Hard disk drive seek-arrival vibration reduction with parametric damped flexible printed circuits

Seek-arrival track-mis-registration (TMR) is one of the most critical dynamic design factors for modern hard disk drives to achieve high data transfer-rate performance goal. With its flexible structural nature, the flex cable itself inevitably renders low-frequency natural modes which have been a challenge with respect to balancing design efforts among servo control, mechanical design, and manufacturing process in disk drive industry. In this paper, particular focus will be given to vibration damping approach to reduce flex cable related seek-arrival dynamics in a state of the art magnetic disk storage drive. Experimental parameter studies of a typical constrained-layer damped flex cable vibrations are presented with cable exposed to various damper length and fold in different geometries. Effectiveness of the damper is also demonstrated by frequency responses with random excitation from actuator arm. Several design options toward reducing the flex circuit related arrival TMR will also be discussed in this paper.