Forty percent of the San Jose 2 facility is dedicated to analysis. Despite the innocuous simplicity of a shiny little disk, there’s a substantial amount of examination and validation needed to confirm that each platter works as it should. Each disk has a sort of soft underlayer, then a couple of magnetic metal layers, then a carbon overcoat. Each layer may only be a few angstoms thick, and each needs to be analyzed for its individual characteristics.
One machine for doing this is the Transmission Electron Microscope (TEM). When I approached this room, the door was closed and plastered with warnings, reminiscent of a studio recording chamber or a photography darkroom. After a few moments, the technician inside ushered us into a tiny space not much larger than the desk you see here. Modern TEMs can achieve magnifications of over 1 million times. In this setting, WD is using the TEM to examine media crystal structure, grain dimensions, and sputtered layer thickness. According to the technician who showed us this room, “it can also provide high-spatial resolution diffraction or chemical element analysis.”