Matthew E. Moran

Glenn Research Center, Cleveland, Ohio

Micro-Scale Avionics Thermal Management

NASA/TM—2001-211095

August 2001
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NASA/TM—2001-211095

August 2001

National Aeronautics and

Space Administration

Glenn Research Center

Prepared for the

34th International Symposium on Microelectronics

sponsored by the International Microelectronics and Packaging Society

Baltimore, Maryland, October 9–11, 2001

Matthew E. Moran

Glenn Research Center, Cleveland, Ohio

Micro-Scale Avionics Thermal Management
Available from

NASA Center for Aerospace Information

7121 Standard Drive

Hanover, MD 21076

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22100

This report is a preprint of a paper intended for presentation at a conference. Because

of changes that may be made before formal publication, this preprint is made

available with the understanding that it will not be cited or reproduced without the

permission of the author.

Available electronically at http://gltrs.grc.nasa.gov/GLTRS
Micro-Scale Avionics Thermal Management 

Matthew E. Moran 

National Aeronautics and Space Administration

 Glenn Research Center 

21000 Brookpark Road 

Cleveland, Ohio 44135 

Phone: 216–433–8324, Fax: 216–433–8311, Email: mmoran@grc.nasa.gov

Abstract 

Trends in the thermal management of avionics and commercial ground-based microelectronics are converging, and 

facing the same dilemma: a shortfall in technology to meet near-term maximum junction temperature and package 

power projections. Micro-scale devices hold the key to significant advances in thermal management, particularly 

micro-refrigerators/coolers that can drive cooling temperatures below ambient. A microelectromechanical system 

(MEMS) Stirling cooler is currently under development at the NASA Glenn Research Center to meet this challenge 

with predicted efficiencies that are an order of magnitude better than current and future thermoelectric coolers. 

Introduction 

 The critical need for advanced thermal 

management technologies is well recognized in the 

semiconductor industry. In fact, according to Intel’s 

Chief Technology Officer Pat Gelsinger, heat is 

becoming one of the most critical issues in computer 

and semiconductor design [1]. The most recent 

edition of The International Technology Roadmap for 

Semiconductors (ITRS) predicts [2]: 

“... the thermal management challenge will 

significantly increase in the future due to 

increasing power, decreasing junction 

temperatures, and a continuing need to have 

cost-effective solutions.” 

 Examination of key projections extracted 

from the ITRS data, and plotted in Fig. 1, 

demonstrates how decreasing junction temperatures 

and increasing power are combining to accelerate the 

thermal management challenge. According to these 

projections, there are no known solutions for 

reaching the reduced junction temperature predicted 

for 2002 and beyond for both high-performance and 

cost-performance (i.e. desktop) systems. Single-chip 

package power reaches this same technology void a 

few years later in 2005 for high-performance 

systems, and somewhere between 2005 and 2008 for 

cost-performance systems. Clearly the need exists 

for advanced thermal management technologies 

development that will meet the junction temperature 

and power dissipation requirements looming on the 

horizon. 

Fig. 1: Projections for package power and 

allowable junction temperature illustrate thermal 

management technology void beginning in 2002. 

Convergence of Thermal Management

 Thermal management of electronics in 

aerospace vehicles (i.e. avionics) is driven by two 

unique environmental factors: limited or no air 

cooling and low gravity. Limited or no air cooling 

results from either high altitude operation where the 

air density and corresponding cooling capacity is 

reduced; or the vacuum of space where all heat must 

ultimately be dissipated by thermal radiation. Low 

gravity conditions, encountered in low-earth orbit and 

beyond, results in negligible buoyancy forces and the 

subsequent practical absence of natural convection. 

Historically, these unique environmental drivers have 

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NASA/TM—2001-211095 1
tended to split the development paths of avionics 

cooling systems relative to commercial ground-based 

electronics systems where natural and forced 

convection air cooling have been routinely employed. 

