Haeng-Soo Lee

VCM design to improve dynamic performance of an actuator in a disk drive

PES design margin of current hard disk drive becomes getting smaller as track density of high-capacity disk drives increases. In the present work, a new actuator design concept is introduced for reducing one of the actuator vibration modes so called a butterfly mode that normally limits expansion of servo bandwidth. The new actuator has single coil with four sections having respective particular directions. By adjusting the length and direction of the sections of the VCM coil, the forces perpendicular to track seeking direction can be balanced with each other, and then the butterfly mode is not excited by the resultant force of VCM. Contribution of the proposed actuator design for the PES management is verified by numerical simulations. As a result, the servo bandwidth is to be increased so that PES can be decreased due to improved dynamics of the proposed method.

Dynamic absorber for actuator arm in a disk drive

Dynamic absorber is introduced to assist in controlling the amplitude and acceleration of the actuator arm in disk drive so that it can improve the shock handling capability in both operation and non-operating condition. The effect of the dynamic absorber on shock performance is examined through numerical simulation and experimental test.

Reliability Study of 3D TSV Package Using Solder Interconnect

TSV(through silicon via)를 이용한 3차원 적층 칩 패키지 기술은 여러 개의 기판 혹은 다른 종류의 칩들이 수직 방향으로 적층(stack)되는 형태의 패키징 기술이다. TSV 기술은 실리콘 웨이퍼를 관통하는 미세 비아(via) 홀을 형성한 후 비아 홀 내부에 전도성 물질, 주로 구리(copper)를 충전시켜 칩 내부에 직접 전기적 연결 통로를 확보하는 기술이다. TSV 기술을 사용할 경우, 기존의 와이어 본딩을 이용한 적층 기술에 비해 고성능, 저전력, 고집적화 및 고기능의 효과가 발생하기 때문에 최근 반도체 업계의 차세대 패키징 기술로서 개발이 한창 진행 중에 있다. 특히 TSV 기술을 스마트 기기에 적용할 경우, 고질적인 문제로 지적되고 있는 배터리의 전력 소모 문제가 어느 정도 해결이 될 수 있기 때문에, 향후 스마트 폰 및 모바일 기기에 사용되는 반도체 칩은 대부분 TSV 기술 방식의 칩 적층 기술이 사용될 것으로 예상된다

Suspension to Reduce Off-track Due to Disk Vibration and Suspension Bending

Design margin of position error signal (PES) is getting smaller as track density of high-capacity disk drives increases. A substantial portion of the PES is caused by disk vibration which makes off-track between head and disk. In this paper, a new HGA design concept is introduced for suppressing the off-track due to disk vibration as well as the off-track due to suspension bending.

Experimental analysis of HDD actuator for the improvement of shock reliability

The shock performance of a hard disk drive has been a serious issue with the use of mobile computer and AV application. Focusing on the motion of actuator, we investigated nonoperational shock mechanism and studied several parameters that affect the shock performance by experimental analysis. It was found that there are two important factors for the actuator to endure high shock level. One is shock transmissibility and the other is beating between the arm blade and the suspension. To generalize the shock transmissibility, the concept of shock response spectrum was introduced. A shock response spectrum of the actuator system was obtained experimentally and compared with that of an analytical single degree of freedom model. There was a good agreement, and the first bending natural frequency of arm blade was found to be the most important factor for the low shock transmissibility. By applying the shock response spectrum and avoiding the beating, we could design an actuator of high shock performance.