c'Jl/11/fillll/il, ___ -
`
`111111111111~1~ ~1rn1nm111111
`
`SEC et al. v. MRI
`SEC Exhibit 1018.001
`IPR 2023-00199
`
`

`

`SEC et al. v. MRI
`SEC Exhibit 1018.002
`IPR 2023-00199
`
`

`

`Tt< -=t~"=l-00 2.5
`.Y4't
`2002.
`
`Copyright © 2002
`The American Society of Mechanical Engineers
`Three Park Ave., New York, NY 10016
`
`All rights reserved. Printed in the United States of America. Except as permitted under the
`United States Copyright Act of 1976, no part of this publication may be reproduced or dis(cid:173)
`tributed in any form or by any means, or stored in a database or retrieval system, without
`the prior written permission of the publisher.
`
`Statement from By-Laws: The Society shall not be responsible for statements or opinions
`advanced in papers . .. or printed in its publications (B7. l.3)
`
`INFORMATION CONTAINED IN THIS WORK HAS BEEN OBTAINED BY THE AMERI(cid:173)
`CAN SOCIETY OF MECHANICAL ENGINEERS FROM SOURCES BELIEVED TO BE
`RELIABLE. HOWEVER, NEITHER ASME NOR ITS AUTHORS OR EDITORS GUARAN(cid:173)
`TEE THE ACCURACY OR COMPLETENESS OF ANY INFORMATION PUBLISHED IN
`THIS WORK. NEITHER ASME NOR ITS AUTHORS AND EDITORS SHALL BE RESPON(cid:173)
`SIBLE FOR ANY ERRORS, OMISSIONS, OR DAMAGES ARISING OUT OF THE USE OF
`THIS INFORMATION. THE WORK IS PUBLISHED WITH THE UNDERSTANDING THAT
`ASME AND ITS AUTHORS AND EDITORS ARE SUPPLYING INFORMATION BUT ARE
`NOT ATTEMPTING TO RENDER ENGINEERING OR OTHER PROFESSIONAL SER(cid:173)
`VICES. IF SUCH ENGINEERING OR PROFESSIONAL SERVICES ARE REQUIRED,
`THE ASSISTANCE OF AN APPROPRIATE PROFESSIONAL SHOULD BE SOUGHT.
`
`For authorization to photocopy material for internal or personal use under circumstances
`not falling within the fair use provisions of the Copyright Act, contact the Copyright Clear(cid:173)
`ance Center (CCC), 222 Rosewood Drive, Danvers, MA 01923, Tel: 978-750-8400,
`www.copyright.com.
`
`Library of Congress Cataloging-in-Publication Data
`
`Yeh, L.-T. (Lian-Tuu), 1944-
`Thermal management of microelectronic equipment: heat transfer theory,
`analysis methods, and design practices I L.-T. Yeh and R. C. Chu.
`p.cm.
`ISBN 0-7918-0168-3
`1. Electronic apparatus and appliances - Cooling. 2. Electronic apparatus and appli(cid:173)
`ances - Thermal properties. 3. Heat - Transmission. I. Chu, R. C. (Richard C.), 1933. II.
`Title.
`
`TK7870.25.Y44 2002
`621.381'04 - dc21
`
`2001034086
`
`SEC et al. v. MRI
`SEC Exhibit 1018.003
`IPR 2023-00199
`
`

`

`TABLE OF CONTENTS
`
`List of Figures
`List of Tables
`Nomenclature
`Foreword
`Preface
`
`xi
`xvii
`xix
`xxiii
`XXV
`
`Introduction
`Chapter 1
`1
`1.1 Need for Thermal Control ............................................................... 1
`1.2 Reliability and Temperature ............................................................ 3
`1.3 Levels of Thermal Resistance .......................................................... .4
`1.4 Thermal Design Considerations ...................................................... 5
`1.5 Optimization and Life-Cycle Cost ................................................... 6
`
`9
`Chapter 2 Conduction
`2.1 Fundamental Law of Heat Conduction .......................................... 9
`2.2 General Differential Equations for Conduction ........................... 10
`2.3 One-Dimensional Heat Conduction .............................................. 16
`2.4 Thermal/Electrical Analogy ........................................................... 17
`2.5 Lumped-System Transient Analysis ............................................... 20
`2.6 Heat Conduction with Phase Change ........................................... 25
`
`SEC et al. v. MRI
`SEC Exhibit 1018.004
`IPR 2023-00199
`
`

