Analyses of CMP Mechanism of NiP Substrate of Computer Hard-Disk with Alkali Slurry

In this paper, the chemical character of NiP substrate of computer disk is analyzed, the CMP kinetics processing is discussed to indicate that the chemical reaction is the slowest and the control process. By analyzing essentiality of slurry on NiP film CMP, it is indicated that the chemical component of slurry acts the important role in CMP. New type of alkali slurry for NiP substrate was prepared and its CMP mechanism is studied with alkali slurry. Strong complexation of complex agent improved selectivity of concave area and convex area to get higher removal rate. Low roughness is realized with small size and low hardness silica sol as abrasive.

Optimal Sliding Mode Dual-Stage Actuator Control in Computer Disk Drives

This paper presents a discrete-time design of a dual-stage actuator control system with sliding mode for computer disk drives. A state estimator based discrete-time boundary layer sliding mode control scheme is developed for a dual-stage actuator, which consists of a voice coil motor and a microactuator. Considering dominant microactuator flexible mode dynamics and the interaction between the two actuators, an optimal sliding hyperplane is designed to maximize their cooperation so as to attain desired responses. An application example demonstrates the utility of the proposed sliding mode dual-stage actuator control scheme for track-seek in the microactuator range, settle, and track-follow.

Submicron-Scale Flexible Ribbon Cable Seek-Settling Induced Vibration Reduction in High Capacity Disk Drives

This paper presents a modeling and design methodology to reduce and even to eliminate flexible ribbon cable seek-settling induced vibrations in modern high capacity computer disk drives. Optimization is first conducted in obtaining proper cable profiles when the rotary actuator swings across the disk using classical elastica theory with consideration of compliant boundary at its J-block conjunction point with rotary actuator and fixed boundary conditions at bracket. In addition to modal kinetic coupling factor, the cable’s vibration modes are projected onto actuator voice coil’s excitations to form as a weighted response factor to serve as the cost function in optimization process. It was found through the proposed process that the seek-settling flexible cable vibration can be minimized and even reduced to zero. Additional servo adaptive control format will be also discussed in this paper to totally eliminate the flexible ribbon vibrations in disk drive’s seek-settling operations.