Temperature Study of Embedded Contact Sensor for HDDS by Using Scanning Thermal Microscopy

2014 ◽  
Author(s):  
Masaru Furukawa ◽  
Junguo Xu ◽  
Jianhua Li ◽  
Kiyoshi Hashimoto ◽  
Makoto Satou
Keyword(s):  
Hard Disk Drives ◽  
Disk Drives ◽  
Scanning Thermal Microscopy ◽  
Height Control ◽  
Head Slider ◽  
Self Bias ◽  
Key Factor ◽  
Contact Sensor ◽  
Sensor Temperature ◽  
Fly Height

An embedded contact sensor (ECS), which is a thermal sensor built into a head slider, has been used for contact detection between the head slider and the disk in hard disk drives. Our previous research showed that ECS could successfully detect pits on the disk and spacing modulation between the head and disk. In this work, the sensor temperature effect caused by self heating and by the thermal fly height control (TFC) heater was studied in a non-flying condition for better understanding ECS. The results showed that the temperature dependency of the TFC heater was 10 times that of ECS self-bias heating. TFC heating is dominant and the key factor in ECS sensitivity to pit detection and spacing monitoring.

Thermal Fly-Height Controlled Glide for Disk Defect Detection and In-Situ Defect Size Estimation for Disk Drives

2013 ◽  
Author(s):  
Aravind N. Murthy ◽  
Karl A. Flechsig ◽  
Wes Hillman ◽  
Keith Conard ◽  
Remmelt Pit
Keyword(s):  
Hard Disk Drives ◽  
Sem Analysis ◽  
Disk Drives ◽  
Size Estimation ◽  
Optical Surface ◽  
Force Microscopy ◽  
Height Control ◽  
Atomic Force ◽  
Fly Height

Current hard disk drives (HDD’s) use thermal fly-height control (TFC) during read/write operations. In this study, we use TFC technology during the disk glide process to determine sub-5nm height defects. We also utilize TFC to measure the height of the defect during glide operation. Addtionally, we magnetically mark the disk locations where defects are detected for further post-processing of the defects using optical surface analysis (OSA), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The defect height estimation during the glide was confirmed to be accurate by AFM and SEM analysis. Finally, we will present the TFC glide sensitivity showing capability of detecting smaller defects than conventional non-TFC glide technologies.

Dimension Effect of Embedded Contact Sensor on Disk Defect Detection

2013 ◽  
Author(s):  
Masaru Furukawa ◽  
Junguo Xu ◽  
Jianhua Li
Keyword(s):  
Defect Detection ◽  
Thermal Contact ◽  
Hard Disk Drives ◽  
Defect Size ◽  
Contact Detection ◽  
Disk Drives ◽  
Magnetic Head ◽  
Head Slider ◽  
Contact Sensor

A thermal contact sensor embedded in a magnetic-head slider was developed. The sensor has been used for contact detection between a head slider and a disk in hard disk drives, and, our previous research has shown that the sensor could successfully detect disk defects including asperities and pits. In this work, the sensor dimension effect and characterization of defect size was studied in order to better understanding of defect size. The results showed that the defect size can be clarified by considering sensor size and scan pitch.

An Insight Into the Nonlinear Touchdown Dynamics of TFC Active Slider

2013 ◽  
Author(s):  
Gang (Sheng) Chen ◽  
Jianfeng Xu ◽  
J.-Y. Chang
Keyword(s):  
Nonlinear Dynamics ◽  
Hard Disk Drives ◽  
Disk Surface ◽  
Flying Height ◽  
Disk Drives ◽  
Height Control ◽  
Intermittent Contact ◽  
Fly Height ◽  
Insight Into ◽  
Small Spacing

Storage of 10 Tb/in 2 in hard disk drives within the next decade requires a significant change to reduce the physical spacing as little as 0.25 nm at the read-write transducer location. A lot of tribology issues exist to such a low flying height, the touch down and take off instability and hysteresis, the flying height avalanche, the influences of surface topography and morphology, the lubricant modulation and pick-up, robust air bearing surface and suspension design, just to name a few. Understandings of the complex tribo-dynamics issues in the near contact and contact states are very important to further reduce the flying height. At such a small spacing intermittent contact between the slider and disk surface becomes inevitable and the current MEMS-based thermal fly-height control (TFC) technology needs further improvement to satisfy the future needs. How to control the slider to reduce touchdown instability and eventually eliminate bouncing has been a pressing and challenging research topic. Most of existing work on touchdown dynamics applied conventional nonlinear dynamics theory and spectrum as well as harmonics analysis, which could suffer from the assumptions of small nonlinearity and stationary. This study presents a concurrence plot and Lyapunov exponent analysis which could offer an insight to the problem in the context of contemporary nonlinear dynamics theory.

