SOC BGA NVIDIA Design

In this case, there may be a difference in the size of BGA balls between the inner and outer sides of the package. (inner 0.45mm, outer 0.50mm)
Is it possible to implement BGA balls of different sizes, and what is the purpose behind it?

  • Another possible conjecture is that the variation in solder paste quantity between the inner and outer sides of the PCB may cause a difference in ball size after reflow."
    “Is the above method (different ball size) used generally?
    Or is it a patented method by NVIDIA ?”