We published a video on with some tips on soldering header pins on to your Teensy board.

A couple of tips to remember when soldering header pins to your board:

1 – You MUST solder the pins.  Setting the Teensy on the header pins without completing the soldering will not work.

2 – Use a breadboard to keep the pins straight and stable when soldering

3 – Leave the soldering iron on the pad for a moment after you solder.  This will bring all the components – the pad, the header pin, and the solder up to the same temperature so they will cool together to form a proper molecular bond.