I'm running a Pi4 with a 32Gb SanDisk Extreme SD card and essentially just AdBlock. The board is powered by the official usb-c plug and has a passive cooling case around.

Since last week my system kept crashing. I finally managed to capture the logs:

Jul  5 12:54:03 raspberrypi kernel: [ 3227.388458] blk_update_request: I/O error, dev mmcblk0, sector 534240 op 0x1:(WRITE) flags 0x103000 phys_seg 1 prio class 0
Jul  5 12:54:03 raspberrypi kernel: [ 3227.388484] Buffer I/O error on dev mmcblk0p2, logical block 220, lost async page write
Jul  5 12:54:03 raspberrypi kernel: [ 3227.388748] mmc0: card aaaa removed

I checked the SD card and there was some white stuff around the SD card pins. Once I removed that carefully, I realized the pins look kind of melted.


I guess there's not much I can do without soldering equipment, except try warranty? We had a heat wave, so I expect the average room temperature plus load caused this, but it's still puzzling to me how.

Can this be fixed / is it worth it to try to fix myself, or should I see if the manufacturer will replace it under warranty?

  • Just wondering what your question is. How did this happen? Is that what happened? Can this be fixed? Should I try to get the manufacturer to replace it? I added suggested questions; hopefully my edit will be accepted. Jul 5, 2021 at 14:08
  • 1
    Thanks Pete. Patrick, it would be good if you edited in a few details about what was connected to the pi and how it was powered.
    – goldilocks
    Jul 5, 2021 at 14:47
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    it very difficult for the pins to melt ... that is probably corrosion
    – jsotola
    Jul 5, 2021 at 16:36
  • There's no humidity or water nearby. It was just really hot the last few days. The device isn't 3 months old. If it is corrosion though, can I fix it somehow?
    – Patrick
    Jul 5, 2021 at 16:37
  • 1
    don't use a cloth to wipe circuit boards ... cloth catches on components and can bend them ... use 99% isopropanol and a soft toothbrush
    – jsotola
    Jul 6, 2021 at 5:49

1 Answer 1


It looks like you got a board which has been through rework after production. The SD card slot was not properly soldered after reflow, so it was re-soldered manually, and manual soldering doesn't look as pretty as reflow (and has a higher failure rate).

The white stuff around the pads is the solder flux which whoever who did the repair didn't bother to clean. It's not harmful though, the failure is most probably due to soldering temperature being too low or movement/vibration during hardening of the tin, which resulted in a crack making poor contact.

It's also possible that the board is refurbished, but normally refurbished devices are clearly marked as such when they are sold.

In any case, there is no way this is a result of ambient temperature.

If the board is still under warranty, you should definitely send it back. Only try to fix it if you can't get a replacement, though the fix is not hard to do: heat every pin with a soldering iron, and then try to lift it with a needle: if it moves, resolder it again. If that doesn't help, the copper trace on the board is cracked as well, and the board is beyond repair unless you a quite skilled (and for a 50$ board I wouldn't bother).

  • Thanks Dmitry, that's a great explanation. I'm going to change the board as it's still under warranty.
    – Patrick
    Jul 7, 2021 at 6:03

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