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Hui, Tak-wai. "Solder paste inspection based on phase shift profilometry." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39558411.
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Hui, Tak-wai, and 許德唯. "Solder paste inspection based on phase shift profilometry." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39558411.
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Landman, Erik. "Viscosity control of solder paste by ultrasound actuation." Thesis, KTH, Mekatronik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-245871.
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The thixotropic characteristics of solder paste are an obstacle in improving the consistency with which solder paste droplets can be deposited by jet printers. Controlling the viscosity of solder paste may be an important step in improving the deposition. This thesis investigates whether ultrasound can be used as an actuation method to control the viscosity. Rheological measurements were performed to determine the thixotropic flow behaviour of a batch of solder paste. Various thixotropic complex fluid models were evaluated with respect to their ability to describe and predict this flow behaviour. To measure how large the effect of ultrasound on the viscosity of solder paste is, a piezo-element was used to apply ultrasonic vibrations to solder paste flowing through a capillary tube. These measurements were repeated with various frequencies and amplitudes. The amplitude of the ultrasound determines the magnitude of change of the viscosity, but the effect is small for the tested amplitudes: max 4%. The frequency of the ultrasound did not have a clear effect on the viscosity change. The results from these measurements are used to derive a control framework that describes the feasibility of using ultrasound to control the viscosity of solder paste. Ultrasound is only feasible if the amplitude of the ultrasound can be made large enough.<br>Lödpastans tixotropa beteende är ett hinder för att förbättra repeterbarheten med vilken jet printers kan skjuta lödpastadroppar. Att reglera lödpastans viskositet kan vara ett viktigt steg för att förbättra repeterbarheten. I det här examenarbetet undersöks möjligheterna att använda ultraljud för att påverka viskositeten. De reologiska egenskaperna för en sats lödpasta har uppmätts. Flera modeller för tixotropa vätskor har testats för att identifiera dem som är bäst för att beskriva lödpastans egenskaper. För att testa ultraljudets effekt på viskositeten, har tester utförts där lödpasta flödar genom ett kapillärrör medan ett piezoelement skickar vibrationer med ultraljudfrekvens. Ultraljudet visade sig ha en liten effekt på viskositeten: maximal 4%. Effekten är större för högre amplituder, medan frekvensen inte har en tydlig påverkan på hur stor viskositetsförändringen är. Resultaterna från båda mätningar har använts för att skapa ett regleringsramverk som beskriver möjligheterna att använda ultraljud för att reglera lödpastans viskositet. Det är möjligt att reglera viskositeten med ultraljud, om ultraljudets amplitud är tillräckligt stor.
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Reid, Pamela Patrice. "Variable Frequency Microwave Reflow of Lead-Free Solder Paste." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5011.
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As the world moves towards eliminating lead from consumer products, the microelectronics industry has put effort into developing lead-free solder paste. The major drawback of lead-free solder is the problems caused by its high reflow temperature. Variable frequency microwave (VFM) processing has been shown to allow some materials to be processed at lower temperatures. Issues addressed in this study include using VFM to reduce the solder reflow temperature, comparing the heating rate of different size solder particles, and comparing the reliability of VFM reflowed solder versus conventionally reflowed solder. Results comparing the effect of particle size on the heating rate of solder showed that the differences were negligible. This is due in part to the particle sizes overlapping. Many lead-free solder pastes reflow around 250℃. Results indicate that when using the VFM, lead-free solder paste will reflow at 220℃. The reliability of solder that was reflowed using the VFM at the reduced temperature was found to be comparable to solder reflowed in a conventional manner. Based on these findings, VFM processing can eliminate the major obstacles to making lead-free solder paste a more attractive option for use in the microelectronics industry.
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Braunstein, Daniel J. (Daniel Judah). "Real time process monitoring of solder paste stencil printing." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35374.
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Svanberg, Carl. "Pump test analogy." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-257510.
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Mycronic is a company that manufactures a solder paste printer used to manufacturecircuit boards. Inside the printer solder paste is fed with the help of a screw pump.The solder paste, consisting of relatively soft metals has a tendency to stick to thescrew surface and form particles. These are then detached and passed on in thesystem and can clog the nozzle of the printer. This project investigated the possibilityof creating a model test where different parameters can be varied to evaluate itsinfluence on the amount of solder paste sticking to the surface of the screw. Testingthese parameters directly in the solder paste printer would be time consuming andexpensive.A pin-on-disk set up with some modified parts was used to emulate the solder pastemotion in the screw pump. The results were then analyzed in light optical microscope(LOM) and scanning electron microscope (SEM) equipped with energy dispersivex-ray spectroscopy (EDS).The parameters that were varied were pressure, temperature, rotation speed,substrate, content of the paste and the shape of the profile, which is supposed toemulate the ridge of the screw. It was shown that the profile shape, the substrate andthe pressure was of great importance in the deformation of the solder balls while therotation speed and the paste content had a small or no effect.The goal of the project is to recreate the agglomerates that have led to malfunctionsin the printing and evaluate which parameters that have the greatest significance.
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Bhave, Aniket. "A leaded and lead-free solder paste evaluation screening procedure." Diss., Online access via UMI:, 2005. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1425610.
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Mitchell, Charles Clayton. "PBGA reliability of lead free solder balls assembled with tin lead solder paste for harsh environment electronics." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Summer/Theses/MITCHELL_CHARLES_16.pdf.
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Chu, Ming-hei. "Solder paste inspection and 3D shape estimation using directional LED lightings." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39634176.
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Chu, Ming-hei, and 朱銘熙. "Solder paste inspection and 3D shape estimation using directional LED lightings." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39634176.
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Vinnars, Jacob, and Johan Vinnars. "Correlations Between Rheological Properties and Jetting Results in Solder Paste Jetting." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-324700.
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The purpose of this project has been to investigate potential correlations between rheological properties and jetting quality of solder paste. The project was carried out for Mycronic AB. Data from previously obtained measurements for both rheological properties and jetting quality were used in the analysis. We were only able to suggest preliminary correlations. One reason for this was that the jetting data was not designed for correlation work. It was performed to set parameters for new fluids. The data was inconsistent and difficult to work with in a correlation studie. However, the work led to a framework for future studies and correlation work.
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Rodriguez, German Dario. "Analysis of the solder paste release in fine pitch stencil printing processes." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/18867.
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Jomy, Vachaparambil Kurian. "An analytical and numerical study of droplet formation and break-off for jetting of dense suspensions." Thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-194501.
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The jet printing of solder paste from a uid dynamics perspective involves viscosity change due to varying shear rate and eventual break o of the ejected solder paste droplet from the uid in the printer head. The ability to model the jetting process in a simulation package is important as it can be used as a tool for future development of the jetting device. The jetting process is modelled as a two phase (air - solder paste) ow with interface tracking performed using phase eld method and temporal stepping based on a second-order Backward Di erence Formula with relaxed tolerences. This thesis investigates the droplet morphology, volume and speed predictions for three di erent piston actuation modes and solder paste viscosity denitions given by the Carreau- Yasuda model. A Darcy condition with the porosity parameter is calibrated equal to unity such that the droplet speed is within the realistic range of 20 m/s - 30 m/s. The simulations are compared against previous simulation results from IBOFlow, performed within a collaboration between Mycronic AB and Fraunhofer-Chalmers Centre. As the Carreau models cannot capture the dependence of the uid viscosity of ow history, an indirect structure based viscosity model is used to compare the thixotopic behaviour. The expressions for the parameters of the structure based viscosity model are derived based on an analytical model which assumes that shear rate is constant. Experimental data for constant shear rate is curve tted on a Carreau model and an initial estimate of the parameters are obtained. The parameters are then adjusted to match experimental thixotopic behaviour. This method can be used to obtain parameter values for structure based viscosity models for uids with no previous data. Once the solder paste is ejected through the nozzle and the piston retracts, the uid undergoes stretching. Studying lament stretching during jetting is dicult as it can be driven by both droplet and piston motion. The data from an extensional rheometer is analyzed to study the lament stretching phenomenon for solder pastes. An analytical model for the critical aspect ratio is derived for a Newtonian uid lament undergoing a pure extension and modelled as a cylinder whose radius is decreases with time. The exponential decrease of the lament radius predicted by the analytical model is found to reproduce the experimental observations very well. The lament radius calculated based on the lament height from the experiments and analytical model shows that the model captures the stretching process, but the formation of beads usually seen in suspensions is not accounted for.
