Madshrimps Forum Madness - Autopsy of an Intel CPU

The first challenge is to get the actual silicon processor chip off of the plastic bonding board. When the processor is finished, it is turned upside down and bonded to the green circuit board. This allows the metal pads on the silicon chip and the pads on the circuit board to join, creating a connection. I believe that the CPU at that stage is heated up in order to melt the joints and thereby solder them together.

This is a piece of the processor. The side you're seeing was once facing towards the plastic circuit board. Each little hole is a metal pad connecting the interior of the chip to a macroscopic lead on the circuit board.

A processor contains many layers of metal leads in order to connect the transistors at the surface of the silicon chip into useful units. The metal layers are clearly visible through the small holes in the chip.

Focus is on middle layer.

In a CPU there are multiple layers of sandwiched metal leads going down to the transistors at the bottom (at the surface of the silicon wafer). I believe what we're seeing is simply those different layers.

http://www.sciencystuff.com/?p=24