PinBall Flippers

Im am having trouble figureing out what I must set up to make is so that when my ball hits my flipper it sends it back up toward the top of the board. Any suggestions on how I could accomplish this?

Add another collider with trigger checked as a part of the flipper.
Then add a script to it that has something like this. I havent tested this though.

function OnTriggerEnter (other : Collider) {
     //add force to anything that comes inside
     other.rigidbody.AddForce (Vector3.up * 10);

}