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Ismail, Ismarani. "Stencil printing of solder paste for reflow soldering of surface mount technology assembly." Thesis, University of Salford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426875.
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Vujadinovic, Alexandar. "A method for evaluating the robustness of a high-speed solder paste printer." Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168843.
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Jetstråleskrivaren MY500 är en del av produktutbudet för PCB-tillverkning som utvecklats och tillverkas av Mycronic AB, tidigare känt som Micronic Mydata AB. Som för många liknande företag, finns det ett tydligt intresse i att minska utvecklingskostnader och göra det möjligt att ta nya produkter och uppgraderingar till marknaden snabbt. Hardware-in-the-loop-simulering är ett sätt att testa delar av ett system innan prototyper konstruerats, och det ger stora fördelar till ett utvecklingsprojekt eftersom olika idéer och systemparametrar kan undersökas till en mycket lägre kostnad jämfört med tester som använder faktisk hårdvara.Syftet med detta magistersexamensprojekt är att skapa en plattform för hardware-in-the-loop-simulering och utvärdering för positioneringssystemet som förflyttar skrivarmunstycket i X- och Y-led. MY500-maskinen skjuter ut punkter bestående av lodpasta längs en förutbestämd bana som även innehåller information om målpositionerna för de olika punkterna. Detta hanteras av en styrenhet, CMOT3, också utvecklad av Mycronic AB, som kör ANSI-C-kod och har olika gränssnitt för interaktion med resten av maskinen. I detta specifika fall användes dess SPI-gränssnitt för att kommunicera med den simulerade systemmodellen, som kördes på en Speedgoat-dator som har en systemarkitektur specifikt framtagen för att köra Simulink-modeller i realtid.Innan detta projekt påbörjades så har redan två olika examensprojekt genomförts kring modelleringen av positioneringssystemet för MY500. Ett av dessa hade målet att implementera den i en HIL-plattform, och även om det ej gjordes på grund av tekniska problem så var slutsatsen att det var rimligt att fortsätta arbetet. Detta projekt använde ett annorlunda tillvägagångssätt för systemstrukturen och resulterade i den första lyckade HIL-plattformen för X- och Y-aktuatorerna för MY500, och den har framgångsrikt producerat realistiska testresultat. En analysmetod baserad på Multivariate Process Capability har tagits fram och använts för att poängsätta data från simuleringarna.I den avslutande delen har testdata som analyserats med den föreslagna utvärderingsmetoden diskuterats, och förslag har tagits fram kring fortsatt arbete på både plattformen och utvärderingsmetoden.<br>The MY500 solder paste jet printer is a part of the PCB production product range developed and produced by Mycronic AB, formerly known as Micronic Mydata AB. As with many other similar companies, there’s a clear interest in reducing development costs and making it possible to bring new products and product upgrades to the market quickly. Hardware-in-the-loop simulations is a way to test parts of a system before any prototypes are constructed, and it brings great advantages to a development project since various ideas and system parameters can be examined at a much lower expense when compared to tests that utilize actual hardware.The purpose of this master’s thesis project was to create a hardware-in-the-loop simulation and evaluation platform for the MY500 machine’s X and Y axis nozzle positioning system. The MY500 machine ejects dots of solder paste on a PCB prior to the placement of electronic components, and it does so along a pre-selected trajectory which also contains information about the target positions for the dots. This is handled by a control unit, also developed by Mycronic AB, called CMOT3, which runs ANSI-C code and has various interfaces for interaction with the rest of the machine. In this particular case, its SPI interface was used to communicate with the simulated system model, which ran on a Speedgoat computer which has a system architecture specifically designed for running Simulink models in real-time.Before the project was started, there have already been two thesis projects that have dealt with modeling of the MY500 machine’s positioning system. One of these had a goal of implementing it in a HIL platform, and although it wasn’t done due to technical issues, the conclusion was that it’s reasonable to continue the work. This project used a different approach for the structure and resulted in the first successful HIL platform for the MY500 X and Y actuators, and it has been shown to produce realistic simulation outputs. An analysis method based on multivariate process capability evaluation has been developed and used to score the data from the simulations.In the concluding part, the test data that has been analyzed with the suggested evaluation method is also discussed, along with some suggestions of further work on both the platform and the method itself.
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Hui, Ip Kee. "Analysis of surface mount technology solder joints." Thesis, Brunel University, 1996. http://bura.brunel.ac.uk/handle/2438/5380.
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The factors determining the quality of surface mount technology (SMT) solder joints are numerous, and complex. The exploration of these factors, and how they may affect the reliability and quality of the joints can only be achieved through continuous research. In this project, essential areas of SMT joints were selected for study and analysis, with the intention of providing additional design and process guidelines for the production of quality SMT joints. In the infrared reflow process, one of the common defect phenomena is the occurrence of tombstoning; that is after soldering only one end of the component is soldered while the other is lifted up, assuming a position like a tombstone. The initiation of tombstoning during reflow was analysed based on the forces acting on the component. A model was developed to predict the initiation of this phenomenon. The model shows that, under vibration-free conditions, the surface tension of the molten solder is the source of the force causing the initiation of tombstoning. The contact angle, which varies with the length of the printed circuit board solder land, has a significant effect on the value of the surface tension acting as a force pulling upward on the component. The model further shows that tombstoning initiation is due to the combined effects of the surface tension; the weight of the component; the dimensions of the component; the length of the solder underneath the component; and the length of the solder protruding from the end of the component. Selected components were used as examples for predicting the conditions of initiation, and these conditions were further substantiated by a series of experiments. Another area of study was a method which directly pulled the components off printed circuit boards and this was used as a means for testing the bond quality of surface mount technology leadless chip solder joints. Components D7243, CC1206, RC1206, RC121O, and CC1 812 were selected for this study. It was found that the ultimate tensile force which breaks a component off the printed circuit board has the potential to be used as a parameter for measuring the quality of the solder joint. The effect of solder thickness on the strength of a joint has also been investigated. The shape of joints soldered by two methods, wave soldering and infrared reflow, were compared. Joints at the two ends of a component produced by infrared reflow were found more uniform than the ones produced by wave soldering. A recommendation is made here for the wave soldering approach in achieving uniform solder joints. The effects of solder shape on the joint strength were further investigated by finite element analysis. A convex joint was found marginally more robust than a concave joint. Two aspects of the internal structure of SMT solder joints were investigated, void content and copper/tin intermetallic compounds. The voiding conditions of wave-soldered and infrared reflow joints were compared. No voids were found in all specimens that were produced by wave soldering. However, there were always voids inside joints produced by infrared reflow. Microhardness tests indicated that the hardness of compounds at the copper/solder interface of infrared reflowed joints is lower than that in the wave-soldered joints. It is considered that the lower hardness of the interfacial region of the infrared reflowed joints is due to the presence of voids. Scanning electron microscopy was used to study the formation of copper/tin intermetallic compounds for joints produced by infrared reflow. The results show that Cu 6 Sn5 was the only compound with a detectable thickness. Other compounds such as Cu3 Sn, were virtually not found at all. Aging of the joints at 100°C, shows that both the Cu 6Sn5 and the overall interfacial thickness grew with time. One of the important areas which had been overlooked previously and was studied in some details was the effects of solder paste exposure on the quality of solder paste. The characteristic changes of solder paste due to exposure were investigated in three areas, weight loss, tackiness, and rheology. The evaporation of low boiling point solvents was considered as the main contribution to the loss in the weight of the solder paste. The weight loss against exposure time was found to follow an exponential behaviour. A method was designed to evaluate the tackiness changes of solder paste due to exposure. It was found that the decay of tackiness against exposure time can be expressed by a power law. It is recommended that solder paste manufacturers should provide the necessary characteristic constants so as to enable the characteristics to be calculated after a specific exposure. The rheological changes of the solder paste as a result of exposure were also investigated. The implication on the printability of the solder paste due to these changes was studied and discussed.
