Intel Ep80579 Integrated Processor Product Line Fanless System

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Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide August 2008 Reference Number: 320299-001US INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH INTEL® PRODUCTS. NO LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. EXCEPT AS PROVIDED IN INTEL'S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, INTEL ASSUMES NO LIABILITY WHATSOEVER, AND INTEL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY, RELATING TO SALE AND/OR USE OF INTEL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. Intel products are not intended for use in medical, life saving, life sustaining, critical control or safety systems, or in nuclear facility applications. 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Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 2 August 2008 Reference Number: 320299-001US Contents Contents 1.0 About This Document ................................................................................................ 5 1.1 Purpose/Scope.................................................................................................... 5 1.2 System Overview ................................................................................................ 5 1.3 Definition of Terms .............................................................................................. 5 1.4 Reference Documents .......................................................................................... 6 2.0 Mechanical Design Considerations ............................................................................. 7 2.1 Package Information............................................................................................ 7 2.1.1 Thermal Solution Fastening Load Requirement ............................................... 7 2.1.2 Volumetric Space for Thermal Solution .......................................................... 7 2.1.3 Mechanical Tolerance Analysis ..................................................................... 7 2.1.4 Shock/Vibe Requirements ........................................................................... 8 3.0 Thermal Design Considerations ................................................................................. 9 3.1 Thermal Solution Design Considerations ................................................................. 9 3.1.1 Thermal Solution Design Factors .................................................................. 9 3.2 Heat Dissipation Path for a Fanless System ........................................................... 11 4.0 Fanless System Design Examples ............................................................................ 12 4.1 Fully Enclosed and Sealed Fanless System ............................................................ 12 4.2 Fanless System with Chassis Ventilation ............................................................... 13 A Thermal Solution Component Suppliers ................................................................... 17 A.1 Reference Heatsink............................................................................................ 17 Figures 3-1 4-1 4-2 4-3 4-4 4-5 4-6 Heat Dissipation Path For Fully Enclosed NC SOC System......................................... 11 Fully Enclosed and Sealed Fanless System with Multiple Board Form Factors .............. 12 Fully Enclosed Fanless System in the ERS Chassis................................................... 13 Fanless System with Ventilation (Chassis Sides Removed) ....................................... 14 Thermal Simulation Model (Chassis Top Removed).................................................. 14 Natural Convection Airflow Plot for Horizontal Chassis Configuration .......................... 15 Natural Convection Airflow Plot for Vertical Chassis Configuration ............................. 16 Tables 1-1 Acronyms............................................................................................................ 5 August 2008 Reference Number: 320299-001US Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 3 Revision History Revision History Date Revision August 2008 001 Description Intitial Release §§ Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 4 August 2008 Reference Number: 320299-001US 1.0 About This Document 1.0 About This Document 1.1 Purpose/Scope This document describes the thermal and mechanical design considerations and guidelines for the Intel® EP80579 Integrated Processor product line in fanless applications. Fanless applications are defined as systems that do not have a fan or forced airflow and dissipate heat via natural convection and conduction cooling. For details of the Intel® architecture (IA) products and system form factors, refer to the product datasheets and form factor specifications links listed in Section 1.4. For customer enabling, see Appendix A. 1.2 System Overview The SOC Fanless System is a system that is specifically targeted for embedded IA applications using the Intel® EP80579 Integrated Processor product line. Due to the wide variety of applications and usage models for embedded designs with the Intel® EP80579 Integrated Processor product line, only critical component and environmental factors were considered