Teensy 4.1 white cracks (heat damage?) on PCB at Q1 and U4 is this a known issue?

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White cracks on PCB on Teensy 4.1, around Q1 and U4 - looks like heat damage to me, although none of the chips are hot to the touch.

20210929 Teesny4_1 heat damage .jpg

Teensy bought at the beginning of this month. It's running what I was expecting to be a very light duty for it, just a serial hub for a number of devices (complete source code in attached zip). It has been on pretty much continuously for all those 3 weeks in this duty, though.

No enclosure, it's just been on my bench in a breadboard whilst I do prototyping on the devices it's attached to.

Powered from USB from PC. The only other board connections are the serial connections: pins0|1 Serial 1; 14|15 Serial 3; 16|17 Serial4; 20|21 Serial 5; 24|25 Serial 6. The devices it's connected to are all esp32 based, 3.3V serial, powered by USB from same PC so should be a common ground (although no physical common ground wire directly between all the devices, yet).

I frist noticed the white cracks yesterday and powered it down. Has been run for a few hours today: they are spreading, although very slowly. No other signs of failure: Teensy still working, still not getting noticably hot, no electrical burning smell.

I'm developing this prototype for a commercial laboratory instrument, so I need to know how to avoid this happening again in the future: on the replacement board I ordered today, and on deployed production machines.

Is this a known issue?


  • 20210929_t4p1.zip
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