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Dosedla, Milan. "Trendy v oblasti pájecích past a vliv nanočástic." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242070.
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This thesis deals with novel trends in solder paste technology. It focuses on nanoparticle applications used as a tool for improving a state of the art lead free solder alloys. The recently published results about the impact of different types of nanoparticles on properties of newly-emerged nanocomposite solders are discussed and summarized in the thesis. Preparation, practical application and testing of new solder paste based on low temperature SnBi alloy with an admixture of titanium dioxide are also discussed. Finally, properties of solder joints using these solder pastes are investigated and the results are evaluated.
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Dokoupil, Jakub. "Porovnání pájecích past z pohledu spolehlivosti pájeného spoje." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-376992.
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This thesis deals with the teoretical description of the solder during reflow soldering the solder paste and describing the defects arising during this process. Practical part of the thesis describes the testing of two solder pastes with different silver content before and after the accelerated temperature cycle.
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Matras, Jan. "Aplikace reaktivních nanočástic do SAC pájecí pasty." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377074.
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This work is a research on the topic of reactive nanoparticles and their agitation into the solder paste, which it also describes. It describes in detail the properties of each solder alloys. It explains the creation of intermetallic layers in the soldering process and examines their structure. It also focuses on the evaluation and methodology of testing the properties of solder pastes. In the practical part, individual tests are performed with PF606 and PF610 solder paste.
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He, D. "Modelling and computer simulation of the behaviour of solder paste in stencil printing for surface mount assembly." Thesis, University of Salford, 1998. http://usir.salford.ac.uk/14676/.
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One of the main challenges facing the electronics manufacturing industry in solder paste printing for ultra-fine pitch surface mount and flip-chip assembly is the difficulty in achieving consistent paste deposit volumes from pad-to-pad. At the very small aperture geometries required for ultra-fine pitch and flip chip assembly, flow properties of the paste becomes one of the dominant factors in the printing process. It is widely accepted that over 60% of assembly defects originate from the solder paste printing stage, and hence the urgent need for a better understanding of solder paste rheology, its behaviour during printing, and its impact on defect generation. This understanding is essential for achieving proper control of the printing process. This thesis presents the result of work on the modelling and computer simulation of solder paste behaviour during printing, and consists of three main parts. The first part concerns the modelling of paste behaviour in stencil printing using a vibrating squeegee. The performance of the vibrating squeegee is analysed and process models developed for predicting the ideal printing conditions. In the second part, the random packing of solder powder and the microstructure of solder paste are numerically simulated by applying Monte Carlo method. The effect particle size distributions on the paste microstructure is studied in this part. Based on the simulation results of the second part, the third part concerns the study of the effect of particle size distribution on the paste viscosity and the hydrodynamic interaction between adjacent particles during paste flow. A theoretical enhanced model for predicting the viscosity of dense suspensions such as solder pastes has been developed. This correlates relative viscosity with particle size distribution and with solid volume fraction of dense suspensions. The results of the work have wide applicability: firstly for solder paste manufacturers in optimising paste printing performance at the development stage and for stencil printing equipment manufacturers in specifying the ideal conditions for defect free printing. The simulation algorithm and the viscosity model are also applicable for a wide range of industrial processing applications; in particular metal or ceramic powder compaction, material surface coating, chemical or food material transportation.
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Wilson, Antony R. "Modelling and simulation of paradigms for printed circuit board assembly to support the UK's competency in high reliability electronics." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10236.
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The fundamental requirement of the research reported within this thesis is the provision of physical models to enable model based simulation of mainstream printed circuit assembly (PCA) process discrete events for use within to-be-developed (or under development) software tools which codify cause & effects knowledge for use in product and process design optimisation. To support a national competitive advantage in high reliability electronics UK based producers of aircraft electronic subsystems require advanced simulation tools which offer model based guidance. In turn, maximization of manufacturability and minimization of uncontrolled rework must therefore enhance inservice sustainability for 'power-by-the-hour' commercial aircraft operation business models.
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Rychlý, Ivo. "SnBi pájecí pasta a vliv reaktivních nanočástic." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377337.
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This work deals with effects of nanoparticles, mainly copper and silver, on properities of lead-free solder pastes. It describes basic tests done on solder pastes according to IPC-TM-650 standards. In practical section this work focuses on the preparation of Sn-Bi solder paste and the measuring of viscosity. After that different concentrations of silver copper alloy nanoparticles are added to the SnBi solder paste. These solder pastes are tested by the IPC standarts and mechanical and resistive tests are done on printed circuit boards where the effects of mixed in nanoparticles are observed.
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Mendes, Luiz Tadeu Freire. "Estudo experimental da migração eletroquímica em soldagem eletrônica Sn/Ag/Cu \"Lead Free\"." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-09092009-100846/.
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Sabemos que em placas de circuito impresso montadas com tecnologia SMD Surface Mount Device podem ocorrer problemas com a migração eletroquímica. O fenômeno aparece principalmente porque os novos encapsulamentos possuem terminais com espaçamentos muito próximos. A migração eletroquímica pode tornar-se um potencial problema no processo de soldagem eletrônica quando é utilizado a tecnologia Lead Free na montagem das placas. O processo de migração eletroquímica ocorre quando temos metal, isolante e metal, em ambiente de alta umidade e sobre polarização elétrica, o metal deixa a posição inicial em forma de íon e se redeposita sobre o isolante. Em uma placa de circuito impresso, dois terminais adjacentes podem tornar-se eletrodos, dessa forma as dendritas crescem do cátodo para o ânodo. Podem aparecer diferentes morfologias com diferentes elementos envolvidos no processo de migração, dependendo da composição da pasta de solda ou acabamento da placa de circuito impresso. Uma estrutura do tipo pente comb feita sobre laminado FR4 foi utilizada nos experimentos. A distância entre as trilhas foram de 102 e 254 mícrons para simular uma distancia real dos terminais dos dispositivos. Os fatores considerados durante os experimentos foram: A distancia entre os terminais na estrutura (102 ou 254 mícrons), tensão aplicada (2 ou 3 V). Foi observado que a pasta de solda e o acabamento final não influenciam no processo de migração eletroquímica. O Estanho foi o principal metal que migrou. Todos os resultados obtidos nesse estudo concordam com a literatura.<br>It is well known that in printed circuits boards assembled by SMT technology may occur Electrochemical migration (ECM). This phenomenon appears mainly because the new packaging has the terminals very close. Also the Electrochemical migration may become a potential reliability problem in electronic soldering when lead free technology is used in soldering electronic devices. Electrochemical migration is an electrochemical process where metal on an insulating material, in a humid environment and under an applied electric field, leaves its initial location in ionic form and redeposit. In a PCB two adjacents terminal may behave as electrodes so the dendrites grow from cathode to anode. It can show different morphologies with the different migration elements involved depending on the solder paste composition or PCB surface finishing. A structure with a comb shape printed on FR4 substrate was used in the experiments. The distance between the fingers in the structure was 102 or 254 microns, in order to simulate a real distance between dispositive terminals. The factors considered during the experiments were surface finishing (ENIG or HASL), solder paste composition, distance between terminals (102 or 254 microns) and applied voltage (2 or 3 V). It was observed that the solder paste and the surface finishing dont influence the ECM process. Tin was the main metal that migrates. All the results obtained in these study agrees with the literature.
