Yep , this heats up the insulator inside and melts it so the part you heated , the 2 copper strips come apart. Or you could use the Aerotech launch controler which has special crocodile clips designed for using on copperheads.
Copperheads work just fine as long as you you do the following three checks before you launch.
1.) Check to make sure that the ignitor does not have a crease in it. A crease cause by a sharp bend can break the conductor. A continuity check will show this condition.
2.) Check to make sure that the ignitor is inserted all the way into the motor and touches the delay column. This insures a prompt ignition of the motor and the delay column.
3.) If you do not use the Aerotech clips, check to make sure that the clips aren't shorted across the ignitor. It won't happen if you use 2 pieces of masking tape, one above the other on opposite sides of the foil and regular clips. This insures that each clip contacts only one side of the foil.
I have only had one copperhead fail, and that was due to (1).
Pretty much what Mr. Krech said. I usually insert it into the nozzle end as far as they will go, then gently bend it over the side of the nozzle and tape it down. Punch a hole in the tape to allow air in through the nozzle. Put it on the rod and slide it down. Put two wraps of masking tape on one "jaw" of each alligator clip. Attach to the copperhead, making sure they don't pull on the ignitor, and the taped sides are on opposite sides of the ignitor. I RARELY have a failure on copperheads.