 More recent drivers in the commercial 

electronics market, however, are causing these 

previously disparate development paths to converge 

in many respects. For example, acoustic noise 

concerns in commercial electronic systems are 

limiting the use of fan cooling; as is the trend toward 

portable devices such as notebook computers, 

personal digital assistants, cell phones, and the like. 

These portable systems are both volume and power 

constrained, and therefore often incompatible with 

fan cooling requirements. In some cases even breadand-butter cooling devices such as finned heat sinks 

are unusable due to the lack of sufficient volume to 

maintain effective natural convection circulation. 

Consequently, heat pipes and conduction methods 

routinely used in avionics are becoming more 

common in commercial systems. 

 Other key drivers – increased heat flux, 

reduced volumes, and lower junction temperatures – 

are equally prevalent in both avionics and 

commercial electronics. As a result, thermal 

management techniques developed in the aerospace 

arena are becoming increasingly relevant to 

consumer electronics, and visa-versa. In both realms, 

thermal management systems are moving beyond 

“fins & fans” into cooling solutions that are 

performance optimized for a particular application; 

and in some cases integrated into the electronics itself 

– often at the chip package level. The pervasive 

trend of continued miniaturization, which has been 

driving the microelectronic industry for decades, is 

also shared by both avionics and commercial 

systems. 

 Avionics and commercial ground-based 

electronics systems still differ of course in terms of 

their economic drivers. In general the primary driver 

for avionics is performance; whereas, price drives 

commercial systems. However, the use of 

commercial off-the-shelf (“COTS”) components in 

avionic systems is a major thrust in recent years 

reflecting the growing emphasis of price (and 

availability) in aerospace applications. Similarly, 

although targeting a price point based on market 

forces is the key economic driver for commercial 

electronics, performance provides critical product 

differentiation in an ever increasingly competitive 

marketplace. Therefore, even in terms of economic 

drivers, avionics and commercial ground-based 

electronic systems have far more in common now 

than in years past. 

The Thermal Management Toolbox 

 Thermal management techniques can be 

conveniently grouped into passive and active. 

Passive methods, which do not require any input 

power, tend to be very reliable and relatively easy to 

implement. However, they are also performance 

limited and therefore inadequate for many highpower applications. Passive methods include: 

• Natural convection (finned heat sinks, ventilation 

slots, board/component placement, etc.) 

• Radiation (paints, coatings, mechanical surface 

treatments, component layout, etc.) 

• Conduction (structures, vias, elastomers, pastes, 

adhesives, pads, chip packages, etc.) 

 Strictly speaking, capillary and phase 

change methods (e.g. heat pipes, wicks, melting wax, 

boiling, etc.) are also passive methods. However, 

they generally provide higher performance 

capabilities and are not as easily implemented as the 

other passive methods. In addition, phase change 

devices are limited in terms of their operating 

temperatures, which are determined by the saturation 

temperature of the working fluid (or melting 

temperature of the solid). 

 Active thermal management techniques – 

those that require input power – provide increased 

performance/capacity, but generally at the price of 

lower reliability and added complexity. Active 

methods include: 

• External forced convection (fans, nozzles, etc.) 

• Pumped loops (heat exchangers, cold plates, etc.) 

• Refrigerators & coolers (thermoelectric/Peltier, 

vapor-compression, vortex, gas cycles, etc.) 

 It should be noted that heating (e.g. 

resistance, induction, etc.) is also an active thermal 

management tool for applications where a lower 

temperature boundary must be avoided. Aerospace 

applications requiring heating are common due to the 

effective thermal radiation sink temperature of space 

being a few degrees above absolute zero. On earth, 

cold region applications may also require heating. In 

addition, measurement electronics or other systems 

where a fixed temperature band must be maintained 

often require an integrated cooling and heating 

system with temperature feedback control. 

