  In this paper, we consider an initial-boundary problem for plane
magnetohydrodynamics flows under the general condition on the heat conductivity
$\kappa$ that may depend on both the density $\rho$ and the temperature
$\theta$ and satisfies $$ \kappa(\rho,\theta)\geq\kappa_1(1+\theta^{q}) \quad
\hbox{\rm with constants}~ \kappa_1>0 ~\hbox{\rm and}~ q>0. $$ We prove the
global existence of strong solutions for large initial data and justify the
passage to the limit as the shear viscosity $\mu$ goes to zero. Furthermore,
the value $\mu^\alpha$ with any $0<\alpha<1/2$ is established for the boundary
layer thickness.
