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FE Malaysia Products

Hard Disk Drive
3.5inch vs 2.5inch
Longitudinal Magnetic
  Recording (LMR)
Perpendicular Magnetic
  Recording (PMR)
Insulated Gate Bipolar
  Transistor (IGBT)

Hard Disk Drive

A magnetic disk consists of several layers formed consecutively on the substrate. These layers include an under layer, an intermediate layer, a magnetic layer, a protective layer and a lubricant layer.

The performance of magnetic disks is determined by a combination of advanced technologies such as thin film control technology, which is the basis for the magnetic layer; ultra precise substrate grinding technology; texturing technology, which controls surface roughness; and clean processing technology, which eliminates impurities down to the level of gas elements

Fuji’s control technologies with angstrom-level accuracy on each process first enable high-density recording. Magnetic disks installed in hard disk drives (HDDs) are key devices for recording, playing and storing digital data.

Large-capacity magnetic disks play an important role in a ubiquitous society where people can use and enjoy large-volume information, images, music and games using a variety of small, mobile terminals.

3.5-inch vs 2.5-inch

At Fuji Electric Malaysia, we offer a series of media disks for our customers. They are 3.5-inch and 2.5-inch aluminum disks we now have on the market. The capacity of 3.5-inch aluminum disks used in desktop computers and HDD recorders normally ranges from 80GB to 120GB per disk. They are installed into hard disk drives and then are sold to end users in the market.

Up to date, we mass-produce and supply 3.5-inch high recording density perpendicular platter aluminum disks, ranging from 160GB to 320GB for consumer-based hard drives. We also manufacture high-quality aluminum substrates for the aluminum disks, some of which are now on the market as well.

Besides 3.5-inch aluminum disks and 2.5-inch aluminum disks which are for portable computers, we have also developed 2.5-inch glass disks with capacity of 40GB to 60GB per disk. These smaller disks are used in a growing number of applications such as notebook computers, home game consoles, car navigation systems and demand is expected to rise further. Currently, 2.5-inch glass disks are solely manufactured in Matsumoto of Japan.

The most crucial element of a magnetic disk is the read/write head interface. While keeping pace with the evolution of head devices, Fuji Electric has developed zone texture technology, which minimizes the flyable height of the head, as the key technology for high-density recording. Abreast with head devices technology, we employ the latest technology, i.e. perpendicular magnetic recording technology (PMR) to achieve higher recording density in our products.

Hard disk drives (HDD) are the most widely used non-volatile recording media for storing digital data because of it’s low cost and it’s ability to store up to several hundreds (or even thousands) of Gigabytes (GB) per disk. A typical HDD on a desktop can have up to 3-4 platters of magnetic disks per drive. For example, if you have a 500GB HDD (abreast with current technology), you would most probably have 2 or 3 magnetic disks in your HDD, with each of them having the capacity of storing about 250GB or 160GB of data per platter.
Given that, FEM has increased its range of products from a measly 3.4GB per disk to approximately 300GB per disk, an increase of 1000% of data storage space over the past decade.

How is data stored onto the magnetic disks? Data is stored by applying a magnetic flux onto the magnetic disk, making a part of the surface of the disk magnetized. A side-view of the magnetic disk is as below. This part of the magnetized disk can be considered as a very small magnet, and in this magnet is where you keep your data such as music, movies, document files and etc.

Longitudinal Magnetic Recording

The type of media products which are made within FEM (as of 2006) is termed as Longitudinal Magnetic Recording (LMR) Media. LMR media means that the data, or magnet, has a magnetic direction facing within the in-plane direction of the disk, just like the image above. This is the same way data has been stored in video cassettes, tapes, and floppy disks over the last 20~30 years.

However, LMR media has limits to how small the magnet (bit) can be. And this is called as the super-paramagnetic effect, where the magnet becomes unstable when it reaches a certain amount of volume. The magnet will be highly susceptible to outer magnetic fields from other sources and will eventually change its orientation accidentally, thus causing HDD to having errors. To counter this, LMR has to have larger grain size, however, if the volume of the magnet is too large, it will also be susceptible to noise, which will in turn weaken the signal which is supposed to be read by the head.