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Jemai, Norchene. "Développement de la technique de sérigraphie pour la formation de billes de connexions inférieures a 100µm pour l'assemblage 3D : optimisation et étude de fiabilité." Thesis, Toulouse, INSA, 2010. http://www.theses.fr/2010ISAT0010/document.
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L’assemblage et le conditionnement en électronique représentent un enjeu de création de nouveaux systèmes électroniques hybrides rassemblant sur un même substrat des éléments électroniques, optiques, mécaniques… La technologie Flip-chip , introduite par IBM et baptisée C4 (Control Collapse Chip Connection), garantit une plus grande densité d’intégration tout en gardant les mêmes dimensions de puce. Au coeur de cette technologie, le « Bumping » est un procédé qui consiste en l’introduction d’une microbille conductrice entre deux plots de connexion des puces afin de réaliser une liaison électrique et mécanique avec le niveau de packaging suivant. La technique de dépôt par sérigraphie de pâte à braser est récemment devenue pratique en raison de son adaptation aux alliages sans plomb. Cette méthode présente l'avantage d'un faible coût et d'une possible production à grande échelle. Nous avons donc choisi de développer cette technique afin d’obtenir des matrices de connexions électriques de dimensions comprises entre 50 μm et 100 μm, pour une pâte à braser de type Sn3.0Ag0.5Cu. Nous avons déterminé les paramètres de sérigraphie afin d’obtenir un minimum d’étalement de pâte pour un remplissage maximum des ouvertures du masque choisi en Ni-électroformé d’épaisseur 50μm : une vitesse de racle de 20mm/s et une vitesse de démoulage de 4mm/s sont par exemple à retenir pour une pâte de type 5. L’étude du masque de sérigraphie a conduit au choix d’ouvertures circulaires. Des formes de billes circulaires ont été obtenues pour des UBM (Under Bump Metallurgy) également circulaires, de diamètre ¼ et ½ le diamètre de l’ouverture du masque. L’optimisation du profil de refusion a permis de déterminer qu’un palier à 180°C, un TAL de 90s ou plus et une température maximale à 250°C favorisaient l’obtention de billes circulaires avec absence de vides. Pour une pâte de type 6, des billes de 60à 70μm de diamètre ont été obtenues pour des ouvertures de masque de 100μm. Une étude de fiabilité de ces billes à partir de tests de cisaillement et de l’analyse des IMC (composés intermétalliques) formés après refusion a permis de montrer que des UBM en Cr-Cu-Au, de diamètre égal à la moitié de l’ouverture du masque, permettaient d’assurer un meilleur maintien mécanique des billes<br>The semiconductor industry has continuously improved its products by increasing the density of integration resulting in an increasing of the I/Os, always with a low cost requirement. To obtain high-density and high-speed packaging, the Flip-Chip interconnection technology was introduced by IBM also called C4 (Control Collapse Chip Connection). Solder bumps have been widely used in electronic industry and were generally based on the Sn-Pb alloy, for its low melting point and good wetting property. Containing highly toxic element (Pb), Pb-Sn solder alloy has been banned. The ternary alloy Sn-Ag-Cu seems to be the best compromise, in fact it as physical and chemical characteristics equivalent to that of Sn-Pb.In this study we are interested to optimize stencil printing process and adjust it with the flip-chip technology, in order to obtain solder bumps which height is between 50µm and 100µm associated to pitches less than or equal to 200µm, using Sn-3.0Ag-0.5Cu solder paste. We have optimized the stencil printing parameters machine, the stencil apertures shape and size (circular shape and 50µm height, for a Ni-electroformed stencil). Spherical solder balls have been achieved with circular UBM (Under Bump Metallurgy), which diameter is ¼ and ½ the diameter of the stencil aperture. The reflow thermal profile is the key to the formation of a reliable solder bump. It must allow a homogeneous reflow for all particles of the metallic solder paste. We define a thermal profile with a Time above liquidus (TAL) of 90s, a temperature in soaking zone (Ts) of 180°C and a maximum temperature (Tmax) of 250°C. For type 6 solder pastes, balls of 60-70µm diameter have been obtained for 100µm stencil apertures.The quality of a solder joint is directly related to the adhesion of the solder ball to the substrate. Among the various methods of mechanical testing, shear testing is the most widely used to assess the strength of the attachment of beads to the substrate and determine the fragility of the ball at the interface caused by the intermetallic layer compounds (IMC) formed after the reflow step. We have shown that Cr-Cu-Au UBM, with a diameter equal to the half of the stencil aperture, ensure the mechanical adhesion of the balls
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Šimon, Vojtěch. "Spolehlivost pájených spojů LED panelů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-319627.
Full textAbstract:
Thesis is focused on the effect of heating factor on quality of solder joints. In theoretical part is solved reflow soldering technology, problematice of solder paste choice or criteria of soldering profile setting. The practical part is dedicated to demonstrating the impact of heating factor on solder joint quality. There are used X-Ray analysis, microsections and electron microscopy. In the final part of this thesis are summarized knowledge from theoretical part and experimental obtained results to defend of next steps in diploma thesis.
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Toufar, Michal. "Analýza metod nanášení tavidel a pájecích past na DPS pro BGA komponenty." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-241971.
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This thesis deals with rework of BGA components. There are described defects and errors in a solder joints. The current trend is focused on thin packages with fine pitch. It is assembled with smaller and smaller solder balls. It is described effect of different application of flux and solders paste for rework. The main part is focused on dipping and dispensing. These methods are suitable for repair process.
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Šimeček, Ondřej. "Problematika šablonového tisku pájecí pasty pro součástky s malou roztečí vývodů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-218992.
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Despote the indisputable advantages of fine-pitch components, is need to calculate with a few trouble during production, especially increased requirements for accuracy of mounting and solder printing. In this work I’m concerned with problems of solder printing for these components and evaluation using SPC. For the evaluation I used 3D paste inspection based on laser scanning of the surface. The output of this work is to describe the principles of solder printing and elaborating of GR&R, SPC analysis and histograms of solder printing for some outputs. I focused in my master thesis on motive design change of problematic components and economic evaluation of the adjustments.
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Seman, Anton. "On-line non-destructive ultrasonic rheology measurement of solder pastes." Thesis, University of Greenwich, 2010. http://gala.gre.ac.uk/5649/.
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In surface mount technology (SMT) electronics assembly, the solder paste is printed onto the PCB's surface through a stencil and the components are later placed over the solder paste deposits. Since 2007, the use of extremely small SMT components for assembly of SMT devices has been widespread, and achieving consistent print deposits for fine pitch (the distance between the leads of the components) components has become a real challenge. The majority of the defects at the printing stage, such as skipping and bridging, were found to be related to the quality of the solder paste. These defects are usually carried over to the reflow process, causing defective final products. Hence, it is important to monitor the quality of the solder paste. Conventional techniques for monitoring the quality of solder pastes during the production and packaging stage are usually based on the viscosity measurements of the solder pastes from the viscometer and rheometer. One of the potential limitations of viscometer- and rheometer-based measurements is that the collection and preparation of the solder paste samples can irreversibly alter the structure and flow behaviour of the sample. Due to the sample preparation process (removal, preshear/ pre-mixing), repeatability issues were often encountered when taking measurements using a viscometer or rheometer. Secondly, rheological measurements and the interpretation of rheological data comprise a very technical and time consuming process, which requires professionally trained research and development (R&D) personnel. Finally, the monitoring/inspection process usually employs random sampling technique from the production batch. Hence, measurement may not represent the actual quality of the whole production batch. This would mean that the conventional solder paste quality control that has been employed in the industry as a benchmark for printability (i.e. checking the viscosity of the paste before being despatched to the customers), would need to be re-evaluated for its feasibility and other possible methods of solder paste quality control would need to be considered. This has brought the ultrasound technique into context as it can offer a non-destructive evaluation of the quality of the solder paste in terms of viscosity. Also, it can be used at different stages of paste production and processing. It is for these reasons that materials suppliers that formulate and produce solder pastes, as well as solder paste consumers (especially contract electronics manufacturers), are keen to see the development of simple, easy-to-use and accurate techniques for the rheological characterisation of solder pastes. This thesis concerns the study of a non-destructive ultrasonic technique for characterising the rheological properties of solder pastes and, specifically, the use of through-mode microsecond ultrasonic pulses for evaluation of viscoelastic properties of solder paste materials. In this study, a wide range of flux systems and solder alloy particle distributions used in the industry are investigated to determine the correlation of the ultrasound attenuation and velocity to the viscosity of the solder paste and their correlation to paste printing performance. The work is part of a bigger study aimed at the development of an on-line quality control technique for paste manufacture based on both conventional rheological tests and ultrasound measurements. Results from the work on the comparative study of standard fluids and both commercial and newly formulated solder pastes and flux vehicle systems have been used to demonstrate the utilisation of the ultrasound technique for on-line, non-destructive measurement of the viscosity of non- Newtonian materials such as solder pastes. The study also found that the viscosity of the solder paste is governed by the intermolecular forces between the solder particles and the flux. The strength of these intermolecular forces depends on the probability of these particles rubbing up against one another while the paste is being sheared. Provided that the right correction factor for a particular shear rate is used, the ultrasound viscosity results obtained were found to be comparable to the rheometer viscosity results or to the viscosity provided by the solder paste manufacturer. The ultrasound technique produced consistent results and was also proven to work at low temperatures. The ultrasound technique may be used to help solder paste manufacturers to add the correct amount of flux or solder particles to their paste in order to reach a desired viscosity. Otherwise, it can be used as a quick go/no-go monitoring tool in the production line for predicting printing quality. Based on the foregoing, it can be concluded that the ultrasound technique is a viable alternative to using a rheometer.
