The Ohio State University

MAGNETIC AND TRIBOLOGICAL EVALUATION OF ADVANCED METAL EVAPORATED TAPES IN AN ADVANCED LINEAR TAPE DRIVE

Anthony D. Alfano
M.S. Thesis,
Department of Mechanical Engineering, March 2006

ABSTRACT

Demand for increased data storage has resulted in the development of various types of magnetic tape. To achieve higher recording density, tape manufacturers are developing thin-film tapes, such as advanced metal evaporated (AME) tape, for use in linear tape drives. The structure of AME tape is fundamentally different from metal particulate (MP) tape. The goal of this study was to determine the methods and mechanisms associated with failure of AME tapes as well as evaluate the magnetic performance of these AME tapes including the impact of tape cupping and initial edge quality in an advanced linear tape drive.

Numerous durability tests are performed in an advanced linear tape drive. To understand the failure mechanisms of the AME tapes, damage to the tape edge and debris accumulation of the head are monitored using optical microscopy. Atomic force microscopy (AFM) is used to determine the roughness of the unworn and worn tapes. Lateral tape motion peak-to-peak amplitude and head-tape interface friction are used as a metric. To evaluate the magnetic performance of the AME tapes head output, dropouts, head-tape interface friction and lateral tape motion are monitored throughout testing. Lateral tape motion has become one of the critical limitations of magnetic performance. To more accurately measure lateral tape motion during drive development, a new method involving the output voltage of a head read element that has been adjusted to be halfway off the recorded track on tape is implemented.

It is shown that AME tape exhibits a slightly lower coefficient of friction than the MP. The negatively cupped AME tape demonstrated a greater value of lateral tape motion peak-to-peak amplitude than both of the positively cupped AME samples as well as the MP tape sample. It was found that poor initial tape edge condition plays a large role in debris generation. The dominant mechanism of failure for the AME samples is adhesive wear resulting in removal of the DLC overcoats and sub layers. It is also shown that positively cupped AME tapes will result in similar head output and fewer dropouts than the current MP tapes. The negatively cupped AME sample resulted in the lowest head output data and the highest amount of dropouts of all the tapes evaluated in this investigation. All tapes evaluated resulted in similar values of lateral tape motion when monitored at the center of the tape. When lateral tape motion was monitored at the lower edge of the tape, the positively cupped AME tape with the worst relative edge contour length resulted in the highest value of lateral tape motion. From this investigation, positively cupped AME tapes with good initial relative edge contour length are recommended for use in linear tape drives similar to that used in this study.