Finite Element Analysis of a Disk Drive Flex Lead

This paper on "Finite Element Analysis of a Disk Drive Flex Lead" was presented at the NAFEMS World Congress on The Evolution of Product Simulation From Established Methods to Virtual Testing & Prototyping - 24-28 April 2001, The Grand Hotel, Lake Como, Italy.

Abstract

A flex lead in a computer disk drive is the communication link between a stationary circuit board and a moving rotary actuator. The rotary actuator positions a number of magnetic recording heads over a series of rotating disks for the purpose of reading and writing data. Because of the rapid oscillatory motion of the actuator during operation, the flex lead can be subjected to very complicated dynamics that can effect the dynamic performance of the actuator.
The flex lead was modeled as a thin symmetric planar laminated shell structure. The layers consist of a central layer of copper runs, two layers of adhesive, and two outer layers of a high temperature polymer. Large deflection static analysis was used to determine the shape of the flex lead in its installed operating position. Modal analysis was then performed for this deflected shape to determine the most significant modes and their natural frequencies. Transient dynamic analysis based on disk drive operating conditions was performed to calculate the torque imparted to the rotary actuator by flex lead vibration. ANSYS Rev. 5.5.1 was used in all phases of the finite element analysis.
The finite element results were found to give good agreement with experimental modal analysis results using high-speed video equipment as well as with measured disk drive performance data. The results helped explain a previously observed disk drive settle phenomenon and the procedure is now proving useful as a design tool for minimizing flex lead vibration in future disk drive designs.