February 11th, 2021
9:00 am CST
Emerging Opportunities for Thermal Materials: Electric Vehicles and 5G
Dr. James Edmondson, BSc MPhys MSc PhD, Technology Analyst - IDTechEx
Thermal management is an often overlooked yet key consideration for nearly every application. The market for electric vehicles (EVs) is rapidly increasing along with a trend for higher energy densities and ultra-fast charging, these factors create high thermal loads, evidenced by several high-profile recalls related to EV fires in 2020. This presents a significant opportunity for thermal management materials as a solution.
The 5G market is still in its infancy, but device manufacturers and customers are already aware of the thermal challenges that 5G infrastructure and smartphones present. Several early 5G smartphones were prone to overheating and dropping to 4G in hot climates, highlighting the thermal issues to customers. Whilst the sub-6 GHz presents moderate challenges for the materials market, the high-frequency mmWave operation is setting out new and significant challenges in heat generation and the materials solutions needed.
This presentation will cover emerging thermal management trends in the EV and 5G market and how this impacts the requirements for thermal materials.
9:45 am CST
Thermal Materials Development with Enhanced and Tunable Thermo-Physical and Electrical Properties
Karla Reyes, Ph.D. - Principal Member of Technical Staff, Materials Chemistry Department • Sandia National Laboratories
In this presentation, Dr. Reyes will present the development of advanced thermal materials for passive thermal management solutions. Particularly, we focus on passive techniques for heat insulation, modulation and dissipation using materials with tunable and enhanced thermal properties for a diverse range of applications.
Anisotropic materials can be engineered as composite or multi-layered materials made up of two or more constituents. Through the mixing of multiple components, we seek to take advantage of certain properties of each individual component. Depending on the desired application of a composite, the heat pathways can be manipulated in a three-dimensional manner. However, creating materials with a controlled directionality of heat flow is very hard and measuring their thermal properties is even harder.
Sandia has developed an experimental capability for the measurements of complex thermal materials based on the Transient Plane Source (TPS) technique coupled with infrared images. With this approach we can measure axial and radial thermal conductivity in the same test using a single sample.
At the Thermo-Physical Characterization Facility, we believe that custom designs and innovative techniques are needed to accurately develop and measure tunable thermal materials for real-world applications.
10:30 am CST
Electrically Insulating TIMs for Component Protection in Electronic Devices
Dr. Joon Lee, R&D Director - Polymer Composite Materials - Nanoramic Labs
Suppressed dielectric loss and higher volume electrical resistivity of thermal interface materials can act as an effective insulating shield against possible leakage current and charge conduction in air which affect the performance of other components.
Where electric insulation are required, thick sheets or pads have received general acceptance for use as interface materials due to its relatively better electrical insulation compared to grease, gel or PCM, which lack the mechanical properties and bondline thickness needed to reliably prevent direct contact between heating and cooling components surfaces. However, thermally but electrically insulating pads tend to perform 2-5 times poorer than their non-insulating pads, needless to say, thin gap TIM such as grease or gel.
Learn about how new thermal material advancements overcome the typical gap pads’ low thermal conductivity without using carbon or metallic fillers, which can cause electrical non-insulation. Their volume resistivity and breakdown strength can be dependent on not only what types of filler materials but also how they are dispersed or oriented. The unique fabrication processes provide excellent thermal conductivity of 20W/mK as well as low dielectric constant of 4.7 and typical voltage breakdown value of 200W/mil. Non-silicone based materials achieve acceptable electrical insulating properties without the sacrifice of high thermal conductivity.
11:00 am CST
Liquid Metal Embedded Elastomers as an Emerging Material Architecture for TIMs in Semiconductor Packaging
Navid Kazem, PhD., Co-Founder & CEO - Arieca Inc.
Current thermal interface materials (TIMs) must have extremely low interfacial contact resistance, while being highly stretchable to accommodate large deformation in semiconductor packages due to mismatch of the coefficient of thermal expansion.
Several innovations in material architectures from vertically aligned carbon nanotubes, and graphite composites to solder based solid metal die attach and liquid metal TIMs have been previously proposed. However, low thermal resistance and high mechanical reliability properties are still mutually exclusive in current TIMs. To address the growing thermal challenges of semiconductor industry, this session will introduce a novel material architecture of Liquid Metal Embedded Elastomers (LMEEs) where we embed micro-droplets of gallium-based alloys (Tm < 16°C) inside a silicone elastomer.
Liquid metal droplets do not impact the overall mechanical properties of the base polymer, resulting in high stretchability, low elastic modulus, high adhesion, and high thermal conductivity (creating an extremely low thermal resistance at the interface). Furthermore, Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) results show that LMEEs maintain their mechanical properties down to temperatures of less than -55°C, which is essential for reliability performances. In this presentation, the session will address LMEEs material architecture and properties that shows high promises for effective thermal managements as a thermal interface material (TIM) in high performance semiconductor packaging.
Practical Aspects of Thermally-Conductive Plastics: An Overview
11:30 am CST
Guy Wagner, Director – Electronic Cooling Solutions
Dave Saums - DS&A LLC
A variety of thermally-conductive polymers have been commercially available for thirty years for electronics thermal management. More attention has been focused on evaluating alternative materials to metal alloys for thermal components and structural components that may have a thermal requirement, as new types of electronic systems have been introduced that have significantly different power dissipation values and, in many cases, other influencing factors such as weight, as well.
This presentation is intended to examine practical attributes of thermally conductive plastics and describe differences in thermally-conductive plastics in comparison to aluminum alloys used traditionally for extruding and casting heat sinks and related thermal components. Knowledge of how these plastics are different, the behavior of the plastics in manufacturing processes, and the effectiveness in natural and forced convection environments is useful in order to properly assess whether a thermally-conductive plastic will be a suitable design choice.
