Thermally-Optimum Design of GaN-on-SiC HEMT

2015 ◽  
Author(s):  
Caleb A. Holloway ◽  
Avram Bar-Cohen
Keyword(s):  
Thermal Resistance ◽  
Optimum Design ◽  
Power Amplifier ◽  
Layer Structure ◽  
Three Dimensional ◽  
Boundary Resistance ◽  
Junction Temperature ◽  
Thermal Boundary Resistance ◽  
Substrate Thickness ◽  
Design Calculations

Three-dimensional finite-element modeling is used to determine the thermally optimum design of a GaN-on-SiC MMIC power amplifier, with a focus on the parametric influence of the thermal boundary resistance (TBR), epitaxial geometry, and dissipated linear power on the HEMT junction temperature rise. A commercial MMIC power amplifier is used to set the baseline geometry and dimensions. It is found that the frequently neglected Thermal Boundary Resistance (TBR), between the GaN and SiC, not only has a significant influence on the maximum junction temperature, but directly influences the thermally-optimal GaN thickness for the HEMT transistor. The thermally-optimal GaN thickness is a balance between spreading, vertical thermal resistance, and the magnitude of the TBR. As a consequence, it is seen the commonly used, submicron l GaN thicknesses approach optimality only when the TBR values are below 10 m2-K/GW. Additionally, it is observed that increasing the gate pitch and substrate thickness helps to diffuse the flow of heat within the substrate before it proceeds into the cooling solution, resulting in an overall decrease in thermal resistance. The numerical results are used to verify the accuracy of an available analytical solution for a surface heat source on an orthotropic multi-layer structure, albeit with assumed temperature-invariant properties, thus enabling use of this relation in scoping and preliminary design calculations.

The Impact of GaN/Substrate Thermal Boundary Resistance on a HEMT Device

2011 ◽  
Author(s):  
Horacio C. Nochetto ◽  
Nicholas R. Jankowski ◽  
Avram Bar-Cohen
Keyword(s):  
Temperature Rise ◽  
Boundary Resistance ◽  
Junction Temperature ◽  
Dominant Factor ◽  
Design Parameters ◽  
Thermal Boundary Resistance ◽  
Substrate Thickness ◽  
High Electron ◽  
The Impact ◽  
Heat Spreading

The present work uses finite element thermal simulations of Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) to evaluate the impact of device design parameters on the junction temperature. In particular the effects of substrate thickness, substrate thermal conductivity, GaN thickness, and GaN-to-substrate thermal boundary resistance (TBR) on device temperature rise are quantified. In all cases examined, the TBR was a dominant factor in overall device temperature rise. It is shown that a TBR increase can offset any benefits offered through a more conductive substrate and that there exists a substrate thickness independent of TBR which results in a minimum junction temperature. Additionally, the decrease of GaN thickness only provides a thermal benefit at small TBRs. For TBRs on the order of 10−4 cm2K/W or greater, decreasing the GaN thickness can actually increase the temperature as the heat from the highly localized source is not sufficiently spread out before crossing the GaN-substrate boundary. The tradeoff between GaN heat spreading, substrate heat spreading, and temperature rise across the TBR results in a GaN thickness with minimum total temperature rise. For the TBR values of 10−4 cm2K/W and 10−3 cm2K/W these GaN thicknesses are 0.8 μm and 9 μm respectively.

Design and Thermal Analysis of SiGe HBT with Segmented Emitter Fingers and Non-Uniform Emitter Finger Spacing

2013 ◽  
Vol 462-463 ◽  
pp. 592-596
Author(s):  
Liang Chen ◽  
Cheng Zhong Hu ◽  
Chun Ling Jiang
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Temperature Distribution ◽  
Thermal Resistance ◽  
Three Dimensional ◽  
Heterojunction Bipolar Transistor ◽  
Junction Temperature ◽  
Ansys Software ◽  
Sige Hbt ◽  
Novel Structure

A novel multi-finger power SiGe heterojunction bipolar transistor (HBT) with segmented emitter fingers and non-uniform emitter finger spacing was proposed to improve the thermal stability. Thermal simulation for a five-finger power SiGe HBT with novel structure was conducted with ANSYS software. Three-dimensional temperature distribution on emitter fingers was obtained. Compared with traditional emitter structure, the maximum junction temperature of novel structure reduce significantly from 429.025K to 414.252K, the thermal resistance reduce from 159K/W to 141K/W, temperature distribution were significantly improved. Thermal stability was effective enhanced.

Design and Thermal Analysis of SiGe HBT with Non-Uniform Segmented Emitter Fingers and Non-Uniform Emitter Finger Spacing

2015 ◽  
Vol 713-715 ◽  
pp. 938-941
Author(s):  
Liang Chen
Keyword(s):  
Thermal Stability ◽  
Thermal Analysis ◽  
Temperature Distribution ◽  
Thermal Resistance ◽  
Three Dimensional ◽  
Heterojunction Bipolar Transistor ◽  
Junction Temperature ◽  
Ansys Software ◽  
Sige Hbt ◽  
Novel Structure

A novel multi-finger power SiGe heterojunction bipolar transistor (HBT) with non-uniform segmented emitter fingers and non-uniform emitter finger spacing was proposed to improve the thermal stability. Thermal simulation for a five-finger power SiGe HBT with novel structure was conducted with ANSYS software. Three-dimensional temperature distribution on emitter fingers was obtained. Compared with non-uniform segmented emitter fingers structure and non-uniform emitter finger spacing structure, the maximum junction temperature of novel structure reduce significantly, the thermal resistance reduce, temperature distribution were significantly improved. Thermal stability was effective enhanced.

