The thermal resistance of electronic components is known to often differ considerably between standard test conditions and those found in service. One way to correct for this is to use multi-parameter thermal resistances. Another, presented here, is to adjust the junction-to-ambient thermal resistance to account for operational conditions. For forced convection applications, two factors are proposed; the first accounts for any upstream aerodynamic disturbance and the second addresses purely thermal interaction. Thus if an upstream powered component interacts with a downstream component, the two factors are combined. It is shown that both factors may be quantified in terms of readily measured temperatures and then used as coefficients to adjust the standard thermal resistance data for operational conditions. To overcome the misconception that the currently published single-value thermal resistances are solely a property of the electronic package, thermal resistance is redefined to include both the resistance of the package and the part of the printed circuit board (PCB) covered by the component thermal footprint. This approach is applied to a symmetrical array of board mounted 160-lead devices and data showing how the factors vary with component position, nondimensional power distribution and Reynolds number is presented. Based on data a new method of generating operational component thermal resistances is proposed. [S1043-7398(00)00603-4]

Issue Section:
Technical Papers
Keywords:
packaging, thermal resistance, forced convection, plastic packaging, printed circuit layout
Topics:
Electronic components, Temperature, Thermal resistance, Junctions
1.
Pecht, M., Lall, P., and Hakim, E., 1995, “Temperature as a Reliability Factor,” Eurotherm Seminar No. 45: Thermal Management of Electronic Systems, IMEC, Leuven, Belgium.
2.
Bar-Cohen
,
A.
,
1993
, “
State-of-the-Art and Trends in Thermal Packaging of Electronic Equipment
,”
ASME J. Electron. Packag.
,
114
, pp.
257
–
270
.
3.
Manno
,
V. P.
, and
Azar
,
K.
,
1990
, “
Thermal-Fluid Interactions of Neighbouring Components on Air-Cooled Circuit Boards
,”
ASME J. Electron. Packag.
,
113
, Mar., pp.
374
–
381
.
4.
Dutta, V. B., 1988, “Junction-to-Case Thermal Resistance–Still a Myth?,” Proceedings of the 4th Annual IEEE SEMI-THERM Symposium, pp. 8–11.
5.
Joiner, B., 1994, “Evaluation of Thermal Characterization Techniques,” Proceedings of the IEPS Conference, pp. 413–420.
6.
Malhammer, A., 1993, “An Experimental Method for Determining Two Thermal Parameters in Microcircuit Packages,” Presented at EUROTHERM Seminar No. 29–Thermal Management of Electronic Systems, Delft, Holland.
7.
Seigal, B. S., 1988, “Factors Affecting Semiconductor device Thermal Resistance Measurements,” Proceedings of the 4th Annual IEEE SEMI-THERM Symposium, pp. 12–18.
8.
Azar, K., 1993, “A New Method for the Measurement of External and Internal Thermal Resistances,” Presented at EUROTHERM Seminar No. 29, Thermal Management of Electronic Systems, Delft, Holland.
9.
Rosten, H. I., 1995, “Delphi–A Status Report on the ESPRIT Funded Project for the Creation and Validation of Thermal Models of Electronic parts,” Presented at EUROTHERM Seminar No. 45, Thermal Management of Electronic Systems, Leuven, Belgium.
10.
Guenin
,
B. M.
,
Chowdhury
,
A.
,
Groover
,
R.
, and
Derian
,
E. J.
,
1996
, “
Analysis of Thermally-Enhanced SOIC Packages
,”
IEEE Trans. Compon., Packag. Manuf. Technol., Part A
,
19
, No.
4
, Dec., pp.
458
–
468
.
11.
Lin, P. C., and Nguyen, L. T., 1993, “Thermal Characteristics of IC Packages,” Presented at EUROTHERM Seminar No. 29, Thermal Management of Electronic Systems, Delft, Holland.
12.
Davies, M., Lohan, J., Punch, J., and Moore, T., 1993, “The Thermal Characteristics of a Board-Mounted 160-lead Plastic Quad Flat Pack,” Proceedings of EUROTHERM Seminar 29, Thermal Management of Electronic Systems, pp. 287–296.
