ESP8266 SMT - Suddenly short between VDD and GND

[chrfriese]

Hello,

I use ESP8266 module on a PCB with power supply and some relais (schematic attached). More than 20 of these setups are running for quite some time now using Tasmota as control software. Now I wanted to add a few using the Adafruit ESP8266 SMT Moduel (#2491). The new one worked for a few weeks but then stopped responding.

After some debugging I measured a resistance between VDD and GND of the module of about 24Ohm. Also desorldering the module from the PCB doesn't help. Other modules from the same order have above 16kOhm.

Now I'm wondering, how can this happen? Did anyone else experience such a failure?

Best regards,
Christoph

[Franklin97355]

Can you post pictures of your esp8266 you are testing?

[chrfriese]

Below the picture of two modules:

• The upper one is a module from the same purchase (DOITING)

• The lower one is the failed module disassembled and removed metal shield.

Even with a microscope I don't see any obvious defects, burn marks, shorts,... I guess something inside the dies.

[Franklin97355]

If you have more than one in your order I would recommend replacing that non-working item with another and see if it was a one-off error or the replacement order has problems. Let me know what you find.

[chrfriese]

On this specific PCB I already soldered a module from a different batch and it's working fine.

I have a second PCB with a module from this batch. As with the failed part it's working now for the programing. But I need to install it for a long term test. I keep you posted on the outcome.