Contamination preventive sheet

PURPOSE:To obtain a contamination preventive sheet capable of freely deformation machining and cutting and to prevent to contamination in the inside of a thin film forming device using the same by forming a ceramic coating film on one face of a flexible Al foil by the use of the anodic spark discharge method. CONSTITUTION:The flexible Al foil is immersed into an aq. solution containing sodium silicate, potassium silicate, colloidal silica or the like or an electrolytic bath made by suspending a ceramic (e.g. Al2O3, ZrO2, TiO2 or the like) particulate therein to make an anode. Using an insoluble electrode such as iron, stainless, nickel as a cathode, spark discharge is executed. And the ceramic coating film is formed at least on one face of the Al foil. As a result, the contamination preventive sheet capable of freely deformation machining and easily cutting by a scissors or the like and small in the generation of dust or the like is obtained.