Step 1: Version 1's Build Log
Version 1 is soldered using the reflow soldering method (see my other instructable: http://www.instructables.com/id/Hack-a-Toaster-Oven-for-Reflow-Soldering/), version 2 was not due to time constraints and l didn't bring my oven to school. I managed to solder the QFN chips with a heatgun.
In version 1, the flyback diode for each motor was mounted onto the arms, but in version 2, the flyback diodes are in the main quadcopter body PCB instead.
In version 1, the propellers required a drilling before they fit onto the motor. The motors in version 2 comes with the propellers pre-attached so the drilling is no longer necessary. However, please read step 6 to see why you should use the motors from version 1 instead.