I2C controlled haptic motor driver packaged in a 3×3 ball 0.5mm WLCSP.
This chip was removed from a PCB which had been damaged during assembly and would otherwise have been scrapped; there is a small amount of flux residue on the underside as a result. For these quick overview shots, no extensive cleaning was performed.
One corner of the die was slightly chipped during removal from the PCB.
No decap was required; the top metal layer is visible through the polyimide overcoat simply by looking at the bottom side of the packaged device.
Author's note: Interestingly enough, the chip I imaged (brand new from Digikey, so presumably authentic) was labeled DRV2604 on the top metal layer, but 2605 on the top of the package. The only difference seems to be whether waveform data is stored in ROM or SRAM… maybe just a fuse difference?
Top metal pitch looks like ~600nm. Maybe 180nm tech?