New GaN Power-Electronics Packaging Solutions: A Thermal Analysis using Raman Thermography

2010 ◽  
Vol 2010 (1) ◽  
pp. 000446-000449
Author(s):  
M. Faqir ◽  
A. Manoi ◽  
T. Mrotzek ◽  
S. Knippscheer ◽  
M. Massiot ◽  
...  
Keyword(s):  
Base Plate ◽  
Heat Diffusion ◽  
Heat Extraction ◽  
Dramatic Improvement ◽  
High Electron ◽  
Operation Condition ◽  
Thermal Dynamics ◽  
Diamond Composite ◽  
Base Plates ◽  
Device Operation

Raman thermography measurements were performed on AlGaN/GaN multi-finger high electron mobility transistors (HEMTs) to determine their channel temperature at various power levels. The devices were mounted on both silver diamond composite and CuW base plates, in order to benchmark the thermal performance of novel diamond composite base plates compared to traditional materials. We illustrate that AlGaN/GaN HEMT devices mounted on silver diamond composite base plates show peak temperatures which are 50% lower than the peak temperatures exhibited by devices mounted on traditional CuW base plates. This is a dramatic improvement in terms of heat extraction, as basis to enabling longer device life-times and better performances. In addition, time-resolved Raman thermography measurements were carrier out to obtain thermal dynamics of devices on the silver-diamond base plate and on heat diffusion during pulsed device operation. This time-dependent information is of great importance for reliability and failure analyses, as pulsed operation of a HEMT is a typically device operation condition. Finite-element thermal simulations were performed for comparison with the experimental results, and good agreement with the experimental data was obtained.

New GaN Power-Electronics Packaging Solutions: A Thermal Analysis Using Raman Thermography

2011 ◽  
Vol 8 (3) ◽  
pp. 110-113
Author(s):  
M. Faqir ◽  
A. Manoi ◽  
T. Mrotzek ◽  
S. Knippscheer ◽  
M. Massiot ◽  
...  
Keyword(s):  
High Electron Mobility Transistors ◽  
Heat Diffusion ◽  
Heat Extraction ◽  
Dramatic Improvement ◽  
High Electron ◽  
Operation Condition ◽  
Thermal Dynamics ◽  
Time Resolved ◽  
Diamond Composite ◽  
Device Operation

Raman thermography measurements were performed on AlGaN/GaN multifinger high electron mobility transistors (HEMTs) to determine their channel temperature at various power levels. The devices were mounted on both silver diamond composite and CuW baseplates, in order to benchmark the thermal performance of novel diamond composite baseplates compared with traditional materials. We illustrate that AlGaN/GaN HEMT devices mounted on silver diamond composite baseplates show peak temperatures that are 50% lower than the peak temperatures exhibited by devices mounted on traditional CuW baseplates. This is a dramatic improvement in terms of heat extraction as a basis to enable longer device lifetimes and better performance. In addition, time-resolved Raman thermography measurements were carried out to obtain the thermal dynamics of devices on the silver-diamond baseplate and on heat diffusion during pulsed device operation. This time-dependent information is of great importance for reliability and failure analyses, as pulsed operation of a HEMT is a typical device operation condition. Finite-element thermal simulations were performed for comparison with experimental results, and good agreement with the experimental data was obtained.

Mapping Thickness Dependent Thermal Conductivity of GaN

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Elbara Ziade ◽  
Jia Yang ◽  
Gordie Brummer ◽  
Denis Nothern ◽  
Theodore Moustaks ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pump Beam ◽  
Continuous Wave ◽  
High Electron Mobility Transistors ◽  
Heat Diffusion ◽  
Phase Lag ◽  
High Electron ◽  
Heat Diffusion Equation ◽  
Phase Images ◽  
Gan Film

