scholarly journals Failure Mechanism of Solid Tantalum Capacitors

1976 ◽  
Vol 3 (3) ◽  
pp. 171-179 ◽  
Author(s):  
B. Goudswaard ◽  
F. J. J. Driesens
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Alternative Hypothesis ◽  
Tantalum Oxide ◽  
Operating Conditions ◽  
Thermal Migration ◽  
Accelerated Life Tests ◽  
Accelerated Life ◽  
Life Tests ◽  
Scanning Electron

It has been suggested that failure of solid tantalum capacitors is due to thermal migration of impurities from the tantalum anode to flaws in the oxide layer. This implies, however, that leakage current gradually increases under normal operating conditions, an effect which has not been observed. An alternative hypothesis advanced here is that failure is due to crystallization of tantalum oxide under the influence of the electric field. Scanning electron microscopy of specially cleaned anodized tantalum sheet on which thin gold electrodes have been deposited clearly shows the occurrence of crystallization after 17 hours at an applied voltage of 75 V and a temperature of 65℃. Results of accelerated life tests on solid tantalum capacitors at temperatures of 85℃ and 125℃, and at up to 2,5 times rated voltage also accord better with a field crystallization hypothesis than with a thermal migration failure hypothesis.

Study of Mechanical Degradation and Microstructural Characterization in a Ni-Based Superalloy Component of a Gas Turbine

2018 ◽  
Vol 941 ◽  
pp. 1248-1253
Author(s):  
Erika O. Avila-Davila ◽  
Victor M. Lopez-Hirata ◽  
Maribel L. Saucedo-Muñoz ◽  
Luis M. Palacios-Pineda ◽  
Ignacio Ramirez-Vargas ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Behavior ◽  
Gas Turbine ◽  
Cross Sections ◽  
Microstructural Characterization ◽  
Operating Conditions ◽  
Critical Parameters ◽  
Ansys Software ◽  
Scanning Electron

The microstructural characterization of a blade made of Ni-based superalloy was carried out and discussed. The blade was removed from service, of a gas turbine, due to preventive maintenance. This component was studied on different cross sections according to the surface temperature obtained by ANSYS software. The cross sections were characterized by Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and High Resolution Scanning Electron Microscopy (HR-SEM). It was determined that the maximum value of total deformation is 0.001717 mm, located in the surface upper section of the blade, which not correspond to the section with the highest value of temperature calculated with ANSYS software. These results were consistent with the rafted microstructure observed at the upper region of the blade. Microcavities close to the MC carbides with a size of about 40x10-6m were also observed. The mechanical behavior of the Ni-based superalloy was studied by Rockwell Hardness testing (RHT). So, morphological changes were identified in the occurrence of the strengthening precipitated, γ', according to the operating conditions: stress and temperature. The average radius of the γ' precipitated was obtained by computer image analysis using ImageJ software. No clear relationship was found between the hardness values obtained and the coarsened γ' precipitated. A bimodal occurrence of coarsened γ' particles was identified distributed through γ matrix by HR-SEM. Thus, this study was carried out with the purpose to identify the critical parameters that promote microstructural changes in the Ni-based superalloy and therefore affect the mechanical behavior in this turbine blade.

scholarly journals Reliability of X7R Multilayer Ceramic Capacitors During High Accelerated Life Testing (HALT)

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1900 ◽  
Author(s):  
Ana Hernández-López ◽  
Juan Aguilar-Garib ◽  
Sophie Guillemet-Fritsch ◽  
Roman Nava-Quintero ◽  
Pascal Dufour ◽  
...  
Keyword(s):  
Operating Conditions ◽  
Time To Failure ◽  
Multilayer Ceramic Capacitors ◽  
Thermal Failure ◽  
Accelerated Life Tests ◽  
Accelerated Life ◽  
Essential Components ◽  
Ceramic Capacitors ◽  
Life Tests ◽  
Multilayer Ceramic

Multilayer ceramic capacitors (MLCC) are essential components for determining the reliability of electronic components in terms of time to failure. It is known that the reliability of MLCCs depends on their composition, processing, and operating conditions. In this present work, we analyzed the lifetime of three similar X7R type MLCCs based on BaTiO3 by conducting High Accelerated Life Tests (HALT) at temperatures up to 200 °C at 400 V and 600 V. The results were adjusted to an Arrhenius equation, which is a function of the activation energy (Ea) and a voltage stress exponent (n), in order to predict their time to failure. The values of Ea are in the range of 1–1.45 eV, which has been reported for the thermal failure and dielectric wear out of BaTiO3-based dielectric capacitors. The stress voltage exponent value was in the range of 4–5. Although the Ea can be associated with a failure mechanism, n only gives an indication of the effect of voltage in the tests. It was possible to associate those values with each type of tested MLCC so that their expected life could be estimated in the range of 400–600 V.

