Advancements in Thermal Management 2021 Preliminary Program
Markets and Opportunities for Thermal Materials: Data Centers and Consumer Electronics
Dr. James Edmondson, BSc MPhys MSc PhD, Technology Analyst - IDTechEx
Thermal materials are ubiquitous in electronics applications and present a huge market across various industries. Whilst many of these markets are very well established and unlikely to see major shifts, there are some areas where demands will be changing, not just in volume but also in the required performance. IDTechEx discuss two case studies for areas that are evolving in their application and demand for thermal materials, data centers and consumer electronics.
Whilst total sales of consumer electronics like smartphones and tablets have largely stalled and even started to decrease, the thermal material requirements are becoming more important. With the development of higher power density chips and the evolution of the 5G market, there are still plenty of opportunities to be had for both high volume and high-performance thermal materials.
This presentation will cover emerging thermal management trends in the data center and consumer electronics markets and how this impacts the requirements for thermal materials.
Thermal Design of Selective Heating Microwave Oven Using GaN Power Amplifiers
Naoya Okamoto, Research Manager for High-Frequency Compound Semiconductor Electron Devices – FUJITSU
In this study, the thermal design of a new selectively heated microwave oven using a solid-state power amplifier (PA) was carried out. The selective heating microwave oven irradiates high-frequency power supplied from the PA through a plurality of patch antennas arranged close to each other. Since the distance between the object to be heated and the antenna radiation surface is sufficiently shorter than the wavelength (12.2 email@example.com GHz), a standing wave unlike a conventional microwave oven does not occur.
As the PA, a GaN high electron mobility transistor on a freestanding GaN substrate (GaN-on-GaN HEMT) was assumed. GaN-on-GaN HEMTs can achieve higher power-added efficiency because of higher quality crystals than conventional GaN-HEMTs on lattice-mismatched substrates such as SiC and Si. However, since the GaN substrate has lower thermal conductivity than SiC, the heat dissipation properties of GaN-on-GaN were investigated by thermal simulation and measurement.
Finally, the heating performance of the 400 W/8-channel selective heating microwave oven fabricated based on these results will be described. This research was partially supported by the Japan Ministry of the Environment as part of the project Technical Innovation to Create a Future Ideal Society and Lifestyle.
High Throughput Thermal Conductivity Measurements of Thin Film Organic Frameworks
Patrick E. Hopkins, Professor in the Department of Mechanical and Aerospace Engineering – University of Virginia
The novel and controllable thermal conductivities of organic materials have offered a unique thermal management solution for electronics, energy storage and conversion, catalysis, and gas capture, to name a few. I will discuss our recent measurements on the thermal conductivity organic-based systems, such as covalent organic frameworks (COFs), metal organic frameworks (MOFs), and synthetic proteins derived from squid ring teeth proteins. These organic systems offer unique multifunctional properties that seemingly defy traditionally assumed heat transport process, such as: i) the ability to increase density of a porous framework while decreasing thermal conductivity (counter to effective medium assumptions), ii) record setting high thermal conductivity to dielectric constant ratios, and iii) thermal conductivity switching.
The measurements of these thin films are conducted with a variety of pump-probe measurement systems, including a recently developed “Steady State Thermoreflectance” (SSTR) system. SSTR uses CW fiber-optically integrated laser sources to measure the thermal conductivity of thin films and bulk systems operating in the steady state regime. We demonstrate the turn-key, high throughput ability of SSTR for measuring heat flow across atomically thin interfaces, to thin films, to sub-surface buried interfaces and substrates, to bulk systems, and resolving thermal conductivities of materials as low as functionalized fullerenes to diamond (0.05 - ~2000 W m-1 K-1). The ease of operation of this technique offers high throughput and spatially resolved thermal conductivity of a wide variety of systems across a range of length scales from nano to bulk.
Choosing the Correct Model for an Air Mover
Guy R. Wagner, Director - Electronic Cooling Solutions, Inc.
Once natural convection fails to provide adequate cooling due to power density, the only alternative to increasing the size of the enclosure is to add an air mover such as an axial fan or a blower. The fan or fans can be located at the air exhaust, midway within the device or at the intake. Placement of the air mover has a large impact on how well the internal electronic components will be cooled. Placement also has an impact on the reliability and the acoustic noise generated by the air mover.
This presentation will cover the pros and cons of the location of the air mover and demonstrate how the air mover must be modeled correctly to simulate the movement of the air inside the enclosure and predict internal component temperatures correctly. The presentation will also demonstrate how to correctly use a rotating frame of reference in CFD fan modeling to determine the airflow magnitude and direction coming out of the fan exhaust and its impact on component cooling.
Predicting Thermal Design Reliability with Simulation Based Surrogate Models
John Wilson, Electronics Business Development Manager - Siemens, Digital Industries Software
Thermal simulation is often used to consider design robustness subject to variations in environmental, power distribution and failure conditions. What is often not considered during thermal simulation is the concept of variability in the physical components effect on reliability. Simulation models are often constructed using nominal inputs of performance characteristics such as thermal resistance of a thermal interface material (TIM). When modeling a TIM bond line, real world variability such as surface flatness and TIM voiding, pump-out, and dry-out are often not considered.
