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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Microstructural Evolution in SAC305 and SAC-Bi Solders Subjected to Mechanical Cycling
摘要： Fatigue failure of solder joints is one of the most common methods by which electronic packages fail. Electronic assemblies usually must cope with a temperature varying environment. Due to the mismatches in coefficients of thermal expansion (CTEs) of the various assembly materials, the solder joints are subjected to cyclic thermal-mechanical loading during temperature cycling. The main focus of this work is to investigate the changes in microstructure that occur in SAC305 and SAC+Bi lead free solders subjected to mechanical cycling. In this paper, we report on results for the SAC+Bi solder commonly known as SAC_Q or CYCLOMAX. Uniaxial solder specimens were prepared in glass tubes, and the outside surfaces were polished. A nanoindenter was then used to mark fixed regions on the samples for subsequent microscopy evaluation. The samples were subjected to mechanical cycling, and the microstructures of the selected fixed regions were recorded after various durations of cycling using Scanning Electron Microscopy (SEM). Using the recorded images, it was observed that the cycling induced damage consisted primarily of small intergranular cracks forming along the subgrain boundaries within dendrites. These cracks continued to grow as the cycling continued, resulting in a weakening of the dendrite structure, and eventually to the formation of large transgranular cracks. The distribution and size of the intermetallic particles in the inter-dendritic regions were observed to remain essentially unchanged.
关键词： Bismuth,Microstructure,SAC Alloy,Hysteresis,Evolution,Lead Free Solder,Cyclic Stress-Strain Curve
更新于2025-09-23 15:22:29
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Application to Artificial Skin of Double Cone Tube Made of Acrylic Resin Formed by Micro Stereolithography
摘要： A functional double cone tube (DCT) array with gas trapping and high durability is developed in the application of artificial skin. A stereo-lithography system is employed to fabricate DCT made of acrylic resin. In an aqueous solution, a certain amount of gas can be trapped in the tube due to capillary force balance. Under applying an external load, internal stress is effectively released at the interface between top and base cones. In the tactile sensing investigation, softness and tackiness senses as an artificial skin are felt.
关键词： Acrylic resin,Gas storage,Double cone tube (DCT),Stress distribution,Artificial skin,Micro stereo-lithography
更新于2025-09-23 15:22:29
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Effects of yttrium doping on the electrical performances and stability of ZnO thin-film transistors
摘要： In this paper, we have investigated the effects of yttrium (Y) doping on the electrical performance and stability of ZnO thin film transistors (TFTs). Here, Y-doped ZnO TFTs were fabricated by using radio frequency magnetron sputtering at 150 °C. As a result, the 1% Y-doped ZnO TFT exhibits a small threshold voltage shifts of 2.5 V under positive bias stress and ?2.8 V under negative bias stress as well as desirable device performance with field effect mobility of 9.8 cm2/V s, a subthreshold swing of 320 mV/decade and on/off current ratio of 107, respectively. Based on the XPS analysis and electrical characterizations, the improvement in stability and electrical properties of ZnO TFTs were attributed to the appropriate Y doping concentration, which not only could control the carrier concentration and broaden the band gap of ZnO film, but also suppress the oxygen vacancy defects and passivate the trap density at the SiO2/ZnO interfaces. Consequently, the high stability and excellent electrical performances of Y-doped ZnO TFTs show great potential for use in flat panel displays.
关键词： Doping,Zinc oxide (ZnO),Thin film transistors (TFTs),Bias stress stability
更新于2025-09-23 15:22:29
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Effect of Anti-vascular Endothelial Growth Factor Antibody on the Survival of Cultured Retinal Ganglion Cells
摘要： Purpose: To investigate the effects of anti-vascular endothelial growth factor (VEGF) antibody on the survival of retinal ganglion cell (RGC)-5 cells differentiated with staurosporine under oxidative stress. Methods: We used real-time polymerase chain reaction and Western blot to confirm the expression of VEGF, VEGF receptor (VEGFR)-1 and VEGFR-2 in RGC-5 cells differentiated with staurosporine for 6 hours. The differentiated RGC-5 cells were treated with 800 μM hydrogen peroxide (H2O2) for 24 hours to induce oxidative stress. Then, the survival rate of RGC-5 was confirmed by lactate dehydrogenase assay at each concentration (0, 0.01, 0.1, and 1 mg) using bevacizumab as the anti-VEGF antibody. The expression of VEGF, VEGFR-1, and VEGFR-2 was confirmed using real-time polymerase chain reaction. Results: VEGF, VEGFR-1, and VEGFR-2 were all expressed in differentiated RGC-5 cells. When RGC-5 cells were simultaneously treated with bevacizumab and 800 μM H2O2, survival of RGC-5 decreased with bevacizumab concentration. VEGF expression in RGC-5 cells increased with increasing concentration of bevacizumab. Similar patterns were observed for VEGFR-1 and VEGFR-2, but the degree of increase was smaller than that for VEGF. Conclusions: When bevacizumab was administered to differentiated RGC-5 cells, the cell damage caused by oxidative stress increased. Therefore, given these in vitro study results, caution should be exercised with bevacizumab treatment.
