Day 2- August 5th
Digital Conference Program Times in US Central Time
Co-Design of Thermal and Electromagnetics for Development of Light & High Efficiency Electric Powertrains
Dr. Michael Ohadi, Professor of Mechanical Engineering - University of Maryland
Dr. Peter de Bock, Program Director - US Department of Energy
Air travel accounts for a considerable and growing portion of the U.S. and global energy imports and greenhouse gas (GHG) emissions. In 2017, the U.S. consumed nearly 3.5 quads equivalent of jet fuel. This accounted for about 3.5% of primary energy consumption. In the same year, air travel accounted for about 174.8 million metric tons of CO2 equivalent emissions in the U.S., or about 2.6% of domestic GHG emissions.
This presentation will discuss challenges and opportunities associated with electrification/de-carbonization of aviation. The presentation focuses on the most recent progress in thermal management of electric motors with particular focus to future electrification of aviation propulsion where ultra-high efficiency and high specific power (kW/kg) electric motors and power electronics are a key enabler. The presentation will also discuss results of a co-design based simulation case study analyzing comparative impacts from selected technological areas that, among others, can enable cost-effective efficiency enhancements and weight reductions while addressing the limitations of existing materials and cooling technologies.
Anisotropic Thermal Conductivity in Metal-Hybrid TIMs and Their Applications
Nikolas Truiak, CEO - HYMET Thermal Interfaces
While graphenes and carbon nano-tubes have been long hailed as a new super material for thermal management applications, many problems still exist including production costs and the high pressures typically required in application. Similarly, heat spreaders have been introduced with some success, although they add extra bulk, expense and lack flexibility.
This presentation will introduce a fundamentally new class of hybrid-metal thermal interface material, a composite pad with strong thermal anisotropy, which is flexible around curved surfaces and deforms well in compression. Experiments have been carried out that have confirmed the effectiveness of the use of this material in multi-chip and heat pipes applications. Additional positive experimental results were obtained in high-power Li-Ion batteries for electro-mobility applications. These results and others will be explored in this lecture.
PCM and Heat Pipes for Temperature Reduction in Electric Vehicle Batteries
Dr. Sohail Zaidi, Mechanical Engineering Department - San Jose St. University
This project utilizes phase change material (PCM) to absorb the instant high-temperature spikes that may appear in electric vehicle batteries. Due to the poor thermal conductivity of PCM, heat pipes (HP) are used to rapidly transfer the heat from the heat source into the PCM. Thus, the advantages of the HP and PCM are effectively combined to reduce the temperature spikes.
A mimic battery is designed to simulate a quarter model of the EV battery. Phase change material (PCM) was obtained from a supplier who provided the specifications of the material that indicted the phase transition temperature (PTT) (50°C). Small flat heat pipes were obtained (75 mm X 11 mm X 3 mm) that were bent before they were installed inside the PCM testing box. The test was conducted in three trials: without using any cooling medium, with PCM, and with PCM-HP. K-type thermocouples were calibrated and were used to obtain the temperature data at various locations inside the test box. Multiple ceramic tubes were used to insert and protect the thermocouple wires. An Agilent Technologies data acquisition system was used to acquire and process the temperature data. Experimental results were plotted and analyzed.
The temperature reduction obtained with the PCM-HP configuration was higher by 13°C to 3°C (or 31.21% to 7.70%) in comparison with PCM configuration. From the temperature distribution plot, it is observed that the HPs help in drawing the heat from mimic battery and spreading it through the PCM. Experimental results are compared with those available in the literature and will be discussed in the presentation.
High Thermal Conductivity Thermal Interface Materials Based on an Epoxy Matrix
Kevin Roth, Project Manager, High Performance Materials - ADA Technologies, Inc.
Thermal interface materials (TIMs) more and more play an important role in thermal management of modern electronics. One such specialized application is in aerospace and satellite electronics, which require TIMs with wide temperature range, high reliability, and low outgassing. TIMs based on thermoset epoxy resins provide advantages over those based on traditional thermoplastics and silicones, and can meet the aforementioned critical application requirements. In this study, two processes have been developed to synthesize high thermally conductive TIM pads based on thermoset epoxy resin matrix. One approach is to directly disperse thermally conductive additives into an epoxy matrix to achieve random dispersion. The other is to align thermally conductive fiber into an epoxy matrix to achieve orderly dispersion. Here, we will present process steps, thermal properties, and potential device application.
Thermally Integrated EMI Shielding Materials, Systems and Approaches
Merima Trako, EMI Shielding & Thermal Composites Product Manager - Vanguard Products Corp.
Mark Hansen, Sales & Marketing Manager - Vanguard Products Corp.
The implementation of millimeter wave systems that can operate at frequencies greater than 25 GHz within 5G and 6G systems has caused internal thermal and signal management to become more important. External packaging, antenna systems design, EMI shielding, heat dissipation, and board layout becomes more difficult as the system sizes shrink and battery consumption is placed at a premium. Various European and US regulations limit the temperatures on user contact surfaces of mobile electronics because of user safety concerns.