`

`vi
`
`• Table of Contents
`
`31
`Chapter 3 Convection
`3.1 Flow and Temperature Fields ........................................................ 31
`3.2 Heat Transfer Coefficient .............................................................. 34
`3.3 Parameter Effects on Heat Transfer .............................................. 35
`3.4 Pressure Drop and Friction Factor ................................................ .43
`3.5 Thermal Properties of Fluids ......................................................... 46
`3.6 Correlations for Heat Transfer and Friction ................................. 47
`
`53
`CHAPTER 4 RADIATION
`4.1 Stefan-Boltzmann Law .................................................................. 53
`4.2 Kirchhoff's Law and Emissivity ...................................................... 54
`4.3 Radiation Between Black Isothermal Surfaces ............................. 55
`4.4 Radiation Between Gray Isothermal Surfaces .............................. 58
`4. 5 Extreme Climatic Condit ions ......................................................... 61
`
`Chapter 5 Pool Boiling
`
`67
`
`5.1 Boiling Curve ...... ····················································:·······················67
`5.2 Nucleate Boiling ............................................................................. 70
`5.3
`Incipient Boiling at Heating Surfaces ........................................... 72
`5.4 Nucleate Boiling Correlations ....................................................... 76
`5.5 Critical Heat Flux Correlations ...................................................... 77
`5.6 Minimum Heat Flux Correlations (Leidenforst Point) .................. 79
`5.7 Parameters Affecting Pool Boiling ................................................ 81
`5.8 Effect of Gravity on Pool Boiling .................................................. 87
`
`95
`Chapter 6 Flow Boiling
`6.1 Flow Patterns ................................................................................. 95
`6.2 Heat Transfer Mechanisms ............................................................ 95
`6.3 Boiling Crisis ................................................................................... 98
`6.4 Heat Transfer Equations ................................................................ 99
`6.5 Thermal Enhancement ................................................................ 109
`6.6 Pressure Drop ............................................................................... 109
`
`SEC et al. v. MRI
`SEC Exhibit 1018.005
`IPR 2023-00199
`
`

`

`Table of Contents
`
`• vii
`
`115
`Chapter 7 Condensation
`7 .1 Modes of Condensation .............................................................. 115
`7.2 Heat Transfer in Filmwise Condensation .................................... 116
`7.3
`Improvements Over Nusselt Analysis .......................................... 121
`7.4 Condensation Inside a Horizontal Tube ..................................... 123
`7 .5 Noncondensable Gas in a Condenser .. : ...................................... 127
`
`131
`Chapter 8 Extended Surf aces
`8.1 Uniform-Cross Section Fins ......................................................... 131
`8.2 Fin Efficiency ................................................................................ 134
`8.3 Selection and Design of Fins ....................................................... 137
`
`141
`Chapter 9 Thermal Interface Resistance
`9.1 Factors Affecting Thermal Contact Resistance ........................... 141
`9.2 Joint Thermal Contact Resistance ............................................... 145
`9.3 Methods of Reducing Thermal Contact Resistance ................... 147
`9.4 Solder and Epoxy Joints ............................................................... 159
`9.5 Practical Design Data ................................................................... 160
`
`169
`Chapter 10 Components and Printed Circuit Boards
`10.1 Chip Packaging Technology ...................................................... 169
`10.2 Chip Package Thermal Resistance ............................................. 172
`10.3 Chip Package Attachment ......................................................... 173
`10.4 Board-Cooling Methods ............................................................ 176
`10.5 Board Thermal Analysis ............................................................. 177
`10.6 Equivalent Thermal Conductivity .............................................. 178
`
`185
`Chapter 11 Direct Air Cooling and Fans
`11.1 Previous Work ............................................................................ 185
`11.2 Heat Transfer Correlations ........................................................ 187
`11.3 Pressure Drop Correlations ........................................................ 190
`11.4 Heat Transfer Enhancement ...................................................... 194
`11.5 Fans and Air-Handling Systems ................................................. 197
`
`SEC et al. v. MRI
`SEC Exhibit 1018.006
`IPR 2023-00199
`
`

