History (1995): Seagate and Sony to Develop Plastic Magnetic Hard Disk Platter

Seagate Technology (Scotts Valley, CA) and Sony (Tokyo, Japan) have signed an agreement to jointly develop and commercialize hard disks utilizing a new Japanese technology based on plastic platters “with five times the areal density of conventional drives,” according a press release from the US company.

The new media envisioned by Sony is called PERM (Pre-Embossed Rigid Magnetic), and is make using a stiff plastic medium relatively comparable to that used for producing compact disks.

Cross section of embossed pattern taken by AFM
Perm

Up to now, the majority of magnetic hard disks were made using a substrate covered with a fine magnetic layer, usually aluminum. More rarely, glass is used, resulting in a superior surface for floating the magnetic heads as close to the platters as possible. The closer the head, the better the quality of the recorded signal in writing and interception during reading.

To obtain a very precise head servo-system on a lower-quality base, Sony has come up with the idea to press holes in the disk beforehand, much like on a CD-ROM. In this way, the indentations will then guide the magnetic head.

“The PERM technology, used in combination with new head and channel technologies, could allow us to develop high-quality, high-capacity, disc drives that are easier and cheaper to build,” said Dr. Hossein Moghadam, SVP and CTO, Seagate.

PERM was unveiled in March 1993 by Sony which, at that time, claimed it would be able to manufacture in early 1995, a 2.5-inch hard disk with a 190GB capacity at a price below $350. These numbers provoke a slight smile 2 years later.

But there is one last bit of information given back then by Sony that has opened the way for higher capacities: “For the first time, densities will reach 5,000tpi.”

At the time this was a considerable amount. Even today, the most sophisticated disks on the market have not gone beyond 4,500tpi. The pre-stamped guiding system has opened some interesting horizons to help increase the number of tracks, more than the linear density inside of the tracks.

This PERM technique is probably comparable to the one used by Insite Peripherals for its 20GB diskettes with a flexible 3.5-inch magnetic base scattered with holes that guide a laser, then able to precisely place a magnetic head.

In a hard disk, the head-media couple is the most expensive element. By moving into plastic disks, the price of drives can decrease effectively, while capacities increase.

But they are not yet a sure thing. Today, there is no multi-platter optical device, due to the difficulty of placing many laser heads between different media.

Will PERM create the possibility for a device with multiple platters, like Winchester?

The 2 partners have not yet announced the date their product will be released; or prices, or capacities.

All too often, announcements of new products that are expected to overthrow an $23-billion industry, fail to deliver. Let’s not forget perpendicular recording, drives with 2 and even 4 heads per platter, the new heads being in direct contact with the disk without destroying it, etc.

In short, to be doubtful is in order, even if the 2 protagonists are Seagate, ≠1 in hard disks, and Sony, which made Winchester disks for Apple before abandoning this activity, ≠1 in optical disks.

This article is an abstract of news published on the former paper version of Computer Data Storage Newsletter on issue 85, published on February 1995.