Effects of temperature on electronics reliability: futile attempts to oversimplify

Speaker: Diganta Das (University of Maryland)

Abstract: The reliability assessment process for electronics is often isolated from the science of how products are impacted by thermal stress and the fundamental driving factors. Ignoring these fundamentals, assuming that they are not tractable, leads to an oversimplified reliability assessment process that takes a limited view of temperature factors and overlooks the interactions with other stress factors and the influences of materials, geometry, and architecture. This presentation will critically review the separation of failure processes from reliability assessment and the negative consequences. It will explore how the electronics component manufacturers can assist the product manufacturers in assessing component reliability in their applications.

Thermal methodologies on scales impacting device reliability

Speaker: Lei Jiang (Intel)

Abstract: Rising power densities at chip-level and device-level pose challenges to reliability and thermal management that spans over 12 orders of length scale and 6 orders of temporal scale. At the transistor device level, there is currently no industry-wide standard model for phonon scattering and heat removal impact to reliability of electromigration and aging for example. We present here some of the first principles and compact modeling efforts to capture the local thermal effect at circuit scale in advanced technologies and how it can be leveraged effectively to optimize the design for reliability. Modeling also plays key role in estimating chip-level self-heat impact on advanced integration schemes such as 3D die stacking. We will present modeling and validation methodologies to bridge these length scales to enable robust and high-performance processor design.

Two-Phase Cooling Opportunities and Challenges for Heterogeneous Microsystems

Speaker: Yogendra K. Joshi (Georgia Institute of Technology)

Abstract: Heterogeneously packaged microsystems incorporating digital, radio-frequency, opto-electronic, and power devices will require embedded cooling, where the coolant is brought in close proximity, and often in direct contact with the active die. Dielectric coolants can be utilized for such applications, with a saturation temperature selected depending on the application. Due to the poor heat transfer properties of these coolants, phase change offers the ability to improve their performance. Evaporative closed loop cooling offers significantly higher heat transfer coefficients and lower coolant circulation rates than single phase cooling. Evaporative cooling can also be effectively utilized in passive devices such as vapor chambers, and thermosyphons. This talk will focus on three topics with applications to two-phase cooling of heterogeneous microsystems: (i) computational simulations of flow boiling in micro-passages, (ii) use of surface modification in flow boiling enhancement, and (iii) passive two-phase thermal management using vapor chambers.

Thermal Challenges and Innovation for Heterogeneously Integrated Packages

Speaker: Rajiv Mongia (Intel)

Abstract:In the last 15 years, both process and packaging technology has advanced to the point that "true" systems on a package are now possible. We can now integrate dies from multiple process nodes and vendors at the package level to achieve heterogeneous computing at the product level. For example, Intel's Stratix 10 product line contains both 2.5D and 3D elements to integrate silicon from up to 3 process nodes in a single product package. This approach has obvious advantages in both product cost, time-to-market and product flexibility; however, it creates unique challenges for the thermal designer and architect. Specifically, with a heterogeneous approach, the conventional approaches of thermal resistance no longer hold sufficient accuracy for thermal solution design.

LITHIUM-ION BATTERY THERMAL MANAGEMENT AND SAFETY NEEDS FOR PLUG-IN ELECTRIC VEHICLES

Speaker: Ahmad Pesaran (NREL)

Abstract: The demand for plug-in hybrid and battery electric vehicles (PEVs) are rising as communities move toward cleaner transportation. Lithium-ion batteries are the dominant technology for these PEVs due to their higher energy and power. The cost of these batteries has been coming down and their performance has been getting better. However, their life can be limited under uncontrolled thermal excursions due to use or climate. As the lithium-ion battery temperature increases its life decreases, so thermal management is needed to keep the battery temperature within desired range. The cooling systems could be air, direct liquid or indirect liquid. In this presentation we will review the latest approach to thermal management and tools needed to design battery thermal management systems. Another aspect of the state of the art of lithium-ion batteries is that they use organic flammable liquids that under abuse conditions could ignite and cause fire in a vehicle. We will discuss how these batteries could go into thermal runaway and what are the tools and approaches that designers use to mitigate the thermal runaway in vehicles.

MULTISCALE HEAT TRANSFER AND THERMAL MANAGEMENT IN LI-ION BATTERIES: CHALLENGES AND OPPORTUNITIES

Speaker: Ankur Jain (University of Texas at Arlington)

Abstract:Li-ion batteries are widely used for energy conversion and storage in electric vehicles, aircraft, consumer electronics and renewable energy storage. While offering excellent energy conversion and storage characteristics, however, these batteries suffer from several safety related problems, as evidenced by recent product recalls and incidents of fires in electric cars and aircraft. A fundamental understanding of heat transfer in Li-ion materials, cells and battery packs is critically needed. Such problems are often multiscale and multi-disciplinary in nature, offering opportunities for novel scientific research as well as engineering development. This Tech Talk will provide an introduction to Li-ion battery technology and the nature of heat transfer across multiple scales, ranging from battery materials all the way to large battery packs. The nature of heat generation and thermal conduction will be discussed and correlated with electrochemical processes that occur within a cell. Key thermal management challenges and approaches will be discussed. The problem of thermal runaway, including key mitigation techniques will be discussed in detail. The emphasis will be both on the fundamental physics underlying these problems, as well as practical engineering approaches that have been proposed for solving such problems. It is expected that this talk will be of interest to students and scientists/engineers with an interest in learning about heat transfer and thermal management in a novel multiscale system.