Micro-Scale Thermal Management

 While the traditional thermal management 

techniques described above have provided systemlevel cooling sufficient to meet past electronics 

cooling requirements, they are unable to meet future 

requirements in their current form as evidenced by 

the ITRS projections [2]. Miniaturization of thermal 

management techniques to the micro-scale, which has 

NASA/TM—2001-211095 2
lagged the semiconductor industry’s advances in 

microelectronics, is receiving increased attention as a 

solution to the future thermal management 

technology shortfall. Micro-scale thermal 

management offers several enticing opportunities: 

1. Ability to “spot cool” high heat flux regions 

with unparalleled resolution to bring down 

critical junction temperatures. 

2. Potential for macro-level performance leaps by 

optimizing micro-level heat transfer. 

3. Improved integration of thermal management at 

the chip level using compatible semiconductor 

materials and fabrication techniques. 

4. Enabling of system-level miniaturization to 

support the pervasive trend toward increased 

capabilities in smaller devices. 

 In addition to increased heat flux for 

traditional scale avionics, the aerospace industry’s 

interest in micro-scale thermal management is being 

driven in part by NASA’s plans to develop microsatellites/spacecraft, and embedded miniature sensors 

and actuators [3]. Likewise, the commercial 

electronics adoption of microsystems is evidenced by 

a recent market study predicting an increase in 

MEMS use in consumer electronics from $200 

million in 2000 to more than $1.5 billion in 2005, 

excluding inkjet print heads and hard disk drives [4]. 

Applications include camcorders, digital cameras, 

cell phones, optical drives, laptops, portable CDs and 

DVDs, game controllers, MP3 players, PDAs/Pocket 

PCs, and digital projection TVs. Currently found in 

less than 0.1% of these consumer electronics 

products, MEMS devices are expected to be found in 

nearly 5% by 2004; and will take until 2006 to 

approach 10%. 

Recent Developments & Ongoing Research

There is a wide range of new technology 

developments in micro-scale thermal management; a 

complete overview of the topic is well beyond the 

scope of this paper. However, brief discussion of a 

few relevant examples sheds some light on the 

promise the field holds for cooling microelectronics. 

 A good deal of work has been done relative 

to microchannels that provide increased surface area 

for improved heat transfer. These devices are 

generally limited to laminar flow regimes since the 

increased surface area also increases pressure drop 

and the subsequent pumping power required. The 

channels can be micromachined from bulk 

semiconductor material, or fabricated by other means 

with a variety of materials. “Microtubes”, for 

example, have been developed by Edwards Air Force 

Base using copper, silver, platinum, glasses, 

polymers, alloys, and other materials with diameters 

ranging from 0.5 to 410 microns [5].

 Development of micro-scale wicking 

structures utilizes surface tension forces of the 

working fluid to induce flow without active pumping. 

Used in conjunction with evaporator and condenser 

regions, these wicking structures become a critical 

component of micro-heat pipes. NASA Glenn 

Research Center has funded work in this area by the 

University of Cincinnati that has fabricated a working 

wick structure with a coherent pattern of 2.5 micron 

diameter pores (channels) 260 microns in length [6]. 

The wick is part of a micromachined silicon loop heat 

pipe concept for removing heat at the chip level with 

a predicted heat flux cooling capacity greater than 

100 W/cm2

. 

 Improved materials offer enhanced microscale thermal conduction. Diamond films have long 

been a material of particular interest in high 

performance electronics cooling due to their unusual 

combination of superior thermal conductivity (~2000 

W/m-o

K) yet low electrical conductivity. Argonne 

National Laboratory has developed a nanocrystalline 

diamond film from fullerenes resulting in freestanding diamond structures as thin as 0.3 microns 

[7]. Another example is the emerging developments 

in carbon nanotubes that offer the potential for ultrahigh strength structures with outstanding thermal 

conduction characteristics (e.g. >5000W/m-o

K). 

Micro-Refrigerators/Coolers

 Micro-refrigerators and coolers have a 

unique characteristic for chip-level cooling that 

differentiates them from all other potential thermal 

management technologies: the ability to generate 

cooling temperatures well below the ambient 

temperature. This key advantage potentially allows 

junction temperatures to be driven much lower 

resulting in improved reliability, faster performance, 

and operation in higher temperature environments. 

