nRF52840 wCSP BGA strain limit

[mmkunz]

What would be the strain limit for the nRF52840 wCSP BGA if planning to mount on a flex circuit?

[Priyanka]

Hi Matt,

I have asked internally regarding this and will get back to you soon. Kindly expect a delay since it's the holiday season and we are short staffed at the moment.

Best Regards,

Priyanka

[Priyanka]

Hi Matt,

I have heard back from our team:
The strain limit is 4000µε (LTPD=3.09% with 90% confidence)

 Simplified monotonic bending test flow:

1. mount daisy-chain IC on specific PCB for bending test.
2. mount few strain gauges on PCB close to the IC.
3. bend the PCB and real-time monitor the strain & daisy-chain resistance.
4. test-to-fail mode: bend the PCB till DC resistance meets failure criteria and record the strain. 
   test-to-target mode: stop bending when target strain reached and record DC pass/fail results.

-Priyanka