The media industry has developed a thin layer design to counter this effect, which is called as Anti-Ferromagnetic Coupling (AFC). This works by inserting a thin insulator between two layers of magnets, thus increasing the stability of the magnet by coupling both layers.

Perpendicular Magnetic Recording (PMR)

However, in recent years the media industry has moved to Perpendicular Magnetic Recording Media (PMR), which offers higher aerial densities with the same disk size. The maximum recording density of perpendicular magnetic disks is 5 times that of longitudinal ones based on comparison between the two of identical size of disks. The difference between PMR and LMR media is that the data (i.e. magnets) which is stored within the disks have a perpendicular orientation rather than longitudinal, i.e. in-plane orientation.

Longitudinal and perpendicular recording follow the same basic principle. As the write head passes by the disk surface, it leaves behind a magnetization pattern. For perpendicular recording, this magnetization pattern is ‘up’ and ‘down’ rather than ‘left’ and ‘right’ as for longitudinal recording.

This allows more data to be stored in one particular area. This means, if one bit can be stored within one area for longitudinal media, then by changing the orientation of the magnet on the media to perpendicular, the number of bits that can be stored in that area will increase. For example, if one room can fit 5 people who are lying next to each other, then that room can fit 25 people if they are standing.

A new feature in perpendicular recording media is the magnetically soft underlayer (SUL). The SUL belongs physically to the medium and magnetically to the head. There are changes from a recording system perspective in transition from LMR to PMR, because an efficient writing process requires the presence of SUL.

The future of HDDs depends on where the media and head industries are heading to. Medias will move on from PMR to Heat Assisted Magnetic Recording (HAMR) or Discrete Track Media (DTM). On the other hand, head devices will move on from Giant Magneto-resistive (GMR) head to Tunneling Magneto-resistive (TMR) head. This will in turn provide computer and electronics users to have larger data storage space over the next few decades, until either the technology itself becomes limited or the world comes to an end.

Insulated Gate Bipolar Transistor (IGBT)

The insulated-gate bipolar transistor or IGBT is a three-terminal power semiconductor device, noted for high efficiency and fast switching. It switches electric power in many modern appliances, namely electric cars, variable speed refrigerators, air-conditioners, and even stereo systems with digital amplifiers. Since it is designed to rapidly turn on and off, amplifiers that use it often synthesize complex waveforms with pulse width modulation and low-pass filters.

The IGBT combines the simple gate-drive characteristics of the MOSFETs (MOS field effect transistor) with the high-current and low–saturation-voltage capability of bipolar transistors by combining an isolated-gate FET for the control input, and a bipolar power transistor as a switch, in a single device. The IGBT is used in medium- to high-power applications such as switched-mode power supply, traction motor control and induction heating. Large IGBT modules typically consist of many devices in parallel and can have very high current handling capabilities in the order of hundreds of amps with blocking voltages of 6,000 V.

High-power semiconductor devices used for electric power conversion and other applications in industrial machinery and robots, air conditioner compressors, semiconductor manufacturing equipment, motor drives of automobiles and hybrid electric vehicles, welders and UPS (uninterruptible power suppliers), medical equipment, and the like, are supplied mainly as power modules. From the commercialization of IGBT products in 1988 through the present, due to their excellent performance and controllability, IGBTs have evolved to become the type of transistors used most commonly in power modules.

At its IGBT module lineup, Fuji Electric first began supplying a standard module series, but then with the 2nd generation of modules, added an IPM (intelligent power module) and PIM (power integrated module) series and, with the 3rd generation dramatically increased the number of types of models, and then with the 4th generation, added a small-size low-cost EconoPACK (trade mark of Eupec GmbH. Warstein) series.

With the 5th generation (U-series released in 2002), Fuji Electric added a 1,700 V series of modules, expanded the large-current series to 3,600 A, started to provide custom designed IGBT modules for hybrid vehicles, and advanced the commercialization of reverse-blocking IGBT modules for matrix converter use. However, with the 6th generation of devices, IGBT performance improvements will approach their limit, and a radically innovative device structure will be needed to realize the 7th generation devices (expected to be released in 2009 or 2010).

We are committed to continuing to expand the voltage and current range of high-power IGBT modules, to achieve even smaller size and lower cost in low-power IGBT modules, and to actively support new applications.


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