during the design and development process of the reference system solution. OEMs wishing to use the reference solution will need to evaluate their environmental boundary conditions and validate system cooling performance. In this document, references to System-on-Chip, SOC, or processor refers to the Intel® EP80579 Integrated Processor product line. 1.3 Definition of Terms Table 1-1 defines acronyms that are used throughout this document. Table 1-1. Acronyms Acronym Definition CFD Computational fluid dynamics EBX Embedded board expandable ECS Intel® Embedded Compact Extended Form Factor EPIC Embedded platform for industrial computing ERS Embedded ruggedized system HDD Hard disk drive IA Intel architecture NC Natural convection PCB Printed circuit board RHE Remote heat exchanger SBC Single board computer SOC System-on-chip August 2008 Reference Number: 320299-001US Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 5 1.0 About This Document 1.4 Reference Documents The reader of this specification should also be familiar with material and concepts presented in the following documents: • EBX / 5.25" Specification, http://www.pc104.org/technology/PDF/ EBX_Specification_v2_0.pdf • Embedded Ruggedized System Thermal Mechanical Design Guide • EPIC Specification, http://www.pc104.org/technology/PDF/EPIC_Spec_2.0.pdf • Intel® Embedded Compact Extended Form Factor Single Board Computer Interface, http://www.intel.com/design/intarch/papers/ECX_form_factor.htm • Intel® EP80579 Integrated Processor Product Line Datasheet • Intel® EP80579 Integrated Processor Product Line Thermal/Mechanical Design Guide • Intel® EP80579 Integrated Processor Product Line Thermal Mechanical Test Vehicle User's Guide • MIL-STD-810F, http://www.dtc.army.mil/pdf/810.pdf • Intel® EP80579 Integrated Processor product line Power Thermal Utility • Intel® EP80579 Integrated Processor product line Thermal Model User’s Guide Note: Technical documents are available at http://www.intel.com/go.soc or through your Intel field sales representative, unless otherwise noted above. §§ Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 6 August 2008 Reference Number: 320299-001US 2.0 Mechanical Design Considerations 2.0 Mechanical Design Considerations This section discusses the mechanical design considerations for designing a fanless system using the Intel® EP80579 Integrated Processor product line. 2.1 Package Information The Intel® EP80579 Integrated Processor product line is packaged in a FCBGA package with an Integrated Heat Spreader (IHS). The IHS transfers the non-uniformly distributed heat from the die to the top of the IHS, where the heat flux is more uniform and spread over a larger surface area (not the entire IHS area). This allows more efficient heat transfer from the package to an attached cooling device. The top surface of the IHS is designed to be the interface for contacting a heatsink. See the Intel® EP80579 Integrated Processor Product Line Thermal/Mechanical Design Guide for more details about the processor package. 2.1.1 Thermal Solution Fastening Load Requirement The attach mechanism for the heatsink or thermal solution should create a maximum static load on the package of no more than 15 lbf throughout the life of the product. The system designer should determine the minimum force to obtain the maximum performance from the thermal interface material. 2.1.2 Volumetric Space for Thermal Solution The system integrator must determine the available volumetric solution space (height, width, and length). This varies by board and chassis form factor. 2.1.3 Mechanical Tolerance Analysis Mechanical tolerance analysis should be performed on each design to ensure that all components fit properly. For systems that have components on the PCB attached to the chassis, the need for tolerance analysis is even greater. Because of dimensional variations in manufacturing, most PCBs that are attached directly to the chassis will implement thermal gap pads between the components and the chassis. These types of thermal materials perform more poorly than standard thermal grease or phase change materials. Ideally, a designer will want to minimize the interface resistance and, through tolerance analysis and manufacturing direction, a system designer can ensure target thermal interface material performance is met. August 2008 Reference Number: 320299-001US Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 7 2.0 Mechanical Design Considerations 2.1.4 Shock/Vibe Requirements Shock and vibration can impact the design of a fanless system. It is critical to analyze shock/vibe when the components on the PCB are directly attached to chassis. System designers need to develop shock/vibe requirements that will meet the end product’s needs. For general information on shock/vibe see the Intel® EP80579 Integrated Processor Product Line Thermal Mechanical Design Guide. §§ Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 8 August 2008 Reference Number: 320299-001US 3.0 Thermal Design Considerations 3.0 Thermal Design Considerations This section provides thermal design considerations and recommendations for developing a fanless system for the Intel® EP80579 Integrated Processor product line. 3.1 Thermal Solution Design Considerations The factors that influence the ability to design a fanless system apply