`

`viii
`
`• Table of Contents
`
`213
`Chapter 12 Natural and Mixed Convection
`12.1 Parallel Plates ............................................................................. 214
`12.2 Straight-Fin Arrays ..................................................................... 220
`12.3 Pin-Fin Arrays ............................................................................. 229
`12.4 Enclosures ................................................. : ................................. 234
`12.5 Mixed Convection in Vertical Plates ......................................... 237
`
`243
`Chapter 13 Heat Exchangers and Cold Plates
`13.1 Compact Heat Exchangers ......................................................... 243
`13.2 Flow Arrangement of Heat Exchangers ................................... 244
`13.3 Overall Heat Transfer Coefficient ............................................. 244
`13.4 Heat Exchanger Effectiveness ................................................... 245
`13.5 Heat Exchanger Analysis ........................................................... 246
`13.6 Heat Transfer and Pressure Drop .............................................. 248
`13. 7 Geometric Factors ...................................................................... 250
`13.8 Cold-Plate Analysis ..................................................................... 251
`13.9 Correlations ................................................................................ 255
`
`Chapter 14 Advanced Cooling Technologies I:
`261
`Single-Phase Liquid Cooling
`14.1 Coolant Selection ....................................................................... 261
`14.2 Natural Convection .................................................................... 265
`14.3 Forced Convection ..................................................................... 267
`
`Chapter 15 Advanced Cooling Technologies II:
`283
`Two-Phase Flow Cooling
`15.1 Figure of Merit ........................................................................... 283
`15.2 Direct-Immersion Cooling ......................................................... 285
`15.3 Enhancement of Pool Boiling ................................................... 287
`15.4 Flow Boiling ............................................................................... 300
`
`309
`Chapter 16 Heat Pipes
`16.1 Operation Principles .................................................................. 309
`16.2 Useful Characteristics ................................................................. 309
`
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`

`

`Table of Contents
`
`•
`
`ix
`
`16.3 Construction ............................................................................... 311
`16.4 Operation Limits ....................................................................... .312
`16.5 Materials Compatibility ............................................................. 318
`16.6 Operating Temperatures ........................................................... 320
`16. 7 Operation Methods ................................................................... 321
`16.8 Thermal Resistances ................................................................... 323
`16.9 Applications ............................................................................... 325
`16.10 Micro Heat Pipes ...................................................................... 330
`
`335
`Chapter 17 Thermoelectric Coolers
`17 .1 Basic Theories of Thermoelectricity .......................................... 335
`17 .2 Net Thermoelectric Effect .......................................................... 337
`17.3 Figure of Merit ........................................................................... 338
`17.4 Operation Principles .................................................................. 339
`17.5 System Configurations ............................................................... 339
`17.6 Performance Analysis ................................................................ 340
`17.7 Practical Design Procedure ........................................................ 344
`
`349
`Appendices
`A. Material Thermal Properties ........................................................ 349
`B. Thermal Conductivity of Silicon and Gallium Arsenide .............. 351
`C. Properties of Air, Water, and Dielectric Fluids ............................ 353
`D. Typical Emissivities of Materials ................................................... 371
`E. Solar Absorptivities and Emissivities of Common
`Surfaces ......................................................................................... 373
`F. Properties of Phase-Change Materials ......................................... 375
`G. Friction Factor Correlations .......................................................... 377
`H. Heat Transfer Correlations ........................................................... 381
`I. Units Conversion Table ................................................................. 403
`
`Index
`
`About the Authors
`
`405
`
`413
`
`SEC et al. v. MRI
`SEC Exhibit 1018.008
`IPR 2023-00199
`
`

