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Fully three-dimensional wavefront matching method for waveguide discontinuity problem is newly developed. In principle, the developed method can be applied to optimize any geometries including reflection. The application for Si mode converters (TE0-TE1, and TE0-TE2) are demonstrated and ultrasmall structure with low-loss is obtained.
Wide-bandgap (WBG) devices are believed as the alternate of silicon switches for high-efficiency and high-power-density power electronics converters. While two major challenges of WBG devices remain as high cost (∼5 times of Si) and less options (the maximum power rating for GaN is only 650V/60A), paralleling GaN with Si could be the potential solution to solve pains above. In this paper, two SMT...
Extensive studies have concluded that breakdown mechanisms in Gallium Nitride (GaN) High Electron Mobility Transistors (HEMT) can be improved by substrate reduction and the addition of field plate (FP) on their structures. A theoretical analysis of the FP effects on the HEMT is carried out by modeling the electric fields inside the structure. The electric field model is deduced by solving the potential...
The lifetime of power DMOS devices subjected to Thermal Induced Plastic Metal Deformation (TPMD) is highly dependent on the design of the metallization systems and thus requires the understanding of temperature, stress and strain distribution. This paper introduces and studies via numerical simulations with finite element method (FEM) a simple three dimensional (3D) transistor substructure commonly...
Over the last decade, clinical studies show a strong interest for real-time 3D imaging. This calls for ultrasound probes with high-element-count 2D matrix transducer array, interfaced to an imaging system using an in-probe Application Specific Integrated Circuit (ASIC) that takes care of element selection, signal amplification, sub-array beamforming, etc. Since the ASIC is based on silicon and is...
Gastrointestinal (GI) disease is one of the most common causes of death. Capsule endoscopy (CE) may contribute to early detection of disease and pathological classification. Current CE relies on optical images of the internal luminal surface of the GI tract to aid diagnosis. With the addition of microultrasound, the imaging capability can be extended within the wall of the GI tract, with the potential...
As compared to piezoelectric technology, MEMS technology employed for Capacitive Micromachined Ultrasonic Transducer (CMUT) fabrication provides increased compatibility with 3D packaging methods, enabling the possible development of advanced transducer-electronics multi-chip modules (MCM) for medical imaging applications. In this paper, an acoustically optimized 3D packaging method for the interconnection...
PZFlex is a commercial FEA software that has been optimized for the ultrasound industry and is commonly used to design piezoelectric ultrasound transducers. However, PZFlex is not commonly used within the CMUT research field. Nevertheless, it has an explicit modeling approach allowing large structures like CMUT arrays to be modeled and its transient analysis intrinsically supplies non-linear and broadband...
A finite element model which contains one sixth of the IGBT module based on a real test chip of IGBT module is established to investigate the temperature and stress distribution of different shape bonding wire. The finite element (FE) analysis which coupled electro-thermal and thermal-mechanical are conducted using commercial software ABAQUS. The thermal performance and stress distribution of IGBT...
The heat generated by self-propagating exothermic reaction can be used to melt solder and then join the components. However, the microstructure of self-propagating interconnects is different from those obtained through traditional soldering process for its unique thermal conditions. In this paper, a finite element model was established to simulate the temperature field of self-propagating joints at...
Bonding front propagation driven by the work of adhesion is restricted by the air drag and mechanical deformation of wafers. Energy variation during room temperature bonding can influence the bonding initiation and front propagation dramatically. In order to evaluate the dissipated energy and elastic strain energy resulting from the air cushion and the wafer bow, both theoretical and finite element...
In a compact power electronics systems such as converters, thermal interaction between components is inevitable. Traditional RC lumped modelling method does not take that into account and this would cause inaccuracy in the predicted temperature in the components of the systems. In this work, numerical simulation have been used to obtain detailed temperature distribution in power devices and the parameters...
In this paper, a 5kW novel multistage axial-flux permanent magnet machine (M-AFPM) is analyzed. As a key part of the machine, stator core of silicon steel and SMC are studied by 3D finite element method (FEM) respectively. No-load, full-load, magnetic field distribution, core loss, etc. are calculated. FEM result indicates that SMC-materials have almost equal influence on EMF, magnetic field distribution...
This paper investigates the radiation characteristics of on-chip microstrip patch reflectarray for 60 GHz system. The proposed reflectarray is fed using on-chip cylindrical dielectric resonator antenna, CDRA placed at a distance 42.5 mm from the array aperture. The antenna introduces good impedance matching at 61 GHz. The impedance bandwidth is 1.35 GHz. The reflectarray consists of 289 unit-cell...
This work reports on the development of new AlN-based vibrational energy harvester architecture, consisting of a standard wide beam with a proof mass shaped into the Si substrate and exploiting a matrix of deep circular holes realized on the hinge backside. This approach was effective in the increase of the mechanical strain of the holed backside (HB) structure device, when compared with the standard...
A dual-nanowire heterostructure with a GeSn layer laterally laying on Ge nanowires is demonstrated by MBE. The strain field analyzed by FEM shows that the novel proposal can significantly release the compressive strain in GeSn for potential direct bandgap conversion as a Si-based light source.
Atomic force microscope (AFM) cantilevers with integrated actuation and sensing provide several distinct advantages over conventional cantilever instrumentation such as clean frequency responses, the possibility of down-scaling and parallelization to cantilever arrays as well as the absence of optical interferences. However, for multifrequency AFM techniques involving higher eigenmodes of the cantilever,...
Thermo-mechanical stress accumulation in the power electronic integrated circuit (PIC) devices influences their lifetime and reliability. In order to determine both the temperature and the stress accumulation, numerical simulation is a very important tool in the design of PIC devices for quantifying and enhancing their lifetime and reliability. An open source solution integrated in Salome-Meca and...
In this work, a system assembly technology will be presented that allows an effective mechanical decoupling of the MEMS element from the environment while maintaining minimal package footprint and cost. It utilizes a Si interposer with planar spring structures for an independent suspension of all interconnects to the MEMS element. The design of the planar springs was optimized for maximum stability...
Fan-out wafer level packaging technology becomes more attractive and popular in the semiconductor packaging industry. The fan-out wafer level package (FOWLP) has the feature of integrating various devices in a tiny form factor. Since the FOWLP size is compact and small, its package strength is critical to its reliability. In this work, the three-point bending test method and finite element method...
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