With today’s computational and modeling resources, simulation can now be used to drive design decisions beyond predicting zero-hour nominal performance, but also consider reliability due to variability. Simulation based thermal analysis driven systematically, combined with statistics, can be used for reliability assessment. Appropriate use of statistics enables the solution space to be explored efficiently to optimize the design choice, and verify the occurrence of failures are suitably low.
This paper introduces the concept of driving design through simulation based reliability assessment with Surrogate models. The study is based on a high power ASIC with variances in TIM performance due to manufacturing tolerances and thermal performance degradation. A Design of Experiments on a 3D simulation model is used to develop a surrogate for ASIC operating temperature. The Monte Carlo method with probability distributions are used to exercise the surrogate to study thousands of design variants efficiently to predict the observed failure rate.
Increasing the Efficiency of High-Pressure Systems Through 3D Metal Printing
Will Hasting, Director of Aviation and Power Turbine Solutions - VELO3D
Heat exchangers are a prolific application found in all things that concerns fluid and power; they are a mission-critical application that affect the overall product performance. Yet, for years, heat exchangers have been constrained by traditional manufacturing in regard to geometric freedom and lengthy lead times. Additive manufacturing, also known as 3D printing, has opened new possibilities for thermal conductivity and part design that enable end users to push the limits of what is possible. Metal additive manufacturing also allows for light-weighting and cost-savings with less material waste.
This presentation will cover new capabilities that enable the manufacture of novel part designs, such as steep angles, high aspect ratios, and ultra-thin walls
Performance Enhancement of Thermal Management Devices Through Additive Manufacturing
Dr. Karthik Kumar Bodla, Senior Thermal Design Engineer - Holo, Inc.
The benefits of additive manufacturing have been successfully demonstrated in performance critical industries. However, the high cost of traditional metal additive manufacturing processes such as Direct Metal Laser Sintering (DMLS) and Electron Beam Melting (EBM) has limited their widespread adoption.
A new Digital Light Processing (DLP) based additive manufacturing process, capable of producing high resolution, low surface roughness parts in both metals and ceramics has breached this gap. Particularly, metals such as pure copper, which are difficult to process via DMLS and EBM can be readily processed.
A few exemplary fin structures with improved heat transfer coefficient & increased surface area for heat transfer are presented, that can only be fabricated via additive manufacturing. 3D printed coldplates employing the developed fin structures are demonstrated for applications such as for CPUs/GPUs, high bandwidth memory, as well as for power inverters for Electric Vehicles (EVs), focusing on performance improvements over the incumbent state-of-the-art coldplates in each application.
Test results on coldplates for CPU/GPU cooling are also discussed, validating the performance improvements predicted by the models. Future designs focusing on customizable flow/fin structures following the underlying heat maps and discrete heat source locations are also discussed for demonstrating the additional performance improvements and customization.
The Compatibility Imperative in Liquid Cooling
Beth Langer, Engineering Manager of the Thermal Business Unit – CPC
Andres Abraham, Applications Engineer of the Thermal Business Unit – CPC
As soon as engineers begin assessing their application, defining their cooling needs and refining selection of the coolant for the system, they should be considering the materials of construction of all components within the system. The wetted loop appears to be straightforward and simple enough after you’ve accounted for flow and pressure. However, materials matter and this seemingly basic aspect of the system can be the source of big problems if not researched and spec’d accordingly.
This presentation is focused on educating engineers about the wetted loop and the imperative for chemical compatibility of all components. Engineers will learn how to identify and mitigate risks associated with material compatibility issues. The information provided applies to all liquid cooling of electronics systems, regardless of application or coolant choice. Ultimately, understanding coolants and components’ materials of construction—and their interaction-- is critical.
Fluorescence Thermography using a Flowable Two-dye Measurement Technique
Deborah Kapilow, PhD candidate in the Multiscale Thermofluidics Laboratory
A two-dye fluorescent technique has been developed to obtain spatially-resolved thermal measurements using visible light. A custom experimental apparatus was built to demonstrate the use of a 0.7 mm thick flowable fluorescent dye to take steady state and transient measurements of surface temperature. Rhodamine B (RhB) and Rhodamine 110 (Rh110) were selected as the temperature dependent and temperature independent fluorophores, respectively, to create a thermal sensing solution. A two-dye solution was utilized to reduce error due to environmental conditions, such as light fluctuations and non-uniform illumination.
An optical setup was created to characterize the RhB-Rh110 solution and a unique calibration experiment was designed to evaluate temperature dependency. The temperature sensitivity of several solutions was experimentally characterized by varying concentration ratio, and an optimal solution was discovered. The effect of concentration ratio on frame rate and working area was studied for illuminated areas between 10 and 200 mm2. Data was obtained at speeds ranging from several hundred to several thousand frames per second to demonstrate the usability of this technique for various experimental conditions and applications. Additionally, in comparison to infrared cameras, which are often used for surface thermography measurements, the use of visible light high-speed cameras is less expensive and allows for compatibility with clear substrates. The photobleaching behavior of the selected fluorophores was examined and the resulting effects were diminished by utilizing a flowable technique. This thermography approach has been demonstrated for backside surface thermography as well as direct temperature measurements in fluid channels.