Microstructure, Damage and Resistance during Electromigration Life-Testing of Al-Cu Interconnects

1993 ◽  
Vol 309 ◽  
Author(s):  
W.C. Shih ◽  
A.L. Greer ◽  
Y.Z. Xu ◽  
B.K. Jones
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Microstructure Evolution ◽  
Accelerated Life Testing ◽  
Life Testing ◽  
Damage Development ◽  
Cu Metallization ◽  
Accelerated Life ◽  
Line Resistance ◽  
Scanning Electron

AbstractUnpassivated 1.4 mm long lines of Al-4wt.%Cu metallization have been successively imaged (by scanning electron microscopy) and electromigration stressed until failure. The resistance of lines, evolution of line microstructure and the development of electromigration damage are thus discontinuously recorded through the accelerated life-testing (260°C, 2 × 1010 A m-2). Correlations are made among microstructure evolution, electromigration damage development and line resistance. The probable mechanisms of damage development are discussed.

Spatial Resolution in Scanning Electron Microscopy and Scanning Transmission Electron Microscopy Without a Specimen Vacuum Chamber

2016 ◽  
Vol 22 (4) ◽  
pp. 754-767 ◽  
Author(s):  
Kayla X. Nguyen ◽  
Megan E. Holtz ◽  
Justin Richmond-Decker ◽  
David A. Muller
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Vacuum Chamber ◽  
Operating Conditions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron

AbstractA long-standing goal of electron microscopy has been the high-resolution characterization of specimens in their native environment. However, electron optics require high vacuum to maintain an unscattered and focused probe, a challenge for specimens requiring atmospheric or liquid environments. Here, we use an electron-transparent window at the base of a scanning electron microscope’s objective lens to separate column vacuum from the specimen, enabling imaging under ambient conditions, without a specimen vacuum chamber. We demonstrate in-air imaging of specimens at nanoscale resolution using backscattered scanning electron microscopy (airSEM) and scanning transmission electron microscopy. We explore resolution and contrast using Monte Carlo simulations and analytical models. We find that nanometer-scale resolution can be obtained at gas path lengths up to 400 μm, although contrast drops with increasing gas path length. As the electron-transparent window scatters considerably more than gas at our operating conditions, we observe that the densities and thicknesses of the electron-transparent window are the dominant limiting factors for image contrast at lower operating voltages. By enabling a variety of detector configurations, the airSEM is applicable to a wide range of environmental experiments including the imaging of hydrated biological specimens and in situ chemical and electrochemical processes.

Surface Analysis of Fretting Damage in Electrical Connectors

1988 ◽  
Vol 140 ◽  
Author(s):  
M. Braunović
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tin Oxide ◽  
Operating Conditions ◽  
Metal Particles ◽  
X Ray ◽  
Distribution Transformers ◽  
Tin Plating ◽  
Fretting Damage ◽  
Scanning Electron

AbstractA number of bolted-type tin-plated copper connectors commonly used for distribution transformers were examined using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDX). The connectors studied had been removed from service because of unsatisfactory performance under normal operating conditions as manifested either by overheating or instability.Detailed examination revealed the presence of extensive fretting damage in thecontacting surfaces. The fretting debris was composed mainly of tin oxide and oxidized base-metal particles. Localized melting and wear of the tin plating were also observed.

ANALYSIS OF WEAR AND TEAR OF WORKING ELEMENTS WITH A REPLACEABLE CUTTING EDGE IN AN ABRASIVE SOIL MASS

Tribologia ◽  
2018 ◽  
Vol 273 (3) ◽  
pp. 101-109 ◽  
Author(s):  
Magdalena LEMECHA ◽  
Jerzy NAPIÓRKOWSKI ◽  
Łukasz KONAT
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Operational Research ◽  
Soil Mass ◽  
Operating Conditions ◽  
Cutting Edge ◽  
Boron Steel ◽  
Wear And Tear ◽  
Characteristic Points ◽  
Scanning Electron

This paper presents an analysis of the wear and tear process of different technological solutions of plough blades with a replaceable cutting edge. The experiment was conducted under natural operating conditions. Workpieces made of B27, Hardox 500, and Hardox 500 with padding weld, and two types of boron steel with non-hardfaced and hardfaced cutting edges were tested. The analyses of chemical composition and microstructure were performed using light microscopy and scanning electron microscopy methods. Operational research included the measurement of mass changes and geometry in the characteristic points of the plough blades. Based on the results obtained, it was found that the components made of Hardox 500 steel with padding welding were more durable than component without the padding layer. In contrast, the weight loss intensity was similar for all the examined materials.