Note that each 10o

C drop in transistor temperature 

results in a 1-3% increase in semiconductor switching 

time [8]. 

 Thermoelectric or Peltier coolers are the 

most common refri gerati on devi ces used for 

electronics cooling, and have been scaled to the 

micro-domain. Unfortunately thermoelectrics have 

very low efficiencies resulting in high power 

requirements and added waste heat. At a no-load 

cooling temperature of 0o

C and a rejection 

temperature of 25o

C, current thermoelectric 

technology has a coefficient of performance (COP; 

the ratio of cooling capacity to input power) of 

approximately 0.3; and predicted to improve to only 

0.4 in the next decade [9]. 

 Much higher efficiencies are possible with 

the Stirling refrigeration cycle. For the same 

conditions described above, current Stirling coolers 

NASA/TM—2001-211095 3
have a COP on the order of 5.0, or roughly an order 

of magnitude increase in efficiency relative to 

thermoelectrics. However, attempts to miniaturize 

such a device for application in electronics cooling 

have been size-limited by the use of traditional 

components (e.g. pistons, linkages, and pressure 

vessels) and traditional fabrication methods [10,11].

 As a result, Stirling coolers have been 

impractical for most electronic packaging 

applications. The only attempt known by the author 

to approach the micro-scale is documented in a series 

of cryocooler patents that use diaphragms instead of 

pistons to drive the working gas[12]. 

MEMS Stirling Cooler 

A device for bringing the inherent high 

efficiency and cooling capacity of the Stirling 

refrigeration cycle to the micro-domain is under 

development at the NASA Glenn Research Center, 

and merges two core capabilities at the Center: 

Stirling machines and microsystems. NASA Glenn 

has been developing Stirling machines for power 

generation and cooling for decades; and more 

recently has developed microsystems capabilities 

initially focused on harsh environments using silicon 

carbide, and is now expanding to other areas. 

Figure 2 illustrates how an ideal Stirling 

cycle for refrigeration is produced using a traditional 

piston-bore geometry and a regenerative heat 

exchanger; along with the corresponding pressurevolume and temperature-entropy diagrams. 

Fig. 2: The Stirling refrigeration cycle creates a 

cold (expansion) region and a hot (compression) 

region. 

 The ideal cycle starts with compression of 

the working gas from state 1 to 2 in an ideally 

isothermal process that increases the pressure and 

decreases the gas volume. The gas is then cooled in a 

constant volume process as it is forced through the 

regenerator into the expansion space (state 2 to 3). 

From state 3 to 4, the working gas is expanded in an 

isothermal process that decreases the pressure and 

i ncreases the gas volume. The cycle returns to i ts 

original state (state 4 to 1) with the heating of the gas 

in a constant volume process as it is forced back to 

the compression space through the regenerator. 

 During steady state operation, this cycle 

produces a cold region in the expansion space for 

cooli ng/refri gerati on and a hot regi on i n the 

compression space for heat dissipation. The 

regenerative heat exchanger functions as thermal 

capacitor transferring heat to and from the working 

gas as it is forced between the expansion and 

compression spaces by the pistons. 

Device Description

 The MEMS Stirling cooler uses diaphragms 

instead of pistons to produce a Stirling refrigeration 

cycle, and is fabricated with semiconductor 

processing techniques to produce a device with 

planar geometry. The result is a flat cold surface for 

extracting heat and an opposing flat hot surface for 

thermal dissipation. Figure 3 shows a partial 

crossectional sketch of one Stirling cycle “cell”. A 

typical device would be composed of numerous such 

cells arranged in parallel and/or in series, with all 

layers joined at the periphery of the device to 

hermetically seal the working gas. 

Fig. 3: Crossectional sketch of one “cell” of the 

MEMS Stirling cooler illustrates the key 

components of the device. 

