XBOX360 Thermal System Design and Verification

Julia Purtell, Paul Wang, Jeff Reents, Michael MillerXBOX, HW Design and Evaluation Group

MEPTEC Symposium

February 15, 2007

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Outline

• Thermal Management Requirements• Main Components• Overall Thermal Management Execution• Details• Design Verification and Validation• Lessons Learned

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Thermal Management Requirements• Meeting consumer requirements in following

areas:graphic quality and speedacoustic noise during game, movies and CD playback operational environmental conditionsexhaust airflow temperature

• Meeting cost of goods target• Meeting ID requirements for overall dimensions

and look

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Thermal Management Requirements

• Minimize thermal performance degradation over the life of the product

• Ability to operate console in both horizontal and vertical orientations

• Ability to use multiple suppliers for each component

• Integration of various interchangeable peripheral devices (HDD, wireless networking adapter, memory units)

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Main Components

• High power CPU• High power GPU• Memory DRAMs• Various ASICs• DC-DC converters• Optical Disk Drive• AC-DC converter• Removable accessories:

Hard Disk DriveWireless Networking AdapterMemory Units

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Overall Thermal Management Execution

• Forced airflow design with multiple inlets and single outlet

• Outlet is located in the back of the console• Airflow is independent of HD presence• Fan is a custom part that contains two motors in

single frame• Lidless CPU and GPU package design

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Overall Thermal Management Execution

• Heatsinks are mounted on CPU and GPU • No other heatsinks are used• High performance Thermal Interface Material us

used for both CPU and GPU• Thermal gap pads are used for memory DRAM• AC-DC converter is external to the console

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Design Details

Fan

• High pressure drop custom fan was developed in collaboration with leading fan companies to cool both CPU and GPU based on detailed specification provided

• To optimize acoustic noise fan is driven by thermal algorithm which controls fan input voltage based on thermal sensors readings

XBOX360 fan curve

0

0.05

0.1

0.15

0.2

0.25

0 10 20 30 40 50 60 70

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Design Details

Airflow management

PCB was laid out so main power generating components (CPU and GPU) have independent airflow path and do not preheat each other

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Design Details

Airflow management

• Plastic baffle is used to direct airflow through CPU and GPU heatsinks

• Fan is located on exhaust side • Exhaust is located in the back of the console as not

to blow preheated air on customer's hands or face• Multiple inlets are used to accommodate both

vertical and horizontal positions

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Design Details

Airflow management

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Design Details

Airflow management

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Design DetailsCPU heatsink

• CPU heatsink was designed in collaboration with leading heatsinkmanufacturers

• It contains single sintered heatpipe and Cu base

CPU Heatsink performance

Flow rate (cfm)

Ther

mal

res

ista

nce,

Rs-

a (C

/W)

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Design Details

GPU heatsink

GPU heatsink is Al extrusion

GPU heatsink

Flow rate (CFM)

Ther

mal

resi

stan

ce, R

s-a

(deg

C/W

)

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Design DetailsThermal Interface Material

High performance phase change TIM is used for both CPUand GPU

Thermal Impedance versus Pressure

Decreasing Pressure (psi)

Ther

mal

Impe

danc

e (K

-in2/

W)

Phase change

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Design Verification and Validation

• Custom designed Thermal Load board was used for evaluation early in design process

• Heaters were used for all components• Power was applied from AC-DC power supplies to

each individual component• Load board was used to determine components

preheating; heatsinks operating points; TIM, heatsinks and fans benchmarking

• Correction factors to account for die size difference were calculated to correlate load board results with real MB

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Design Verification and Validation

• Fans and heatsinks from selected suppliers went through set of mechanical and thermal tests. Statistically significant sample size was used.

• Main purpose of thermal tests was to quantify differences in performance across suppliers to determine the best and the worst case

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Design Verification and Validation• For fans airflow, pressure drop and RPM over the range of

operating voltages were measured.

CFM

1 11 21 31

Measurements

CFM

Supplier1 5VSupplier2 5VSupplier1 12VSupplier2 12VSupplier1 6.3VSupplier2 6.3VSupplier3 12VSupplier3 6.3VSupplier3 5V

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Design Verification and Validation

• For CPU heatsink tests were performed on assembly and heat pipe levels.

• Heat pipes from all suppliers were subjected to end seal integrity and accelerated aging tests.

• Freeze-thaw temperature cycling conducted on assembly level proved to be most difficult test for heat pipes to pass.

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Design Verification and Validation• TIM was subjected to reliability test to determine thermal

performance degradation over the life of the product• 0-110degC thermal cycling was used for reliability test• Thermocouple was embedded in heatsink bases and

temperature difference between junction and heatsink was used as measure of TIM performance

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Design Verification and Validation

• Degradation of overall thermal solution due to sand and dust was evaluated. Xbox consoles returned from the customers at the end of product life were used as benchmark to determine level of contamination.

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Lessons Learned

• Balancing product requirements with thermal performance requirements proved to be the most challenging task

• Lengthy approval process of multiple suppliers completed ahead of shipment date pay off during production

• Creating and maintaining simulation tool allows quick what-if analysis and components benchmarking

• Simulation tool results have to be continuously verified against real product

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Disclaimer

Methodology proposal in this article is an experimental approach for exploiting technical insight. There is no product quality and reliability referencing implied with this approach. Application discretions are needed for all cases.The information contained in this document represents the current view of Microsoft Corporation on the issues discussed as of the date of publication. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information presented after the date of publication.This White Paper is for informational purposes only. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS DOCUMENT.Complying with all applicable copyright laws is the responsibility of the user. Without limiting the rights under copyright, no part of this document may be reproduced, stored in or introduced into a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise), or for any purpose, without the express written permission of Microsoft Corporation. Microsoft may have patents, patent applications, trademarks, copyrights, or other intellectual property rights covering subject matter in this document. Except as expressly provided in any written license agreement from Microsoft, the furnishing of this document does not give you any license to these patents, trademarks, copyrights, or other intellectual property.@2007 Microsoft Corporation. All rights reserved.

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