to both the Intel® EP80579 Integrated Processor product line, and to any components that are to be used in any fanless system. The thermal solution in a fanless system can be placed into two general categories: stand-alone natural convection heatsink and conduction cooling system. A stand-alone natural convection heatsink is similar to a typical, extruded type of heatsink. The heatsink contacts only the component that it is cooling. This thermal solution is placed inside the chassis and relies on natural air movement created by a temperature difference instead of forced convection from an airflow source to remove the heat. A conduction cooled system is one in which the heat dissipating component(s) are attached to the chassis and rely on a majority of the heat being conducted into the chassis. This type of solution relies on natural convection to remove heat from the chassis. In this case, the heat dissipating components are usually directly attached to the chassis or utilize a heatpipe to transfer the heat to the chassis. The next section explains the major factors that influence a fanless thermal solution design. 3.1.1 Thermal Solution Design Factors • Thermal design power (TDP) and ambient temperature: The TDP for a component is probably the biggest factor in whether a component can be cooled in a fanless system. In most cases, a target power for fanless cooling is less than 10 W, but this depends on the target ambient temperature. For the Intel® EP80579 Integrated Processor product line, the 600 MHz are good fits for fanless cooling even though the power is slightly above 10 W. See the Intel® EP80579 Integrated Processor Product Line Datasheet for official thermal specifications. • The area of the surface on which the heat transfer takes place: Without enhancements, this is the surface of the processor package IHS. One method to improve thermal performance to attach a heatsink to the IHS. A heatsink can increase the effective heat transfer surface area by conducting heat from the IHS and into the surrounding air through fins attached to the heatsink base. The Intel® EP80579 Integrated Processor product line requires a heatsink in all applications. • The conduction path from the heat source to the heatsink fins: Providing a direct conduction path from the heat source to the heatsink fins and selecting materials with higher thermal conductivity typically improves heatsink performance. The length, thickness, and conductivity of the conduction path from the heat source to the fins directly impact the thermal performance of the heatsink. In particular, the quality of the contact between the package IHS and the heatsink base has a greater impact on the overall thermal solution performance as processor cooling requirements become stricter. August 2008 Reference Number: 320299-001US Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 9 3.0 Thermal Design Considerations • Thermal Interface Material (TIM): TIM is used to fill the gap between the IHS and the bottom surface of the heatsink, improving the overall performance of the stackup (IHS-TIM-heatsink). With an extremely poor heatsink interface flatness or roughness, the TIM may not adequately fill the gap. The TIM thermal performance depends on its thermal conductivity and the pressure applied to it. See the Intel® EP80579 Integrated Processor Product Line Thermal/Mechanical Design Guide for more information on TIMs. • Heat Distribution: In the case of conduction cooled system thermal solutions, it is very important to optimize the heat distribution from heat source(s). This can be achieved by using multiple heatpipes to transport the heat to a larger area of the system chassis. • Fin thickness and fin pitch: In a natural convection solution, the air flow is induced by the phenomenon of hot air moving to the opposite of gravitational direction. Therefore, the fin to fin spacing and the thickness of the fins play a critical role in improving the air flow and reducing thermal resistance. Thermal solution designers need to optimize these parameters to obtain the best performance while designing for manufacturability. • Fin height: When designing a natural convection system, tall fins with large surface area might not improve the heat transfer, because the height might create a high air resistance film between the tall fins. Therefore, the fin height needs to be considered to achieve an optimized natural convection flow. Sometimes, this parameter will be limited by the form factor or other solution space volumetric constraints. • Orientation of fins: The direction of the airflow caused by natural convection is opposite with respect to gravity direction. The final system orientation should be determined and the fins should be aligned to be parallel to this flow. It should be balanced if the system can be used in both horizontal and vertical configurations. This could mean that the chassis will have two sets of fins with different orientations to achieve optimized heat dissipation. • Heat source location and PCB design: In any fanless system, the PCB should be designed so that it will also act as a heat spreader from the power that is transferred through the package into the board. The thermal solution designer should work with the board designer to ensure that a sufficient amount of copper layers