Wearable computers are rugged, portable computers that can be comfortably worn on the body and easily operated for maintenance applications. The recently developed process of Shape Deposition Manufacturing has created the opportunity to embed the electronics of wearable computers in a polymer composite substrate. As both a protective outer case and a conductive heat dissipating medium, the substrate satisfies two basic constraints of wearable computer design: ruggedness and cooling efficiency. One such application of embedded electronics is the VuMan3R, a wearable computer designed and manufactured at Carnegie Mellon University for aircraft maintenance. This paper combines finite element numerical simulations, physical experimentation, and analytical models to understand the thermal phenomena of embedded electronic design and to explore the thermal design space. Numerical models ascertain the effect of heat spreaders and polymer composite substrates on the thermal performance, while physical experimentation of an embedded electronic artifact ensures the accuracy of the numerical simulations and the practicality of the thermal design. Analytical models using thermal resistance networks predict the heat flow paths within the embedded electronic artifact as well as the role of conductive fillers used in polymer composites. [S1043-7398(00)00102-X]

Issue Section:
Technical Papers
Keywords:
portable computers, thermal management (packaging), finite element analysis
Topics:
Computer simulation, Computers, Design, Electronics, Flat heat pipes, Heat, Polymer composites, Temperature, Thermal conductivity, Thermal management, Thermal resistance, Boundary-value problems, Electronic components, Heat transfer coefficients, Heat conduction, Finite element analysis, Radiation (Physics)
1.
Johnson, R. D., 1989, “Efficient Cooling Increases Component and Equipment Reliability,” Electrotechnology, reprinted by Technical Manager, IREE Monitor, 15, pp. 15–19, Redpoint Ltd. U.K.
2.
Queipo, N., Humphrey, J. A. C., and Ortega, A., 1996, “Multiobjective Optimization of Component Placement on Printed Wiring Boards,” I-Therm ’96, IEEE InterSociety Conference on Thermal Phenomena, Orlando, FL, pp. 359–372.
3.
Siewiorek
,
D. P.
,
Smailagic
,
A.
,
Lee
,
J.
, and
Tabatabai
,
A. R. A.
,
1994
, “
An Interdisciplinary Concurrent Design Methodology as Applied to the Navigator Wearable Computer System
,”
J. Comput. Software Eng.
,
2
, No.
3
, pp.
259
–
292
.
4.
Amon
,
C. H.
,
Nigen
,
J. S.
,
Siewiorek
,
D. P.
,
Smailagic
,
A.
, and
Stivoric
,
J. M.
,
1995
, “
Concurrent Design and Analysis of the Navigator Wearable Computer System: The Thermal Perspective
,”
IEEE Trans. Compon., Packag. Manuf. Technol., Part A
,
18
, No.
3
, pp.
567
–
577
.
5.
Amon
,
C. H.
,
Egan
,
E.
,
Siewiorek
,
D.
, and
Smailagic
,
A.
,
1997
, “
Thermal Management and Concurrent System Design of a Wearable Multicomputer
,”
IEEE Trans. Compon., Packag. Manuf. Technol., Part A
,
20
, No.
2
, pp.
128
–
137
.
6.
Amon, C., Beuth, J., Kirchner, H., Merz, R., Prinz, F., Schmaltz, K., and Weiss, L., 1993, “Material Issues in Layered Forming,” Proc. Solid Freeform Fabrication Symp., H. L. Marcus et al., eds., Austin, TX, pp. 1–10.
7.
Amon
,
C. H.
,
Beuth
,
J. L.
,
Weiss
,
L. E.
,
Merz
,
R.
, and
Prinz
,
F. B.
,
1998
, “
Shape Deposition Manufacturing With Microcasting: Processing, Thermal, and Mechanical Issues
,”
ASME J. Manuf. Sci. Eng.
,
120
, pp.
656
–
668
.
8.
Bigg
,
D. M.
,
1986
, “
Thermally Conductive Polymer Compositions
,”
Polym. Compos.
,
7
, pp.
125
–
126
.
9.
Egan, E., and Amon, C. H., 1996, “Cooling Strategies for Embedded Electronic Components of Wearable Computers Fabricated by Shape Deposition Manufacturing,” I-Therm ’96, IEEE InterSociety Conference on Thermal Phenomena, Orlando, FL, pp. 13–20.
10.
Egan, E. R., and Amon, C. H., 1997, “A Study on the Thermal Conductivity Enhancement of Several Polymer Composites for Embedded Electronics Applications,” ASME-HTD Proc. of the 32nd National Heat Transfer Conference, 6, pp. 103–109.
11.
Ahmed
,
I.
,
Krane
,
R. J.
, and
Parsons
,
J. R.
,
1994
, “
A Preliminary Investigation of the Cooling of Electronic Components with Flat Plate Heat Sinks
,”
ASME J. Electron. Packag.
,
116
, No.
1
, pp.
60
–
67
.
12.
Ellison, G. N., 1984, Thermal Computations for Electronic Equipment, Van Nostrand Reinhold Company Inc., New York, pp. 75–93.
13.
Incropera, F. P., and De Witt, D. P., 1990, Fundamentals of Heat and Mass Transfer, 3rd ed., John Wiley & Sons, Inc., New York, pp. 533–559 and pp. 794–806.
14.
Egan, E., and Amon, C. H., 1995, “Thermal Design of Wearable Computers: Application to the Navigator2, Thermal Management Devices, and Embedded Electronics,” EDRC Report No. 24-123-95, Carnegie Mellon University, Pittsburgh, PA.
Copyright © 2000
 by ASME
You do not currently have access to this content.