| Author | Raksak Rujipornkasem |
| Note | A thesis submitted in partial fulfillment of the requirements for the
Degree of Master of Science in
Mechatronics, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | According to the increasing trend of HDD areal density, there are many factors to
achieve higher areal density, for example magnetic write width reduction and magnetic
spacing reduction. Magnetic spacing reduction can be achieved by both mechanical fly
height and dynamic fly height (DFH). Dynamic fly height relies on the reduction of
magnetic spacing by applying heat to the device as to increase the protrusion.
Magnetic spacing reduction by DFH can increase read back signal and Signal to
Noise ratio. At the same time, too low magnetic spacing can cause HDD problems such as
reliability issue and on head disk interference. Device designer needs to find the optimum
magnetic spacing by performing spin stand level testing and drive testing in order to
characterize DFH to define actuation efficiency. Actuation efficiency is the device
protrusion rate per heater power unit, of which the unit is nanometer per mW.
Operating spacing can be defined as gap of “Touch down point” and “Back off spacing.”
Back off spacing is the term for reliability’s improvement. In addition, an important step
before read and write process is “Touch down point’s identification.” Accuracy of touch
down detection can boost up electrical performance and maintain reliability.
This thesis proposes new technology of touch down point detection by “Touch
down sensor” or TDS which is built in the device. TDS uses a material’s property called
“TCR”, thermal coefficient of resistance, to be the measured parameter. Heat is generated
during very low magnetic spacing or at very near real touch down point. The TDS can
detect the heat and report the change of temperature for touch down point identification.
This thesis compares the conventional detection (Phase modulation) and new technology
(Touch down sensor) detection. The result will be analyzed and considered before
implementation. |
| Year | 2014 |
| School | School of Engineering and Technology (SET) |
| Department | Department of Industrial Systems Engineering (DISE) |
| Academic Program/FoS | Microelectronics (ME) |
| Chairperson(s) | Bargmann, Brent ; |
| Examination Committee(s) | Mongkol Ekpanyapong;Choudhury, Somen;Jim Potter; |
| Scholarship Donor(s) | Western Digital;NECTEC, Thailand;AIT Fellowship; |