JW050A, JW075A, JW100A, JW150A Power Modules:
dc-dc Converters; 36 to 75 Vdc Input, 5 Vdc Output; 50 W to 150 W
Data Sheet
July 1999
Thermal Considerations (continued)
Solder, Cleaning, and Drying
Considerations
Custom Heat Sinks
Post solder cleaning is usually the final circuit-board
assembly process prior to electrical testing. The result
of inadequate circuit-board cleaning and drying can
affect both the reliability of a power module and the
testability of the finished circuit-board assembly. For
guidance on appropriate soldering, cleaning, and dry-
ing procedures, refer to the Board-Mounted Power
Modules Soldering and Cleaning Application Note
(AP97-021EPS).
A more detailed model can be used to determine the
required thermal resistance of a heat sink to provide
necessary cooling. The total module resistance can be
separated into a resistance from case-to-sink (θcs) and
sink-to-ambient (θsa) shown below (Figure 33).
TC
TS
TA
PD
cs
sa
EMC Considerations
8-1304 (C)
Figure 33. Resistance from Case-to-Sink and
Sink-to-Ambient
For assistance with designing for EMC compliance,
please refer to the FLTR100V10 data sheet
(DS98-152EPS).
For a managed interface using thermal grease or foils,
a value of θcs = 0.1 °C/W to 0.3 °C/W is typical. The
solution for heat sink resistance is:
Layout Considerations
(TC – TA)
θsa =
– θcs
------------------------
Copper paths must not be routed beneath the power
module mounting inserts. For additional layout guide-
lines, refer to the FLTR100V10 data sheet
(DS98-152EPS).
PD
This equation assumes that all dissipated power must
be shed by the heat sink. Depending on the user-
defined application environment, a more accurate
model, including heat transfer from the sides and bot-
tom of the module, can be used.This equation provides
a conservative estimate for such instances.
16
Tyco Electronics Corp
TE [ TE CONNECTIVITY ]
