’equip de competició BCN eMotorsport, que sempre treballa per innovar i estar en la Vanguardia, tenim un cotxe elèctric autònom que participa en les competicions internacionals de Formula Student. L'objectiu del treball és determinar l’actuador de direcció més adient pel nou cotxe de competició autònom de l’equip, anomenat Cat14. Primer s’ha fet una breu introducció en les competicions de Formula Student i la seva normativa. S’ha partit de l’anterior cotxe autònom, el “Xaloc”, i s’han analitzat les prestacions i les possibles millores. A continuació s’ha impartit un model simulat de Matlab amb la nova dinàmica del vehicle i s’han assimilat els paràmetres de conducció d’un pilot al funcionament d’un motor. A partir d’aquestes dades s’ha cercat el motor del mercat que millor complís els requeriments. El resultat de l’estudi és l’elecció del motor EC 60 flat de 200 W juntament amb la reductora GP 52C (3,5:1) de la marca Maxon. Un cop escollit l’actuador s’ha dissenyat un suport que compleix els requeriments de funcionament. Finalment, s’han especificat els costos del project

MAGNETIC FIELD DEPENDENCE OF THE 57Fe HYPERFINE INTERACTION IN Y(Fe0.1Co0.9)2 AND (Ho0.1Y0.9) (Fe0.1Co0.9)2

No abstract availabl

MÖSSBAUER AND MAGNETIC INVESTIGATIONS OF Y(FexAl1-x)2

No abstract availabl