A geração global de resíduo eletrônico (REEE) cresce a uma taxa de cerca de 40 milhões de toneladas por ano. Este constante incremento na geração dos REEEs somado às recentes legislações tem impulsionado pesquisas focadas no desenvolvimento de processos para recuperação de materiais e sustentabilidade da indústria eletroeletrônica. Dentro destes resíduos encontram-se as placas de circuito impresso (PCIs) que estão presentes na maioria dos EEEs, têm composição heterogênea que varia conforme a fonte, país de proveniência e época, e tecnologia de fabricação. Assim, este trabalho teve por objetivo a realização de rota hidrometalúrgica (extração sólido/líquido) e biohidrometalúrgica para reciclagem de placas de circuito impresso provenientes de impressoras visando a recuperação de cobre. Para tanto fez-se inicialmente a caracterização da PCI e o desenvolvimento de uma rota combinada de processamento físico seguida por processo hidrometalúrgico ou biohidrometalúrgico. O processamento físico e de caracterização foi composto por etapas de cominuição, separação magnética, classificação granulométrica, visualização em lupa binocular, microscópio eletrônico de varredura acoplado com detector de energia dispersiva de raios X (MEV/EDS), digestão ácida, perda ao fogo e análise química por AAS e ICP. Já, o processamento hidrometalúrgico foi composto por duas etapas de extração sólido/líquido: a primeira em meio sulfúrico e a segunda em meio sulfúrico oxidante. Para os ensaios de biolixiviação utilizou-se uma cepa bacteriana composta por 3 espécies microbianas: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans e Leptospirillum ferrooxidans. Verificou-se que a placa possui 4 camadas de Cu intercaladas por fibra de vidro, é lead free e seus componentes representam 53,3 % do seu peso. A porcentagem em massa correspondente ao material não magnético é de 74,6 % e do magnético 25,4 %. Os materiais moído e não magnético apresentaram tendência em se acumular nas frações mais grossas. Já na fração magnética, o acúmulo do material ocorreu na fração mais fina (0,053 mm). A separação dos metais através de classificação granulométrica não foi possível. A PCI estudada é composta por: 44% de metais, 28,5 % de polímeros e 27,5 % de cerâmicas. Sendo: Ag-0,31 %; Al3,73 %; Au0,004 %; Cu 32,5 %; Fe1,42 %; Ni0,34 %; Sn0,96 % e Zn0,64 %. A extração de Cu no processamento hidrometalúrgico foi de 100 % e o fator de recuperação 98,46 %, o que corresponde a uma recuperação de 32 kg de Cu em 100 kg de PCI. Já no processamento biohidrometalúrgico, a extração de Cu alcança 100 % quando utilizados 2 % de densidade de polpa e 100 % de inóculo. O fator de recuperação é de 100 % e a recuperação de Cu em 100 kg de PCI é de 32,5 kg. O processamento hidrometalúrgico apresenta como vantagens quando comparado ao biohidrometalúrgico: menor tempo de extração (8 h versus 4 dias); seletividade de Cu; maior densidade de polpa (10 % versus 2 %). Já a biolixiviação utiliza menor temperatura de trabalho (36 ºC versus 75 ºC) e dispensa a etapa de separação magnética. / The increase in the generation of waste electrical and electronic equipment (WEEE), 40 tons per year, allied with the enactment of new laws encouraged researches focused on the developing of processes to reclaim materials and on the sustainability of the electrical and electronics industry. Whithin the WEEEs, printed circuit boards (PCB) composition is heterogeneous and varies according to several factors, including: kind of EEE, when and where it was produced and fabrication technology. The goal of this work is to perfom a hydrometallurgical route (solid/liquid extraction) and a biohydrometallurgical route to recycle PCB from discarded printers aiming the recovery of copper. To do so, the first step is to characterize the PCB and the development of a combined fisical processing followed by hydrometallurgical and biohydrometallurgical routes. The fisical and the characterization processes, in that order, consisted on griding, magnetic separation, granulometric screening, visual assessement by binocular magnifier, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS), acid digestion, loss on fire, and chemical analyzes by AAS and ACP-OES. The hydrometallurgical stage consisted on two steps: solid/liquid extraction by sulfuric acid leaching and solid/liquid extraction by sulfuric acid leaching with an oxidizing agent. The bioleaching tests used a mixed bacterial strain: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans. The results showed that PCB consisted on 4 layers of copper and fiber glass, not possesing lead (leadfree) on its composition and its components constitute 53.3 % weight percentage. The non-magnetic fraction (NMA) weight percentage represents 74.6 %, the magnetc fraction (MA) represents 25.4 %. The grinded material and the non-magnetic fraction presented an inclination to build up on thickest fractions. On the magnetic fraction this behavior occurred on the thinnest fraction (0.053 mm). The metal separation using granulometric screening was not possible and the visual assessement by binocular magnifier was conclusive for this research. The composition of the studied PCB is: 44 % metal, 28.5 % polymer and 27.5 % ceramics. Beeing: Ag-0.31 %, Al-3.73 %, Au-0.004 %, Cu-32.5 %, Fe-1.42 %, Ni-0.34 %, Sn-0.96 %, Zn-0.64 % and other metals-4.10 %. Copper extraction in the hydrometallurgical process achieved 100 % and the recuperation factor 98.46 %, which means a recovery of 32 kg of copper in 100 kg of PCB. However in biohydrometallurgical process, the copper extraction reached 100 % on the forth day using a 2 % pulp density and 100 % inoculum. The recuperation factor achieved 100 % and, therefore, copper recovery in 100 kg of PCB is equivalent to 32.5 kg. The hydrometallurgical processing has many advantages compared to the biohydrometallurgical processing: a smaller extraction time (8 h versus 4 days); Cu selectivity; higher pulp density (10 % versus 2 %). However, bioleaching uses an inferior working temperature (36 ºC versus 75 ºC) and dont require magnetic separation.

