Ball bonders are used in wire bonding in order to establish electrical connections from silicon chips to the outside through external leads on the semiconductor device. This is the most common way of creating these connections. It is a necessary communication that allows for monitoring and control of the semiconductor should anything happen to it.
The two elements which can be used to create a wire bond are copper and gold. Gold is the most commonly bonded material, as it has fewer complications in welding than copper wire. Copper wire requires nitrogen gas to be used in order to keep oxides from forming. It is also a tougher material than gold. Because of this, the chip's surface is more likely to undergo stress, resulting in damage. Because of its inexpensiveness, however, the use of copper is growing in ball bonding.
Ball bonders operate using a capillary that the wire is fed through. This capillary holds the wire while a ball, made from whichever material is being used, is created at the end of the wire. This is done by applying a high-voltage electrical charge. It is able to morph the tip of the wire into a ball due to surface tension. Heat, mixed with electricity, heats the chip so that the ball can then be melded to the chip. The capillary lowers to the chip and welds the ball to it, literally bonding the ball.
Once the ball has bonded to the chip, the wire moves through the capillary and the machine relocates to the leadframe, where the chip will be wired up. The machine then moves to the surface, crushing the wire between the capillary and the leadframe. This weld, the tail bond, relates the wire back to the chip. The machine then feeds through a small amount of wire, which will then have the same process occur to it in order to create a new connection.
As far as ball bonders go, gold ball bonding is faster and more efficient than aluminum wedge bonding. This is why it is used so prominently in plastic packaging. Aluminum wedge bonding must be used for other packages, however, as gold ball bonding does not work on all packages, due to the high sealing temperatures that vary from package to package.
Ball bonders create important communication pathways for semiconductors. They allow the silicon chips to communicate externally with the outside world and relate any problems or data. Ball bonders create small ball-like structures at the end of either gold or copper wire, which is then attached to chips. This creates the connection necessary for communication. Ball bonders make interlaying data much more simplified and possible.