A printed circuit board (PCB) is generally a multilayered board made of dielectric material and several layers of traces and vias. Performing detailed system-level computational fluid dynamics (CFD) simulations of PCBs including meshed trace and via geometries for each of the layers is impractical. In the present approach, the effects of the trace and via geometry are accurately modeled in the physical model by importing electronics computer aided-design data consisting of the trace and via layout of the board and computing locally varying orthotropic conductivity ($kx$, $ky$, and $kz$) on the printed circuit board using a background mesh. The spatially varying orthotropic conductivity is then mapped from the background mesh to the CFD mesh and used in a system-level simulation of the PCB with a minimal increase in the overall computational cost. On the other hand, as PCB component densities increase, the current densities increase thereby leading to regions of hot spots due to Joule heating. Hence, it is essential that the computational heat transfer simulations account for the heating due to the high current carrying traces. In order to accurately model the Joule heating of traces and vias, it is of essence to solve for the conservation of current in each of these traces. In this study, the effects of both trace layer nonhomogeneity and Joule heating are examined on a sample PCB with several components attached to it. The results are then compared with those from the conventional modeling techniques. It is demonstrated that there is considerable difference in the location of the hot spots and temperature values between two different methods.

1.
Graebner
,
J. E.
, and
Azar
,
K.
, 1997, “
Thermal Conductivity Measurements in Printed Wiring Boards
,”
ASME J. Heat Transfer
0022-1481,
119
, pp.
401
405
.
2.
Sarvar
,
F.
,
Poole
,
N. J.
, and
Witting
,
P. A.
, 1990, “
PCB Glass-Fibre Laminates: Thermal Conductivity Measurements and Their Effect on Simulation
,”
J. Electron. Mater.
0361-5235,
19
, pp.
1345
1350
.
3.
Coppola
,
L.
,
Cottet
,
D.
, and
Wildner
,
F.
, 2008, “
Investigation on Current Density Limits in Power Printed Circuit Boards
,”
Proceedings of the 23rd IEEE Applied Power Electronics Conference and Exposition – APEC
, Austin, TX.
4.
Yu
,
E.
, and
Joshi
,
Y.
, 1997, “
Effects of Orthotropic Thermal Conductivity of Substrates in Natural Convection Cooling of Discrete Heat Sources
,”
Numer. Heat Transfer, Part A
1040-7782,
32
, pp.
575
593
.
5.
Eveloy
,
V.
,
Lohan
,
J.
, and
Rodgers
,
P.
, 2000, “
A Benchmark Study of Computational Fluid Dynamics Predictive Accuracy for Component-Printed Circuit Board Heat Transfer
,”
IEEE Trans. Compon. Packag. Technol.
1521-3331,
23
, pp.
568
577
.
6.
Shabany
,
Y.
, 2003, “
Effects of Boundary Conditions and Source Dimensions on the Effective Thermal Conductivity of a Printed Circuit Board
,”
ASME
Paper No. IPACK2003-35201.
7.
Liu
,
W.
,
Lee
,
M.
,
Shabany
,
Y.
, and
Asheghi
,
M.
, 2005, “
A Novel Scheme in Thermal Modeling of Printed Circuit Boards
,”
ASME
Paper No. IPACK2005-73268.
8.
Galloway
,
J.
, and
Shidore
,
S.
, 2004, “
Implementing Compact Thermal Models Under Non-Symmetric Trace Routing Conditions
,”
Proceedings of the 20th IEEE SEMITHERM Symposium
, San Jose, CA.
9.
,
J.
, 2004, “
New Correlations Between Electrical Current and Temperature Rise in PCB Traces
,”
Proceedings of the 20th IEEE SEMITHERM Symposium
, San Jose, CA.
10.
Ling
,
Y.
, 2002, “
On Current Carrying Capacities of PCB Traces
,”
Proceedings of the Electronic Components and Technology Conference
, pp.
1683
1693
.
11.
Mao
,
J.
,
Aleksandrova
,
S.
, and
Molokov
,
S.
, 2008, “
Joule Heating in Magnetohydrodynamic Flows in Channels With Thin Conducting Walls
,”
Int. J. Heat Mass Transfer
0017-9310,
51
, pp.
4392
4399
.
12.
IPC-2221
, 1998, “
Generic Standard for Printed Wiring Boards
,” p.
38
.
13.
FLUENT 6.3.36 User’s Guide2007, Lebanon, NH.
14.
Patankar
,
S. V.
, 1980,
Numerical Heat Transfer and Fluid Flow
,
Hemisphere Publishing Co.
,
New York, NY
.
15.
ANSYS ICEPAK 12.0.2 User’s Guide2009.