Analysis of flying characteristics of magnetic heads with ultra-thin spacings based on the Boltzmann equation

Numerical analyses of flying characteristics of magnetic heads for magnetic disk storage with ultrathin spacings are presented, applying the general lubrication equation based on the Boltzmann equation as an exact solution. The analyses are then compared with those using the slip flow approximation equations with accommodation coefficients of momentum. For conventional magnetic heads with nominal submicron spacings, differences between flying characteristics based on the generalized equation and the approximation equation are not necessarily significant (10% or less). This can explain why the experimental results agree well with numerical solutions based on a slip flow approximation. The differences for small heads with ultrathin spacings (less than 0.1 μm) can be more than 20%, indicating that for such heads the generalized lubrication equation based on the Boltzmann equation should be used to predict the flying characteristics for slider designs