 The expansion and compression diaphragms 

are the only moving parts, and are deflected toward 

and away from the regenerator region in phaseshifted sinusoidal fashion to produce the Stirling 

refrigeration cycle. Expansion of the working gas 

directly beneath the expansion diaphragm in each 

cycle creates a cold (top) end for extracting heat; 

while compression at the other (bottom) end creates a 

hot region for dissipating heat. 

 Heat is transferred to and from the working 

gas as it is forced through the regenerator region by 

the moving diaphragms. The slanted geometries of 

s

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v T

Regenerator

Compression

Space (hot)

Expansion

Space (cold)

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Regenerative Cooling

Expansion

Regenerative Heating s

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Regenerative Cooling

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Diaphragm

Motion

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Motion

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Diaphragm

Compression

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Cap Plate

Cap Plate

Regenerator

A A

View A-A

NASA/TM—2001-211095 4
the diaphragm and regenerator surfaces are 

characteristic of the wet etching process used to 

create the structure, and advantageously increase the 

potential swept volume in the expansion and 

compression regions. The regenerator can 

alternatively be made up of constant crossection 

passages that are created after the regenerator layers 

are bonded.

 A thin film temperature sensor deposited on 

the surface of the cap plate (not shown) provides 

control feedback. This sensor, along with the ability 

to switch hot and cold ends by altering the cycle with 

control software, permits the device to be used for 

precise thermal control as well as cooling. 

 Unique characteristics of the device include: 

scalability, modularity, simplified interfaces, robust 

design, and minimal vibration. The ability to 

fabricate the device at the microsystem level brings 

precise temperature control and cooling capabilities 

to a rapidly expanding variety of micro-scale devices. 

Modular design allows for operation of identical 

devices in parallel to increase capacity, or staging of 

identical devices by stacking in series to obtain lower 

temperature ranges. Electrical power alone is 

required for operation; and structurally-deflected 

diaphragms are the sole moving parts of the device 

resulting in limited failure modes. Induced vibration 

is minimized by the low inertial forces produced by 

the diaphragms, and can be potentially eliminated by 

the use of multiple devices operating out-of-phase 

with each other. 

 The MEMS Stirling cooler advances thermal 

management capabilities for microelectronics in four 

key areas: 

1. Extended environmental temperature ranges 

2. Precision spatial and temporal thermal control 

for temperature sensitive devices 

3. Lowered operating temperature for increased 

reliability and performance 

4. Enabling of micro-scale devices that require 

active cooling and/or temperature control 

Theoretical Performance

 The results of a first-order analysis of the 

device [13] are shown in Fig. 4. Based on the design 

parameters and assumptions shown, energy (per cycle 

frequency, unit device volume, and initial working 

gas pressure) is plotted as a function of the 

temperature ratio between the hot and cold ends. 

Using this performance plot, the heat extracted and 

dissipated for a given power input and temperature 

differential can be estimated for an application of 

interest. 

 For example, assume the case temperature 

of a chip package is to be maintained at 20o

C 

(293o

K). Approxi mately 6 cm3 (less than one-inch 

square by 3/8-inch thick) of volume is available on 

the top surface of the chip to mount the MEMS 

cooler. If the warm upper end of the cooler is set at 

80o

C (353oK) to dissipate heat to the ambient air, 

then the absolute temperature ratio is 1.2. Assuming 

the MEMS cooler has an initial working gas pressure 

of 20 bars and operates at 1KHz, Fig. 2 yields the 

following theoretical performance estimates: 

» Heat extracted = 168 W 

» Heat rejected = 204 W 

» Power input = 36 W 

Fig. 4: Performance plot based on a first-order 

analysis of the MEMS Stirling cooler provides an 

estimate of the theoretical performance for chosen 

operating conditions. 

