The part you mention is 0.56mm thick including solder balls (0.37mm nominal without), and a credit card is 0.8mm thick. The thinnest 'normal' PCB is 0.4mm. Add

The part you mention is 0.56mm thick including solder balls (0.37mm nominal without), and a credit card is 0.8mm thick. The thinnest 'normal' PCB is 0.4mm. Add some thickness from the exterior packaging, and the product will be the thickness of two credit cards, at least. You'd need to use a wafer-chip (with no package) to get to credit card thickness, then add a very thin battery of some sort. This is a very challenging and expensive project.