C. F. LIN ET AL.
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or TIM2 decreases, the thermal
pe
s but the improve-
m
ce of the assembly increa-
se
nd to have lesser impact o
pa
FERENCES
[1] G. H. Wu, S.HThree-Dimensional
Finite Elemenechanical Behavior
terial selection. Increasing the fin length, fin number, and
base thickness of the extruded-fin heatsink results in in-
creased thermal performance of the assembly. For the
cases studied, simulation results show that the fin length
and fin number have a stronger influence on the thermal
performance than base thickness. The effect of fin thick-
ness is negligibly small.
2) As for conductivity, when TIM1 or TIM2 increases
or the thickn ess of TIM1
rformance of the assembly increases. Simulation re-
sults show that TIM1 has a stronger influence on assem-
bly thermal performance than TIM2.
3) As conductivity of the underfill increases, thermal
performance of the assembly increase
ent is not very significant.
4) It is found that as the thickness of the substrate core
decreases, thermal performan
s. Thermal performance of the assembly can be en-
hanced by using a thinner core. Also, higher conductivity
of the substrate core is desirable for better thermal per-
formance of the assembly.
5) The effects of the lid-substrate adhesive parameters
are also considered and foun
ckage thermal performance. However, higher conduc-
tivity and lower thickness of the lid-substrate adhesive
are found preferable.
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Nn: empirical factor.
P:it bd.
device power, W.
: empirical factor. ll grid array. PCB: printed circuoar
FC-PBGA: flip-chip plastic ba
a
T
: temperature difference between the surface and
: heat dissipation rate per unit volume in the chip, the ambient air, ˚C.
T
: ambient air tem
3. Wm
kperature, ˚C.
: thermal conductivity, WmK.
k: thermal conductivity in the x direction, WmK
.
k: thermal conductivity in the y direction, WmK
.
k: thermal conductivity in the z direction, WmK
.
c
h: convection heat transfer coefficient, 2
Wm K
.
rad : radiation heat transfer coefficient, h2
Wm K
.
ch
L: characteristic length, m.
a
T:
R: thermal resistance of the assembly, ˚C/W.
temperature, ˚C.
T
C. : predicted maximum temperature of an assembly,
˚: surface temperature of the assembly, ˚C.
s
T
V: air velocity, m/s.