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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Evaluation of halogen-free laminates used in handheld electronics

Lau, David Yuk Ho January 2009 (has links)
The purpose of this study is to examine the thermal and mechanical properties of various halogen-free laminates used in handheld electronic products and to correlate these properties to the manufacturing requirements and mechanical performance. Thermal properties determined for the laminates are the glass transition temperature, x,y,z-axis CTE, time to delamination at 260˚C and 288˚C, temperature to decomposition and interconnect stress test. SEM and EDS mapping analyses have been done on the laminates to determine the chemical composition and area fraction of the filler used in the epoxy. Three different fillers are identified from the laminates: Al(OH)3, Mg(OH)2, SiO2. Results show that the SiO2 fillers presented in the laminates reduce the z-axis CTE changes and increase the time to delamination. The x and y axis CTE is found to be lower than the z-axis CTE due to the glass fibers reinforcement in both the x and y directions. The temperature to decomposition is dependent on both the fillers and epoxy chemistry. Al(OH)3 starts to decompose above 200˚C and increases the rate of decomposition at 260˚C. Its decomposition also leads to an increase in z-axis CTE above 240˚C. Interconnect stress test results show that laminates with higher temperature to decomposition exhibit longer cycles to failure. Mechanical test results indicate that the halogenated laminates without fillers perform better than the halogen-free laminates with fillers. High fillers loading increase the flexural modulus and Vickers hardness properties of the laminates but decrease both the flexural strength and energy to fracture. Silica fillers in particular are susceptible to weaken these mechanical properties. Laminates without any fillers show plastic deformation of the epoxy matrix after fracture and result in a high energy to fracture. The adhesion of fillers to the matrix is important as the better the adhesion the higher the flexural strength is for the laminates. Results show that laminates with Al(OH)3 as the major filler have higher flexural strength than laminates with silica fillers, which also demonstrates that adhesion of the Al(OH)3 fillers are better than the silica. Laminates without any filler have higher copper peel strength than laminates with fillers.
2

Evaluation of halogen-free laminates used in handheld electronics

Lau, David Yuk Ho January 2009 (has links)
The purpose of this study is to examine the thermal and mechanical properties of various halogen-free laminates used in handheld electronic products and to correlate these properties to the manufacturing requirements and mechanical performance. Thermal properties determined for the laminates are the glass transition temperature, x,y,z-axis CTE, time to delamination at 260˚C and 288˚C, temperature to decomposition and interconnect stress test. SEM and EDS mapping analyses have been done on the laminates to determine the chemical composition and area fraction of the filler used in the epoxy. Three different fillers are identified from the laminates: Al(OH)3, Mg(OH)2, SiO2. Results show that the SiO2 fillers presented in the laminates reduce the z-axis CTE changes and increase the time to delamination. The x and y axis CTE is found to be lower than the z-axis CTE due to the glass fibers reinforcement in both the x and y directions. The temperature to decomposition is dependent on both the fillers and epoxy chemistry. Al(OH)3 starts to decompose above 200˚C and increases the rate of decomposition at 260˚C. Its decomposition also leads to an increase in z-axis CTE above 240˚C. Interconnect stress test results show that laminates with higher temperature to decomposition exhibit longer cycles to failure. Mechanical test results indicate that the halogenated laminates without fillers perform better than the halogen-free laminates with fillers. High fillers loading increase the flexural modulus and Vickers hardness properties of the laminates but decrease both the flexural strength and energy to fracture. Silica fillers in particular are susceptible to weaken these mechanical properties. Laminates without any fillers show plastic deformation of the epoxy matrix after fracture and result in a high energy to fracture. The adhesion of fillers to the matrix is important as the better the adhesion the higher the flexural strength is for the laminates. Results show that laminates with Al(OH)3 as the major filler have higher flexural strength than laminates with silica fillers, which also demonstrates that adhesion of the Al(OH)3 fillers are better than the silica. Laminates without any filler have higher copper peel strength than laminates with fillers.
3