In resource recovery from end-of-life printed circuit board (PCB), the physical processing route is considered most environmentally friendly. The −75 µm fraction generated during the comminution assays well above many precious and base metal deposits, but contributes overall drop in value recovery. This investigation was aimed at exploiting the versatility of froth flotation for beneficiation of the PCB comminution fines. Chemical composition characterisation work shows wet assay of constituents in the sample vary with digestion condition. Absolute assays as for hazardous constituents thus require comparison of data from more than one digestion condition. Comparative assaying of samples from beneficiation treatments can use aqua regia digestion which gives a less hazardous procedure compared to hydrogen fluoride combined with microwave and nitric acid treatments. It also gives leach liquor from which all constituent elements can be analysed, compared to that from total digestion via sodium peroxide fusion. For this sample total digestion will therefore not always give better results compared to partial digestion. Findings also show that thermogravimetric analysis may not be recommended in PCB characterisation. It gave no distinct inflexion point to characterize any constituent. This is due to the very diverse material constituents of the sample. Further on characterisation, the sample gave a loose bulk density lighter than water, and true sample density of 3 g/cm3. This coupled with surface hydrophobicity observed necessitates that pulping the sample must be done under water. Light optical and scanning electron microscopy showed particle liberation was very high, but not total. Morphology of the metallic particles was very diverse, with average circularity shape factor of 0.63. This coupled with the material diversity is a major constraint in sub-sieve size analysis of the sample. As shown by scanning electron microscopy energy dispersive X-ray spectroscopy, the liberated particles themselves contain more than one chemical element, being alloys. Beneficiation operation therefore cannot attempt to separate such particles into constituent elements but some bulk collection of metallic values into a concentrate. Reverse flotation of metallic values based on a scheme described as natural hydrophobic response (NHR) was found successful. Favorable kinetics under the scheme gave about 500 rpm and 500 ml/min aeration rate, at 300 g sample in a 3.5 l Leeds cell. Without the use of a collector, natural hydrophobic response was observed. The system also gave a stable froth without the aid of a frother. Investigations (surface tension and dynamic froth stability height measurements, combined with general literature) show the NHR froth is a fine particle stabilised froth, and not surfactant stabilised. Au and Pd, were among the elements best enriched into the sink; 64 % recovery for Au at enrichment ratio of three. Flotation over narrower and coarser fraction (+106 – 75 µm) shows the NHR scheme can be successfully applied at this size. Chemical conditioning schemes investigated shows very minimal responses to reagents. Potassium amyl xanthate (PAX) did not condition the metallic particles for flotation remarkably as it does with native metals. Sulfidation with sodium hydrogen sulfide shows a little improvement in response to PAX. Sodium mercaptobenzothiazole – a very selective collector for tarnished copper and lead minerals – did not show such selectivity in the PCB comminution fines pulp. Some cationic pull with tetrabutyl ammonium chloride towards selective pull of non-metallic values after NHR pull has subsided was observed, although very little also. Macromolecular depression with carboxyl methyl cellulose did not subdue the natural hydrophobic response up to profuse percentage dosages. Depression by lowering surface tension, described as gamma depression, using Betamin 127A (active constituent: ethoxy nonyl phenol) was effective to wet hydrophobic particles, but still not helpful for selective pull after chemical conditioning. At the lowered surface tension, frothing sets in coupled with entrainment. Probable causatives for the poor response to reagents are surface oxidation of the metallic particles and depression by calcium ions in pulp. Surface studies with field emission scanning electron microscope and auger electron spectroscopy composition depth profiling, show presence of organic layers on the surface of the metallic particles. The surfaces were also found to be oxidised down to about 340 nm depth profiled. None of the surfaces is a pure alloy, but occurring in forms that will be relatively inert to reagents. Beside these, from aqua regia wet assaying, the sample contains about 7 % calcium by mass, and ICP-MS trace element analysis of the process water confirms calcium presence up to 7 ppm equilibrium concentration in the pulp. Judging from the responses, the natural hydrophobic response scheme can be well recommended for PCB comminution fines flotation. Optimisation of the performance of the scheme responds remarkably well to kinetic parameters variation. With the generally low impeller energy and aeration rate found favourable for PCB CF flotation, and the zero reagent cost (no collector, no frother) of the NHR scheme, PCB comminution fines flotation shows good prospects. / Thesis (PhD)--University of Pretoria, 2010. / Materials Science and Metallurgical Engineering / unrestricted

This work deals with the design scheme and printed circuit boards for drives teaching laboratory Stand, for teaching at the Department of Power Electrical and Electronic VUT Brno.

