RE: nRF52840 - components on both layers

Fran89 — Mon, 03 Aug 2020 17:46:32 GMT

Thanks a lot.

I will try this and comment after the boards are built.

RE: nRF52840 - components on both layers

Andreas — Wed, 22 Jul 2020 10:50:03 GMT

Hi,

The ANT pin is DC short to ground, so ~2Ohm resistance is as expected.

1) No, the QIAA variant pinout is completely different from the WLCSP ballout and the passives are on different sides (the die is flipped), you need to use the variant your layout is made for. We have some eagle libraries here, but they are not our official reference layouts and not regularly maintained. unfortunately the WLCSP variant of nRF52840 is not in there, and it probably will not be for some time.

2) You should have GND pour where possible in all layers, a single layer for ground is not optimal. A keepout in L2 is possible, but as mentioned you might instead make a local ground pour to maximize the amount of ground.

Components in the bottom layer is generally fine by us, provided the grounding is done well. You should try to keep the RF part in one layer though. Also check with your EMS that they can support this.

Best regards,

Andreas