Closing the Lab-to-Fab Gap with Inkjet-Printed Organic Photovoltaics

Almasabi, Khulud M. 08 August 2019 (has links)
Inkjet printing promises to be an invaluable technique for processing organic solar cells with key advantages such as low material consumption, freedom of design and compatibility with different types of flexible substrates making it suitable for large-area production. However, one concern about inkjet printed organic solar cells is the common use of chlorinated solvents during the ink formulation process. While chlorinated solvents suit the inkjet printing process due to their high boiling points, suitable viscosity, and excellent solubility of organic donor and acceptor compounds, they still pose some risks for both human health and the environment, excluding them from being the ultimate choice for large-area production. As a step towards commercialization of OPV, we demonstrated the possibility to close the laboratory to fabrication gap, through the engineering of environmentally friendly inks, using a blend of non-halogenated benzene derivatives solvents optimized to meet the viscosity and surface tension requirements for the inkjet printing process. Starting from using the non-fullerene acceptor O-IDTBR combined with the commercially available donor polymer P3HT we obtained solar cell device with efficiency up to 4.73% - the best efficiency achieved by the P3HT:O-IDTBR system processed with all non-halogenated solvents via inkjet printing. We also delivered highly transparent active layer with device power conversion efficiency of up to 10% with a highly efficient blend of polymer donor PTB7-Th in combination with the ultranarrow band gap NFA IEICO-4F, using hydrocarbons solvent. Lastly, we demonstrated both high efficiency, transparency, and stability by presenting a novel approach based on NFAs consisting of lowering the donor:acceptor ratio in the photoactive layer ink formulations, resulting in more stable devices with comparable power conversion efficiencies to those achieved by lab methods. This breakthrough in ink engineering paves the way in closing the lab-to-fab gap in organic photovoltaic using the low-cost, high throughput inkjet printing technology while considering both environmental and health-conscious mass production and device stability of organic photovoltaics.
4

Uso de aditivos não tóxicos como retardantes de chama em ABS. / Use of additives no toxic with flame retardant at ABS.

Martins, Priscila Alves 28 May 2013 (has links)
Os retardantes de chama são usados em diversos produtos, especialmente na indústria de eletroeletrônico. A irrevogável finalidade dos retardantes é proteger a vida das pessoas, reduzindo ferimentos e a destruição de propriedades. Contudo, devido à percepção dos riscos ambientais e toxicológicos presentes nas composições comerciais halogenadas e tóxicas, o seu uso está sendo proibido. Apesar da comum comercialização, novas pesquisas têm se desenvolvido visando à substituição destes retardantes, acompanhando medidas legais. Este trabalho visa estudar uma alternativa de aditivo retardante de chama livre de halogênio, tendo como matriz polimérica o copolímero de ABS, combinando aditivos: argila organofílica Cloisite 20A, argila Cloisite Na+ tratada com sal quaternário de fosfônio, polifosfato de amônio, melamina, partículas micrométricas e nanométricas de hidróxido de alumínio, dióxido de titânio e sílica formando assim um compósito. Para a caracterização foram realizados ensaios de térmicos de TGA e DSC, ensaios mecânicos de resistência à tração e resistência ao impacto Izod sem entalhe, avaliação da morfologia através de MEV e MEV-FEG, análise de difração de Raios-X (DRX), espectroscopia de infravermelho acoplado ao acessório de reflexão atenuada (FTIR-ATR), ensaios de retardância à chama com base na norma ASTM D635-10 e norma UL 94. Por meio dos resultados foi possível observar efeitos da adição dos aditivos na obtenção de compósitos de ABS com aditivos retardante de chama inertes, que atingiram classificação V-0 e V-2 na Ul 94, com redução da velocidade propagação da chama entre 18% e 80% conforme a ASTM D635. / The flame retardant are used in several products, specialty for electrical and electronics industry. The irrevocable finality from flame retardant is fires protection to help safeguard of people, reduce injury and reduce destruction of property. However, due the perception of environmental risk and toxicity in composites commercial with halogen and toxic, it has been prohibited. Despite the common commercialization news researches has been developing to substitute this flame retardant, together accompany the new position of law. This work wanted to study an alternative of additive free halogen flame retardant, with polymer matrix the ABS copolymer, combinations the additive: organoclay Cloisite 20A, organoclay Cloisite Na+ treated with quaternary phosphonium salt, ammonium polyphosphate, melamine, micrometric and nanometric particles of aluminum hydroxide, titanium dioxide and silica forming that a composite. To characterization was doing thermal test of TGA and DSC, mechanical test of tensile and impact Izod strength, morphologia available through of MEV and MEV-FEG, X-ray diffraction analysis(XRD), infrared spectroscopy with attenuated total reflectance accessory (FTIR-ATR), flame retardant test based the ASTM D635-10 norm and UL 94 norm. Although the result was possible to observe effects about the addition the additive to obtain the ABS composite with inert flame retardant additives, that achieved V-0 and V-2 on the Ul 94, with reduction of linear burning rate between 18% to 80% from ASTM D635.
5

