0
\$\begingroup\$

I have a PCBA with a BGA microcontroller on it. I found that two UART pins send/receive garbled output unless I press my finger down on the BGA package itself. I've seen this on a few boards and I assume something went wrong with the assembly (done by a professional board house) but I don't know what. The board house assures me they did bake the components before assembly as I keep re-using them from the same batch.

The footprint lines up with the datasheet and worked well on a different board. Any ideas what could be going on?

\$\endgroup\$
10
  • \$\begingroup\$ Does this board house X-ray the mounted BGA? They had better because that's half the reason you get a board house to mount your BGA for you. Sounds like they didn't if the assurance they gave you was that they baked it instead of just saying that they x-rayed it. \$\endgroup\$
    – DKNguyen
    Commented Nov 17, 2022 at 5:05
  • \$\begingroup\$ They actually did X-Ray and it looked correct \$\endgroup\$
    – Ryan W
    Commented Nov 17, 2022 at 5:05
  • 1
    \$\begingroup\$ No ultrasonic cleaning, and ENIG finish \$\endgroup\$
    – Ryan W
    Commented Nov 17, 2022 at 5:30
  • 2
    \$\begingroup\$ Send it out to experts. i.e. somebody who isn't the board house who runs X-ray. There are plenty unbiased professional test labs out there. \$\endgroup\$
    – Kyle B
    Commented Nov 17, 2022 at 6:03
  • 2
    \$\begingroup\$ The xray doesnt show you the z axis details. If you press the IC down that’s the z axis. Can you provide a footprint detail and a photo? \$\endgroup\$
    – RemyHx
    Commented Nov 17, 2022 at 7:12

0

Reset to default

Browse other questions tagged or ask your own question.