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Yin, Liang. "Reactive wetting and spreading in binary metallic systems." Diss., Online access via UMI:, 2005.
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Currie, Mark Andrew. "Characterisation of solder pastes used in the reflow soldering of surface mount assembly." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360450.
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Durairaj, Rajkumar. "Rheological characterisation of solder pastes and isotropic conductive adhesives (ICAs) for microsystems assembly technology." Thesis, University of Greenwich, 2006. http://gala.gre.ac.uk/6153/.
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The printing of solder pastes through very small stencil apertures required for flip-chip pitch sizes, is expected to result in increased stencil clogging and incomplete transfer of paste to the printed circuit board pads. The paste printing process depends on conditions such as good paste roll, complete aperture filling and paste withdrawal. The paste rheology is important in the printing process because the viscosity of the paste must be low enough for the squeegee to force the paste through the stencil apertures, but high enough to recover to its required shape and not flow beyond its stencilled area. Rheological measurements can be used as a tool to study the deformation or flow experienced by the pastes during the stencil printing process. In addition, the rheological measurements can also be used as a quality control tool in the paste production process for identifying batch to batch variation; and to reduce the associated printing defects in the paste printing process. The work reported here on the rheological characterisation of novel pastes used in Microsystems assembly applications is divided into four main parts. The first part concerns the study of the effect of wall slip on paste viscosity measurement. For this study, a novel technique was developed for flow visualisation experiments using video observation to characterise the pastes wall slip behaviour. The second part of the study concerns an investigation of the visco-elastic behaviour of the pastes, and the main focus of the work was to determine the linear visco-elastic region using oscillatory shear stress experiments. The third part of the work deals with the study of the thixotropic behaviour of pastes using both hysteresis loop and constant shear rate tests. The final part of the study concerns the printing trial of three different paste formulations (XP22, Tamura and Polysolder) paste using a UV-LIGA manufactured stencil recently developed at Heriot-Watt University. The work is part of EPSRC funded research project on Microsystems Assembly Technology for the 21st Century under grant GR/R09206/02, and was carried out in collaboration with five industrial collaborators and two other academic partners. The Individual Grant Review (IGR) for the MAT21 project was assessed as internationally leading' by the EPSRC committee. The extensive set of results from the experimental programme, in particular, on the aspect of key paste performance indicators has been adapted by one of the industrial partners (a paste manufacturer) for implementation as part of a quality assurance (QA) tool in their production plants in various part of the world, and the results have also been disseminated widely through journal publications and presentation at international conference.
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Marks, Antony Edward. "Characterisation of lead-free solder pastes and their correlation with the stencil printing process performance." Thesis, University of Greenwich, 2012. http://gala.gre.ac.uk/9456/.
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Solder pastes are complex materials whose properties are governed by many factors. Variations exhibited in solder paste characteristics make it increasingly difficult to understand the correlations between solder paste properties and their printing process performance. The recent EU directives on RoHS (Restriction of Hazardous Substances – enacted by UK regulations) and WEEE (Waste from Electrical and Electronic Equipment) has led to the use of lead-free soldering in the SMA (surface mount assembly) process, and an urgent need for better understanding of the characteristics and printing performance of new solder paste formulations. Equally, as the miniaturisation of hand-held and consumer electronic products continues apace, the solder paste printing process remains a real challenge to the electronics assembly industry. This is because the successful assembly of electronic devices at the ultra-fine pitch and flip-chip geometry requires the deposition of small and consistent paste deposits from pad to pad and from board to board. The paste printing process at this chip-scale geometry depends on conditions such as good paste roll, complete aperture filling and paste release from the apertures onto the substrate pads. This means that the paste flow and deformation behaviour, i.e. the paste rheology, is very important in defining the printing performance of any solder paste. Rheological measurements can be used as a tool to study the deformation or flow experienced by the pastes during the stencil printing process. In addition, the rheological measurements can also be used as a quality control tool in the paste production process for identifying batch-to-batch variation, and to reduce the associated printing defects in the paste printing process. The work reported here on the characterisation of lead-free solder pastes and their correlation with the stencil printing process is divided into five main parts. The first part concerns the study of the effect of variations in flux and particle size distribution (PSD) on the creep recovery performance of lead-free solder pastes used for flip-chip assembly. For this study, a novel technique was calculating the extent of paste recovery and hence characterising the slumping tendency in solder pastes. The second part of the study concerns the influence of long-term ageing on the rheology and print quality of lead-free solder pastes used for flip-chip assembly, and the main focus of the work was to develop methodologies for benchmarking new formulations in terms of shelf life, rheological deterioration and print performance. The third part of the work deals with a rheological simulation study of the effect of variation in applied temperature on the slumping behaviour of lead-free solder pastes, and the fourth part considers the rheological correlation between print performance and abandon time for lead-free solder paste used for flip-chip assembly. The final part of the study concerns the influence of applied stress, application time and recurrence on the rheological creep recovery behaviour of lead-free solder pastes. The research work was funded through the PRIME Faraday EPSRC CASE Studentship grant, and was carried out in collaboration with Henkel Technologies, Hemel Hempstead, UK. The extensive set of results from the experimental programme, in particular relating to the aspect of key paste performance indicators, has been adapted by the industrial partner for implementation as part of a quality assurance (QA) tool in its production plant, and the results have also been disseminated widely through journal publications and presentations at international conferences.
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Dhakal, Ramji. "Failure mechanism of lead-free Sn-Ag-Cu solder BGA interconnects." Diss., Online access via UMI:, 2005.
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Raut, Rahul. "Thermal management of heat sensitive components in Pb-free assembly." Diss., Online access via UMI:, 2005.
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Marquez, de Tino Ursula. "Reduction of nitrogen consumption of lead-free reflow processes and prediction models for behaviors of lead-free assemblies." Diss., Online access via UMI:, 2009.
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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Systems Science and Industrial Engineering, 2009.<br>Includes bibliographical references.
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Bibette, Jérôme. "Interactions de déplétion et équilibre fluide-solide des émulsions." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1990. http://pastel.archives-ouvertes.fr/pastel-00650854.
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Nase, Julia. "Décollement de matériaux viscoélastiques : du liquide visqueux au solide élastique." Phd thesis, Paris 6, 2009. https://pastel.archives-ouvertes.fr/pastel-00005510.
