nrf52840 mechanical specification issue

[olivdeso]

Dear Nordic team

It seems there is a small mistage in the mechanical specification of the AQFN package in the nrf52840 datasheet v1.1 p582

The e2 dimension seems wrong : as far as I understand, it should be 0.5mm * sqrt (2) = 0.707mm and not 0.559mm as stated in the datasheet which is a little bit confusing.

However, the e2 dimension is not needed to make the footprint and is redundant. Yoy can just remove it from the next issue of the datasheet I guess.

best regards

Olivier

Olivier

[Kaja]

Hi Oliver, 

e2 should be  = 0.559 mm. 
You can use the formula for right-angled triangle, to calculate the hypotenuse, or e2 in this case. 

e2 = sqrt((e/2)^2 + e^2)) = sqrt(0.25^2 + 0.5^2) = 0.559. 

Best regards,
Kaja

[olivdeso]

Hi Kaja

Of course you are right !!!!  It was time to take a rest after a long week...

Thought I did not use this data (0.559) this was actually what I had on my own PCB that were beeing manufactured.

Since I received the board and they work fine.

I used a Kicad footprint, with 0.3mm pads, no pad on via, and 0.05 mask opening. So far so good...

Thank you Kaja

best regards

Olivier

[Kaja]

Hi Olivier, 

that happens to all of us some times! 

I'm glad it's working, let us know if we can help you with anything! 
I'm happy to review you design, if you want feedback on schematic and/or layout. 

Best regards,
Kaja