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(Solved)What's the emissivity of plastic chip package and aluminum heatsink?

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sam1275:
Hello.
What's the emissivity for plastic chip package, and black aluminum heatsink?
Thanks.

Fraser:
Sam,

If you Google for emissivity tables or even download a FLIR /Fluke camera instruction manual you will find a nice list of differing materials and their emissivities. As you know, getting the correct emissivity setting is important to accurate measurements.

You can also determine a pretty close emissivity value for an unknown material by measuring the surface temperature with a decent contact thermonmeter and adjusting the camera emissivity until its temperature measurement of the surface tallies with the contact thermometer reading.

You can also apply PVC ielectrical insulation tape to a surface and set the emissivity for that material when needing a known emissivity for measurements. PVC tape is normally listed in the emissivity tales I mentioned.

An IC plastic case will likely be just an emissivity for ABS or ''rigid plastic'
Remember the colour of a surface means little at renal wavelengths. A light paint can emit at the same level as a darker paint etc.

The Heatsink emissivity varies massively depending upon whether ir is  plain shiny, anodised, painted or oxidised. The emissivity tables show the different settings foe different aluminium surface finishes. Painted just uses the emissivity for cellulose, acrylic or enamel paint usually.

Best Wishes

Fraser

Fraser:
Sam,

Here you go, a comprehensive Emissivity table for you.

http://www-eng.lbl.gov/~dw/projects/DW4229_LHC_detector_analysis/calculations/emissivity2.pdf

Fraser

Fraser:
And another.........

http://www.scigiene.com/pdfs/428_InfraredThermometerEmissivitytablesrev.pdf

Just search for emissivity table :)

A plastic IC case will be 0.95.

Aluminium can vary depending upon coating. It is worth comparing a thermometer measured reading with that of the camera to check you have a reasonable emissivity setting. You could do this at room temperature and when the heatsink is hot.


Always remember that a thermal camera has a measurement to,erance of PLUS/ MINUS 2C or 2% plus any emissivity, reflected energy and atmospheric error. A super accurate absolute temperature tool it is not !

Fraser

sam1275:
Thank you very much Fraser.
I was troubleshooting a home router that auto-reboots under heavy load, I suspected heat issue, so I added a heatsink, but still not solved. So I'm pretty sure it's a software problem. (I have 2 different routers using the same SOC and same version of OpenWRT, both are affected, so there's no way for the hardware to be defected.)
This is the first time I actually use my thermal camera to diagnostic electronic stuff, I start the adventure of thermal camera just because I was amazed by it's picture, from the first time saw it, that looks like a device only in sci-fi movie.

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