The project idea was created from the demand of a renewal for a Power Distributor Unit also known as a PDU. The current product had successively turned in to a cable mess because of short term solutions. This made the product non user friendly, inconvenient and non-agile to handle troubleshooting. To develop this project, a PCB design was created by simplifying and improving circuit diagrams until satisfied. Once the final circuit diagram was obtained, a PCB layout design was created. The result of the project, due to limited time, was only theoretical. The finished product was not tested as there was no time allowing this.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第17966号 / エネ博第291号 / 新制||エネ||60(附属図書館) / 30796 / 京都大学大学院エネルギー科学研究科エネルギー社会・環境科学専攻 / (主査)教授 石原 慶一, 教授 東野 達, 教授 酒井 伸一 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Environmental issues related to the Electronic and Electrical Equipment industry lead companies to consider a new sustainability model to decouple economic growth from resource consumption and waste generation. A significant body of literature focuses on materials and process innovation in the field of Printed Circuit Board (PCB), simultaneously limited attention has been given to industry practices and circular economy strategies. This study aims to contribute insights into sustainable circular economy practices in the PCB industry; it examines the current integration of sustainability and circularity principles in PCB companies in Sweden and assesses the associated strengths, weaknesses, opportunities, and threats. Drawing on the strategies outlined in the Circular Electronic Roadmap, the study identified four main pathways relevant to design and development, procurement, and business model. The study, being exploratory and qualitative in nature, conducted semi-structured interviews with six PCB companies in Sweden. The results show that the concept of sustainability is dynamic, factors such as business nature, company size, market competitiveness, regulations, stakeholder’s expectations and priorities, and emerging frameworks are influencing the degree to which these practices are integrated into the companies. Numerous strengths include utilizing Life Cycle Analysis (LCA), adopting circular business model, sustainable technology innovation, and prioritizing environmental sustainability as an impact. Two main weaknesses are customers restriction and constrain in PCB design and upfront resource investment. Collaboration, local and regional innovation, active role of business association, and prospects for secondary market materials are discovered to serve as opportunities to advance the circular transition for companies Threats to sustainability practices include a lack of customer demand or interest, limited material information and traceability, and technical complexity of PCB. Overall, these findings could provide practical guidance for PCB companies and other stakeholders to support decision-making and actions to improve sustainability practices in the industry. / Miljöutmaningar relaterade till elektronisk- och elektrisk utrustningsindustri får företag att överväga en ny hållbarhetsmodell för att frikoppla ekonomisk tillväxt från resursförbrukning och avfallsgenerering. En betydande mängd litteratur fokuserar på material och processinnovation för tillverkningen av kretskort (eng. PCB), samtidigt som begränsad uppmärksamhet har ägnats åt industripraxis och strategier för cirkulär ekonomi. Den här studien syftar till att bidra med insikter om hållbar cirkulär ekonomi inom PCB-industrin. Den undersöker den nuvarande integrationen av hållbarhets- och cirkularitetsprinciper i PCB-företag i Sverige och bedömer associerade styrkor, svagheter, möjligheter och hot. Utifrån de strategier som beskrivs i färdplanen för cirkulär elektronik (eng. Circular Electronics Roadmap) identifierade studien fyra huvudområden som är relevanta för design och utveckling, upphandling och affärsmodell. I studien, som är explorativ och kvalitativ till sin karaktär, genomfördes semistrukturerade intervjuer med sex PCB-företag i Sverige. Resultaten visar att hållbarhetsbegreppet är dynamiskt, och att faktorer som typ av verksamhet, företagets storlek, marknadskonkurrens, regleringar, intressenternas förväntningar och prioriteringar, samt framväxande ramverk påverkar i vilken utsträckning dessa metoder integreras i företagen. Styrkor inkluderar användning av livscykelanalys (LCA), att anamma cirkulära affärsmodeller, hållbar teknikinnovation och prioritering av miljömässig hållbarhet. Två huvudsakliga svagheter är kundernas restriktioner i PCB-design samt resursinvesteringar i början av processen. Samarbete, lokal och regional innovation, aktiv roll för industriorganisationer och framtidsutsikter för återanvändning av material på den sekundära marknaden har upptäckts som möjligheter att främja den cirkulära övergången för företag. Hot inkluderar bristande efterfrågan eller intresse från kunderna, begränsad information och spårbarhet av material, samt PCB:s tekniska komplexitet. Sammantaget kan dessa resultat ge praktiska riktlinjer för PCB-företag och andra intressenter för att vägleda beslutsfattande och åtgärder för att förbättra hållbarhetsarbetet i industrin.

