Last but not least, top side we find:

Toshiba TSB 4226VE9461CHNA1 1927 64 GB flash storage

YY NEC 9M9 (likely accel/gyro)

In addition to all these chips, we tease apart several layers of graphite thermal transfer material backing the RF board.

Apple says its improved thermal design gives these iPhone Pros the "best sustained performance ever in an iPhone." That's accomplished by pulling heat from the logic board straight through several layers of graphite where it dissipates into the rear case.

This may not seem as fancy as the liquid cooling systems we've seen in some Android phones, but it certainly must be enough to keep the super-efficient A13 cool, while not interfering with any signals traveling to or from the RF board that it clings to.