Electronics Protection - Winter 2015 - (Page 12)

Feature Thermal Management of Electronic Devices Utilizing LHS Materials Mark Hartmann, CTO/R&D, Outlast Technologies LLC Globally the number of mobile electronics is steadily increasing as they become a critical facet of everyday life, including electronics such as wearables, tablets, 2-in-1s and thinner, smaller laptops. Concomitantly, all of these device types are continuously achieving higher speeds, higher power and higher capacity battery components. As devices get smaller and thinner, manufacture's are packing more and powerful processors into devices such as the current quad and octa-core configurations. Battery technology has also improved in that more powerful batteries now take up significant area of the device architecture and are in closer proximity to the heat generating processors, antennas, cameras and displays. As the processors and batteries create more intense thermal flux, the detrimental effects of this heat are seen in quicker CPU throttle back to slower speeds, higher surface touch temperatures, video and display resolution quality reduction, component degradation due to excessive contraction/expansion, and battery life reduction due to degradation from overheating. The majority of consumers are either unaware of these thermal issues from poor design, or accept these issues, or worse they can exacerbate the issue by adding a thick bulky protective cover and trapping heat in the device. These newer high end devices create unique challenges in thermal management 3D design that requires an integrated approach to find a balance between device performance and cost, and most beneficially allow for value added performance enhancement. Passive thermal management systems employing Outlast LHS gels, moldable plastics, and composites offer benefits such as heat absorption and spreading, which can lead to cooler chipset temperatures, longer run times at higher speeds and stability, while providing for lower surface temperatures. These products are offered as a robust, low density, RoHS compliant and cost effective alternative to current thermal management systems. LHS materials have high energy capacities of >200 J/g, multiple temperature absorption ranges, consistent cycling without pumpout and no electrical conductivity. These attributes allow for easy optimization for the various device architectures, firmware programming and different thermal issues. Outlast LHS passive thermal management material can also act as a thermal capacitor which provides another key benefit of reduced lifetime thermal history. For instance, shown in Figure 1 is a typical tablet test thermal curve (top curve) and a thermal curve of the tablet containing LHS material (bottom curve) showing the temperature reduction and energy absorption. In this example, by integrating the area between the curves on this cycle, it is shown that an overall reduction in thermal exposure of 705oC min can be obtained in the device during the 80 minute testing period. Throughout the hundreds of cycles that a device will see, this leads to a large reduction in high temperature Figure 1. Thermal History Example thermal events, less hardware contraction/expansion, which leads to less hardware and material breakdown. Extensive work by Outlast has found that every electronic device is different, produces different thermal issues and therefore no one solution or product solves the various thermal issues. Different device designs produce different thermal events and transient parameters due to firmware programming, materials of construction, various power requirements, and internal heat spreading or absorption, therefore an optimized solution depends on using the correct absorption/transition temperature, correct design, placement and amount of LHS material in the device. Reported herein is optimization work performed on a standard commercial tablet showing the thermal management and benefits that can be obtained with proper LHS materials. Testing and Methodology A standard commercial Nexus 7 was purchased from an internet electronics store for use. The Nexus 7 was a July 2013 version running Android OS v4.3 (Jellybean). The platform consisted of Snapdragon S4Pro Quad-core 1.5 GHz Krait with Adreno 320 GPU. Data logging was by internal Trepn Profiler app. Hot spots on the front display and back surface were detected by IR camera. The running temperature data from these hot spots were then recorded by thermocouples taped to the surface. 12 Winter 2016 * www.ElectronicsProtectionMagazine.com http://www.ElectronicsProtectionMagazine.com

Table of Contents for the Digital Edition of Electronics Protection - Winter 2015

Electronics Protection - Winter 2015
Contents
Editor's Choice
Thick Print Copper Technology Increases Thermal Reliability
Slashing Printed Circuit Board Design Cycle Time Using Real-Time PCB Thermal Analysis Tools
Thermal Management of Electronic Devices Utilizing LHS Materials
Enclosures
Thermal
Power
Hardware
EMC/EMC/RFI
Industry News
Calendar of Events

Electronics Protection - Winter 2015

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