Finite differences software for the numeric analysis of a non-destructive electromagnetic testing system
In this paper, theoretical bases for the development of a software for electromagnetic effects simulation based on the approximation method of finite differences using Scilab are presented. A methodology for programming the algorithm is discussed and a simulation test is conducted in order to validate it, which consists of a coil with a ferromagnetic core. Finally, this software is used in studies related to magnetic flux leakage by a simulation of a system for the measurement of magnetic flux density in plates with different defects, which include both 2D and 3D and defects with orientation of 45 degrees.
PROCESSAMENTO E CARACTERIZAÇÃO DE NÚCLEO DE FERRO PURO OBTIDO POR METALURGIA DO PÓ PARA APLICAÇÃO COMO CAPTADOR EM ENERGY HARVESTING
Nos ultimos anos, o termo colheita de energia tem sido utilizado em uma grande classe de aplicacoes, cuja principal funcao e a recuperacao da energia disponivel a partir de fontes, por exemplo, mecânica, solar, termica, entre outras, que de outro modo seria desperdicada. O objetivo deste estudo e o desenvolvimento e caracterizacao de um nucleo de po de ferro obtido por moagem de alta energia, bem como a utilizacao desse nucleo como captador em um processo de colheita de energia por inducao no intuito de observar a sua capacidade de colher energia. O ferro foi caracterizado por difracao de raios X e microscopia eletronica de varredura e realizados testes de bancada para avaliar a quantidade de energia colhida do captador desenvolvido. A analise estrutural mostrou que o po obtido e monofasico, sem presenca de impurezas. As micrografias apresentam caracteristica homogenea, com pouca porosidade. As caracteristicas magneticas do material obtido o classificam como material ferromagnetico mole, devido ao estreito laco de histerese. No testes para captacao de energia, o nucleo apresentou resultados satisfatorios, pois foi capaz de fornecer um nivel maximo de potencia de 0.41mW quando submetido a uma corrente eletrica em seu enrolamento primario de 15 A
Ultrathin Wafer Pre-Assembly and Assembly Process Technologies: A Review
Ultrathin silicon wafer technology is reviewed in terms of the semiconductor applications, critical challenges, and wafer pre-assembly and assembly process technologies and their underlying mechanisms. Mechanical backgrinding has been the standard process for wafer thinning in the semiconductor industry owing to its low cost and productivity. As the thickness requirement of wafers is reduced to below 100 μm, many challenges are being faced due to wafer/die bow, mechanical strength, wafer handling, total thickness variation (TTV), dicing, and packaging assembly. Various ultrathin wafer processing and assembly technologies have been developed to address these challenges. These include wafer carrier systems to handle ultrathin wafers; backgrinding subsurface damage and surface roughness reduction, and post-grinding treatment to increase wafer/die strength; improved wafer carrier flatness and backgrinding auto-TTV control to improve TTV; wafer dicing technologies to reduce die sidewall damage to increase die strength; and assembly methods for die pick-up, die transfer, die attachment, and wire bonding. Where applicable, current process issues and limitations, and future work needed are highlighted.