nRF52840 Lead Finish of the BGA Balls

[John]

We are having a very difficult time soldering the nRF52840 to the PCB. Our Operations Department is asking what the lead finish of the BGA balls is. Would be great to get on the phone with you guys to discuss all the things we have tried. You might have some ideas. Thank you!

[Kaja]

Hi John, 

we are waiting for a reply form our production house at the moment,to see if they have an updated reflow profile for us. 
If they have an updated one it would be great if you could test that before sending us boards, to see if that fixes the problem. 
Could you send some pictures of the failing boards? 
Have you preformed some X-rays? - If yes, tt would be great to have a look at those as well. 

John said:

I was wondering, however, if the VSS ball (B7) becomes unsolderd from the PCB, will that cause the internal 1.3V or 1.1V regulators to fail? We are using the on-board buck regulator to generate the core voltage as shown in Figure 212 of the product spec.

John said:

We don't believe the reset issue is due to the power circuitry, but we will tripple check this.

- Difficult to say, but not having proper grounding of the IC, not specifically B7, can probably contribute to the issue. 

Could you also share the design files? - So that I can have a look at the design as well. 

Best regards,
Kaja