Frequency domain thermoreflectance (FDTR) is used to create quantitative maps of thermal conductivity and thickness for a thinning gallium nitride (GaN) film on silicon carbide (SiC). GaN was grown by molecular beam epitaxy on a 4H-SiC substrate with a gradient in the film thickness found near the edge of the chip. The sample was then coated with a 5 nm nickel adhesion layer and a 85 nm gold transducer layer for the FDTR measurement. A piezo stage raster scans the sample to create phase images at different frequencies. For each pixel, a periodically modulated continuous-wave laser (the red pump beam) is focused to a Gaussian spot, less than 2 um in diameter, to locally heat the sample, while a second beam (the green probe beam) monitors the surface temperature through a proportional change in the reflectivity of gold. The pump beam is modulated simultaneously at six frequencies and the thermal conductivity and thickness of the GaN film are extracted by minimizing the error between the measured probe phase lag at each frequency and an analytical solution to the heat diffusion equation in a multilayer stack of materials. A scanning electron microscope image verifies the thinning GaN. We mark the imaged area with a red box. A schematic of the GaN sample in our measurement system is shown in the top right corner, along with the two fitting properties highlighted with a red box. We show the six phase images and the two obtained property maps: thickness and thermal conductivity of the GaN. Our results indicate a thickness dependent thermal conductivity of GaN, which has implications of thermal management in GaN-based high electron mobility transistors.

Thermally Optimum Natural Convection Cooled Longitudinal-Plate Heat Sinks With Horizontal Base Plates

2001 ◽  
Author(s):  
K. K. Sikka ◽  
C. George
Keyword(s):  
Natural Convection ◽  
Heat Sink ◽  
Base Plate ◽  
Heat Sinks ◽  
Geometrical Parameters ◽  
Plate Heat ◽  
Horizontal Orientation ◽  
Fin Spacing ◽  
Base Plates ◽  
Weakly Dependent

Abstract Longitudinal-plate fin heat sinks are optimized under natural convection conditions for the horizontal orientation of the heat sink base plate. The thermal performance of the heat sinks is numerically modeled. The fin height, thickness and spacing and heat sink width are systematically varied. The numerical results are validated by experimentation. Results show that the thermal resistance of a heat sink minimizes for a certain number of fins on the base plate. The fin spacing-to-length ratio at which the minimum occurs is weakly dependent on the fin height and thickness and heat sink width. The flow fields reveal that the minimum occurs for the heat sink geometry in which the number of fins are maximized such that the flow velocity as the air exits the fins is fully developed. A correlation of the heat transfer with the heat sink geometrical parameters is also developed.

A Resistive GaN-HEMT Mixer for a Cable Modem Operable up to 250°C for Downhole Communications

2017 ◽  
Vol 14 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Jebreel M. Salem ◽  
Dong Sam Ha
Keyword(s):  
High Temperature ◽  
Oil And Gas ◽  
High Electron Mobility Transistor ◽  
Oil And Gas Industry ◽  
Intermediate Frequency ◽  
Local Oscillator ◽  
Heat Extraction ◽  
High Electron ◽  
Reliable Operation ◽  
Ambient Temperatures

It is necessary for the oil and gas industry to drill deeper due to decrease of easily accessible natural reserves. Temperatures of deep wells can exceed 210°C, and conventional cooling and heat extraction techniques are impractical in such a harsh environment. Reliable electronic designs that can sustain high temperature become necessary. This article presents a high-temperature passive radio frequency (RF) mixer for downhole communications. The proposed mixer is designed to upconvert or downconvert the incoming signal with low conversion loss (CL), high linearity, and reliable operation at the ambient temperature up to 250°C. GaN is a wide-bandgap technology that can provide a reliable operation at high ambient temperatures, and the proposed mixer adopts a commercial GaN high-electron-mobility transistor. Measurement results indicate that the proposed mixer achieves a CL of 7.1 dB at local oscillator (LO) power of 2.5 dBm for the downconversion from 230–253 to 97.5 MHz at 250°C and the input P1dB compression point lies at 5 dBm. The designed mixer also achieves 24.5 dB RF-to-intermediate frequency (IF) isolation and 28 dB LO-to-IF isolation at 250°C. The power dissipation of the mixer is virtually zero.

scholarly journals ТЕОРЕТИЧНЕ ДОСЛІДЖЕННЯ НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ БАЗОВИХ ПЛИТ УЗРП-16

2020 ◽  
pp. 151-164
Author(s):  
Є. А. Фролов ◽  
Б. О. Коробко ◽  
С. В. Попов
Keyword(s):  
Strain State ◽  
Structural Parameters ◽  
Plate Thickness ◽  
Bending Moment ◽  
Base Plate ◽  
Plate Surface ◽  
Stress Strain ◽  
Stress Strain State ◽  
Study Results ◽  
Base Plates

