History (1982): Film Media Increases HDD Density

This article comes from the Computer History Museum.

1982: Film media increases disk storage density
Carbon coating enhances reliability of magnetic film media

SyQuest Q-100 disk cartridge with carbon overcoated layer (1982)

(T. Gardner)

An individual disk, sometimes called a platter, of a HDD drive (‘hard’ to distinguish it from the flexible ‘floppy’ variety) comprises a rigid substrate of non-magnetic metal, glass, or ceramic coated on both sides with a magnetic medium. Particles of gamma phase ferric oxide (y-Fe2O3) combined with binder, lubricant and other materials formed the, so called, ‘particulate’ or ‘oxide’ media employed on early disk and tape storage devices.

Researchers noted that magnetic media deposited as a film by plating or sputtering processes yielded superior coercivity and low noise characteristics compared to particulate coating. The smooth surface also allowed reduced flying height of the R/W head and therefore increased potential areal storage density. But when established HDD suppliers, such as CDC, Fujitsu, Hitachi, IBM, and NEC, adopted thin-film R/W heads to increase recording density they continued to use particulate disks due to concerns about wear and corrosion of sputtered media under high humidity and temperature conditions.

Francis King at Datapoint developed a ‘diamond-like’ carbon overcoating process on a cobalt-nickel plated disk that solved the early reliability concerns with film media.

Syed Iftikar, Marvin Garrison and Venu Menon at SyQuest commercialized the technology for the Q100 removable disk cartridge used in the SQ306 drive in 1982 with an areal density of 5.22Mb per square inch.

Tu Chen and Scott Chen founded Komag in 1983 to produce carbon overcoated sputtered disks for start-up drive vendors to the PC industry, such as Maxtor, Quantum and Seagate. Other film disk start-ups included Akashic, Domain, Lin Data, and TriMedia. Hewlett Packard began commercial shipment of the HP 97501A with a carbon coated 10MB disk in 1985. IBM added an organic vapor lubricant to the carbon layer and introduced film disks in 1987. The rest of the industry adopted film disks by 1990.