In the past few years, the hard disk density slowdown the growing speed. Although Seagate and the West continue to work hard, put more discs, use helium, continue to introduce a larger capacity hard drive, but the hard disk density to enhance the speed gradually slow down, it is an indisputable fact. Now West and Seagate are working hard on 20TB high-capacity hard drive which is manufactured with glass substrate.
So far, only the notebook hard drive using glass substrate. Compared with the aluminum plate glass has several advantages. First, the glass is stronger than aluminum, allowing manufacturers to put thinner and lighter discs. In addition, compared with the aluminum substrate, the glass substrate is more flat and more smooth, more closely together, when the heat expansion is much weaker, that is to say the ability to cope with thermal expansion stronger. Also, let the spindle press the glass plate at a given speed, the need for less power, if the use of aluminum discs, because of its weight heavier, so a little higher energy consumption.
Japanese company Hoya believes that HDD manufacturers will use glass in 3.5-inch hard drive. Hoya shows a prototype glass disc that has two thicknesses, one for 0.5 mm and another for 0.381 mm. Currently the disc thickness is 0.635 mm. There must be a gap between the disc and the disc. If the disc size is reduced by 40%, more discs can be loaded in the same capacity. The glass substrate facilitates the introduction of heat-assisted magnetic recording (HAMR). If you want to write data on the hard disk, the hard disk will heat the writing part with the laser. Seagate is ready to roll out HAMR drives in 2018 and expand capacity to 20TB by 2020.