Study of Polyimide Films as Passivation for High Temperature High Voltage Silicon Carbide Devices

2007 ◽  
Vol 556-557 ◽  
pp. 671-674 ◽  
Author(s):  
Sombel Diaham ◽  
Marie Laure Locatelli ◽  
Thierry Lebey
Keyword(s):  
Silicon Carbide ◽  
Dielectric Constant ◽  
High Temperature ◽  
Dielectric Loss ◽  
Loss Factor ◽  
Electrical Behavior ◽  
Power Devices ◽  
Polyimide Films ◽  
Temperature Operating ◽  
Conduction Properties

Characterizations of Al/Polyimide/Al capacitors in a temperature range extended up to 400°C are presented. The aim is to determine the retained BPDA/PPD polyimide (PI) intrinsic dielectric and conduction properties, as a first stage in the evaluation of its ability to be applied as a passivation material for high temperature operating silicon carbide power devices. The dielectric constant, dielectric loss factor, and the static leakage current of the “as-prepared” Al/PI/Al structures are strongly affected above 175°C, reaching critical values at 400°C with regard to the aimed application. However, an evolution of these characteristics after the sample exposure at high temperature is observed, resulting in a very good and stabilized electrical behavior even at 400°C.

Microwave Nondestructive Sensing of Moisture Content and Water Activity of Almonds

2021 ◽  
Vol 64 (4) ◽  
pp. 1373-1379
Author(s):  
Samir Trabelsi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Moisture Content ◽  
Bulk Density ◽  
Water Activity ◽  
Free Space ◽  
Loss Factor ◽  
Dielectric Loss Factor ◽  
List Type

HighlightsMoisture and water activity were determined nondestructively and in real time from measurement of dielectric properties.Moisture and water activity calibration equations were established in terms of the dielectric properties.Situations in which bulk density was known or unknown were considered.SEC ranged from 0.41% to 0.68% for moisture and from 0.02 to 0.04 for water activity.Abstract. A method for rapid and nondestructive determination of moisture content and water activity of granular and particulate materials was developed. The method relies on measurement of the dielectric constant and dielectric loss factor at a single microwave frequency. For the purpose of illustration, the method was applied to predicting the moisture content and water activity of almond kernels. A free-space transmission technique was used for accurate measurement of the dielectric properties. Samples of Bute Padre almond kernels with moisture content ranging from 4.8% to 16.5%, wet basis (w.b.), and water activity ranging from 0.50 to 0.93 were loaded into a Styrofoam sample holder and placed between two horn-lens antennas connected to a vector network analyzer. The dielectric properties were calculated from measurement of the attenuation and phase shift at 8 GHz and 25°C. The dielectric properties increased linearly with moisture content, while they showed an exponential increase with water activity. Situations in which the bulk density was known and unknown were considered. Linear and exponential growth regressions provided equations correlating the dielectric properties with moisture content and water activity with coefficients of determination (r2) higher than 0.96. Analytical expressions of moisture content and water activity in terms of the dielectric properties measured at 8 GHz and 25°C are provided. The standard error of calibration (SEC) was calculated for each calibration equation. Results show that moisture content can be predicted with SECs ranging from 0.41% to 0.68% (w.b.) and water activity with SECs ranging from 0.02 to 0.04 for almond kernel samples with water activity ranging from 0.5 to 0.9 and moisture contents ranging from 4.8% to 16.5% (w.b.). Keywords: Bulk density, Dielectric constant, Dielectric loss factor, Free-space measurements, Loss tangent, Microwave frequencies, Moisture content, Water activity.

Effect of High Temperature Ageing on Active and Passive Power Devices

2010 ◽  
Vol 2010 (HITEC) ◽  
pp. 000228-000235
Author(s):  
Cyril Buttay ◽  
Remi Robutel ◽  
Christian Martin ◽  
Christophe Raynaud ◽  
Simeon Dampieni ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Magnetic Materials ◽  
Power Converter ◽  
Power Devices ◽  
Active Devices ◽  
Passive Power ◽  
Temperature Ageing

The power devices needed to build a high-temperature converter (inductors, capacitors and active devices) have been stored at 200°C for up to 1000 hrs. Their characteristics have been monitored. Capacitors and magnetic materials from various manufacturers and technologies are tested, as well as silicon-carbide diodes. It is shown that by carefully choosing the components, it is possible to build a reliable power converter operating at high temperature.

scholarly journals Characterization and Comparison of 1.2kV SiC Power Devices from Cryogenic to High Temperature

2015 ◽  
Vol 821-823 ◽  
pp. 814-817 ◽  
Author(s):  
Thibaut Chailloux ◽  
Cyril Calvez ◽  
Dominique Tournier ◽  
Dominique Planson
Keyword(s):  
Silicon Carbide ◽  
High Temperature ◽  
Electrical Characteristics ◽  
Power Devices ◽  
Effects Of Temperature

