> Whilst this technique is becoming more common it's outstanding to see it on as assembly like this.... Raspberry Pi has someone who is really good at electroni

> Whilst this technique is becoming more common it's outstanding to see it on as assembly like this.... Raspberry Pi has someone who is really good at electronics packaging! Worth noting that RPi company are not responsible for doing this chip level packaging. Device vendors (in this case Cypress/Infineon) are the ones who produce their chips in wafer level chip scale package (WLCSP), which involves some more steps applied to the die during manufacturing that protects it from the elements, including chemical passivization to resist oxidation and moisture. At the integrator's level (PCB assembly) the WLCSP package behaves much like a traditional BGA chip, only perhaps with smaller dimensions and pitch. The datasheet for CYW43439 also specifically mentions that it is sold in a "63-ball WLBGA package"