This is a video showing how a wire bonding machine connects the wires between the microchip and the leads going to the outside world using ball bonds.  A ball bond is a kind of bond that looks spherical because it starts as a molten ball of metal (known as the 'free-air' ball) before it is connected to the bond pad of the chip using a bonding tool known as a capillary. The other commonly used bond in semiconductor packaging is known as a wedge bond, which looks flat because it is produced by a wedge-shaped bonding tool.

  

See also: Wedge Bonding Process Video