 In the previous example, the 204 W must be 

rejected from the hot surface of the MEMS Stirling 

cooler (e.g. by conduction to the metal chassis of the 

device) in order to supply the 168 W of cooling at the 

cold surface. That is, the overall cooling system must 

be balanced and properly designed from chip package 

to heat sink in order to realize the theoretical cooling 

capacity indicated. However, the key feature of the 

MEMS Stirling cooler is the ability to drive the cold 

surface below ambient resulting in cooler junction 

temperatures; while driving the hot end to high 

temperatures (compared to a passive device) resulting 

in higher driving temperature differentials, and higher 

subsequent heat dissipation efficiency.

Development Approach & Challenges

 The initial concept and analysis for the 

MEMS Stirling cooler was created in-house at NASA 

Glenn, and a patent application has been submitted 

based on the technology. The next phase of 

development is focused on building a working model 

by teaming with key partners possessing the critical 

capabilities needed. 

 Several primary challenges must be 

addressed with the working model prior to optimizing 

a prototype design. First, the diaphragm actuation 

technique must be developed and demonstrated to 

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Temperature Ratio [K/K]

Energy [mW/(KHz-mm^3-bar)]

Individual Cell Parameters:

•Height = 0.310 mm

•Width = 0.145 mm

•Volume = 0.007 mm^3

•Regenerator thickness = 10 microns/layer

•Regenerator layers = 4

•Regenerator orifice size = 2 microns

•Regenerator openings per layer = 4

•Diaphragm thickness = 45 microns

Individual Cell Parameters:

•Height = 0.310 mm

•Width = 0.145 mm

•Volume = 0.007 mm^3

•Regenerator thickness = 10 microns/layer

•Regenerator layers = 4

•Regenerator orifice size = 2 microns

•Regenerator openings per layer = 4

•Diaphragm thickness = 45 microns

Assumptions

1. Perfect regeneration

2. Constant instantaneous pressure

3. Ideal gas behavior

4. Constant gas mass

5. Sinusoidal volume variations

6. Cap plate temp = diaphragm temp

7. Constant diaphragm & wall temps

8. Perfect gas mixing

Heat Rejected

Heat Extracted

Power Input

Optimized swept 

volume ratio & 

phase angle at each 

temperature ratio

Region of

interest

NASA/TM—2001-211095 5
produce the required force to compress, expand, and 

transfer the working gas. Second, details of the 

control electronics to drive the diaphragms and 

related electrical connections must be defined and 

tested. 

 A third area requiring attention is the 

regenerator design. The regenerator must be 

thermally conductive in the direction perpendicular to 

the flow passages to permit effective heat transfer to 

and from the working gas. At the same time, the 

regenerator must be thermally isolating in the (axial) 

direction parallel to the passages in order to maintain 

the required temperature differential between the 

expansion and compression regions, and minimize 

performance losses due to axial conduction. The 

layered construction of the regenerator is compatible 

with these requirements, allowing insulating coating 

materials (e.g. silicon dioxide) between layers and 

potential removal of bulk silicon by selective wet 

etching to increase the axial regenerator thermal 

resistance in the axial direction. 

 The interface between the cap plate and 

diaphragm layers is a fourth area of concern. 

Structural design and operation of the device must 

maximize heat transfer from the expansion and 

compression spaces to their respective cap plates. In 

addition, gas film damping between the diaphragms 

and cap plate must be addressed. 

 Finally, packaging of the working model – a 

crucial issue in general for MEMS devices – will 

require hermetic sealing of the pressurized working 

gas. For the working model, this may be limited to 

low pressure air. However, in an optimized 

prototype, the working pressure will be maximized 

since the device performance is directly (linearly) 

proportional to this parameter. The prototype may 

also utilize helium or hydrogen as a working gas, 

which may necessitate the use of diffusion mitigating 

coatings such as nitride. 

Concluding Remarks 

 Micro-scale thermal management devices 

hold promise for meeting the upcoming technology 

void in avionics and commercial electronics cooling 

technologies. Current and ongoing research in 

microchannels/tubes, micro-heat pipes, high 

conductivity micro/nano materials, and microrefrigerators offer the potential for significant leaps in 

thermal management performance relative to existing 

technologies routinely used in practice. 

