PROCESSING BALL GRID ARRAYS (BGA'S)
As the demand has increased for more connectivity withing PCB assemblies the complexity of components such as integrated circuits has increased.  An example of a solution to this challenge is the BGA or 'Ball Grid Array'.  The BGA is very different to devices with leads such as QFP's in that the electrical connections are all underneath as oppose to around the perimeter.  Another fundamental difference is that electrical connections are balls of solder (hence the name) and need special consideration to the soldering process.

BALL GRID ARRAY X-RAY INSPECTION

Picture
Surface mount resistor underneath BGA

BALL GRID ARRAY OPTICAL INSPECTION