Uso de aditivos não tóxicos como retardantes de chama em ABS. / Use of additives no toxic with flame retardant at ABS.

Priscila Alves Martins 28 May 2013 (has links)
Os retardantes de chama são usados em diversos produtos, especialmente na indústria de eletroeletrônico. A irrevogável finalidade dos retardantes é proteger a vida das pessoas, reduzindo ferimentos e a destruição de propriedades. Contudo, devido à percepção dos riscos ambientais e toxicológicos presentes nas composições comerciais halogenadas e tóxicas, o seu uso está sendo proibido. Apesar da comum comercialização, novas pesquisas têm se desenvolvido visando à substituição destes retardantes, acompanhando medidas legais. Este trabalho visa estudar uma alternativa de aditivo retardante de chama livre de halogênio, tendo como matriz polimérica o copolímero de ABS, combinando aditivos: argila organofílica Cloisite 20A, argila Cloisite Na+ tratada com sal quaternário de fosfônio, polifosfato de amônio, melamina, partículas micrométricas e nanométricas de hidróxido de alumínio, dióxido de titânio e sílica formando assim um compósito. Para a caracterização foram realizados ensaios de térmicos de TGA e DSC, ensaios mecânicos de resistência à tração e resistência ao impacto Izod sem entalhe, avaliação da morfologia através de MEV e MEV-FEG, análise de difração de Raios-X (DRX), espectroscopia de infravermelho acoplado ao acessório de reflexão atenuada (FTIR-ATR), ensaios de retardância à chama com base na norma ASTM D635-10 e norma UL 94. Por meio dos resultados foi possível observar efeitos da adição dos aditivos na obtenção de compósitos de ABS com aditivos retardante de chama inertes, que atingiram classificação V-0 e V-2 na Ul 94, com redução da velocidade propagação da chama entre 18% e 80% conforme a ASTM D635. / The flame retardant are used in several products, specialty for electrical and electronics industry. The irrevocable finality from flame retardant is fires protection to help safeguard of people, reduce injury and reduce destruction of property. However, due the perception of environmental risk and toxicity in composites commercial with halogen and toxic, it has been prohibited. Despite the common commercialization news researches has been developing to substitute this flame retardant, together accompany the new position of law. This work wanted to study an alternative of additive free halogen flame retardant, with polymer matrix the ABS copolymer, combinations the additive: organoclay Cloisite 20A, organoclay Cloisite Na+ treated with quaternary phosphonium salt, ammonium polyphosphate, melamine, micrometric and nanometric particles of aluminum hydroxide, titanium dioxide and silica forming that a composite. To characterization was doing thermal test of TGA and DSC, mechanical test of tensile and impact Izod strength, morphologia available through of MEV and MEV-FEG, X-ray diffraction analysis(XRD), infrared spectroscopy with attenuated total reflectance accessory (FTIR-ATR), flame retardant test based the ASTM D635-10 norm and UL 94 norm. Although the result was possible to observe effects about the addition the additive to obtain the ABS composite with inert flame retardant additives, that achieved V-0 and V-2 on the Ul 94, with reduction of linear burning rate between 18% to 80% from ASTM D635.

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