Charging Processes in Low Vacuum Scanning Electron Microscopy

2004 ◽  
Vol 10 (6) ◽  
pp. 711-720 ◽  
Author(s):  
Bradley L. Thiel ◽  
Milos Toth ◽  
John P. Craven
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electric Fields ◽  
Charge Trapping ◽  
Operating Conditions ◽  
X Ray ◽  
Physical Mechanisms ◽  
Charge Field ◽  
Ion Recombination ◽  
Scanning Electron

A framework is presented for understanding charging processes in low vacuum scanning electron microscopy. We consider the effects of electric fields generated above and below the specimen surface and their effects on various processes taking place in the system. These processes include the formation of an ionic space charge, field-enhanced electron emission, charge trapping and dissipation, and electron–ion recombination. The physical mechanisms behind each of these processes are discussed, as are the microscope operating conditions under which each process is most effective. Readily observable effects on gas gain curves, secondary electron images, and X-ray spectra are discussed.

Study of the fouling of inorganic membranes by acidified milks using scanning electron microscopy and electrophoresis. II. Membrane with pore diameter 0·8 μm

1991 ◽  
Vol 58 (1) ◽  
pp. 51-65 ◽  
Author(s):  
Hamadi Attia ◽  
Michel Bennasar ◽  
Blas Tarodo De la Fuente
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pore Diameter ◽  
Retention Rate ◽  
Operating Conditions ◽  
Low Flow ◽  
Inorganic Membranes ◽  
Average Pore ◽  
Static Conditions ◽  
Scanning Electron

SummaryThe functioning of an inorganic microfiltration membrane (Membralox-SCT) with an average pore diameter of 0·8 μm, used for processing milk, acidified milk and lactic coagulum, was studied using dynamic and static conditions. Milk processing (pH 6·62) gave acceptable rates of protein retention but at low flow rates. Study of the effect of operating parameters during microfiltration of coagulum led to determination of optimal operating conditions leading to satisfactory performance and adequate retention rate. The results are explained using a model of the formation and development of internal and external fouling of a mineral membrane. Observations using scanning electron microscopy related to the pH of milk were used to verify the model by showing that internal fouling occurred only when the pH was higher than 5·50. This internal fouling was closely linked with the physicochemical state of milk proteins. Indeed, the fouling particles visualized at the alumina grains of the membrane support changed progressively from individual micelles (pH 6·62) to a chain or clustered structure (pH 5·60). Electrophoretic study confirmed this observation and showed that casein was present in milk permeates (pH 6·62) but not in coagulum permeates (pH 4·40).

scholarly journals Niobium Oxide and Tantalum Oxide Micro- and Nanostructures Grown Using Material Recovered from Mining Tailings

2021 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Belén Sotillo ◽  
Lorena Alcaraz ◽  
Félix Antonio López ◽  
Francisco José Alguacil ◽  
Olga Rodríguez ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Niobium Oxide ◽  
Tantalum Oxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Mining Tailings ◽  
Scanning Electron

Niobium and tantalum-based oxides were recovered from mining tailings. These oxides were used as starting material for growing micro- and nanostructures by the evaporation method. The morphology and crystal structure of the final oxides were evaluated using X-ray diffraction (XRD), micro-Raman spectroscopy, and scanning electron microscopy (SEM). After the thermal treatment, microrods of both oxides were obtained, which presented exotic stoichiometries Nb22O54 and K6Ta10.8O30, respectively.

scholarly journals Is Low Accelerating Voltage Always the Best for Semiconductor Inspection and Metrology?

2004 ◽  
Vol 12 (1) ◽  
pp. 46-47
Author(s):  
M. T. Postek ◽  
A. E. Vladár
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
Operating Conditions ◽  
Dynamic Charging ◽  
Induced Signal ◽  
And Control ◽  
Scanning Electron ◽  
Semiconductor Production

Low accelerating voltage operation is an excellent mode of scanning electron microscopy and it is extensively used for measurements in semiconductor production. The beam penetration is small, and if properly applied, the specimen charging is kept at acceptable levels. But, is this always enough? Today, the scanning electron microscope (SEM) is being used in photomask metrology and imaging where charging is excessive. Charging is difficult to quantify and control as it varies greatly with instruments, operating conditions and sample. Therefore, it is also very difficult to model accurately. For accurate metrology charging must be overcome because the dynamic charging of the sample deflects the electron beam from its intended position and the intensity of the induced signal may vary uncontrollably. Deflection of the electron beam of even a few nanometers potentially results in a measurement error that is significant to modern semiconductor production.

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