The aim of this study consists in comparing effects of temperature on various Silicon Carbide power devices. Static and dynamic electrical characteristics have been measured for temperatures from 80K to 525K.

scholarly journals Dielectric properties of zinc sulfide concentrate during the roasting at microwave frequencies

2017 ◽  
Author(s):  
Guangjun He ◽  
Shiwei Li ◽  
Kun Yang ◽  
Jian Liu ◽  
Peng Liu ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Zinc Sulfide ◽  
Apparent Density ◽  
Loss Tangent ◽  
Loss Factor ◽  
Microwave Energy ◽  
Dielectric Loss Factor ◽  
Sulfide Concentrate

Microwave technology has a potential application in the extraction of zinc from sulphide ores, knowledge of the dielectric properties of these ores plays a major role in the microwave design and simulation for any process. The dielectric properties of zinc sulfide concentrate for two different apparent densities—1.54 and 1.63 g/cm3—have been measured by using the resonance cavity perturbation technique at 915 and 2450 MHz during the roasting process for the temperature ranging from room temperature to 850 °C. The variations of dielectric constant, the dielectric loss factor, the dielectric loss tangent and the penetration depth with the temperature, frequency and apparent density have been investigated numerically. The results indicate that the dielectric constant increases as the temperature increases and temperature has a pivotal effect on the dielectric constant, while the dielectric loss factor has a complicated change and all of the temperature, frequency and apparent density have a significant impact to dielectric loss factor. Zinc sulfide concentrate is high loss material from 450 to 800 °C on the basis of theoretical analyses of dielectric loss tangent and penetration depth, its ability of absorbing microwave energy would be enhanced by increasing the apparent density as well. The experimental results also have proved that zinc sulfide concentrate is easy to be heated by microwave energy from 450 to 800 °C. In addition, the experimental date of dielectric constant and loss factor can be fitted perfectly by Boltzmann model and Gauss model, respectively.

scholarly journals Dielectric and Conductivity Properties of Some Wood Composites

2016 ◽  
Vol 8 ◽  
pp. 51-60
Author(s):  
K.Ch. Varada Rajulu ◽  
B.N. Mohanty
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Low Temperature ◽  
Temperature Region ◽  
Loss Factor ◽  
Wood Composites ◽  
Frequency Range ◽  
Increasing Temperature ◽  
Coaxial Probe

This study presents the dielectric and conductivity properties as function of temperature and frequency of wood based composites. These properties were measured by an open-ended coaxial probe at frequency range between 100 kHz to 100MHz, temperature from 30OC to 200OC which is fully computer interfaced. It has been observed that dielectric constant (ε') and dielectric loss factor (ε") increase with increasing temperature and decrease with increasing frequency. At low temperature region, the conductivity depends significantly on the frequency. However, with the increase in temperature dielectric relaxation takes place and the dependency of the conductivity on frequency get reduced. The patterns of variation were established for the studied specimens and discrepancies were discussed. The study of dielectric properties will help in improving the drying, heating and gluing processes of wood and wood based products.

EFFECT OF DIELECTRIC PROPERTY OF HYDROUS DISPERSOID ON ELECTRORHEOLOGY

1996 ◽  
Vol 10 (23n24) ◽  
pp. 2849-2855 ◽  
Author(s):  
Akiko KAWAI ◽  
Kunio UCHIDA ◽  
Kunio KAMIYA ◽  
Akihiro GOTOH ◽  
Satoshi YODA ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Property ◽  
Dielectric Loss ◽  
Water Content ◽  
Loss Factor ◽  
Free Water ◽  
Relaxation Frequency ◽  
Dielectric Loss Factor ◽  
Silicon Oil

The effect of the dielectric property was investigated of titania and microcrystalline cellulose particles dispersed in a silicon oil on Electrorheology(ER). A commom understanding of the mechanism of ER is the electrical interaction by the interfacial polarization of dispersed particles. Block et al. reported the relaxation frequency of ER fluids, i. e. the rate of polarization, was very important to have an appreciable ER effect. We found that the free water on the cellulose and the titania particles dispersed in the silicon oil, which is respectively dehydrated below the temperature of ca. 110 and 300 degree centigrade, was necessary for an appreciable ER effect. The relation was measured between the water content and the dielectric properties such as dielectric constant ε ’ and dielectric loss factor ε ", as the water adsorbed on the particles was estimated to alter the dielectric properties of the ER fluid. Both the dielectric constant and the relaxation frequency, which is defined by the applied frequency for a peak of the dielectric loss factor, increased with the increase of the water content The relation was discussed between the ER effect and the dielectric properties.

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