The basic method of surface cleaning for PVD coating before plating is solvent cleaning. The commonly used cleaning fluid as bellow:
(1) Soften water or water system, For example, water containing detergent, dilute acid or alkali.
(2) Anhydrous organic solvents, Such as ethanol, isopropyl alcohol, ketone, acetone, etc.
(3) Petroleum distillates, chlorination or fluorination hydrocarbon.
(4) Emulsion or solvent vapour.
(5) Metal cleaner. Gold metal cleaning agent can be divided into acidic, alkaline and neutral alkaline three categories, its uses are respectively: acidic for the cleaning of oxides, rust and corroding substances; alkaline containing surfactants to remove light oil pollution; neutral alkali can avoid acid and alkali damage to the surface.
Which cleaning solvent is chosen depends on the nature of the contaminants. For example, animal and plant oils on plating surfaces may be chemically degreased with alkali solutions; mineral oils may be removed with organic solvents. But in fact, two types of grease often exist at the same time, so cleaning often requires the use of different cleaning solvents.