`

`Chapter 1
`
`INTRODUCTION
`
`Electronics are the heart of any modern equipment. Thermal control of elec(cid:173)
`tronic equipment has long been one of the major areas of application of heat
`transfer technologies. Many improvements in reliability, power density, and
`physical miniaturization of electronic equipment over the years can be attributed
`in part to improved thermal analysis and design of systems. Improved thermal
`design has been made possible through advances in heat transfer technologies as
`well as computational methods and tools.
`The primary function of cooling systems for electronic equipment is to pro(cid:173)
`vide an acceptable thermal environment in which the equipment can operate. To
`achieve this goal, it is necessary to maintain a thermal path with a minimum
`resistance from equipment heat sources to the ultimate heat sink.
`
`1.1 NEED FOR THERMAL CONTROL
`
`Because of advances in circuit and component technologies, electric circuits
`have become more efficient, and thus heat dissipation from individual devices
`such as transistors has also become less. Miniaturization of circuits greatly
`decreases the size of individual devices, however, and increases the number of
`such devices that can be integrated on a single chip. The net result is that the chip
`heat flux (heat flow per unit surface area) has significantly increased in recent
`decades as chip development has moved from small-scale integration (SSI) to
`very large-scale integration (VLSI), and further to ultra-large-scale integration
`(ULSI). The chronology of advances in the integrated circuit (IC) is outlined in
`the following steps, with the trends shown in Figure 1.1.
`
`1960-Small-scale integration (SSI), fewer than 100 devices per chip
`1966-Medium-scale integration (MSI), fewer than 1000 devices per chip
`1969-Large-scale integration (LSI), fewer than 10,000 devices per chip
`1975-Very-large-scale integration (VLSI), fewer than 107 devices per
`chip
`1990-Ultra-large-scale integration (ULSI), more than 107 devices per
`chip
`
`Decreasing the temperature of a component increases its performance as
`well as its reliability. In addition to lowering the junction temperatures within a
`
`SEC et al. v. MRI
`SEC Exhibit 1018.009
`IPR 2023-00199
`
`

`

`2
`
`• THERMAL MANAGEMENT OF MICROELECTRONIC EQUIPMENT
`
`1G---------------------.
`0 Microprocessor/Logic
`100M -
`A Memory
`
`a. :c
`0 .. Q) a.
`C -0 .. Q) .c
`
`Ill
`Q)
`(.)
`
`·s:
`
`Q)
`
`E
`~ z
`
`10M -
`
`1M -
`
`100K -
`10K -
`1K -
`
`100
`1960
`
`I
`1970
`
`I
`1980
`Year
`
`I
`1990
`
`2000
`
`FIGURE 1.1
`
`Increase in circuit complexity.
`
`component, it is sometimes also important to reduce the temperature variation
`between components that are electronically connected in order to obtain opti(cid:173)
`mum performance. Thermal considerations become an important part of elec(cid:173)
`tronic equipment because of increased heat flux.
`An increased demand on system performance and reliability also intensifies
`the need for good thermal management of electronic equipment. Further evi(cid:173)
`dence of the importance of thermal management to electronic systems is shown
`in Figure 1.2, based on a survey by the U.S. Air Force and indicating that more
`than 50% of all electronics failures are caused by shortcomings in temperature
`control [1].
`Although a great deal of attention has recently been paid to high-heat-flux
`systems, the opportunity also exists to improve thermal performance and
`reliability in low-heat-flux equipment. Therefore, the challenge in the field of
`thermal management of electronic equipment resides not only with very-high(cid:173)
`performance (high-heat-dissipation) devices, but also with intermediate- and
`
`SEC et al. v. MRI
`SEC Exhibit 1018.010
`IPR 2023-00199
`
`