The objective of this research is to determine and develop a model that is capable of accurately measuring customer satisfaction for different industries and in particularly for the Printed Wiring Boards (PWB) Manufacturers. The new model will incorporate data not being collected or utilized by the survey method of determining customer satisfaction. The method used is a weighted average of satisfaction among several researched categories with percentages that accurately represent the relative importance of multiple facets of the PWB manufacturers customer satisfaction. A very common term in quality assurance is that "What is not measured accurately can not be evaluated or managed correctly," thus customer satisfaction is a very important aspect of any business, industry, or government. A satisfied customer will do more business and recommend it to other potential customers. Thus the business will grow and more revenues result. On the other hand, an unsatisfied customer will abandon the business and encourage more customers not to get involved with the same business so the business may decline and lose its market share and profitability. The categories that contribute to PWB customer satisfaction will be determined by conducting surveys among the leaders and best in the business of the PWB industry in addition to discovery of related articles that define the categories of the customer satisfaction for the PWB manufacturers. Once the categories are determined, the research concentrates on the weighting of the categories that most contribute to the PWB customer's satisfaction and a measure of satisfaction is derived. The model is easily applied to any other kind of PWB business or service industry. The model is based on empirical methods that will give an accurate measurement for the PWB customer's satisfaction. This in turn allows organizations the opportunity for improving customer satisfaction and increasing market share. The algorithm is based on characteristics deemed important by customers. Thus the customer satisfaction index can be computed and monitored on a regular basis without costly surveys. The major difference between this new model and the standard methods of determining customer satisfaction using the surveys is that this model will utilize data available with the proposals, sales, shipping, receiving, quality, engineering, manufacturing, and purchasing departments. The developed method to measure customer satisfaction utilizing internal data can be more cost effective, more accurate, can provide individual customer satisfaction scores, can measure whether or not these individual scores are statistically lower than the majority, and can provide satisfaction measures in real time none of which can be supplied by the survey method.

This thesis investigates the impact of vibration isolators on circuit boards during harsh vibrationenvironments that occur when they are mounted on the wings of a fighter jet. To examine thisphenomenon, a mathematical model and a simulated model were developed to determine theresonant frequencies of the circuit board under various boundary conditions. Subsequently, theresonant frequencies of the circuit board were validated through experimental tests, allowing forthe establishment of the material properties of the circuit board. In order to prevent structuralfailure, this thesis employs α-gel dampers as the damped attachments for the circuit board.These vibration isolators belong to the category of silicone gel dampers and were evaluatedthrough experimental vibration testing. The two employed vibration isolators are denoted asmodels A1 and A2, exhibiting respective damping ratios of 0.1 and 0.05. By utilizing thesevibration isolators during the experimental vibration tests, the structure demonstrated resilienceagainst natural frequency coupling, thereby preventing failure. / Den här masteruppsatsen undersöker effekten av vibrationsisolatorer på kretskort under detuffa vibrationsmiljöer som sker vid vingarna på ett stridsflyg. För att undersöka detta såanvänds en matematisk modell samt en simulerad modell för att hitta resonansfekvensernaför kretskorten vid olika randvillkor. Resonansfrekvenserna från modellerna jämfördes medresonansfrekvenserna som kom tillhanda efter vibrationsprover och med dem så kunde ävenmaterialegenskaperna bestämmas. För att unvika kollaps av strukturen användes α-geldämpare till kretskorten. Dessa dämpare är gjorde av silikongel och utvärderades genomexperimentella vibrationsprover. Dessa vibrationsisolatorer var av modell A1 och A2 ochkorresponderande modell hade dämpningsförhållande 0.1 respektive 0.05. Genom att användadessa vibrationsiolatorer under de experimentella virbationstesterna så undvek strukturenkollaps genom att resonansfrekvenserna inte triggades.

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