Papers by Keyword: Thermal Conductance

Abstract: In the present study effect of different plasters like cement plaster, mud, cow dung and coatings like paint, hydrated lime, charcoal on the thermo – physical properties such as thermal conductivity, overall thermal transmittance, resistance of Light Weight Blocks (LWB) using pond ash has been evaluated. Result of the study state that, cow dung is the best amongst all other plasters used. Cow dung increases thermal resistance of Light Weight Block (LWB) from 0.391 to 0.505 m²K/W. Thermal resistance increased by using other plasters lies between 0.391 to 0.505 m²K/W. The study of curing of LWB from 56 days to 90 days has been made and it is found that thermal conductivity is reduced by 5% and thermal resistance is increased by 3% comparing the duration of curing from 56 to 90 days. Further, effect of activator on the compressive strength & demolding time has also been studied. When activator is used, there is an increase in compressive strength at 56 & 90 days at all levels of replacement when compared to without activator. Reduction in demolding time from 48 hrs. varies between 6 – 12 hrs.

Abstract: Carbon nanotubes are being seen as a promising new class of electronic materials owing to the change in their properties with chirality and geometry of the nanotube. They are being considered for future VLSI applications due to their superior conductance and inductance properties which are important parameters while considering any material for an interconnect or via applications.In this paper, we report the variation in electrical and thermal conductance as well as inductance of a CNT with its geometrical features using a diameter dependent model. Also the dependence of conductance and inductance of a CNT on the type of nanotubes, tube length and tube diameter has been studied. As we know that at nanometre scale, the electrical and thermal transport properties of the components become extremely important as regards the functioning of the device and it is difficult to accurately measure these properties, therefore predictions using modeling and simulation play an important role in providing a guideline for design and fabrication of CNT interconnects and understanding the working of various other CNT based devices.

Abstract: Thermal conductance of microbolometer has a directly impact on Noise Equivalent Temperature Difference (NETD) and thermal time constant which are the key indicators of uncooled IR detector. It is of great significance to calculate and evaluate thermal conductance. A calculate approach of thermal conductance for uncooled microbolometer detectors is introduced in this paper. Accurate three-dimensional modeling of microbolometer is found by using MEMS analysis software Intellisuite. Dynamic thermal analysis of this model is solved and then thermal time constant can be read from thermal time curve of the analysis mentioned above. Combined with the calculation of thermal capacitance, more precisely thermal conductance value can be reached which is more accurate than theoretical calculations result and meaningful for design and fabrication of the device.

Abstract: In this paper a high-performance single level uncooled microbolometer detectors with a unit cell size of 25um×25um is introduced. An efficient detectors requires low Noise Equivalent Temperature Difference(NETD) (<80mK,f/1,60Hz)and low thermal time constant (<8.3ms). The trade-offs between physical parameters are studied to attain the optimum design parameters including the thermal conductance, the thermal time constant and the active area, consequently, optimum design parameters such as the width and the length of the support arms, which can satisfy the demand of an efficient detectors is achieved.

Abstract: A new idea of improving complementary metal-oxide-semiconductor (CMOS) thermopile performance is introduced to reduce the thermal conductance by leading the microcracks into structure of thermopile, which greatly increases the heat flow barrier. A highly sensitive infrared detector requires a low thermal conductance to maximize the temperature change and signal induced by incident IR radiation. Several designs of infrared microsensors are proposed to study influential parameters from microcrack for improving performance of thermopile. To that end, by using some adequate designs of polysilicon architecture, we can greatly reduce the heat flow from the main stream without introducing further electric resistance, which is related with noise. Firstly we develop such a structure of thermopile with low thermal conductance and high performance by using CMOS compatible process which can be easily and exactly fabricated. The suspended structure of infrared sensors is used in this study to provide ideal, thermally isolated, structures for support of the thin film detector. We also simulate the heat flow of the new structures. The results show good match with our original idea.

Abstract: A high-sensitivity infrared detector requires small thermal capacitance and small thermal conductance to maximize the temperature change and signal induced by incident IR radiation. The suspended structure of infrared sensors provides ideal, thermally isolated, structures for support of the thin film detector. A new idea of improving CMOS thermopile performance is introduced to reduce the thermal conductance by dividing the thermocouple into several segments, which greatly increase the heat flow barrier. Then, adjacent segments are connected by a minimum width of alumina wire, which change the heat path and accumulated heat at the joint points. Several designs of infrared microsensors can improve performance of signal with reduce of thermal conductance. To that end, by using some adequate designs of polysilicon architecture, we can greatly reduce the heat flow from the main stream without introducing further electric resistance, which is related with noise. The design and simulation of thermopile sensors are realized by using the process parameters of standard 0.351m CMOS IC technology. Firstly we develop such a structure of thermopile with low thermal conductance and high performance by using CMOS compatible process which can be easily and naturally fabricated. The simulation results show good match with our original idea and great performance than before.