Finite element simulation of a laser scribing process for a head suspension in hard disk drives

Abstract

Quality control in production process of head suspension plays an important role in Hard Disk Drive (HDD)manufacturing. In order to ensure an accurate read/write operation of hard disk, a major assembly step of flying height, a distance between disk surface and head, must be examined. Recently, laser scribing technique has been applied to alter flying height to desired values of Pitch Static Attitude (PSA) and Roll Static Attitude (RSA). These two parameters are used as industrial standard for production of hard disk drive. This study concerns a prediction of deformation behaviour of head suspension undergoing laser scribing process by means of Finite Element Analysis (FEA). Material properties of austenitic steel 304 customarily employed for the head suspension were investigated depending on temperature. Finite element simulations combined with an isotropic hardening as well as a non-linear kinematic hardening model were carried out in order to study material responses after the cyclic laser scribing. The results from simulations using those material models were compared with experimental results, in which thekinematic hardening model provided more accurate predictions.

Keywords: Laser scribing, Non-linear kinematic hardening, Head suspension,Flying height, Finite element analysis, Austenitic steel 304