Three Dimensional CFD Conjugate Analysis of Two Inline PLCC Packages Horizontally Mounted

2004 ◽  
Vol 1 (4) ◽  
pp. 244-260 ◽  
Author(s):  
B. Jayakumar ◽  
G. A. Quadir ◽  
M. Z. Abdullah ◽  
K. N. Seetharamu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Resistance ◽  
Transfer Coefficient ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Junction Temperature ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Air Inlet

A three dimensional conjugate analysis of heat and fluid flow of two 84-pin PLCC packages mounted horizontally on a printed circuit board in a wind tunnel is carried out using a commercial CFD code, FLUENTTM. Various inlet air velocities are used to emulate natural, mixed and forced convection conditions. Some parametric studies are carried out by varying the package chip power, gap between the packages and air inlet velocities. The results are presented in terms of the junction temperature, thermal resistance and top surface average heat transfer coefficient for each package under different operating conditions. The decrease in the junction temperature of the packages with the increase in air inlet velocity is clearly predicted. Further, the leading edge heat transfer coefficient of the packages is always higher than that at the trailing edge for all inlet air velocities considered. It is found that the variation in the package chip power does not influence the average heat transfer coefficient and the thermal resistance of the package at a particular inlet air velocity. Different correlations in terms of the junction temperature as well as the Nusselt number are presented for each package under different convection conditions.

INTERLAYER THERMAL BOUNDARY RESISTANCE OF WSe2 INVESTIGATED BY USING TIME-DOMAIN THERMOREFLECTANCE MEASUREMENT

2018 ◽  
Author(s):  
Young Gwan Choi ◽  
Chan June Zhung ◽  
Chang Jae Roh ◽  
Hwi In Ju ◽  
Tae Yun Kim ◽  
...  
Keyword(s):  
Time Domain ◽  
Boundary Resistance ◽  
Thermal Boundary Resistance

scholarly journals Influence of a Thermal Pad on Selected Parameters of Power LEDs

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3732
Author(s):  
Krzysztof Górecki ◽  
Przemysław Ptak ◽  
Tomasz Torzewicz ◽  
Marcin Janicki
Keyword(s):  
Optical Properties ◽  
Thermal Resistance ◽  
Optical Power ◽  
Junction Temperature ◽  
Operating Parameters ◽  
Cold Plate ◽  
Optical Efficiency ◽  
Forward Current ◽  
Measurement Results ◽  
Set Up

This paper is devoted to the analysis of the influence of thermal pads on electric, optical, and thermal parameters of power LEDs. Measurements of parameters, such as thermal resistance, optical efficiency, and optical power, were performed for selected types of power LEDs operating with a thermal pad and without it at different values of the diode forward current and temperature of the cold plate. First, the measurement set-up used in the paper is described in detail. Then, the measurement results obtained for both considered manners of power LED assembly are compared. Some characteristics that illustrate the influence of forward current and temperature of the cold plate on electric, thermal, and optical properties of the tested devices are presented and discussed. It is shown that the use of the thermal pad makes it possible to achieve more advantageous values of operating parameters of the considered semiconductor devices at lower values of their junction temperature, which guarantees an increase in their lifetime.

The Role of Interface Vibrational Modes in Thermal Boundary Resistance

2021 ◽  
Author(s):  
Christopher M. Stanley ◽  
Benjamin K. Rader ◽  
Braxton H. D. Laster ◽  
Mahsa Servati ◽  
Stefan K. Estreicher
Keyword(s):  
Boundary Resistance ◽  
Thermal Boundary Resistance ◽  
Vibrational Modes

Optimization of the Wrist Pin End of an Automobile Engine Connecting Rod With an Interference Fit

1990 ◽  
Vol 112 (3) ◽  
pp. 406-412 ◽  
Author(s):  
Vijay Sarihan ◽  
Ji Oh Song
Keyword(s):  
Finite Element ◽  
Optimum Design ◽  
Three Dimensional ◽  
Stress Singularity ◽  
Design Strategy ◽  
Structural Components ◽  
Connecting Rod ◽  
Fem Model ◽  
Automobile Engine ◽  
Interference Fit

Current design procedures for complicated three-dimensional structural components with component interactions may not necessarily result in optimum designs. The wrist pin end design of the connecting rod with an interference fit is governed by the stress singularity in the region where the wrist pin breaks contact with the connecting rod. Similar problems occur in a wide variety of structural components which involve interference fits. For a better understanding of the problems associated with obtaining optimum designs for this important class of structural interaction only the design problems associated with the wrist pin end of the rod are addressed in this study. This paper demonstrates a procedure for designing a functional and minimum weight wrist pin end of an automobile engine connecting rod with an interference fit wrist pin. Current procedures for Finite Element Method (FEM) model generation in complicated three-dimensional components are very time consuming especially in the presence of stress singularities. Furthermore the iterative nature of the design process makes the process of developing an optimum design very expensive. This design procedure uses a generic modeler to generate the FEM model based on the values of the design variables. It uses the NASTRAN finite element program for structural analysis. A stress concentration factor approach is used to obtain realistic stresses in the region of the stress singularity. For optimization, the approximate optimization strategy in the COPES/CONMIN program is used to generate an approximate design surface, determine the design sensitivities for constrained function minimization and obtain the optimum design. This proposed design strategy is fully automated and requires only an initial design to generate the optimum design. It does not require analysis code modifications to compute the design sensitivities and requires very few costly NASTRAN analyses. The connecting rod design problem was solved as an eight design variable problem with five constraints. A weight reduction of nearly 27 percent was achieved over an existing design and required only thirteen NASTRAN analyses. It is felt that this design strategy can be effectively used in an engineering environment to generate optimum designs of complicated three-dimensional components.

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