20TB Hard Drives Will be Made of Glass

Over the past few years, the rate of hard drive density improvements has dropped significantly. While Seagate and Western Digital have both pushed ahead with larger hard drives (often thanks to more platters and the use of helium), the actual rate of areal density increase has slowed these last few years. As Seagate and Western Digital push towards 20TB, glass substrates could be a critical component of that effort.

Right now, only laptop drives use glass substrates, which have several advantages over aluminum. First, glass is more rigid than aluminum, which allows the platters to be thinner (and lighter). Glass substrates are smoother and flatter than aluminum, which allows them to be packed together more tightly, and they expand less than aluminum under heat, which makes it easier to cope with thermal expansion. The amount of energy required to spin a glass platter at a given spindle speed will also be at least slightly lower than if the same platter was made of aluminum, due to the latter’s higher weight.

A Japanese company, Hoya, believes that current HDD manufacturers will