`

`Introduction
`
`• 3
`
`Temperature
`55%
`
`FIGURE 1.2 Major causes of electronics failures [1].
`
`lower-power components where improved reliability objectives require cooler
`operation of chips.
`
`1.2 RELIABILITY AND TEMPERATURE
`
`Reliability-that is, the reciprocal of the mean time between failures (MTBF)-is
`described as the statistical probability that a device or system will operate with(cid:173)
`out failure for a specific time period. Each component or device has its failure
`rate curve. The reliability of a system is determined by combining many individ(cid:173)
`ual part failure rates in series and/or parallel. System reliability is also affected by
`the relative importance of the . individual part to the system, and it can be
`improved by redundancy at th~ component, packaging, or system level.
`Table 1 lists the possible effect of temperature on the part failure under vari(cid:173)
`ous thermal conditions such as thermal shock, temperature under continuous
`operation (steady state), and temperature cycling. In the temperature range spe(cid:173)
`cific to electronic equipment, it is an established fact that the reliability of elec(cid:173)
`tronics is a strongly inverse function (a near exponential dependency) of a
`component's temperature. The reliability of a silicon chip is decreased by about
`10% for every 2°C of temperature rise [2]. A typical temperature limit for a silicon
`chip is 125°C; however, a much lower design limit is commonly sought to main(cid:173)
`tain the desired reliability, especially in military products.
`The component failure rate is also related to temperature cycling, which
`results from either device power cycling or cycling of environmental conditions.
`In a U.S. Navy-sponsored study [3], an eightfold increase in failure rate was
`
`SEC et al. v. MRI
`SEC Exhibit 1018.011
`IPR 2023-00199
`
`

`

`4 . THERMAL MANAGEMENT OF MICROELECTRONIC EQUIPMENT
`
`Table 1.1 Effect of Thermal Conditions on Part Failure
`
`Condition
`
`Steady-state
`(hot)
`
`Cause
`
`Effect
`
`Possible failure
`
`Ambient exposure,
`equipment-
`induced
`
`Aging-discoloration
`Insulation
`deterioration
`Oxidation
`Expansion
`Viscosity decrease
`Softening/hardening
`Evaporation/drying
`Chemical changes
`
`Alteration of
`properties
`Shorting
`Rust
`Physical damage,
`increased wear
`Loss of lubrication
`Physical breakdown
`Dielectric loss
`
`Steady-state
`(cold)
`
`Ambient exposure,
`mission-
`induced
`
`Contraction
`Viscosity increase
`Embrittlement
`Ice formation
`
`Thermal cycling
`
`Ambient-induced,
`mission
`operation
`
`Temperature
`gradients
`Expansion/
`contraction
`
`Wear, structural
`failure, binding
`Loss of lubricity
`Structural failure,
`cracked parts
`Alteration of electric
`properties
`Loss of resilience-
`seal leaks
`
`Mechanical failure of
`parts, solder joints,
`and connections
`Delimitation of
`bonding line
`
`Thermal shock
`
`Mission profile
`
`High temperature
`gradients
`
`Mechanical failure,
`cracks, rupture
`
`encountered in equipment subjected to a deliberate temperature cycling of more
`than 20°c.
`
`1.3 LEVELS OF THERMAL RESISTANCE
`
`The component-level resistance, which is often referred to as a component's inter(cid:173)
`nal resistance, is defined as the thermal resistance from the device junction (heat
`source) to some predetermined reference point on the outside surface of the
`component or package. In most component assemblies, heat must be transferred
`through a number of different materials and interfaces. The total thermal resist(cid:173)
`ance is the sum of several individual resistances in series and/or parallel. The pri(cid:173)
`mary heat transfer mode inside the component or package is conduction. In
`well-designed component packaging, the number of interfaces should be mini(cid:173)
`mized, and bonding and sealing operations should also be selected to create the
`lowest interface resistance. The coefficient of thermal expansion (CTE) is a major
`concern at the interfaces of all materials laminated together. Any mismatch of the
`coefficient of thermal expansion would increase the thermal resistance, and even
`
`SEC et al. v. MRI
`SEC Exhibit 1018.012
`IPR 2023-00199
`
`

