RE: IR Susceptibility of WLCSP Package

Hung Bui — Wed, 21 Aug 2024 12:02:00 GMT

Hi Cameron,

The general recommendation is stated in the product's specification:

8.1 WLCSP light sensitivity
All WLCSP package variants are sensitive to visible and close-range infrared light. This means that a final
product design must shield the chip properly, either by final product encapsulation or by shielding/coating
of the WLCSP device.
Some WLCSP package variants have a backside coating, where the marking side of the device is covered
with a light absorbing film, while the side edges and the ball side of the device are still exposed and need
to be protected. Other WLCSP package variants do not have any such protection.
The WLCSP package variant CKAA has a backside coating.

As you may find in other tickets discussing this, the IR doesn't do permanent damage to the chip but it affect the current consumption and the analog parts. This includes the radio. So our recommendation is to have protection over the WLCSP chip.

light sensitive of nRF52832 WLCSP package

Coating WLCSP for Light Sensitivity

52810 WLCSP Light Sensitive