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We have an IR thermometer at work, but sometimes I feel like the results aren't completely accurate due to the beam width (especially on small components) or material emissivity.

Another way I've tried is to use a thermocouple temperature sensor from my DMM, but unless I put thermal paste, it wasn't accurate and. Using thermal paste was super messy, and it was hard to keep the thermocouple in place.

Are there any other methods or tricks for accurately and easily measuring temperature of individual components on PCBs?

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  • \$\begingroup\$ Using a thermal imaging camera would be "easy". But expensive as well. \$\endgroup\$
    – Rev
    Apr 13, 2015 at 14:13
  • \$\begingroup\$ I've definitely used a thermal camera when I've had them. If I want a really good reading I use thermal epoxy and a thermal couple. If I want just a close guess I'll use some kapton tap or the tension of the thermocouple wire to hold it in place. That or the internal temperature sensor if the IC has it, although they aren't always super accurate. \$\endgroup\$
    – Some Hardware Guy
    Apr 13, 2015 at 14:50
  • \$\begingroup\$ I've stuck little thermal couples down with Kapton tape. It's nice to use small ones. And include a fair amount of the lead to the TC. A lot of the heat is coupled in through the leads. \$\endgroup\$
    – George Herold
    Apr 13, 2015 at 15:05
  • \$\begingroup\$ @SomeHardwareGuy: Even if the internal temperature sensor isn't especially accurate, wouldn't you still prefer this measurement? After all, what really matters isn't the package temperature, but the junction temperature... \$\endgroup\$
    – Zulu
    Apr 13, 2015 at 17:06
  • \$\begingroup\$ @ZekeR depends on the circumstances I guess, but yes I agree you are interested in the die temperature. For instance I have a chip who's internal temperature sensor is accurate to +/- 8 degrees but its theta JC is almost nothing. \$\endgroup\$
    – Some Hardware Guy
    Apr 13, 2015 at 17:11

2 Answers 2

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While any regular glue will work in a pinch, there exist a class of epoxies with enhanced thermal characteristics. Arctic Silver epoxy is one of them and it's available in small quantities from places like Amazon; there are several more - look at any major LED manufacturer's website (not surprisingly, appnotes discussing LED case temperature measurements often contain detailed procedures). Omega also have a family of sticky thermocouples that would work well for your purpose, if you can afford them.

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Use a tiny spot of regular epoxy to glue the thermocouple in place.

Its almost as conductive as thermal paste, and still far far better than air.

And it keeps the thermocouple from falling off. (you'll need to cut and repair the thermocouple wire each time, so use a long scrap wire).

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