Theoretical studies of the stress-strain state of base plates, which are the base of the UZRP-16 universal collapsible machines have been done. These machines are used for welding works in machine building industry. The finite element method was applied to solve the problems. Nature of influence of strength and structural parameters on the base plate stress-strain state in operation has been determined, namely: the relations between displacements and stresses arising in the base plates and the bending moment magnitudes have been recorded; the stress-strain state pattern of the base plates has been obtained depending on the place of bending moment application; influence of the conditions for bearing and fastening the plates on their stress-strain state has been investigated; influence of the plate geometric parameters on stress and displacement has been studied; The stress-material and displacement-material relations have been obtained for the plates. Based on the theoretical study results of the base plate stress-strain state, the following have been obtained: stress plots and patterns of deformed surfaces, which are symmetrical with respect to the plate central axes; maximum values of normal and tangential stress components arising in the field of bending moment application; stress on the rectangular base plate surface is 2.1 times higher than the stress on square plate surface under the same conditions of bearing and loading; stresses acting on the plate surfaces and being tensile stresses within the range of 10 to 70 MPa. It was found that the square shape of the plates, according to the stress state, is predominant in relation to the rectangular shape. The optimal condition for bearing is fixing the plates at nine points. For the first time, graphs were drawn for choosing the base plate thickness under action of various operational loads.

scholarly journals Monotonic Response of Exposed Base Plates of Columns: Numerical Study and a New Design Method

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 396
Author(s):  
Héctor Díaz ◽  
Eduardo Nuñez ◽  
Claudio Oyarzo-Vera
Keyword(s):  
Numerical Study ◽  
Design Method ◽  
Numerical Models ◽  
Failure Mechanisms ◽  
Plate Thickness ◽  
Base Plate ◽  
Traditional Design ◽  
Current Design ◽  
Bending Loads ◽  
Base Plates

This paper describes a numerical study of the behavior of exposed base plates of columns under the action of axial and bending loads. The aim of this research is to evaluate numerically the failure mechanisms on stiffened and non-stiffened base plates and propose a new design method. The effects of base plate thickness, location of anchor rods, location of stiffeners and tensile strength of anchor rods were considered in the analysis. Sixteen finite elements simulations were performed considering different combinations of the above mentioned parameters. The results show a fragile response in the base plates when high resistance anchor rods are used. The anchor rods worked as fuse elements in base plates with a large thickness or many stiffeners. Additionally, the models with anchor bars located outside of the column flanges showed lower flexural strength and rotational stiffness compared to the models with anchor rods located between column flanges. The simulations showed that the base plate strength was determined by the simultaneous failure mechanisms of two or more components, different to what is stated in current design guides. Finally, the new method is suitable to design base plates with stiffened and not stiffened configurations, which unlike traditional design methods, show a good adjustment with numerical models.

DEVELOPMENT OF CONCRETE SHEAR STRENGTH FOR SHEAR LUGS IN UNCONFINED GROUT POCKETS

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Pradip K. Khan ◽  
Phillip J. Harter
Keyword(s):  
Shear Strength ◽  
Base Plate ◽  
High Strength ◽  
Free Edge ◽  
Shear Forces ◽  
Anchorage System ◽  
Anchor Bolts ◽  
Major Equipment ◽  
Base Plates ◽  
Support Reactions

The base plate anchorage system for major equipment supports is often designed with a combination of shear lugs and anchor bolts to resist equipment support reactions. Shear lugs are designed to transmit the design shear forces from the support base plates to the foundation concrete. The shear lugs are commonly placed inside a pre-formed grout pocket that is eventually filled with non-shrink high strength grout. The pre-formed grout pockets are sometimes left open to a free edge of concrete on one or more sides for ease of equipment installation and alignment before they are filled with grout. Where the equipment loads are applied in the direction of the free edge, the absence of adequate confinement makes it difficult to develop sufficient breakout strength in shear. This paper addresses a few practical issues that an engineer may face while designing non-confined grout pockets encasing equipment anchorage. It will also demonstrate different ways of improving the concrete breakout strength due to shear by means of providing reinforcements across the anticipated failure planes following the recommendations from different US codes and standards.