Performance Optimization of Thermal Nano-Actuator for Fly Height Control in Disk Drives

2009 ◽  
Author(s):  
Haisan Tan ◽  
Bo Liu ◽  
Mingsheng Zhang ◽  
Shengkai Yu
Keyword(s):  
Performance Optimization ◽  
Power Input ◽  
Vertical Position ◽  
Disk Drives ◽  
Height Control ◽  
Line Spacing ◽  
Simulation Results ◽  
Heater Design ◽  
Fly Height ◽  
Actuator Design

Slider with thermal fly height control (TFC) uses a thermal heater to produce localized thermal protrusion and adjust the vertical position of the read/write head. This paper reports authors’ efforts in exploring large protrusion stroke with minimal heater power input whilst preserving heater robustness in the TFC slider, with an optimized thermal nano-actuator design. Effects of both heater line width and line spacing on TFC slider performances are investigated. A novel ‘Stream-River’ heater design approach is proposed. Simulation results conclude that the “Stream-River” approach is of both high power-protrusion efficiency and high heater robustness.

A Method to Reduce Head-Disk Interface (HDI) Degradation Risk During Thermal Asperity (TA) Mapping in a Hard Disk Drive

2020 ◽  
Author(s):  
Abhishek Srivastava ◽  
Rahul Rai ◽  
Karthik Venkatesh ◽  
Bernhard Knigge
Keyword(s):  
Hard Disk Drive ◽  
Bias Voltage ◽  
Disk Drive ◽  
Test Time ◽  
Head Disk Interface ◽  
Disk Interface ◽  
Height Control ◽  
Contact Sensor ◽  
Fly Height ◽  
Sample Set

Abstract One of the issues in thermal asperity (TA) detection using an embedded contact sensor (ECS) is the degradation caused to the read/write elements of the head while interacting with the TA. We propose a method to reduce such head-disk interaction (HDI) during TA detection and classification by flying higher at low thermal fly-height control (TFC) power, which minimizes the interaction of the TA with the head. The key idea is to scan the head at higher fly height, but with higher ECS bias voltage. Initial experiments have shown that the TA count follows a negative cubic relationship with the backoff at various bias levels, and that it follows a square relationship with bias at various backoff levels. Using a sample set, the calibration curves i.e. the golden relationship between these parameters can be established. Using these, one can start the TA detection at the highest backoff and high ECS bias, and start to estimate the nominal TA count. By mapping out these TAs and ensuring the head does not fly over them again to prevent HDI, the fly height can then be lowered, and the rest of the TA cluster can be scanned. Following this method iteratively, the entire TA cluster can be mapped out with minimal interaction with the head. Although this method entails an increase in the test time to detect and map all TAs, compared to detecting them with TFC being on, this can help improve the reliability of the drive by protecting the sensitive read/write elements especially for energy assisted recording from HDI.

Thermal mechanics of a contact sensor used in hard disk drives

2013 ◽  
Vol 19 (9-10) ◽  
pp. 1607-1614 ◽  
Author(s):  
Jianhua Li ◽  
Junguo Xu ◽  
Jin Liu ◽  
Hidekazu Kohira
Keyword(s):  
Hard Disk Drives ◽  
Hard Disk ◽  
Disk Drives ◽  
Contact Sensor

Contact and temperature rise of thermal flying height control sliders in hard disk drives

2012 ◽  
Vol 18 (9-10) ◽  
pp. 1693-1701 ◽  
Author(s):  
Liane Matthes ◽  
Uwe Boettcher ◽  
Bernhard Knigge ◽  
Raymond de Callafon ◽  
Frank E. Talke
Keyword(s):  
Temperature Rise ◽  
Hard Disk Drives ◽  
Hard Disk ◽  
Flying Height ◽  
Disk Drives ◽  
Height Control ◽  
Thermal Flying Height Control
Sign in / Sign up

Export Citation Format

Share Document