`

`Introduction
`
`• 5
`
`cause part failure. Note that the thermal designer may have no control over the
`internal resistance if commercial components are used.
`The packaging-level resistance is generally defined as the thermal resistance
`from the aforementioned surface reference point (the terminal point for measur(cid:173)
`ing component-level resistance) to some designated point in a convective stream.
`For example, this designated point may be the local air temperature over a given
`component or the local fluid or wall temperature of a cold plate.
`The system-level resistance is defined as the thermal resistance from the desig(cid:173)
`nated terminal point for measuring the packaging-level resistance to the ultimate
`heat sink of the equipment or system. The ultimate heat sink is the environment
`in which the system operates. Sometimes, the combined resistance of packaging
`and system levels is referred to as the external thermal resistance.
`The foregoing definitions are somewhat arbitrary; however, they give an
`insight into the contribution of each level of resistance to the total resistance of a
`system, and thus provide thermal engineers an opportunity to optimize the over(cid:173)
`all thermal resistance by working at the individual levels.
`
`1.4 THERMAL DESIGN CONSIDERATIONS
`
`Thermal control of electronic equipment may employ several different heat
`transfer modes simultaneously and may consist of up to three tasks: ( 1) removing
`heat from the sources (components), (2) transporting heat to system internal
`heat sinks, and (3) rejecting heat from the internal heat sinks to the ultimate heat
`sink, the environment. Sometimes, tasks 2 and 3 are lumped into a single task.
`The purpose of a thermal design is to provide equipment that will induce ther(cid:173)
`mal energy to flow properly from heat sources to the ultimate heat sinks. The
`goal of thermal control is to prevent part failures and also to achieve desired sys(cid:173)
`tem performance and reliability. Another goal of thermal control is to obtain an
`optimum design. The optimum system will result from a series of trade-off stud(cid:173)
`ies considering several factors:
`
`1. Performance. The primary and foremost consideration is that the sys(cid:173)
`tem must be able to perform its required functions and the specific
`tasks for which it is designed.
`2. Producibility. The system under consideration must be producible
`without involving a very complicated manufacturing process.
`3. Serviceability (or maintainability). The equipment under design must
`be readily and easily accessible for testing, repair, or replacement. The
`design approach may also be affected by the system maintenance
`methods-e.g., whether the equipment will be maintained in the field
`or in the shop.
`4. Compatibility. The system, including the coolant used, must be com(cid:173)
`patible with the environment in which it is being used.
`5. Cost. The final product must be cost-effective. Cost may be the most
`important factor in product design. In determining the cost of a
`product, one should consider not only manufacturing but also main(cid:173)
`tenance costs.
`
`SEC et al. v. MRI
`SEC Exhibit 1018.013
`IPR 2023-00199
`
`

