Abstract: A sputtering apparatus is constructed in modular form to facilitate changes in sputtering processes and target materials. At least two sputtering modules and a pumping stack module are arranged in series and in any desired order between a load module and an exit module. Each module is attached to another module by sealingly abutting flanges which are connected by externally accessible bolts. The use of gate valves between the modules is avoided by the provision of connecting sleeves which are each at least as long as the mean free path of the sputtered target atoms.