Hi eli_az,
We don't have any published thermal resistance values, sorry.
I've never heard of thermal problems with the ESP32 Thing development boards**, or any ESP32 development board for that matter (assuming reasonable ambient temps).
There are ESP32 chips that run in high temperature environments (like the inside of light bulbs) that require some thermal design considerations. But these also work (and are in shipping products).
If I had to guess, I would say if it is a thermal issue then maybe the ESP32 on your ESP32 Thing has some soldering problem - maybe the thermal pad under the chip somehow didn't get soldered fully so the chip is not sinking heat to the PCB correctly.
It's also possible to have a cold solder joint where thermal expansion of another part causes it to lose connection and then cooling it causes it to make the connection again.
A third possibility is that there's a short which is causing a lot of power consumption and heat near the chip. How much current is the ESP32 drawing from the power supply?
A fourth thing which will create excess heat from the chip is if the VCC voltage is over 3.6V (ie out of spec) but it sounds like you've checked this already.
If none of this helps, I have a few more questions:
- When you say the chip refused to turn on, do you mean you got absolutely no output at all from the UART after a reset? Or that the chip would start running but not connect to Wi-Fi?
- How did you measure the 100C on the chip?
- How sure are you that cooling the chip is the factor which makes it "come good" again?
** One exception for ESP32 Thing: as it uses the much less common 26MHz crystal, if
"autodetect" is set for the crystal config mode then ESP-IDF may fail to detect the crystal speed correctly depending on temperature. Something will still happen, but UART output may be garbled and the firmware won't connect to Wi-Fi. Setting the crystal speed to 26MHz in the config should work around the issue.