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I need to calibrate temperature sensors (ADT7481). My DMM can measure temperature with a thermocouple. And I expect it to be reasonably accurate (within ~1.0 Celsius degree).

Question at large however is the heating method. I can blow my temperature sensor on the PCB with my digitally controlled rework station, but I am afraid that this method will damage other components on the board. Also it won't be very accurate as the air will cool down when it reaches the surface of my sensor.

I have looked around a little bit, and found this product called Briskheat which uses silicone rubber tape to directly heat up the component [1]. I believe such method will be very accurate. Unfortunately it has a lead time of more than a month.

Are there any other ways to control the temperature accurately and safely with readily available tools (ie. alternate to Briskheat)?

[1] http://www.briskheat.com/p-401-silicone-rubber-heating-tape-bs0-with-sdc-digital-temperature-controller-special-bundle-price.aspx

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  • \$\begingroup\$ Water could be helpful when calibrating temperature sensors to 0 and 100 degrees. Whether your board can be exposed to water is another question. \$\endgroup\$ Commented May 10, 2016 at 18:54
  • \$\begingroup\$ I don't think I want to take the risk of exposing my board to water! Thanks for suggestions tho! \$\endgroup\$
    – Adam Lee
    Commented May 10, 2016 at 19:16

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The device is pretty accurate as-is, probably more so than your thermocouple meter at low-ish temperatures. I suspect you'll make things worse than they are from the factory with such crude equipment.

But if you insist, glue a 1K platinum RTD element to the top of the device and put it in a convection oven with simple temperature controller (or, preferably, a proper environmental chamber).

Use a good ohmmeter to measure the temperature of the device.

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  • \$\begingroup\$ Thanks for your input. I am using Keysight's U1186A Thermocouple, which claims to have 1.1 degree Celsius accuracy [1]. If this is true, how can I make things worse? Thanks! [1] keysight.com/en/pd-1191771-pn-U1186A/… \$\endgroup\$
    – Adam Lee
    Commented May 10, 2016 at 19:28
  • \$\begingroup\$ Very nice meter. My interpretation of the accuracy spec is 1% + 1°C + 1.1°C for the probe plus (I think) some unspecified cold junction error. So it could be a couple degrees off at 100°C. The bead type of T/C also requires care to get it to track something like an SOIC because loss down the leads can easily be much more than the heat transfer from the IC package. Flat ribbon type is better. \$\endgroup\$ Commented May 10, 2016 at 19:44
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If your board contains only SMD/through-hole components which can be reflow soldered, you could simply adjust your hot air rework station to a temperature below the solder melting point (mine goes down to 100C) and place your DMM's thermocouple directly on the ADT7481. In this way, you could measure the exact heat output at the temperature sensor, as well as avoid damage to the components since they are designed to withstand higher reflow temperaturess anyway.

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  • \$\begingroup\$ Thanks. I think this is actually easiest way assuming my DMM is accurate. \$\endgroup\$
    – Adam Lee
    Commented May 10, 2016 at 19:30
  • \$\begingroup\$ It would also eliminate the concern with inaccurate hot air temperature or distance from the part, as the temp would be measured at the part, not at the nozzle. \$\endgroup\$ Commented May 11, 2016 at 18:34

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