Site: Fujifilm Company, Ltd.
Odawara Factory
Recording Media Product Division
2-12-1 Oogi-cho, Odawara
Kanagawa, Japan
http://www.fujifilm.co.jp/

Date Visited: 11 March 1998

WTEC:

Hosts:

BACKGROUND

Fujifilm Company was established in 1934; it has about a 65 year history. The Odawara factory was constructed in 1937. The first research on magnetic recording media was started about 45 years ago. At that time, tape for quadraplex video systems developed by the Ampex Company was one of the main targets. Later, Fujifilm developed and marketed many kinds of tapes, including audio, video, and computer media. In 1988, the first product for the VHS market was developed, using simultaneous dual coating technology. Fujifilm also developed metal particulate media technology in parallel with this coating technology. In 1992, Fujifilm succeeded in developing ATOMM tape, which has a non-magnetic under layer and a high- performance and super thin magnetic overcoat. Presently in Fujifilm's R&D laboratory almost all kinds of new flexible magnetic recording media are under development. Fujifilm claims to have a good reputation as the best flexible magnetic media manufacturer. The recording media product division employs 1,000 people. The R&D section employs 200 researchers, including R&D for CD-R. Fujifilm has 20% of the Japanese VHS market and is the main supplier of DLTs. Fujifilm buys the metal particulates and base films from outside vendors.

DISCUSSION

Dr. Inaba gave an in-depth presentation on present status and future directions of tape media at Fujifilm. Key points he addressed included the following: choice and preparation of magnetic powder, with a comparison of MP and barium ferrite; the substrate material; the coating and slitting processes; and issues in reducing spacing.

Over the last decade, Fujifilm has maintained a continuous increase in coercivity of MP using first FeNi and later Fe-Co powders. Coercivities at the range of 2,300 Oe can now be obtained. At the same time the switching field distribution has dropped significantly to about SFD=0.2. In addition particle volumes have been greatly reduced to about 10-5 Ám3. Presently each powder grain consists of only a few domains and the objective remains that of obtaining single domain particles. The advances in MP are summarized in Table C.3.

On the other hand, Dr. Inaba and his team see certain advantages in barium ferrite. It exhibits interesting properties including higher coercivity or smaller magnetization suitable for MR heads, good noise performance (fine grain) exceeding MP noise performance by 6 dB, good stability derived from its oxide nature and durability. The key limitations of barium ferrite are considered to be lack of reliable suppliers, the requirements for MR heads, and assymetrical signal waveform requiring different signal processing techniques.

Table C.3
Advances in MP
 

Unit

Advanced MP

HI8 MP

8 mm Tape

Coercivity

kA/m

Oe

190

2,410

142

1,800

121

1,520

Saturation Magnetization

Am2/kg

153

131

121

Co Content

Atm%

30

10

0

Particle Length

nm

93

102

148

Particle Length Distribution

%

29

38

53

Content of Single Crystal Metal

%

31.5

24.7

22

In the area of substrates, Dr. Inaba's roadmap includes transitioning from PET --> PEN --> aramid within the next decade. He also points out the PBO material manufactured by Toyobo that provides the biggest stiffness with very large isotropic modulus (4,000/4,000). He expects that by increasing the availability of aramid produced by Toray and Asahi-Kasei, it should be possible to reach substrate thickness of about 3 Ám within five years and perhaps down to 2 Ám over the next decade.

Using an accurate coating process such as the DWT die coater, Fujifilm has been able to reduce the thickness of the substrate from 0.4 Ám to 0.2 Ám with a significant reduction in defect densities. Dr. Inaba pointed out that coating thicknesses less than 0.1 Ám are now within reach. Defect densities have been reduced by controlling dust particles but also by improving monitoring techniques such as improved optical defect sensors.

In order to improve track linearity, accurate slitting is required. Fuji researchers seem to have put an early emphasis on this aspect, trying out laser-assisted slitting. But because a certain texture is required for reducing wear and tear they continue to use shear cutting methods.

To reach smoother surface quality, Fuji researchers put emphasis on the formulation using special lubricants. In order to reduce real area of contact to decrease friction, yet to achieve less separation between the head and tape (for more resolution) several aspects are being investigated:

Using these techniques Dr. Inaba and his team project a roadmap for the next 10 years, as shown in Table C.4.

Table C.4
10 Year Projections

DVC/LP

Now

Aggressive

Conservative

+ 5 Years

+10 Years

+5 Years

+10 Years

Tape Thickness

7

4.5

3

4.5

3

Wavelength

0.49

0.3

0.2

0.4

0.3

Track Pitch

6.67

3

1.5

5

3

Linear Density (kbpi)

103

169

253

127

169

Track Density (tpi)

3,800

8,400

17,000

5,060

8,400

Areal Density (Mb/in2)

390

1400

4300

640

1400

Volume Density (Tb/in3)

1.4

7.9

36.3

3.6

11.8

OTHER DISCUSSION

Disk and Optical Tape Media vs. Magnetic Tape

Fujifilm researchers did not perceive optical tape as a major competitor since sensitivity to dust, difficulty in precise tracking and lack of critical mass are expected to restrict the applicability of optical tape. Also they perceive tape technologies and disk technologies as being aimed at different markets and applications: tape media for professional markets that cannot use compression and disks for consumer use. In addition, the researchers perceive the volumetric density and low cost advantage of tapes as an essential point for the future success of tape media (Fig. C.2).

Figure C.2
Fig. C.2. Projection for volumetric density.


Published: June 1999; WTEC Hyper-Librarian