Technology of large focal planes of CCDs

e2v technologies has demonstrated capability in the supply of state-of-the-art CCDs for large area scientific focal planes. We discuss technical developments and lessons learnt from the manufacture and supply of large-format CCDs. Several large mosaics have now been built or are under construction, using e2v sensors- these include CFHT Megacam, ESO VST, SAO Megacam, Kepler, and GAIA. Design, assembly and operational issues are presented.