`

`6
`
`• THERMAL MANAGEMENT OF MICROELECTRONIC EQUIPMENT
`
`01
`
`02
`
`Cooling
`Air
`
`0 Typical Temperature Profile
`A Optimum Temperature Profile
`
`110
`100
`G)
`90
`.!!!
`~u.
`G) 0 80
`_a 1if 70
`; £ 60
`Ei so
`~ g 40
`.§ <; 30
`g i; 20
`:::,..C
`-, <( 10
`0 _____ .._. .............. __, ........ _ _... ......
`2 3 4 5 6 7 8 910111213
`0
`Component Position
`
`Cooling
`Fins
`
`FIGURE 1.3 Effect of part placement on component junction
`temperature.
`
`The relative importance of these five individual factors is mission-related; for
`example, the cost may become a secondary issue for some military equipment,
`where performance and reliability are the major concerns. A concurrent engi(cid:173)
`neering approach must be adopted in the development of a new product. The
`design philosophy or basic rule is that the best design is the simplest and lowest(cid:173)
`cost one that will meet the specified requirements.
`
`1.5 OPTIMIZATION AND LIFE-CYCLE COST
`
`Because of the strong dependence of microelectronic device reliability on tem(cid:173)
`perature, it is important and desirable in the thermal management of electronic
`systems to pursue temperature distributions that are not merely acceptable but
`are optimal. Mayer [ 4] discusses the opportunities for optimization at all pack(cid:173)
`aging levels. These opportunities include (1) optimal thermal placement of elec(cid:173)
`tronic components on circuit boards and optimal arrangement of boards within
`boxes or assemblies, and (2) optimal distribution of thermally conductive lay(cid:173)
`ers and optimal distribution of coolant flow rates. As an example of the first
`type, Figure 1.3 compares junction temperatures with and without optimiza(cid:173)
`tion at different component positions on a printed circuit board cooled by
`forced-air convection. The left diagram in the figure is for the purpose of illus(cid:173)
`tration and does not include all components. By switching component loca(cid:173)
`tions, a significant improvement in overall temperature (near 40°F reduction
`for half of the components) is found with optimization, even though the maxi(cid:173)
`mum temperature is about the same for both cases. This in turn improves the
`overall system reliability.
`It is important to involve thermal design in the early phase of the equipment
`design process. The design approach should place emphasis at the system level
`for optimizing the thermal control unit. However, since for most electronics there
`
`SEC et al. v. MRI
`SEC Exhibit 1018.014
`IPR 2023-00199
`
`

`

`Introduction
`
`• 7
`
`105 °C (Design Limit)
`
`: ~
`
`I
`
`ailure Rate
`Curves
`
`Components
`
`90°C 110°c 90°C
`
`Heat Sink
`
`1.0
`0.8
`~ 0.6
`0 :c
`...
`o 0.4
`i
`I!!
`.2 0.2
`~
`
`200
`150
`100
`50
`Component Junction Temperature, °C
`
`FIGURE 1.4 Example of current thermal design practice.
`
`is a direct relationship between a component's junction temperature and its fail(cid:173)
`ure rate, the current design practice is often to establish an upper temperature
`limit that is below the maximum allowable temperature set by manufacturers,
`ensuring that no component junction temperatures exceed this temperature
`limit. Currently, an upper limit of 105°C for semiconductor devices is being used
`by the U.S. Air Force and Navy [ 4, 5]. In theory, the actual temperature limit
`should be determined by the required reliability of each individual piece of
`equipment.
`As pointed out by Berger [6], the problem with this temperature limit design
`approach stems from the attempt to analyze the reliability of equipment by look(cid:173)
`ing at the individual components in terms of their temperature rather than their
`actual part failure rate. The goal should not be to minimize component tempera(cid:173)
`tures but to minimize component failure rates that directly impact the reliability
`of the equipment.
`A simplified example given by Berger as shown in Figure 1.4 illustrates the
`preceding statement. Component B, in the center of the layout diagrammed in
`the figure, is at 110°C and thus is the hottest component. A redesign is in order, to
`get the temperature of all parts below l0S°C, if that particular standard is to be
`applied. One of the simplest ways to redesign is just to switch component B with
`component A at left, thereby placing the hot component close to the heat sink.
`Acceptable design criteria would be met under the standard if components A and
`B both turned out to be at 100°C. The graph in the figure reveals, however, that
`the increase in the failure rate of component A for a l0°C rise outweighs the ben(cid:173)
`efits obtained for a 10°C reduction in temperature for component B. The man(cid:173)
`dated redesign actually results in a reduction of the overall reliability of the
`equipment. Any design change, therefore, should not be initiated unless it will be
`an overall improvement in equipment reliability and the change can also be justi(cid:173)
`fied on the basis of a system life-cycle cost (LCC) reduction. In short, the equip-
`
`SEC et al. v. MRI
`SEC Exhibit 1018.015
`IPR 2023-00199
`
`