Loop Thermosyphons and Pumped Two-Phase Cooling for High Power, High Voltage Power Electronics
Bryan Muzyka, Thermal Management Solutions Sales – Advanced Cooling Technologies, Inc.
This presentation will outline two advanced thermal management solutions; Loop Thermosyphons (LTS) and Pumped Two-Phase (P2P) are technologies that create these SWaP benefits while also providing intrinsic safety and adaptability for high voltage systems.
LTS technology provides extremely high heat transfer capacity for a passive device and allows the user to concentrate a significant number of heat loads, from multiple devices to a single air-cooled heat sink. Passive heat transfer naturally provides the user with the lowest potential energy consumption and LTS technology can increase the thermal capacity from traditional conduction/heat spreading and even more enhanced heat transfer methods such as heat pipes. Similarly, P2P technology provides a low-flow, active two-phase heat transfer method which provides heat flux and packaging advantages over single-phase liquid loops. Both technologies can leverage di-electric fluids and provide versatility and scalability, creating ideal solutions for any application requiring high power and low delta T from source to sink.
This presentation will cover basic technology theory, practical design considerations, and applications with fielded examples that have benefited from these solutions.
Thermal Conductivity Mapping and Filler Settling Detection in Polymer Composites
Arya Hakimian, MSc, Application Scientist - C-Therm Technologies Ltd.
Creating composite materials can introduce new and beneficial performance properties. Whether the goal is to increase thermal heat transfer properties through conductive fillers, or increase thermal resistance via insulative additives, the uniformity of filler dispersion will be crucial to overall performance. Localized agglomeration and inhomogeneous dispersion will adversely affect the performance of the material and can lead to thermal management issues. The ability to detect this is important to ensure materials are being manufactured and function as intended, whether injection molded, mechanically mixed or 3D printed.
Thermal conductivity (k) can be used as a metric to help detect these potential issues. While thermal conductivity can be measured via multiple methods, the ability to detect localized differences related to fillers is readily accomplished using C-Therm’s Modified Transient Plane Source (MTPS). The single-sided sensor with a small active area (approx. 18 mm) makes it is easy to detect differences related to the additives, both across the face of a material or through the thickness. As a transient method, it offers extremely fast test times allowing full characterization in minutes which is invaluable in both R&D and QA/QC applications.
Topics discussed will include the importance of thermal mapping and spot testing of doped materials to assess filler uniformity. The MTPS will be highlighted as the ideal method for this type of characterization and examples on how this testing can be performed will be shown on a variety of material and filler types. Also covered will be various highlights on general filled polymer materials across various industries and their implications on end use performance.
Foldable Thermal Ground Planes for folding electronic Thermal Management
Dr. Ryan Lewis, Director of R&D - Kelvin Thermal Technologies
Foldable electronic systems include recently developed folding phones, tablets, and wearables as well as laptops and hinged system. Such electronic systems need thermal management, and achieve best performance with foldable thermal management solutions.
We have developed foldable thermal grounds planes for such a solution. A thermal ground plane (TGP) is a type of vapor chamber or 2-dimensional heat pipe: a passive heat spreading solution that employs evaporation and internal convection of an encapsulated fluid in order to reach effective thermal conductivities 10x higher than copper. Key aspects of a TGP include the wick which pumps water to a heat source by capillary force, the hermetic cladding which prevents water from leaking out or air from leaking in, and the vapor support structure, which ensures a path for vapor flow after evaporation. Each of these elements must be made foldable, which has often proved challenging.
Using flexible circuit board substrates with copper clad polyimide laminates as the cladding introduces some degree of flexibility. Furthermore, shaping the cladding into an origami-like series of peaks and valleys introduces further mechanical compliance, as reported previously. We have improved on the origami-like compliant design, and developed a foldable TGP capable of bending over 20,000 cycles about a 5 mm bending radius. The foldable TGP measures 5 cm x 10 cm, with a thickness of 0.35 mm in the flat region and 0.5 mm in the folding region, with an effective thermal conductivity in the range of 6,000 - 20,000 W/m-K and maximum power of 10 W. This presentation will cover development and analysis of the foldable TGP as well as thermal design applications for foldable electronics based on foldable TGPs.
Cost Effective Technology for Optimized Management of Heat Dissipation
Keerti Chand Bhupathi, Engineer - Aurora Circuits
Heat removal from high heat generating components on printed circuit assemblies has become function limiting in many current and future circuit designs. A copper pedestal with a thermal conductivity of greater than 350 W/m2 oK can dramatically reduce component operating temperatures. This process has produced over a million assemblies to date. Experimental data is procured by measuring the operating temperatures with respect to the variable power supply. A discussion on the actual operating temperatures versus theoretical temperatures for a variety of component power consumptions is presented.