Hello,
We've recently had some issues with the TPS22916BYFPR load switch on our PCBs.
Our PCBs have TI load switches in three different locations on the PCB. We use the TPS22916BYFPR in two separate locations and the third load switch is a TPS22902YFPR.
We noticed that a significant amount of boards had issues with their load switches and upon closer investigation we noticed physical defects on the packages.
The pictures above are from two different units that had a cracked TPS22916BYFPR.
A visual inspection of the PCBs pointed to the bare silicon package developing cracks in two specific places for the first TPS22916BYFPR and in one place for the second TPS22916BYFPR of the PCBs that were inspected.
Contrary to that, the TPS22902YFPR seemed to be intact in every one of the boards that had either one or two cracked TPS22916BYFPRs.
Investigating further we could notice a distinct layer on the TPS22902YFPR (above the silicon layer) that seemed like an additional backside coating was applied to the ICs.
Complicating matters further, digging into the datasheet for the TPS22902YFPR there are no mentions of a backside coating being applied to the IC even though under the microscope there is a distinct layer visible above the silicon. In addition the finish of the part is dull compared to the shiny bare silicon TPS22916BYFPRs.
Has this issue of cracked chips ever come to your attention? Considering the amount of faulty products currently in our hands due to this issue, it feels like there is not adequate documentation covering handling and placement of these fragile devices or even some guidelines.
I found a forum post that lists similar behavior issues as the once we initially noticed but there is no mention of the device's structural integrity other than the one pointing to the WCSP ICs being less resilient to placement damage from the pick and place process. Relative link: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1044793/tps22916-reliability/3915775?tisearch=e2e-sitesearch&keymatch=TPS22916%20crack#3915775
Finally I would like to ask if we could verify the existence of a backside coating on the TPS22902YFPR considering there is no mention of it in any of the available documentation we could find. A confirmation of the existence of the backside coating would help explain why we had no cracking issues on the sole TPS22902YFPR on our boards.
Thank you in advance.
Kind regards,
Chris
