Electronics > Metrology

Practical accuracy of IR thermometers on PCBs

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I'm thinking about getting an IR thermometer to measure electronics, mainly chips and PCBs.

I suppose plastic chips shouldn't be an issue with emissivity close to 1, but how much error should I expect on those shiny soldermasks?

On the soldermask it will be more or less fine. However on metal parts, especially non anodized heat-sinks, ir will be completely useless. Also IR thermometer is not very useful tool compared to the thermal imager. The biggest issue is that you never know if it shows you some bullshit, like reflected IR and similar. As laser aim usually is not precise at all, you won't be completely sure what part you actually are measuring.

Since the OP does not indicate their country - I will say that I got one from Harbor Freight in the US.  I have found it useful for about $30, but I am sure it is not as useful as an thermal imager for $300 or more.  You can move the spot around to find what you think is correct.  Also you can get some flat black paint or dark nail polish and put on the object to reduce reflections.

Try the corners of the components, but anyway you can learn how to move the IR spot around.  Well worth the money.

If I were a millionaire, I would have a nice thermal imager, but for now my cheap IR will have to do.  :(

Don't rule out getting a cheap ebay thermocouple thermometer, and a roll of Kapton tape. They tend to be useful in situations that IR thermometers aren't, eg. shiny heatsinks. They can also be used to give you an indication of how far off the IR thermometer is on a particular surface finish.

Thanks for the responses. Thermocouple is exactly what I've used so far, but it's slow, conductive :-BROKE and a bit of PITA to use at times.

I know that IR doesn't (easily) work on metals, but if it can quickly measure a random spot on PCB without requiring some insulation or risking shorting stuff and without >10°C errors, I'll be all happy :)

As for thermal imagers, nice toy, but I don't need it yet.


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