Agnieszka Samson

Estimation of heat transfer coefficient temperature dependence from cooling curve measurements

This paper discusses on the practical example of a power diode attached to a heat sink the problem of heat transfer coefficient temperature dependence and its importance for free convection cooled electronic systems. The average values of this coefficient are estimated from multiple measurements of device cooling curves performed for different device heating currents. These values are used then for transient simulations of the device with compact thermal models.

Comparison of Green's function solutions for different heat conduction models in electronic nanostructures

This paper compares Greens function solutions obtained for different heat conduction models, such as the Fourier-Kirchhoff heat equation, the Cataneo-Vernotte wave equation and the Dual-Phase-Lag equation. The solutions are computed for a nanometer size one-dimensional benchmark structure with Neumann and Dirichlet conditions imposed at its boundaries. Particular attention was paid to the analysis of heat diffusion speed predicted by the considered heat conduction models and its dependence on the time lag values.

Thermal simulation of nanoscale platinium heaters

This paper demonstrates the temperature distribution in the structure which contains two platinum resistors. The Finite Element Method solution of Fourier-Kirchhoff and Dual-Phase-Lag models for two-dimensional problem is presented. Simulation results are compared and carefully discussed.

The Numerical Approaches to Heat Transfer Problem in Modern Electronic Structures

The main aim of this paper is to present a detailed description of the research related to the modeling of heat conduction in modern electronic structures including special consideration of numerical aspects of analyzed algorithms. The motivation to undertake the research and some most important results of experiments and simulations are also included. Moreover, the numerical appoximation of the problem as well as the methodology and the sample solution of mentioned problem are presented. In the main part, the discretisation techniques, Ordinary Differential Equation algorithms and simulation results for Runge-Kutta and Gears algorithms are analysed and discussed. Additionally, a new effective approach to modelling of heat transfer in electronic nanostructures is demonstrated.

Thermal analysis of hybrid circuits with variable heat transfer coefficient

This paper, based on the practical example of a hybrid test circuit, illustrates the importance of proper modeling of the heat transfer coefficient dependence on surface temperature rise and fluid velocity in air cooled electronic systems. The presented experiments show that for the considered circuit the value of the heat transfer coefficient strongly depends on both these factors, thus its changes have to be taken into account in thermal simulations. A simple empirical relation proposed here by the authors allows accurate assessment of local heat transfer coefficient values in different cooling conditions and significant increase of thermal simulation accuracy.

DPL based electro-thermal modelling of Fin-FET transistors

In this paper the electro-thermal analyses related to the modelling of heat transfer in modern electronic structure, consisting of two nanosized transistors, are presented. The Dual-Phase-Lag model appropriate for such kind of structure instead of the classical Fourier-Kirchhoff model is used. Moreover, the thermal and electric domains coupling is described. Furthermore, the paper contains empirical information connected with implementation of algorithms using multiprocessor supercomputers built in the Intel Xeon CPU technology.

DPL thermal model of test microchip structure without cavity dedicated to estimation of nanoelectronic circuits thermal properties

This paper presents the comparison of the temperature distribution in the test structure chip obtained using Fourier-Kirchhoff and Dual-Phase-Lag heat transfer models. The investigated test structure consisting of two polysilicon resistors used as the heater and thermometer, which are located inside the silicon dioxide layer. The simulation results are compared with those which have been received using similar test structure containing two platinum resistors. Some numerical problems observed during the simulation of Dual-Phase-Lag heat transfer model have been also briefly presented.

Modelling of average radiation and convection heat transfer coefficient value in electronic systems

This paper discusses, based on a practical example, the problem of estimating the average radiation and convection heat transfer coefficient value in thermal models of electronic systems. The proposed empirical formulas are fitted to the results of temperature measurements taken for a power diode attached to a heat sink. The measurements were repeated in natural and forced air cooling conditions. These empirical relations were used subsequently in device simulation with compact thermal models.

Investigation of heat transfer coefficient variation in air cooled hybrid electronic circuits

This paper discusses the problem of heat transfer coefficient variation in air cooled hybrid circuits. The investigations are based on a practical example of a circuit containing a bipolar transistor heat source. Its temperature is measured using the base-emitter junction. Additionally, infrared measurements of circuit surface temperature are taken. The measurements are carried out in a wind tunnel for different values of dissipated power and with variable cooling air speed. The measurement results are analysed allowing the assessment of heat transfer coefficient variation with surface temperature and cooling air velocity. Based on the analyses, compact thermal models are generated for the circuit allowing fast and accurate simulation of circuit temperature in various cooling conditions.

Green's function solution for dual-phase-lag heat conduction model in electronic nanostructures

This paper presents the Greens function solution of the dual-phase-lag heat equation. The solution is derived for a thin one-dimensional slab heated on one side by a heat flux and cooled on the other side by the imposed isothermal boundary condition. The simulation results are compared with the ones obtained previously for the Fourier-Kirchhoff heat equation.