One such technology under development at 

the NASA Glenn Research Center, a MEMS Stirling 

cooler, will permit below-ambient cooling and 

temperature control at efficiencies that are an order of 

magnitude improvement over current and future 

thermoelectric coolers. This technology has notable 

implications for microelectronic thermal management 

including the enabling of further system-level 

miniaturization. Furthermore, advances in this 

technology may lead to related developments of 

MEMS power converters that operate on the Stirling 

cycle to convert heat (e.g. dissipated from 

microelectronic components) into electrical power. 

References 

[1] CNET News.com, February 5, 2001. 

[2] “International Technology Roadmap for 

Semiconductors: 1999 Edition”, Assembly and 

Packaging section, Semiconductor Industry 

Association. 

[3] “NASA Strategic Plan 2000”, NPD 1000.1b, 

September, 2000. 

[4] “Market Forecast Sees Rise of MEMS in 

Consumer Electronics”, Micromachine Devices, 

Vol. 6, No. 3, p. 4, March, 2001. 

[5] Federal Lab Consortium Newslink, February, 

2001. 

[6] Hoelke, A., et.al., “Analysis of the Heat Transfer 

Capacity of a Micromachined Loop Heat Pipe”, 

International Mechanical Engineering Congress 

& Exposition, The Winter Annual Meeting of 

ASME (WAM), November, 1999. 

[7] “Coming to a MEMS Near You”, Mechanical 

Engineering, February, 2001. 

[8] Schmidt, Roger, “Low Temperature Electronic 

Cooling”, Electronics Cooling Journal, Vol. 6, 

No. 3, pp. 18-24, September, 2000. 

[9] Phelan, P.E., Chiriac, V., and Lee, T.T., “Current 

and Future Miniature Refrigeration Cooling 

Technologies for High Power Microelectronics”, 

Proceeding of the SEMI-THERM XVII, San 

Jose, CA, March 20-22, 2001. 

[10] Stetson, N.B., “Miniature Integral Stirling 

Cryocooler”, U.S. Patent No. 5,056,317, October 

15, 1991. 

[11] Solomon, R., “Integrated Refrigerated Computer 

Module”, U.S. Patent No. 5,349,823 (Assignee: 

Intel Corp.), September 27, 1994. 

[12] Bowman, L., et.al., “Microminiature Stirling 

Cycle Cryocoolers and Engines”, U.S. Patent 

No. 5,457,956 (10/17/95) and continued-in-part 

in 5,749,226 (5/12/98) and 5,941,079 (8/24/99) 

(Assignee: Ohio Univ.). 

[13] Moran, M.E., “Multidisciplinary Analysis of a 

Microsystem Device for Thermal Control”, 

Proceedings of the 11th Thermal & Fluids 

Analysis Workshop, Cleveland, OH, August 21-

25, 2000. 

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12

Micro-Scale Avionics Thermal Management

Matthew E. Moran

MEMS; Microsystems; Refrigerator; Microelectromechanical systems;

Microelectronics; Coolers; Stirling cycle

Unclassified -Unlimited

Subject Categories: 34, 33, and 18 Distribution: Nonstandard

Prepared for the 34th International Symposium on Microelectronics sponsored by the International Microelectronics and

Packaging Society, Baltimore, Maryland, October 9–11, 2001. Responsible person, Matthew E. Moran, organization code

5490, 216–433–8324.

Trends in the thermal management of avionics and commercial ground-based microelectronics are converging, and facing

the same dilemma: a shortfall in technology to meet near-term maximum junction temperature and package power projections. Micro-scale devices hold the key to significant advances in thermal management, particularly micro-refrigerators/

coolers that can drive cooling temperatures below ambient. A microelectromechanical system (MEMS) Stirling cooler is

currently under development at the NASA Glenn Research Center to meet this challenge with predicted efficiencies that are

an order of magnitude better than current and future thermoelectric coolers.