`

`8
`
`• THERMAL MANAGEMENT OF MICROELECTRONIC EQUIPMENT
`
`ment design should be thermally optimized to minimize the LCC and maximize
`the reliability and operation life of the system.
`
`REFERENCES
`
`1. U.S. Air Force Avionics Integrity Program (AVIP) notes, 1989.
`2. A. Bar-Cohen, A. D. Kraus, and S. F. Davidson, "Thermal Frontiers in the
`Design and Packaging of Microelectronic Equipment," Mech. Eng., June
`1983.
`3. W. F. Hilbert and F. H. Kube, "Effects on Electronic Equipment Reliability of
`Temperature Cycling in Equipment," Report No. EC-69-400 (Final Report),
`Grumman Aircraft Corp., Bethpage, NY, February 1969.
`4. A. H. Mayer, "Opportunities for Thermal Optimization in Electronics Packag(cid:173)
`ing," Proc. 1st Int. Electronics Packaging Soc. Conf, 1981.
`5. "Thermal Design, Analysis, and Test Procedures for Airborne Electronic
`Equipment," MIL-STD-2218, 1987.
`6. R, L. Berger, "A System Approach-Minimizing Avionics Life-Cycle Cost,"
`SAE Technical Paper Series 831107, 13th Intersociety Conf on Environmental
`Systems, San Francisco, 1983.
`7. L. T. Yeh, "Future Thermal Design and Management of Electronic Equip(cid:173)
`ment," in Wei-Jei Yang and Yasuo Mori, eds., Heat Transfer in High Technol(cid:173)
`ogy and Power Engineering, Hemisphere, New York, 1987.
`8. A. D. Kraus, Cooling Electronic Equipment, Prentice-Hall, Englewood Cliffs,
`NJ, 1965.
`9. J. H. Seely and R. C. Chu, Heat Transfer in Microelectronic Equipment: A Prac(cid:173)
`tical Guide, Marcel Dekker, New York, 1972.
`10. A. W. Scott, Cooling of Electronic Equipment, Wiley, New York, 1974.
`11. D. S. Steinberg, Cooling Techniques for Electronic Equipment, Wiley, New
`York, 1980.
`12. A. D. Kraus and A. Bar-Cohen, Thermal Analysis and Control of Electronic
`Equipment, Hemisphere, New York, 1983.
`13. G. N. Ellison, Thermal Computation for Electronic Equipment, Van Nostrand
`Reinhold, New York, 1984.
`14. L. T. Yeh, "Review of Heat Transfer Technologies in Electronic Equipment,"
`J. Electronic Packaging 11 7, 199 5.
`15. M. Pecht, "Why the Traditional Reliability Prediction Models Do Not Work(cid:173)
`Is There an Alternative?" Electronics Cooling 2(1), 1996.
`
`SEC et al. v. MRI
`SEC Exhibit 1018.016
`IPR 2023-00199
`
`

`

`Chapter 2
`
`CONDUCTION
`
`Heat conduction is a process by which heat flows from a region of higher tem(cid:173)
`perature to a region of lower temperature through a solid, liquid, or gaseous
`medium, or between different media in intimate contact. Generally, heat con(cid:173)
`duction is due to movement and interaction of molecules. Therefore, a solid is
`superior to a liquid in transferring heat by conduction because of its shorter dis(cid:173)
`tance between molecules. Similarly, a liquid has better thermal conduction
`characteristics th