are used in the board to help aid in heat dissipation into the board. Additionally, the location of heat-dissipating components on the PCB can have an affect on each other depending on how close together they are. High power dissipating parts should be placed as apart as the motherboard size and electrical routing constraints allow. The distance reduces the mutual heating affect. • Radiation. Heat transfer through radiation impacts a fanless cooling system. The amount of heat radiated out from the surface of the chassis is influenced by the surface emissivity. The heat transfer via radiation is improved by surfaces with higher emissivity. A surface's emissivity can be improved by painting the surface a dark color, with black being the optimum color. • Location of venting in the chassis. The vents in the chassis allow for heat to escape and for external air that is at a lower temperature to enter the chassis. Critical components with the highest amount of power generation (usually the processor), need to be placed close to the chassis vents. This placement facilitates the movement of air caused by thermodynamic effects. • Heat trapped inside fully enclosed system. For fanless systems that are fully enclosed, not all heat sources have direct heat conduction to the heatsink(s) or chassis. Therefore, the heat generated could eventually lead to internal heat accumulation until system failure results due to raising the internal local ambient temperature (TLA). System thermal solution designers must take into account this potential impact to temperature inside the chassis. • Maximum allowable chassis temperature. The external chassis temperature should be considered in applications where a fanless system will have potential users come Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 10 August 2008 Reference Number: 320299-001US 3.0 Thermal Design Considerations in contact with the chassis. Due to the amount of heat transfer to the outer chassis there is potential for the surface to burn a user who comes in contact with the device. System designers need to monitor the surface temperature of the chassis to ensure that end users will not be harmed and the chassis temperature meets applicable standards. To analyze all these design factors it is recommended that designers utilize third-party CFD thermal analysis software such as Flotherm* and Icepak*. Intel has package models for the Intel® EP80579 Integrated Processor product line available for these software packages. Contact your Intel Field representative for more information. 3.2 Heat Dissipation Path for a Fanless System It is critical to examine and plan the heat dissipation path from the heat source(s) to the chassis. In a fanless system, the main heat dissipation mode to the surroundings is natural convection and radiation. In the following figure the heat from the major components is transferred from the heat source(s) to the chassis wall via heat pipes. The heat is then transferred throughout the chassis via conduction and out to the surrounding environment through convection and radiation. Figure 3-1. Heat Dissipation Path For Fully Enclosed NC SOC System Ideally, the system designer should optimize this entire heat transfer system using the recommendations in Section 3.1.1. §§ August 2008 Reference Number: 320299-001US Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 11 4.0 Fanless System Design Examples 4.0 Fanless System Design Examples This section details case studies for fanless system design for the Intel® EP80579 Integrated Processor product line either in a fully enclosed or a ventilated system environment. These examples all utilize the chassis for heat dissipation. A system designer that wishes to develop a stand-alone natural convection thermal solution would apply the same design principles. It is very important to note that there isn't a one size fits all fanless thermal solution. Fanless designs are custom designs and each application needs to be modeled and tested. 4.1 Fully Enclosed and Sealed Fanless System The fully enclosed and sealed fanless system eliminates dust and other contaminants that could affect the functionality of the system. The system board and processor are isolated from the external environment with the fully enclosed system solution. The fully enclosed system chassis solution, Embedded Ruggedized Solution (ERS), can accommodate three PCB of form factors: • Intel® ECX Form Factor / 3.5" SBC Form Factor • EPIC Form Factor • EBX / 5.25" SBC Form Factor. See the following figure for diagrams with the target board form factors. Figure 4-1. Fully Enclosed and Sealed Fanless System with Multiple Board Form Factors This fully enclosed and sealed system has the I/O ports inside the system chassis, so I/O connections needs to be routed through an interface or high-density connector. This kind of sealed connector would allow a system to withstand being submersed in water and still function. Figure 4-2 shows example of the ERS cable connectors. Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 12 August 2008 Reference Number: 320299-001US 4.0 Fanless System Design Examples Based on lab testing with fully assembly ERS and the Intel® EP80579 Integrated Processor Thermal Test Vehicle (TTV), this system thermal solution can achieve a caseto-ambient (ΨCA) thermal resistance of 1.5° C/W when mounted vertically and 1.6° C/ W when mounted horizontally. This translates into maximum allowable temperature of 80° C when using the 600 MHz SKU of the Intel® EP80579 Integrated Processor with Intel® Quick Assist Technology. The performance of the chassis will be affected by mutual heating if other components are attached to the chassis to dissipate heat. This must be considered when determining thermal solution performance and maximum allowable ambient temperature. The thermal performance presented had only one heat source attached to the chassis. The system integrator must test and validate the entire thermal solution to ensure that it meets thermal specifications and requirements. See the ERS Thermal Mechanical Design Guide for mechanical details of the ERS solution for implementation. Figure 4-2. Fully Enclosed Fanless System in the ERS Chassis 4.2 Fanless System with Chassis Ventilation This example of a fanless system has vents in the chassis that allow external ambient air to enter the chassis and hot air escape the chassis. This design is based on the miniITX* form factor. It is desirable to use a standard DIMM and other components on the motherboard, so the thermal solution uses a conduction block to transfer the heat from the processor to the chassis. Ideally, low-profile components should be used on the board so that the distance between the components and the chassis is minimized. Heatpipes could be used in place of a conduction block to transfer the heat. The following figures show the system and thermal modeling layout. August 2008 Reference Number: 320299-001US Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 13 4.0 Fanless System Design Examples Figure 4-3. Fanless System with Ventilation (Chassis Sides Removed) Top of chassis used as Heatsink Memory Graphics Chip Battery Aluminum conduction block from processor to chassis Figure 4-4. Intel® EP80579 Integrated Processor Connectors Thermal Simulation Model (Chassis Top Removed) Vent Battery DIMM SOC Misc. Power Vent Graphics Chip Misc. Power PCIe connectors (not populated) Back panel connectors •6 Ethernet •2 USB •1 Serial Vent Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 14 August 2008 Reference Number: 320299-001US 4.0 Fanless System Design Examples Thermal analysis was performed for this chassis in both a vertical and a horizontal position. The following figures show the airflow movement created through natural convection. It is important for system designers to analyze the movement of heat within the system and help determine the location and size of the chassis vents. Figure 4-5. Natural Convection Airflow Plot for Horizontal Chassis Configuration The airflow plot (Figure 4-5) shows airflow entering at the bottom of the side vents, traveling inward to the conduction block, and then exiting at the top of the side vents. The airflow velocities shown are fairly typical for natural convection in that the velocity is very low. To enhance the airflow venting could be added in the top of the chassis to aid in the plume effect. August 2008 Reference Number: 320299-001US Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 15 4.0 Fanless System Design Examples Figure 4-6. Natural Convection Airflow Plot for Vertical Chassis Configuration The airflow plot in Figure 4-6 shows an increase in airflow velocity when compared to the chassis in a horizontal configuration. This is based on the fact that the vents are in the same direction as gravity and it is much easier for the airflow to enter and exit the chassis. A vertical configuration will almost always perform better than a horizontal configuration. Based on thermal simulation and analysis, this system thermal solution can achieve a case-to-ambient (ΨCA) thermal resistance of 2.8° C/W in the horizontal configuration and 2.6° C/W in the vertical configuration for the 600 MHz Intel® EP80579 Integrated Processor product line. The system integrator must test and validate the entire thermal solution to ensure that it meets thermal specifications and requirements. For more information on testing metrology see the Intel® EP80579 Integrated Processor Product Line Thermal Mechanical Design Guide. CFD thermal simulation software allows a design engineer to try different component placements, orientations, and geometries so the end product will have optimized performance and meet all component specifications. This software also allows a designer to potentially identify opportunities to reduce cost in the case of a solution that has a lot of thermal margin. The 600 MHz SKUs of the Intel® EP80579 Integrated Processor product line are ideally suited for fanless applications. With diligent analysis and using the recommendations in this document, a system designer can develop a fanless system. §§ Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 16 August 2008 Reference Number: 320299-001US Appendix A Thermal Solution Component Suppliers A.1 Reference Heatsink Table A-1. Suppliers Part Cooler Master Part Number Part Description ECE-34001-B1-GP Full system chassis excluding SBC and DCDC conversion module Contact Information Debby 886-2-3234-0050 [email protected] §§ August 2008 Reference Number: 320299-001US Intel® EP80579 Integrated Processor Product Line Fanless System Thermal/Mechanical Design Guide 17