Many of the new 5G/6G mm wave systems can generate internal operating temperatures approaching and exceeding 100°C when operating at full capacity. As a result, manufacturers often throttle these chipsets periodically to minimize temperature rise of the chipsets.
Further, the presence of sensitive antennas within the systems along with potential cross talk issues drives the need for extensive interference protection within the systems, especially in systems incorporating advanced Wi-Fi. Engineers and designers are presented with the challenge of optimizing systems to increase heat transfer from the system without negatively interfering with antenna systems and EMI shielding performance, all the while ensuring that high volume producibility of the systems is not negatively impacted.
Cost Effective Technology for Optimized Management of
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.
Panel Session: Thermal Management of SiC and GaN
Moderator - Maurizio Di Paolo Emilio, Editor-in-Chief of Power Electronics News – Aspencore
Speakers - Alex Lidow, CEO - EPC
Jonathan Dodge, Senior Application Power Expert - UnitedSiC
Salvo Coffa, Group VP & GM R&D, Automotive & Discrete Group - STMicroelectronics
Wide bandgap (WBG) semiconductors such as silicon carbide (SiC) and gallium nitride (GaN), significantly improve system efficiency and current density in various power electronics applications. SiC and GaN devices enable power designs to optimise the amount of metal in heat sinks and various housings. While WBG devices promise higher operating temperatures and greater efficiencies, there are thermal management concerns that engineers need to consider when designing these devices into a system. With the latest generation of GaN and SiC devices thermal design becomes very important.
Maximizing Thermal Interface Material Performance in High-Reliability Applications
Joey Scimeca, Associate Materials Engineer - Nanoramic Laboratories
In this talk, we’ll discuss the thermal management problems faced by high reliability electronics systems designers. High performance thermal interface materials (“TIMs”) are typically silicone-based. In thermal and vacuum environments, silicone-based materials have the tendency to outgas and break down. This behavior induces thermal performance degradation within the electronic system. Consequently, thermal engineers who focus on space and aerospace applications are often forced to avoid silicone based TIMs at all costs.
We will present a method in which thermal interface materials can meet outgassing standards required by such harsh environments. The presentation will focus on thermal design engineer experiences in selecting silicone-free resin a suitable solution for their high reliability applications.
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.
Additively Manufactured Heat Sinks for Thermal Management of High-Flux Electronics Packages
Bharath Bharadwaj, Department of Mechanical Engineering - Virginia Tech
With increasing thermal footprint in electronic packages, metal foams or lattices offer avenues for better thermal management in passively cooled heat sinks. Advances in metal additive manufacturing can be leveraged to realize complex designs that offer superior heat transfer characteristics with smaller and lighter components.
In this work, a metal foam heat sink for passive cooling applications by natural convection is presented. The heat sink is designed to cool a heat flux of 10 4 W/m 2 with a 2-inch x 2-inch base plate. Numerical computations using the ANSYS Fluent commercial package have been carried out to study the effect of various physical parameters of the foam structure for optimized thermal performance.
Further a Design for Additive Manufacturing (DfAM) approach is employed in the design to account for manufacturing constraints. The optimized metal lattice heat sink compared to its traditional longitudinal counterpart can provide ~55% increase in performance while simultaneously reducing the weight by ~60%. There is a need for effective passive cooling strategies due to constantly increasing thermal loads in power electronics industry. Using rapidly developing metal additive manufacturing to provide custom, lighter, reliable, metal lattice heat sinks could be one of the solutions for effective thermal management of these devices in the future.
Thermal Ground Planes for Smartphones and Laptop PCs
Y. C. Lee, President and CEO - Kelvin Thermal Technologies
Kelvin Thermal’s TGP (Thermal Ground Plane) is a thin vapor chamber, i.e. a 2-D flat heat pipe, fabricated using flexible printed circuits (FPC)-compatible processes. TGPs are mass produced for cooling smartphones and laptop PCs today with production rates to reach 10M/month in a couple of years. TGP can be low-cost, thin (0.15 - 0.25mm), light (0.05 - 0.15 g/cm2), flexible (bending radius of 10 - 3mm) and large (100 - 1,000mm) for heat fluxes ranging from 1 to 1,000 W/cm2. In addition to mobile systems, TGP is also critical to high power and/or high heat flux applications such as GaN/SiC-based power electronics, battery packs in electric vehicles, and edge and cloud computing systems. Kelvin Thermal’s TGPs with effective thermal conductivities ranging from 4,000 to 25,000 W/mK, reduce a system’s skin and junction temperatures with less dimensional constraints in design than existing thermal management solutions using metal (200 to 400 W/mK), graphite (400 to 1,500 W/mK), heat pipes and traditional vapor chambers.
This presentation will review different TGPs developed with an emphasis on designs. A thermal designer should not use TGP’s effective thermal conductivities in their system analysis. With the same TGP, we may achieve different performance measures w.r.t. different heating and cooling arrangements.