关键词： Oxidative stress,RGC-5,Retinal ganglion cell,Anti-vascular endothelial growth factor,Bevacizumab
更新于2025-09-23 15:22:29
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Chlorogenic Acid Supplementation Improves Multifocal Electroretinography in Patients with Retinitis Pigmentosa
摘要： To evaluate the effect of chlorogenic acid supplementation in patients with retinitis pigmentosa, we evaluated objective change in visual function with multifocal electroretinography, along with visual acuity, visual field, standard electroretinography, and contrast sensitivity. Eighteen patients diagnosed with retinitis pigmentosa were enrolled in this prospective, non-comparative, single-arm study. Multifocal electroretinography, best-corrected visual acuity in Early Treatment Diabetic Retinopathy Study letters, total point score on visual field examination with Humphrey Field Analyzer II, electroretinography, and contrast sensitivity were measured and repeated after 3 months supplementation with chlorogenic acid. The amplitude of ring 5 was significantly higher on multifocal electroretinography after 3 months of chlorogenic acid supplementation (7.2 ± 9.5 vs 8.3 ± 10.8 nV/deg2, mean ± standard deviation, P = 0.022). There were no significant changes in the best-corrected visual acuity, total point score on Humphrey Field Analyzer, 30 Hz flicker amplitude on standard electroretinography, or contrast sensitivity. Chlorogenic acid may have a beneficial effect on the peripheral area at the margins of retinal degeneration, and should be considered as an anti-oxidant for the management of retinitis pigmentosa.
关键词： Retinitis Pigmentosa,Oxidative Stress,Chlorogenic Acid,Retinal Degeneration,Antioxidants
更新于2025-09-23 15:22:29
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THROUGH THE LOOKING GLASS: Real-Time Imaging in Brachypodium Roots and Osmotic Stress Analysis
摘要： To elucidate dynamic developmental processes in plants, live tissues and organs must be visualised frequently and for extended periods. The development of roots is studied at a cellular resolution not only to comprehend the basic processes fundamental to maintenance and pattern formation but also study stress tolerance adaptation in plants. Despite technological advancements, maintaining continuous access to samples and simultaneously preserving their morphological structures and physiological conditions without causing damage presents hindrances in the measurement, visualisation and analyses of growing organs including plant roots. We propose a preliminary system which integrates the optical real-time visualisation through light microscopy with a liquid culture which enables us to image at the tissue and cellular level horizontally growing Brachypodium roots every few minutes and up to 24 h. We describe a simple setup which can be used to track the growth of the root as it grows including the root tip growth and osmotic stress dynamics. We demonstrate the system’s capability to scale down the PEG-mediated osmotic stress analysis and collected data on gene expression under osmotic stress.
关键词： root,real-time imaging,osmotic stress,Casparian bands,Brachypodium,PDMS,neutral red,PEG-6000
更新于2025-09-23 15:22:29
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Carrier Transport Mechanisms Underlying the Bidirectional VTH Shift in p-GaN Gate HEMTs Under Forward Gate Stress
摘要： The threshold voltage (VTH) instability of p-GaN/AlGaN/GaN HEMTs was investigated under forward gate stress. A unique bidirectional VTH shift (ΔVTH) with the critical gate voltage (VG) of 6 V was observed. The carrier transport mechanisms underlying the ΔVTH were extensively investigated through the voltage-dependent, time-resolved, and temperature-dependent gate current. The gate current is decomposed into electron and hole current in three distinct regions with respect to VG, which are off-state for VG < 1.2 V (VTH), on-state for 1.2 V < VG < 5 V and “gate-injected” region for VG > 5 V. In off-state, the electrons were thermally activated and transport towards the gate, while electron-trapping governed by the space charge limited conduction (SCLC) in AlGaN barrier was observed in on-state and “gate-injected” region. Such an electron-trapping effect results in the positive VTH shift for VG < 6 V. Meanwhile, the marginal hole transport from gate by thermal activation was also captured by gate current, which features negligible impact on VTH. However, for VG > 6 V, a drastic hole injection triggered by high VG takes place that causes subsequent hole-trapping in AlGaN barrier and hole-injection into GaN buffer. The injected holes enhance the positive charge in the gate region and turned the positively shifted VTH into a negative shift.