13.
Lohan, J., and Davies, M. R. D., 1994, “Transient Thermal Behavior of a Board-Mounted 160-lead Plastic Quad Flat Pack,” Presented at ITHERM Thermal Phenomena in Electronic Systems Conference, Washington, May.
14.
Lohan, J., and Davies, M. R. D., 1996, “Thermal Interaction Between Electronic Components,” ASME Proceedings of the 31st National Heat Transfer Conference, HTD-Vol. 329, Vol. 7, Houston, Texas, pp. 73–82.
15.
Lohan, J., Davies, M., and Cole, R., 1997, “Thermal Superposition on a Populated Printed Circuit Board,” ASME Proceedings of the 32nd National Heat Transfer Conference, HTD-Vol. 343, Vol. 5, Baltimore, MD, pp. 73–82.
16.
Kang
,
S.
,
1994
, “
The Thermal Wake Function for Rectangular Electronic Modules
,”
ASME J. Electron. Packag.
,
116
, Mar., pp.
55
–
59
.
17.
Anderson
,
A. M.
, and
Moffat
,
R. J.
,
1992
, “
The Adiabatic Heat Transfer Coefficient and the Superposition Kernel Function: Part 1-Data for Arrays of Flatpacks for Different Flow Conditions
,”
ASME J. Electron. Packag.
,
114
, Mar., pp.
14
–
21
.
18.
Moffat
,
R. J.
, and
Anderson
,
A. M.
,
1990
, “
Applying Heat Transfer Coefficient Data to Electronics Cooling
,”
ASME J. Heat Transfer
,
112
, pp.
882
–
890
.
19.
Rosten, H. I., Parry, J. D., Addison, J. S., Viswanath, R., Davies, M., and Fitzgerald, E., 1995, “Development, Validation and Application of a Thermal Model of a Plastic Quad Flat Pack,” Presented at the 45th Electronic Component Technology Conference, Las Vegas.
20.
Rodgers, P., Eveloy, V., Lohan, J., Fager, C. M., Tillika, P., and Rantala, J., 1999, “Experimental Validation of Numerical Heat Transfer Predictions for Single- and Multi-Component Printed Circuit Boards in a Natural Convection Environments,” Proceedings of the 15th IEEE SEMI-THERM Symposium, pp. 55–64.
21.
JEDEC International Standards, 1999, JESD51-7 “High Effective Thermal Conductivity Test Board for Leaded Surface Mount Packages,” Electronic Industries Alliance, Eng. Dept.
22.
Arvizu, D. E., and Moffat, R. J., 1982 “The Use of Superposition in Calculating Cooling Requirements for Circuit Board Mounted Electronic Components,” Proceeding of the 32nd Electronic Components Conference IEEE EIA and CHMT, San Diego, California, May, pp. 133–144.
23.
Biber, C. R., and Sammakia, B. G., 1986 “Transport from Discrete Heated Components in a Turbulent Channel Flow,” ASME Paper No. 86-WA/HT-68, pp. 1–9.
24.
Dalton, T. M., and Davies, M. R. D., 1997, “Convection Dimensional Analysis,” ASME Proceedings of the 32nd National Heat Transfer Conference, HTD-Vol. 346, Vol. 8, Baltimore, MD, pp. 33–39.
25.
Punch, J., and Davies, M. R. D, 1997, “Still-Air Junction-to-Ambient Thermal Resistances of Different Devices as Functions of the Effective Conductivity of Printed Circuit boards,” Presented at the EUROTHERM Seminar No. 58, Thermal Management of Electronic Systems, Nantes, France, Sept.
26.
SEMI International Standards, 1992, “G38-87 Test Method–Still and Forced, Junction-to-Ambient Thermal Resistance Measurements if Integrated Circuit Packages,” Packaging Volume, pp. 173–177.
27.
SEMI International Standards, 1992, “G42-88 Test Method–Thermal Test Board Standardisation for Measuring Junction-to-Ambient Thermal Resistance of Semiconductor Packages,” Packaging Volume, pp. 195–200.
28.
Holman, J. P., 1989 Experimental Methods for Engineers, McGraw-Hill, New York.
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