From a consumer’s point of view, it can often appear that products simply appear on the shelves in our shops. But the reality is that everything that we buy is made somewhere in a more or less complicated process. For Blu-ray disc manufacturing, this process is long and tricky and must be done by state of the art machines. On the surface the BD factory is mystery – so let’s satisfy our curiosity and take an in depth look at how these discs are made.
All BDs start life as a collection of tiny, clear granules of the plastic polycarbonate. These granules arrive at the factory in trucks and are stored in silos, waiting for the process of Blu-ray disc manufacturing to begin. They are then siphoned into pipes, which take them through the factory to ‘hopper’s which measure out a certain number of granules and melt them down, sending them to the moulding machine.
The moulding machine then compresses the liquified polycarbonate into a disc. The mould for the machine is created from a glass master copy of the first layer of data data to be stored on the BD so not only does this machine create the basic shape of the disc, but it also punches the first layer of data into it. The data takes the form of ‘bumps’ or positive and negative indentations on the surface of the disc, which will later be covered for protection, and then read by the ‘blue’ BD laser.
Moved by a robotic arm, the disc is now ready for the next stage in Blu-ray manufacturing. The disc is then coated in a layer of silver. This layer is miniscule – only 90 angstroms thick (and an angstrom is only 100 millionths of a centimetre!) The layer is created by a process called sputtering. In this case, ‘sputtering’ involves hundreds of thousands of atoms of silver being bombarded. The particles of metal are ‘energised’ or made magnetic so that they will stick to the surface they are applied to. In Sony Blue-ray disc manufacturing plant, their sputtering machine has a magnetic field so strong that it affects pacemakers that are brought nearby!
The disc is then coated in a layer of special UV resin, which is hardened by being exposed to a special kind of light. Then, a second layer of data is added if needed and the disc is given another UV resin coating and a final protective layer.
But this is not then end of the Blu-ray disc manufacturing process: Half the energy goes into making sure the product is reliable. The discs are machine-checked for any sign of scratching or bubbling between the layers before being scanned and checked for playback integrity.
And what would a disc be without its artwork? The discs then have to be loaded onto spools to go to the printing machines, which vary in technique according to the factory. Finally, the BDs find their way to the assembly line where they are clothed in their cases, with any inserts and covers the designer has chosen.
So that is how Blu-ray discs are manufactured! They don’t just magically appear, but are sent through a complex and highly scientific process before arriving on the shelves or our stores!