Page 1 of 1
Misaligned IC under metal shield
Posted: Fri Aug 11, 2023 3:07 pm
by zuissmc
I am running into several ESP32-WROVER-E modules where the ESP32-DOWD-V3 IC is misaligned under the metal shield. Wanted to see if anyone else has seen this. Pictures attached below.
Thanks,
Matthew
Re: Misaligned IC under metal shield
Posted: Sat Aug 12, 2023 4:18 am
by ESP_Sprite
That is very odd... were these modules already soldered down before, or did anything happen to these? As far as I know, we do QA on the modules before we ship them, so this is highly unusual.
Looking at the second picture, low right corner, the solder pads almost look like the ESP was soldered correctly but somehow heated up until the solder melted again and then mechanically shocked before the solder solidified; you can still kinda see the position the ESP32 rested on the solder pads before. It must have been shocked pretty hard, as normally the adhesion of the EP keeps it in place pretty solidly even if the solder is molten.
Also, how did you remove the shield? If you did that by heating it up and removing it, are you sure you didn't nudge the ESP32 in the removal process?
Re: Misaligned IC under metal shield
Posted: Mon Aug 14, 2023 2:42 pm
by zuissmc
ESP_Sprite wrote: ↑Sat Aug 12, 2023 4:18 am
That is very odd... were these modules already soldered down before, or did anything happen to these? As far as I know, we do QA on the modules before we ship them, so this is highly unusual.
Looking at the second picture, low right corner, the solder pads almost look like the ESP was soldered correctly but somehow heated up until the solder melted again and then mechanically shocked before the solder solidified; you can still kinda see the position the ESP32 rested on the solder pads before. It must have been shocked pretty hard, as normally the adhesion of the EP keeps it in place pretty solidly even if the solder is molten.
Also, how did you remove the shield? If you did that by heating it up and removing it, are you sure you didn't nudge the ESP32 in the removal process?
We soldered these modules to a PCB, so they have gone though an oven and have likely reflowed. I haven't seen any other evidence of mechanical shock in our process - no other components on our boards are having this issue. To remove the shield I just used pliers. I could peak into small hole of the shield to confirm the IC is misaligned before removing the shield. So far I've run into over 50 boards with this issue.
Re: Misaligned IC under metal shield
Posted: Mon Aug 21, 2023 7:17 pm
by jiqz--
Make sure there is no vibration in your oven and that the PCBs are kept perfectly flat whilst moving them if the solder is still molten. Best to keep flat in the oven, let cool, then take out without risk. You've run into over 50 out of how many boards with this problem?
Re: Misaligned IC under metal shield
Posted: Tue Aug 22, 2023 8:18 am
by martins
I would also check actual temperature curve that the oven does with external sensor. Temperatures used for solder paste reflow should normally not cause reflow of already soldered components.
Re: Misaligned IC under metal shield
Posted: Tue Aug 22, 2023 8:51 pm
by jiqz--
Still, if you tilt the board whilst the solder is still molten the chip may slide. Please pay extra attention and post an update when you reflow some more
Re: Misaligned IC under metal shield
Posted: Thu Aug 24, 2023 3:08 pm
by zuissmc
The 50 boards were out of around 1500 boards run. We are running an additional 1500 and will post an update with what we find. We have made efforts to reduce vibrations and jerking in the oven. We will also test the actual temps in the oven. Our current highest set point is 260C.
