Reasearch On Chemical Mechanical Polishing Mechanism And Static Characteristics Of Head/Disk System

With the rapid development of the computer, hard disk drives (HDDs) develop toward the corresponding tendcy of larger-capacity, higher speed, smaller size and higher security. In order to reduce the minimum record area of HDDs and enhance storage density, in HDDs the distance between the head and the magnetic media should be reduced increasingly. In such a small gap, the waviness, roughness and nano-scratches of disk surface effect the stability of flying head in HDDs has become increasingly evident, so study on the influnce of the disk platter surface quality to the static characteristics of the HDDs system is of great significance.Chemical mechanica lpolishing (CMP) is used to get a smooth surface quality in HDDs as the final finishing means which is the only finish machining technique up to date for surface global planarization, which has been widely used in prensen day. But the technology is developed from the practice which still lack in in-depth study theoretically. In the study of mechanical removal mechanism the material removal model accommodating both plastic and elastic deformation of pad asperity is proposed by analyzing the contact of the polishing pad, abrasive particles and the polished surface. The model is simulated to predict the effect of three variables such as pressure, relative velocity between pad and the polished surface and the abrasive concentration on CMP material removal rate.As the distance between the head slider and the disk continues reducing, the impact of the hard disk surface roughness also becomes increasingly significant. In the present study, the Reynolds equation considering the gas rarefaction effect is used taking into account surface surface roughness which is a sine curve to calculate the static characteristics of a slider with ultra-thin spacing. Pressure distribution, pressure amplitude and amplitude point of pressure distribution are calculated by solving reynolds equation considering the gas rarefaction effect numerically using a mesh-free method called LSFD when the disk surface roughness along the slider length direction, the disk surface roughness along the slider width direction and three kinds of roughness pattern on the disk surface. The three kinds of roughness pattern on the disk surface which are reaserched in the article are transverse roughness, the isotropic roughness, longitudinal roughness.In the present study, the free molecular MGL equation is used taking into account surface accommodation coefficients (ACs), a, for the free molecular limit, and it is used to calculate the static characteristics of a slider with ultra-thin spacing. Pressure distribution and shear stress distribution were calculated by solving the molecular gas film lubrication (MGL) equation in the free molecular region numerically using a mesh-free method, and static characteristics of air bearing film in hard disk drives (HDDs) with the linear ACs are investigated.The results of this study will be helpful to improve the disk surface quality of HDDs and provide some insights into the disk surface quality’influnce on the static characteristics of the hard disk head/disk system in HDDs., which are of guiding significance to the design and production of HDDs.