12:00 pm - 1:00 pm CST
1:00 pm CDT
Mitigation of Thermal Runaway Events in Batteries by Reducing Cell-to-Cell Thermal Communication
Kevin B. Roth, Project Manager and Senior Research Engineer - ADA Technologies
Lithium ion (Li-ion) batteries are ubiquitous in space and military applications, allowing for development of more efficient and effective systems. The increase in Li-ion cell usage corresponds to an increase in risk associated with cell failure.
During thermal runaway, an individual cell overheats and can violently deflagrate, resulting in mission failure and personnel injury. Moreover, due to the proximity of cells in most battery systems, such a runaway event can cause overheating and subsequent thermal runaway of adjacent cells, resulting in a cascading failure event.
To address this potential failure mode, especially for high-rate and high-energy battery chemistries, ADA has developed a family of thermal protection materials. Learn how a passive protection system comprised of proprietary materials on a thin foil substrate that is applied directly to the
surface requiring protection.
Learn how material insulates the protected object, refracting flame and heat. Simultaneously, the metal substrate works as a heat spreader, dissipating heat away from the wrapped cell to ensure no negative impact on normal/healthy cell operation. ADA has demonstrated effective mitigation of cascading thermal runaway events in batteries that employ new technology on all cells for multiple cell formats. In particular, testing has focused on cylindrical cells and pouch cells ranging from 3 to 16Ah ratings. ADA has teamed with leading battery manufacturers and power systems integrators to appropriately design the system for functionality and performance in space and military environments.
1:45 pm CST
The Thermal Conductivity of Phase Change Materials used in Batteries Thermal Management
Dr. Sofia Mylona, Principal Research Scientist - Thermtest Instruments
The design of a Battery Thermal Management System (BTMS) is vital for the efficient use and safety of the battery, keeping the temperature of the battery between the required operation range. Traditionally air-cooling and liquid-cooling BTMS are used but the added cost of the pumps, fans, blowers needed increase the cost and the complexity of the system.
Lately, Phase Change Materials (PCMs) gain the interest of more researchers because of their high energy storage density. PCMs have the advantage of creating a cooling effect when heat from the battery is absorbed, and heating effect is creating during the solidification of the PCM while no external cooling/heating source is required from the BTMS.
The efficiency of a Battery Thermal Management System can be improved with the use of suitable PCMs based on their melting point region, the high thermal conductivity and the small volume change between the phase transition. In addition, a preferred PCMs should have low cost and be no poisonous or flammable. The preferred melting point for the PCMs varies from 20 to 50oC depending on the systems they are applied.
In this work the thermal conductivity of Phase Change Materials commonly used at BTMS is measured. The thermal conductivity measurements include the liquid and solid phase of the materials and the phase transition region where an “anomalous” thermal conductivity is recorded. The thermal conductivity measurements employed with a Transient Hot-Wire device inside a specially designed measuring cell which ensures constant contact of the sample with the wire during the phase transitions.
2:30 pm CST
A Novel Thermal Conductivity Measurement for Micron and Sub-Micron Thick Films and Coatings
John Gaskins, President - Laser Thermal Analysis
Steady-State Thermoreflectance (SSTR) is a novel measurement technique capable of measuring the thermal conductivity of materials. Using two continuous wave lasers, a steady state temperature rise is induced with a pump laser, while a probe laser measures the change in reflectivity of the surface, which can be related to surface temperature. Varying the power of the pump laser and examining the resultant changes in surface reflectivity (related to temperature) allow for correlation between input heat flux and change in temperature which then allow for calculation of thermal conductivity via Fourier's law.
This session willpresent SSTR measurements on a variety of materials with thermal conductivity from 0.05 W/m/K up to 2,500 W/m/K and films and coatings with thickness from single nanometers up to tens of microns. For films with thickness less than approximately 100 nanometers, SSTR measures the interface conductance across the film and substrate interface.
3:00 pm CST
Development of Ultra-Thin Insulations for Various Applications
Steve Miller, President & CEO • HeetShield Inc.
A new family of insulations has been developed for use where thin, flexible, high performance insulations are required. Some are enhanced with aerogels while others are optimized to attenuate thermal radiation. These products are based on 20 years of research sponsored by NASA, Air Force and the NSF to develop efficient insulations for re-entry vehicles and fire shelters and electronics.
This presentation will review the new materials developed, their strengths and weaknesses and some potential applications.
3:30 pm CST
New Textile-Based Hybrid Photovoltaic / Thermal (PV/T) System
Dr. Barbara Pause, Founder • Textile Testing & Innovation, LLC. (TTI LLC)
A textile-based PV/T system will be introduced in the presentation which was developed to overcome problems related to the application of commercialized PV/T collectors. The textile-based PV/T collector consists of a spacer fabric in which thin pipes are integrated. The front side of the spacer fabric faces thin film PV cells and is coated with a compound containing phase change material (PCM) as a thermal storage means.
As soon as the temperature of the PV cells reaches a given trigger temperature, the excessive heat is absorbed by the PCM. In this way, the PV cells are cooled and can operate at their optimal temperature, staying at their highest possible efficiency leading to a maximum electrical output. Tests have shown that the PCM cooling applied in the introduced PV/T system is more efficient than the forced liquid or air cooling used in commercialized PV/T systems, since the approach discussed in the presentation provides a direct contact between the PV cells and the heat absorber. The absorbed heat is stored in the PCM and is released when water is pumped through the pipes. This process recharges the PCM for the next cycle of heat absorption. There is no need for a constant water flow through the textile-based PV/T system because the PV cells are cooled by the latent heat absorption of the PCM and not by circulating water used in conventional systems.