Long-term Archivability and Stability of Fujifilm magnetic tape using Barrium Ferrite (BaFe) particle.

September 10, 2010

FUJIFILM Corporation (President and CEO: Shigetaka Komori) has proven that more than a 30 year archival period is possible with Fujifilm's unique Barrium Ferrite (BaFe) tape and that the tape is stable and reliable after such time period.

Due to internal controls and regulations, the amount of long term archival data is increasing every year. Since magnetic tape does not need to be periodically operated or connected to a power source, there will be no data loss because of performance degradation due to the drive actuator. This means magnetic tape is a reliable long term storage solution.

Magnetic tape uses magnetic particles as a recording medium. For further capacity and expansion of magnetic tape, it is necessary to micrify the particle size and increase the recording density. Today, metal particle tape is the most popular among the magnetic tape market. However with metal particle, it is extremely difficult to maintain each particle’s magnetic force when using microscopic particles in order to increase the recording capacity. Therefore ahead of other tape manufacturers, Fujifilm has advanced the development of BaFe particles and BaFe tape to achieve large recording capacity. This advanced development aims to keep higher coercivity (using micro fine particles), lower noise, higher frequency characteristics and superior storage performance in comparison to other metal particles.

Fujifilm performed their original accelerated evaluation (temperature 60°C, relative humidity 90%) in order to confirm the changes of demagnetization, friction coefficient and tape surface over time. In addition, a storage test in a polluted environment (“Battelle experiment”) was performed. Thru this series of testing, it was proven that the data storage of 30 years or more with BaFe particle is possible and the tape can maintain its magnetic characteristics for long term storage.

1. Accelerated evaluation: Amount of demagnetization comparison:

BaFe tape and the latest metal particle tape were stored under 60°C 90% relative humidity environment for 30 days to measure the changes of demagnetization. After 30 days, which corresponds to 30 years when stored naturally*1, there was no change in the amount of demagnetization with BaFe tape, proving that it can maintain its excellent magnetic property for more than 30 years (Fig 1.). Under the same testing conditions, although a decrease in the amount of magnetization can be seen in the latest metal particle tape, there is no impact on read and write performance. BaFe tape shows even better performance than metal particle tape as it is oxide and is chemically stable. Therefore, influencers within a storage environment do not affect the stability of the magnetic properties under long term storage conditions.

  • *1 Magnetic properties have actually been measured in metal particle tape which was manufactured in 1985. It was proven that one day corresponds to one year of ambient storage when testing the same tape in a 60°C 90%RH environment.

Fig1.Change in the amount of demagnetization for BaFe tape and metal particle tape (Fujifilm estimate)

2. Accelerated evaluation: Change in tape surface and friction coefficient

BaFe tape was stored under 60°C and 90% relative humidity environment for 30 days. A Differential Interference Contrast microscope (“DIC”) was periodically used to monitor the tape surface. As a result, there was no surface extraction which is usually the cause of errors or drop-outs*2. In addition, friction coefficient was measured using an AlTiC*3 cylinder which is made of the same material as an actual drive head. The BaFe tape was run while wrapping its surface around the AlTiC and the change in friction coefficient was measured over time. The results show that there was no change in friction coefficient (Fig 2) after 30 days. Moreover, the AlTiC cylinder which was used in the friction testing was monitored using DIC and there was no increase in the amount of debris from the tape which is usually the cause of errors or drop-outs. Therefore these results verify that BaFe tape is stable and can be run after 30 years of archival storage.

  • *2 Drop-out is a momentary defect cause by a temporary loss of signal.
  • *3 AlTiC is Alumina Titanium Carbide (AlO2 / TiC ceramic)

Fig2. Change in friction coeffient of BaFe tape (Fujifilm estimate):

There was no change in the friction coefficient after storing BaFe tape for 30 days under 60°C and 90% relative humidity. This indicates that BaFe is stable and can be run after 30 years of archival storage.

Before
After

3. Storing test under corrosive gas environment “Battelle evaluation”

A “Battelle test”*4 simulates the change in BaFe tape and metal particle tape over time. This test was performed in a polluted environment generating the corrosive gas chlorine. It was confirmed that there was no corrosion on the tape surface with BaFe tape even if it was left in the corrosive gas for 14 days (Fig 3). Also there was no decrease in the amount of magnetization. This proves that BaFe tape is stable for long term storage even after exposure to a polluted environment.

  • *4 Test condition - H2S 10ppb, NO2 200ppb, Cl2 10ppb at 30°C / 70% relative humidity for 14 days.
    The “Battelle test” was originally used to simulate the corrosion process of electronic equipment or parts over time. It was developed by the Battelle laboratory in the United States. It is assumed that 48 hours under the above conditions will correspond to 4 years when stored naturally (which means one day corresponds to two years). The Battelle test can be categorized into 4 different environment classes (Class 1-4), Fujifilm tested under the “Class-2” conditions for 14 days which simulates an office environment without air / temperature / climate control.

Fig3.Change in the tape surface in a corrosive gas environment using DIC (Fujifilm estimate). Magnification: x 200.

<BaFe tape surface>: There was no change in BaFe tape surface after storing it in a corrosive gas environment.

Before the test - BaFe tape

After the test - BaFe tape

<Metal particle tape surface>: Black spots which were caused by corrosion can be seen on the metal particle tape surface.

Before the test - metal particle tape

After the test - metal particle tape

For reference, similar testing has been done on BaFe archivability and its stability which was announced by IEEE Transactions on Magnetics Vol 44, No.11, November 2008. It was proven that there was no loss in the output level of recorded signal after storing BaFe tape at high temperature.*5

Fujifilm will continue to take the lead in the development of BaFe particle which is a proven reliable long term storage solution that will expand the capacity of data storage tape in the field of recording tape products. This includes the highly functional material field, which supports the development of advanced data storage systems.

  • *5 Reference: M. L. Watson, R. A. Beard, S. M. Keintz, and T. W. Feebeck, “Investigation of Thermal Demagnetization Effects in Data Recorded on Advanced Barium Ferrite Recording Media” IEEE Transaction on Magnetics, vol 44, No. 11, Nov 2008.

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FUJIFILM Corporation
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