  The proximity effect and the Josephson current in a
superconductor-insulator-ferromagnet-superconductor (SIFS) junction are
investigated within the framework of the quasiclassical Eilenberger equations.
This investigation allows us to compare the dirty and the clean limits, to
investigate an arbitrary impurity scattering, and to determine the
applicability limits of the Usadel equations for such structures. The role of
different types of the FS interface is analyzed. It is shown that the decay
length and the spatial oscillation period of the Eilenberger function may
exhibit a nonmonotonic dependence on the properties of the ferromagnetic layer
such as exchange field or electron mean free path. The results of our
calculations are applied to the interpretation of experimentally observed
dependencies of the critical current density on the ferromagnet thickness in
Josephson junctions containing a Ni layer with an arbitrary scattering.
