  We show that the main features of the cuprates superconductors phase diagram
can be derived considering the disorder as a key property of these materials.
Our basic point is that the high pseudogap line is an onset of phase separation
which generates compounds made up of regions with distinct doping levels. We
calculate how this continuous temperature dependent phase separation process
occurs in high critical temperature superconductors (HTSC) using the
Cahn-Hilliard approach, originally applied to study alloys. Since the level of
phase separation varies for different cuprates, it is possible that different
systems with average doping level pm exhibit different degrees of charge and
spin segregation. Calculations on inhomogeneous charge distributions in form of
stripes in finite clusters performed by the Bogoliubov-deGennes superconducting
approach yield good agreement to the pseudogap temperature T*(pm), the onset of
local pairing amplitudes with phase locked and concomitantly, how they develop
at low temperatures into the superconducting phase at Tc(pm) by percolation.
