C Thermal Analysis
MVME51005E Single Board Computer Installation and Use (6806800A38B)
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Allow the board to reach thermal equilibrium before taking measurements. Most circuit boards
reach thermal equilibrium within 30 minutes. After the warm up period, monitor a small number
of components over time to assure that equilibrium is reached.
Measuring Junction Temperature
Some components have an on-chip thermal measuring device such as a thermal diode. For
instructions on measuring temperatures using the on-board device, refer to the MVME5100
component manufacturer’s documentation listed in
Appendix D, Related Documentation
.
Measuring Case Temperature
Measure the case temperature at the center of the top of the component. Make sure there is
good thermal contact between the thermocouple junction and the component. We recommend
you use a thermally conductive adhesive such as Loctite 384.
If components are covered by mechanical parts such as heatsinks, you need to machine these
parts to route the thermocouple wire. Make sure that the thermocouple junction contacts
only
the electrical component. Also make sure that heatsinks lay flat on electrical components.
Figure C-3
shows one method of machining a heatsink base to provide a thermocouple routing
path.
Note
Machining a heatsink base reduces the contact area between the heatsink and the
electrical component. You can partially compensate for this effect by filling the
machined areas with thermal grease. The grease should not contact the thermocouple
junction.
