nRF54L15-CAAA WLCSP Light Sensitivity and Underfill Requirements

[AntonioFCDS]

I am working with the WLCSP version part (nRF54L15-CAAA) and it calls out that there is light sensitivity. The note seems to indicate that only underfill around the perimeter of the part is required.

For this part, what type of coating or underfill is recommended? Are there any guidelines for what materials and properties of those materials can and should be used? 

[Amanda Hsieh]

Hi, 

I am waiting for the information update from the internal. Now it's the Easter holiday in Nowray, so it might update next week. Sorry for the inconvenience. 

Regards,
Amanda H.

[AntonioFCDS]

Amanda, 
Any update?

[Amanda Hsieh]

Sorry for the late reply due to the Easter holidays in Norway. 

The statement indicates that the entire chip needs to be properly blocked from any visible or infrared spectrum including edge and bottom. 

It says that there is a back side coating that can protect the chip, but the edge and bottom are still exposed. 

This is common to all WLCSP chips and often it is suggested to apply glob top covering epoxy or metal shield to block any lights hitting the chip.