can't flash nrf9160 on custom board

[gzigzeo]

I have an issue with my nrf9160 custom board.

I flashed successfully only 3 of 30 pieces batch. Other boards fail with "Failed to connect to target. No idcode detected".

After powering up the board I see 0 V on nRESET pin and meander on SWDIO with different period on different boards (200 - 800 ms)

Supply voltage seems to be ok and is the same on boards that flashed and boards with flashing issue.

VDD_GPIO = 3,28 V

VDD1 and VDD2 are 4.65 V

What can be the reason of such behavior?

[Marjeris Romero]

Hi,

Have you tried to reflow the modules that you are not able to flash and see if it fixes the issue? Since you could flash successfully 3 pieces perhaps it could be a soldering issue.

Best regards,

Marjeris

[gzigzeo]

One more question regarding this issue. On one of that problem boards after soldering nrf9160 out  I found short circuit on GND of one of VDD and VIO as well. Could that chip breakage be caused by soldering issue?