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Dans le cadre de cette thèse expérimentale, nous étudions le décollement en géométrie de probe tack lors de la transition d'un liquide visqueux vers un solide élastique mou. Notre système modèle (du PDMS à différents degrés de réticulation) assure une transition continue entre ces classes de matériaux. Au début du décollement, une instabilité de digitation avec une longueur d'onde caractéristique apparaît. Pour une huile newtonienne nous expliquons le coarsening des structures par analyse de stabilité linéaire. Pour des propriétés du liquide jusqu'au solide, nous identifions des mécanismes volumiques ou interfaciaux et analysons quantitativement leur longueur d'onde initiale respective. Nous montrons que le mécanisme de décollement est déterminé par la viscoélasticité linéaire et des propriétés de surface. Au cas interfacial, nous expliquons la dépendance en vitesse de l'énergie d'adhésion par des propriétés volumiques et confirmons ainsi une loi empirique. En adaptant une technique 3D récente, nous visualisons in situ la ligne de contact entre le matériau viscoélastique et le substrat rigide, offrant ainsi un accès direct aux conditions aux limites.
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Brunel, Marc. "Etude de matériaux solides solgel présentant la proprieté de transmission saturable." Phd thesis, Université Paris Sud - Paris XI, 1996. http://pastel.archives-ouvertes.fr/pastel-00713902.
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Le développement rapide des sources lumineuses intenses, accordables en longueur d'onde, représente une menace croissante pour les différents détecteurs existant, et tout particulièrement l'il. Une méthode de protection envisageable est l'utilisation de composes organiques presentant un comportement d'absorption saturable inverse: leur absorption augmente lorsqu'ils sont eclaires par des faisceaux lumineux tres intenses. En utilisant le procede sol-gel, nous avons pu élaborer des materiaux solides compacts dopes avec des molecules de la famille des phtalocyanines. A la longueur d'onde de 532 nanometres, des echantillons de transmission initiale 0,7, ont permis d'induire une densite optique de 1 sous l'effet d'impulsions de forte densite. Avec des echantillons de transmission lineaire 0,4, la densité optique induite est egale a 1,6. Afin de mieux comprendre le processus de saturation de la transmission, nous avons écrit des programmes informatiques permettant de simuler le comportement observe. Ils se sont averes etre d'excellents outils pour mieux cerner les phenomenes mis en jeu. Pour améliorer les performances obtenues, differents types de synthèses ont ete entrepris, et differentes molecules organiques ont ete introduites dans des matrices sol-gel: des tetrabenzoporphyrines, des molécules de fullerènes et de hitci. Pour déterminer les plages spectrales d'efficacité de ces echantillons, des sources impulsionnelles accordables en longueur d'onde ont ete installees. Apres la synthèse de premiers échantillons efficaces dans la partie bleue du spectre visible, il a ete possible d'en elaborer d'autres efficaces dans la partie rouge du spectre. Disposant de materiaux actifs a la longueur d'onde de 620 nanomètres, nous avons alors pu montrer a cette longueur d'onde qu'il s'agit d'un processus ultrarapide qui intervient en moins de cent femtosecondes. Enfin, en utilisant les programmes de simulation developpes, nous avons étudie les performances que nous sommes en droit d'esperer de composes absorbants saturables inverses qui seraient inseres dans un systeme limiteur optique.
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Petit, Johan. "Monocristaux dopés ytterbium et matériaux assemblés pour lasers de fortes puissances." Phd thesis, Paris 6, 2006. http://pastel.archives-ouvertes.fr/pastel-00001720.
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Les lasers solides dopés terres rares ont certains avantages: ils sont compacts, possèdent un fort rendement et leur faisceau est de bonne qualité. Le principal problème limitant la puissance est la production de chaleur inhérente au processus laser. Cette thèse comporte un premier volet consacré à l'étude de nouveaux matériaux à forte résistance à la puissance de pompage: GdVO4 :Yb et CaGdAlO4 :Yb en particulier. Des émissions laser quasiathermiques et des impulsions ultra-brèves ont été obtenues dans ce dernier. Dans un second volet, une nouvelle méthode d'assemblage par voie sol-gel a été étudiée pour créer des sources composites permettant une dissipation efficace de la chaleur. Avec cette technique, les homo-assemblages (matériaux de même nature chimique) présentent les mêmes capacités de résistance que ceux obtenus par la méthode de soudage par diffusion. Les hétéroassemblages (deux matériaux différents) sont difficiles à obtenir par diffusion mais, avec une interface issue du procédé sol-gel, ils ont résisté jusqu'à 200°C et 15 W de pompage. Les pertes lasers à l'interface sont négligeables et la température dans le matériau est abaissée de près de 40%.
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Schwartz, Sylvain. "Gyrolaser a l'Etat Solide Application des Lasers a Atomes a la Gyrometrie." Phd thesis, Ecole Polytechnique X, 2006. http://pastel.archives-ouvertes.fr/pastel-00714245.
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Schwartz, Sylvain. "Gyrolaser à état solide. Application des lasers à atomes à la gyrométrie." Phd thesis, Ecole Polytechnique X, 2006. http://pastel.archives-ouvertes.fr/pastel-00002959.
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Le gyrolaser est un capteur de rotation utilisé dans la plupart des centrales de navigation inertielle. Dans sa forme usuelle, il est constitué d'une cavité laser en anneau remplie d'un mélange d'hélium et de néon pompé par des électrodes à haute tension. L'utilisation d'un milieu amplificateur gazeux, si elle permet de garantir naturellement le fonctionnement bidirectionnel stable nécessaire à la mesure des rotations, constitue en revanche la principale limitation industrielle des gyrolasers actuels en termes de coût, fiabilité et durée de vie. On étudie dans ce mémoire la possibilité de substituer au milieu à gain gazeux un milieu solide (Nd-YAG pompé diode). On présente pour cela une étude théorique et expérimentale des différents régimes de fonctionnement du laser en anneau à état solide. On montre que la stabilité du régime bidirectionnel peut être garantie par une boucle de contre-réaction agissant sur les états de polarisation pour créer des pertes différentielles proportionnelles à la différence d'intensité entre les modes contrarotatifs. Cette technique permet l'obtention d'un gyrolaser à état solide, dont la réponse en fréquence est perturbée par les couplages entre modes. Plusieurs solutions, optiques et mécaniques, destinées à améliorer la qualité de cette réponse en fréquence sont successivement étudiées. On se pose enfin la question d'un possible équivalent atomique du gyrolaser, en soulignant les analogies qui existent entre la physique du gyrolaser à état solide et celle de certains dispositifs à onde de matière. Un modèle original de description unidimensionnelle d'un condensat de Bose-Einstein dans un piège torique en rotation dans le cas d'un fort confinement transverse est présenté. Quelques applications possibles de ce modèle théorique sont finalement discutées. Ces travaux ont donné lieu au dépôt de 9 brevets en France et à l'étranger, ainsi qu'à plusieurs publications scientifiques, dont une dans la revue Physical Review Letters. Ils ont également débouché sur la réalisation d'un prototype industriel de gyrolaser à état solide, actuellement en cours d'étude et de caractérisation par la division Thales Aerospace. Enfin, ils ont été couronnés par le Prix de Thèse de l'École Polytechnique 2007 et par le Prix de l'Innovation Technologique Air et Espace 2007.
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Ramasubramanian, Arun Shrrivats. "Advanced process window design for 01005 assemblies." Diss., Online access via UMI:, 2008.
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Thesis (M.S.)--State University of New York at Binghamton, Department of Systems Science and Industrial Engineering, Thomas J. Watson School of Engineering and Applied Science, 2008.<br>Includes bibliographical references.
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Mallik, Sabuj. "Study of the time-dependent rheological behaviour of lead-free solder pastes and flux mediums used for flip-chip assembly applications." Thesis, University of Greenwich, 2009. http://gala.gre.ac.uk/8149/.
