ECE 442
1
Clip-On Heat Sinks
ECE 442
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Thermal Resistance for Clip-On
ECE 442
3
Bond-On Extrusions for DIP Packages
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Thermal Performance
ECE 442
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Thermal Resistances for Bond-On
ECE 442
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Example
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TO-220 case style dissipating 5 watts
RJC = 3.0 C / Watt (from device spec)
TJmax = 150 C
TAmax = 50 C
Find the proper heat sink to keep the junction
temperature from exceeding 150C in natural
convection.
ECE 442
7
T T
P 
R R R
T T
R 
 (R  R )
P
J
A
D
JC
CS
J
SA
A
SA
JC
CS
D
Need to determine a value for RCS – depends on the
mounting technique.
If the device is mounted without an insulator, but
only with Thermalcote, (silicone grease), check page
57, Figure 9 for TO -220 case style.
ECE 442
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Use Thermalcote
RCS = 1 C/W
ECE 442
No Insulator9
T T
R 
 (R  R )
P
(150  50)C
C
R 
 (3  1)
5W
W
C
R  16
W
J
A
SA
JC
CS
D
SA
SA
ECE 442
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Thermalloy P/N 6030
Temperature rise above ambient@ 5 Watts Power Dissipation = 66 C
ECE 442
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Thermal Resistance RSA
66C
C
R 
 13.2
5W
W
SA
As long as RSA is less than 16 C/W, the
requirement is met.
ECE 442
12
Thermalloy P/N 6030
ECE 442
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