[btoptical]

I think this process is really baking out moisture as the PCBA is not in the oven long enough to get to temperature and the temperature is not hot enough to reflow the solder.

Most of the components on the board are not hermetically packaged and there probably are moisture sensitive parts on the PCBA. So the baking at 170C for 7 minutes is essentially a drying process.

Also, I think Apple probably has to be ROHS compliant and that means they have to use lead-free TnSn solder. The transition temperature for lead-free solder is typically about 20C higher than normal leaded solders.