关键词： hole injection,threshold voltage shift,p-GaN HEMT,electron trapping,carrier transport mechanisms,gate stress
更新于2025-09-23 15:22:29
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Electrowetting (Fundamental Principles and Practical Applications) || Electrostatics
摘要： Electrowetting (EW) is driven by electrostatic forces. While various basic aspects of electrostatics are taught in high school, EW involves a number of subtleties and somewhat more advanced concepts, e.g. regarding the details of the electric field distribution and forces in complex geometries as well as the response of materials to electric fields. This chapter therefore starts by recapitulating basic principles of electrostatics, focusing on the specific needs of electrowetting. Next to the fundamental laws, boundary conditions, and materials response to electric fields (conductor, dielectrics, leaky dielectrics), we discuss in particular complementary manners of calculating the resulting electrostatic forces based on general principles of energy gradients, global momentum conservation arguments, and local force balance. We will also discuss the solutions of a few specific electrostatic problems of particular interest for EW.
关键词： conductors,Maxwell stress tensor,electrostatics,leaky dielectrics,electric fields,electrowetting,capacitance,dielectrics
更新于2025-09-23 15:22:29
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Trap-assisted enhanced bias illumination stability of oxide thin film transistor by praseodymium doping
摘要： Praseodymium-doped indium zinc oxide (PrIZO) have been employed as the channel layer of thin film transistors (TFTs). The TFTs with Pr doping exhibited a remarkable suppression of the light induced instability. A negligible photo-response and remarkable enhancement in negative gate bias stress under illumination (NBIS) were achieved in the PrIZO-TFTs. Meanwhile, the PrIZO-TFTs showed reasonable characteristics with a high field effect mobility of 26.3 cm2/Vs, SS value of 0.28 V/decade, and Ion/Ioff ratio of 108. X-ray photoelectron spectroscopy (XPS), microwave photoconductivity decay (Micro-PCD) and photoluminescence spectra (PL) were employed to analyze the effects of the Pr concentrations on the performance of PrIZO-TFTs. We disclosed that acceptor-like trap states induced by Pr ions might lead to the suppression of photo-induced carrier in conduction band, which is a new strategy for improving illumination stability of amorphous oxide semiconductors. Finally, a prototype of fully transparent AMOLED display was successfully fabricated to demonstrate the potential of Pr-doping TFTs applied in transparent devices.
关键词： Praseodymium doping,negative bias illumination stress,metal oxide,thin film transistor,photo-response
更新于2025-09-23 15:22:29
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Microscopic-Stress-Induced Retardation between amorphous silicon nitride and amorphous indium zinc oxide having different stresses
摘要： It is very important to increase the contrast ratio in liquid crystal display (LCD) TV using polymer-stabilized vertical alignment (PS-VA) mode. The luminance of the black state is greatly reduced by changing the parameters of the polarizer, the color filter, and the liquid crystal. However, these have the side effect of reducing the characteristics such as the transmittance, the response time, and the viewing angle. In this paper, the luminance of the black state can be reduced by lowering the stress induced retardation at the edge of pixel electrode without changing the materials in the PS-VA mode. It has been shown for the first time that the stress difference in the heterogeneous layers such as amorphous indium zinc oxide (a-IZO) and amorphous silicon nitride (a-SiNx) can optically create birefringence in the microscopic region. By controlling the stress difference in the heterogeneous membrane, the microscopic-stress-induced retardation (MSIR) could be lowered and the contrast ratio of the PS-VA mode could be increased up to 10%.
关键词： stress,birefringence,polymer-stabilized vertical alignment mode,retardation
更新于2025-09-23 15:22:29