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The two most important trends in electronic industry are "miniaturisation" and "increased functionality". Over the last fifteen years, the electronic manufacturing industries have experienced tremendous pressure to meet the requirements for miniaturised products, particularly, hand-held consumer products. Functionality of these products has also evolved at the same pace through packing in more and more features. As these trends are set to continue, there is an increasing demand for better understanding of soldering technology, particularly in the area of solder pastes used in the reflow soldering of surface mount devices. Successful assembly of electronic devices for ultra-fine pitch and flip-chip applications requires the deposition of small and consistent paste deposits from pad to pad, and from board to board. The paste printing process at this chip-scale geometry depends on conditions such as good paste roll, complete aperture filling and paste release from the apertures onto the substrate pads. This means that the paste flow and deformation behaviour is very important in defining the printing performance of any solder paste. In order to understand rheological phenomena associated with the flow of solder pastes, it is necessary to understand time dependent rheological behaviour. Such behaviour is common to many industrial fluids and consequently has been of interest to rheologists for many years. The time dependent behaviour observed in solder pastes is largely due to the breakdown of the flocculated structure formed during storage or idle period. In general, the breakdown of the structure with shear results in a decrease in apparent viscosity. Recovery after shear is generally a very slow process and depends on the intensity of the breakdown and previous shear history. The work reported in this thesis on the characterisation and modelling of time-dependent rheological behaviour of solder paste and flux mediums used in surface mount applications is made up of four main parts. The first part concerns the characterisation of the time-dependent behaviour of solder pastes and flux mediums. Two types of tests were performed at this stage: hysteresis-loop test and step-shear-rate test. In the second part of the study the time-dependent rheology of solder pastes and flux mediums has been modelled to evaluate the mechanisms for the break-down of the internal structure of the paste materials. A novel technique has been developed which combines the experimental rheological data with a modified structural kinetic model (SKM) to investigate the rate and extent of structural change of solder paste and flux medium. The third part of the study deals with the experimental and modelling studies of the short term build-up of solder paste and flux medium structure using the stretched exponential model. In the final part of the study the printing trials of four different solder paste samples were carried out to investigate the effect of post-print rest period on slumping behaviour of solder paste. From the experimental characterisation it was evident that both the solder paste and flux samples are strongly thixotropic and shear-thinning in nature. The thixotropic breakdown behaviour of solder paste and fluxes has been satisfactorily modelled using a second-order structural kinetic model. The results from this study can be of great help for the solder paste manufacturers and formulators in quantifying and predicting the effect of long term shearing on the solder paste samples. The technique developed can also be utilized for similar materials such as solar pastes and conductive adhesives. The short-term build-up of solder pastes and fluxes has been successfully modelled using the stretched exponential model. The paste manufacturers and formulators can use the technique developed to predict and quantify the slumping behaviour of solder paste. The end-users, for example the electronics assemblers may use the technique to optimize their assembly process by minimising/preventing slumping of solder paste.
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Moto, Mpong Serge. "Etude rhéologique et simulation numérique de l'injection d'un alliage d'aluminium à l'état semi-solide." Phd thesis, École Nationale Supérieure des Mines de Paris, 2002. http://pastel.archives-ouvertes.fr/pastel-00001341.
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Ce travail, qui a été réalisé dans le cadre d'un projet européen, avait pour objectif de faire la simulation numérique de l'injection d'un alliage d'aluminium (A356) à l'état semi-solide. Pour atteindre cet objectif, nous avons travaillé sur deux principaux axes qui sont l'expérience et la simulation numérique. Sur le plan expérimental, l'objectif était de trouver une loi de comportement et ses paramètres pour caractériser le comportement de notre alliage à l'état semi-solide. Cette étude nous a conduit d'une part à passer en revue les différentes classes de loi disponibles dans la bibliographie et à utiliser une loi de comportement viscoplastique, et d'autre part à réaliser un nouveau test rhéologique, le test de l'écoulement de Stephan. Les résultats expérimentaux ont été satisfaisants et l'identification des paramètres a pu être faite, en utilisant une stratégie de type essai-erreur. Ceci nous a permis de trouver pour notre cas des paramètres en concordance avec ceux trouvés dans la bibliographie et d'obtenir un accord raisonnable entre simulation numérique et mesures sur l'ensemble des essais effectués. Sur le plan purement numérique, nous avons dans un premier temps adapté le code de calcul R3 à la mise en forme à l'état semi-solide. Ce travail nous a conduit à y introduire un module de contact matière/matière et à développer le module de contact matière/outil existant. Nous avons alors été confrontés au problème de préconditionnement de la matrice hessienne, dont le conditionnement est fortement dégradé par l'ajout de la condition de non-interpénétration du contact matière/matière. Ce problème a été résolu grâce à l'utilisation du préconditionneur par factorisation incomplète de Crout. Nous avons ensuite travaillé sur la formulation eulérienne lagrangienne arbitraire et sur la procédure de remaillage automatique. Malheureusement, ces travaux ne nous ont pas permis de pouvoir simuler jusqu'au bout le remplissage de pièces industrielles. Nous sommes alors passés dans un deuxième temps à une formulation eulérienne en utilisant le code de calcul Rem3D, initialement développé pour l'injection de thermoplastiques. Nous y avons introduit les termes d'inertie, ainsi que notre loi de comportement. Ce dernier code de calcul nous a alors permis de simuler l'injection de notre alliage d'aluminium à l'état semi-solide. Les résultats obtenus montrent une bonne concordance avec le procédé industriel et le logiciel peut constituer un outil précieux d'aide à la conception.
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Guemnie-Tafo, Alain. "Faisceau de protons générés par l'interaction d'un laser ultra court avec une cible solide." Phd thesis, Ecole Polytechnique X, 2007. http://pastel.archives-ouvertes.fr/pastel-00003039.
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L'accélération de protons par laser a connu une expansion exponentielle ces dernières années principalement grâce à une amélioration des lasers de puissance associée à une diminution de la taille et du coût de telles installations. Les applications envisagées de ces faisceaux sont nombreuses, tant dans le domaine médical (proton thérapie, création d'isotopes pour la TEP...) que dans le domaine énergétique (fusion inertielle, allumeur rapide...). L'interaction entre un faisceau laser intense et une cible solide permet de générer différents types de rayonnement ionisant, notamment des électrons, ions, neutrons, rayons X et protons. L'intérêt de ma thèse est de caractériser les faisceaux de protons produits par laser (divergence, energie, spectre, stabilité...) en fonction des différents paramètres laser, afin d'optimiser la conversion de l'énergie laser en protons énergétiques, pour, à plus long terme, une utilisation éventuelle de ce faisceau lors de traitements en proton thérapie. Ceci nous a amené, dans un premier temps, à développer des diagnostics adaptés pour une détection en temps réel du faisceau de protons puis, dans un deuxième temps, à ouvrir une discussion sur les paramètres laser d'intérêt intervenant dans la génération du faisceau de protons. L'énergie maximale des protons atteinte avec des impulsions courtes est de 10 MeV (LOA), en utilisant des impulsions plus longues (et plus d'énergie laser), le record est de 58 MeV (LNL). Ces résultats sont prometteurs et encourageants pour l'avenir, mais encore bien loin de la gamme 70 - 200 MeV nécessaire pour des traitements en proton thérapie.
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Brahim, Cyrine. "Conception et performances électrochimiques de matériaux nanostructurés pour piles à combustible à oxyde solide." Phd thesis, Paris 6, 2006. http://pastel.archives-ouvertes.fr/pastel-00002545.