Controlling The Lateral Photoeffect In a-Si:H Heterojunction Structures: The Influence of The Band Offset Analysed Through A Numerical Simulation

2001 ◽  
Vol 664 ◽  
Author(s):  
A. Fantoni ◽  
M. Fernandes ◽  
P. Louro ◽  
R. Schwarz ◽  
M. Vieira
Keyword(s):  
Electric Field ◽  
Incident Light ◽  
Lateral Diffusion ◽  
Field Vector ◽  
Band Offset ◽  
Operation Condition ◽  
Dark Zone ◽  
Incident Light Wavelength ◽  
Local Illumination ◽  
Device Operation

ABSTRACTWhen an a-Si:H p-i-n structure is locally illuminated by a light spot, the non uniformity of light causes the appearance of a gradient in the carrier concentration between the illuminated and the dark zone. Carrier start to flow in agreement with such gradients, and when equilibrium is reached, the lateral diffusion process is counterbalanced by the appearance of a lateral component of the electric field vector in addition to the transverse usual one. The lateral fields act as a gate for the lateral flow of the carriers and small lateral currents appears at the transition region between the illuminated and the dark zone.Such lateral photoeffect depends on the incident light wavelength, light intensity and on the device operation condition (mainly the applied bias). The introduction of carbon in the doped layers modifies the intensity and the extension of these lateral effects through the potential barriers deriving from the band banding at the interfaces.We have used the 2D numerical simulator ASCA to analyze the behavior of an a-Si:H p-i-n structure under local illumination with the goal of observing the appearance of the lateral components of the electric field and current density vectors. Different homo and heterojunctions have been simulated, outlining how the band offset at the interfaces influences the induced lateral photoeffect and aiming to explain how a correct device design and engineering can, depending on the foreseen application, alternatively enhance or reduce the intensity of such lateral effects.

Strain distribution in steel base plates under eccentric loads

1989 ◽  
Vol 24 (3) ◽  
pp. 173-183
Author(s):  
P Paramasivam ◽  
D P Thambiratnam
Keyword(s):  
Base Plate ◽  
Lateral Strain ◽  
Test Results ◽  
Element Analysis ◽  
Bending Strain ◽  
Steel Base ◽  
Steel Column ◽  
Flexible Base ◽  
Base Plates ◽  
Column Base

Experiments have been conducted on steel column base plates subjected to eccentric loads and the strain distributions in the base plates at various stages of loading have been determined. The thickness of the base plate and the eccentricity of load have been treated as parameters. Test results for the maximum bending strains, which always occurred at the column–base plate junction on the side of the load, compare reasonably well with those from a finite element analysis. However, the present results for the bending strains in the cantilever portions of the base plates which failed by yielding are greater than those obtained from classical theory, which is, therefore, seen to be conservative for these cases. Longitudinal and lateral strain distributions, strain contour plans, maximum bending strain variation with load, and interaction diagrams are presented and the results discussed. From these results it is evident that flexible base plates, especially when loaded at higher eccentricities, behave somewhat differently from what is assumed in classical methods.

scholarly journals Device-Level Multidimensional Thermal Dynamics With Implications for Current and Future Wide Bandgap Electronics

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
James Spencer Lundh ◽  
Yiwen Song ◽  
Bikramjit Chatterjee ◽  
Albert G. Baca ◽  
Robert J. Kaplar ◽  
...  
Keyword(s):  
Steady State ◽  
Thermal Imaging ◽  
Thermal Characterization ◽  
High Electron Mobility Transistor ◽  
Wide Bandgap ◽  
High Electron ◽  
Thermal Dynamics ◽  
Practical Applications ◽  
Self Heating ◽  
Transient Thermal

Abstract Researchers have been extensively studying wide-bandgap (WBG) semiconductor materials such as gallium nitride (GaN) with an aim to accomplish an improvement in size, weight, and power of power electronics beyond current devices based on silicon (Si). However, the increased operating power densities and reduced areal footprints of WBG device technologies result in significant levels of self-heating that can ultimately restrict device operation through performance degradation, reliability issues, and failure. Typically, self-heating in WBG devices is studied using a single measurement technique while operating the device under steady-state direct current measurement conditions. However, for switching applications, this steady-state thermal characterization may lose significance since the high power dissipation occurs during fast transient switching events. Therefore, it can be useful to probe the WBG devices under transient measurement conditions in order to better understand the thermal dynamics of these systems in practical applications. In this work, the transient thermal dynamics of an AlGaN/GaN high electron mobility transistor (HEMT) were studied using thermoreflectance thermal imaging and Raman thermometry. Also, the proper use of iterative pulsed measurement schemes such as thermoreflectance thermal imaging to determine the steady-state operating temperature of devices is discussed. These studies are followed with subsequent transient thermal characterization to accurately probe the self-heating from steady-state down to submicrosecond pulse conditions using both thermoreflectance thermal imaging and Raman thermometry with temporal resolutions down to 15 ns.

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