BME280 - Distance From Edge of PCB

[pulse]

Hi, 

The BME280 Handling, Soldering, and Mounting Instructions document mentions that "it is not recommended to place the sensor close to the edge of the PCB".

Is there any more clarification on how close is too close?

What sort of issues could we see from placing the sensor too "close"? How would these issues manifest themselves?

How can we mitgate those, apart from moving the sensor more inward?

Thank you. 

[o_o · Accepted solution]

Hi Pulse,

There are no specific minimum distance, but as you know MEMS devices have tiny mechanical structures inside. The main issue with mounting parts at the very edge of the PCB, is when the design is panelized, assembled at the panel level, then PCB are separated by snapping or cutting.

The high mechanical stress that can occur with the sawing of the PCBs can exceed the absolute maximum rating and damage the sensor internal structures. (This is true for all MEMS).

With that in mind, please find a suitable placement for the sensor, taking into account thermal effects from other components, as well as airflow. If the sensor must be placed on the edge of the board, adding a few millimeters of distance can increase your yield, depending on how the PCBs are manufactured.

o_o