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Une solution pour limiter les pertes ohmiques résultant de la réduction de la température de fonctionnement des SOFC consiste à élaborer des matériaux d'électrolyte sous forme de couches minces. Dans ce contexte, des couches ultraminces de YSZ et de CGO ont été synthétisées séparément ou sous la forme d'un électrolyte bicouche par dépôt de couches atomiques (ALD) et par pulvérisation cathodique magnétron en condition réactive sur des substrats conducteurs électroniques denses ou poreux. Le dépôt chimique en solution (CBD) a aussi été envisagé comme une technique de dépôt moins onéreuse pour CGO. Les films déposés ont été caractérisés par plusieurs techniques physico-chimiques (microscopie électronique à balayage, diffraction des rayons X, spectrométrie de rayons X à dispersion d'énergie), puis leurs propriétés électriques ont été étudiées par spectroscopie d'impédance. La complexité de l'étude du comportement électrique des couches minces par cette technique a été soulignée. Ces caractérisations ont permis de mettre en évidence et de comparer les principales caractéristiques de ces méthodes d'élaboration et de montrer l'influence du choix de la technique de dépôt sur le comportement électrique des couches minces. Enfin, une étude préliminaire a été menée sur l'élaboration par ALD et les caractérisations physico-chimiques et électriques de couche minces d'oxyde zirconium dopé à l'oxyde d'indium (IDZ).
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Miled, Houssem. "Modélisation de l'orientation de fibres induite par l'écoulement et comportement élastique anisotrope à l'état solide." Phd thesis, École Nationale Supérieure des Mines de Paris, 2010. http://pastel.archives-ouvertes.fr/pastel-00712985.
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L'objectif de cette thèse consiste consiste à décrire, en un premier temps, l'orientation des fibres pendant la phase d'injection des polymères renforcés à l'état fondu, et comment, en deuxième partie, cette orientation affecte le comportement à l'état solide. Nous avons listé plusieurs modèles dans cette thèse, et nous avons considéré que l'orientation des fibres est régie par l'équation de Folgar et Tucker. Après le procédé d'injection, nous avons considéré que la pièce a un comportement thermo-élastique linéaire anisotrope. Ce comportement thermo-mécanique est relié à l'orientation des fibres, ainsi que les propriétés thermo-élastiques de la matrice du polymère et des fibres. Et la prédiction de ce comportement a été effectuée par des approches analytiques et numériques. Dans cette thèse nous présentons une comparaison entre ces deux approches.
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Thorin, Anders. "Modèle non-régulier de la touche de piano à queue." Phd thesis, Ecole Polytechnique X, 2013. http://pastel.archives-ouvertes.fr/pastel-00939493.
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Le mécanisme de la touche de piano à queue sert à propulser le marteau vers les cordes. Ce mécanisme permet au pianiste de contrôler avec précision la vitesse et l'instant d'impact du marteau sur la corde. Il est raisonnable de penser que c'est le comportement dynamique de la touche qui permet cette contrôlabilité. Avec pour perspective l'amélioration du rendu haptique des claviers numériques, cette thèse propose une méthode de simulation d'un modèle complet du mécanisme. Le son généré par la vibration qui suit l'impact du marteau sur les cordes n'entre pas dans le cadre de l'analyse. Des modèles du mécanisme comportant plusieurs degrés de liberté, des frottements et des contacts intermittents, ont été proposés depuis une quinzaine d'années. Notre approche se distingue de celles suivies jusqu'ici par un changement du point de vue adopté pour valider et pour simuler le modèle. En se fondant sur l'étude approfondie d'un modèle à un degré de liberté, il est en effet montré que la simulation d'un modèle dynamique complet doit se faire à l'aide d'un pilotage en déplacement, tandis que les travaux récents et anciens présentent des simulations pilotées en force. Une analyse des problèmes numériques liés aux discontinuités de vitesses survenant au sein du mécanisme durant l'enfoncement de la touche est présentée. Ils sont résolus par des méthodes de dynamique non-régulière implémentées dans le logiciel XDE. Les résultats sont présentés sous forme de comparaison avec les mesures expérimentales. La plupart des irrégularités des forces mesurées se retrouvent dans les forces simulées, en jeu piano comme en jeu forte. Les simulations rendent également bien compte de la cinématique de chaque élément du mécanisme. Une analyse de sensibilité du comportement dynamique aux paramètres du modèle est enfin exposée.
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Folzan, Gauthier. "Modélisations multi-matériaux multi-vitesses en dynamique rapide." Phd thesis, Ecole Polytechnique X, 2013. http://pastel.archives-ouvertes.fr/pastel-00803315.
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De nombreuses simulations dans les domaines des impacts, des interactions fluide-structure ou des écoulements multiphasiques impliquent différentes structures indépendantes interagissant entre elles à travers des interfaces complexes. Pour ces problèmes, les stratégies classiques utilisent souvent une approche lagrangienne utilisant un maillage éléments finis par structure et des stratégies de couplage et de mise en contact adéquates. Ceci est très coûteux en terme de génération de maillages et difficile à mettre en place en présence de grandes déformations. Une alternative est d'utiliser une stratégie " eulérienne " décrivant les différentes structures sur une grille unique en utilisant une vitesse moyenne unique et en développant des lois d'état ad hoc pour gérer le caractère multiphasique des éléments traversés par l'interface. La physique de l'interface de ces modèles est en générale assez grossière. Dans ce contexte, il y a un regain d'intérêt pour les modèles utilisant un maillage global unique non conforme avec les structures et définissant des champs de vitesses éléments finis indépendants pour décrire le mouvement de chacune des structures. Cette stratégie est intéressante mais induit différents problèmes : suivi d'interface, développement d'une formulation ALE adaptée car les matériaux et le maillage ont des vitesses différentes, traitement correct de la contrainte cinématique à l'interface entre les structures. Une grande attention doit être portée à ce dernier point pour proposer une approche stable, sans verrouillage numérique et restant robuste en cas de grandes déformations. Dans cette thèse, nous proposons une stratégie originale basée sur une méthode d'éléments finis enrichis. Elle définit un champ de vitesse éléments finis par matériau sur un unique maillage. Les différents champs se recouvrent et forment un champ enrichi qui peut avoir une discontinuité à l'interface et permet de décrire le glissement entre les matériaux. La discontinuité est contrôlée par une contrainte de continuité des vitesses normales et par une inconnue supplémentaire, la pression d'interface qui est le multiplicateur de Lagrange associé à la contrainte cinématique. La formulation ALE utilisée est basée sur une décomposition du pas de temps entre phase lagrangienne et phase de projection. La phase lagrangienne est résolue par le schéma de Wilkins classique des codes hydrodynamiques alors que la projection est réalisée par calcul d'intersection entre les maillages lagrangiens déformés par la matière et un maillage commun plus régulier. L'interface est construite à partir de la fraction volumique de chaque matériau et sa reconstruction peut être discontinue entre les éléments. Deux variantes sont introduites, analysées et comparées. Elles diffèrent par la discrétisation du multiplicateur de Lagrange et donc, par celle de la contrainte de vitesse : -la continuité par nœud utilise un multiplicateur défini aux nœuds. Cette variante est simple et rapide mais ne prend pas correctement en compte les différences de compressibilité entre matériaux, -la continuité par maille utilise un multiplicateur constant par segment d'interface. Cette variante donne des résultats meilleurs que la première version. La méthode est stabilisée par l'ajout de nœuds internes dans les mailles mixtes dont les fonctions bulles associés sont linéaires par morceaux dans chaque élément ainsi que par une condensation de la masse adaptée pour assurer un équilibre stable de l'interface. L'équation de mouvement du nœud interne est discrétisée par un schéma implicite en temps. En conséquence, nous devons résoudre un système couplant tous les nœuds de l'interface pour calculer les vitesses autour de l'interface. Les deux variantes ont été implantées dans un code industriel. Elles sont validées et comparées dans plusieurs cas tests impliquant diverses situations comme des interactions fluide-structure ou du glissement entre solides.
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Trisorio, Alexandre. "Developpement d'une source laser femtoseconde de quelques cycles optiques pour la generation d'harmoniques sur cible solide." Phd thesis, Ecole Polytechnique X, 2008. http://pastel.archives-ouvertes.fr/pastel-00522561.
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