The vacuum coating machine is a technology of continuous coating on flexible substrate by physical vapor deposition. The coating on the surface of flexible substrate has two functions: one is functional and the other is decorative. Functionality means that flexible substrates such as plastic film, paper, metal tape and cloth are coated with semiconductor film, metal film and optical multilayer film by different coating methods, which can not only improve their surface hardness, mechanical strength and water resistance, but also increase oil resistance and solvent resistance, improve aging resistance, and have conductivity, reflectivity, absorption, insulation, barrier and static electricity prevention, so that these flexible materials have some special functions.

Common winding vacuum coating machine can be divided into evaporation winding coating, magnetron sputtering winding coating and combined winding coating according to the working principle. The evaporation winding coating is divided into three types: resistance heating evaporation, induction heating evaporation and electron beam heating evaporation. Magnetron sputtering winding coating can be divided into DC sputtering and intermediate frequency reactive sputtering. Combined winding coating can be divided into resistance evaporation and magnetron sputtering, resistance evaporation and electron beam evaporation, electron beam evaporation and magnetron sputtering, etc.

The web vacuum coating machine has made great progress in the past 30 years. The coated products are widely used in decoration, packaging, capacitors and other fields, and can be coated with optical, electrical, electromagnetic and conductive films. The used substrates include PE, PET, PI, PP, OPP, BOPP, paper, foam plastic and cloth. Generally, the water content of plastic-based film material is 1% ~ 2%, while that of paper is larger, generally 5% ~ 7%. After coating and drying, the water content is still 3%. Because of the high water content of the substrate, the coating chamber has developed from the initial single chamber to the current double-chamber or multi-chamber structure. The evaporation source can be resistive, inductive, electron beam and magnetron sputtering. Two-chamber structure is widely used, and its advantages are:

(1)  It can evaporate paper substrates with large outgassing and guarantee the coating quality. A large amount of gas emitted from the paper is discharged from the winding chamber. Because the narrow gap between the winding chamber and the evaporation chamber is very small, the released gas is not easy to enter the evaporation chamber.

(2)  The single-chamber structure must be equipped with a large exhaust system to ensure the working pressure during vapor deposition, while the vapor deposition chamber in the double-chamber structure has a small amount of gas, which can be equipped with a small pump unit, thus reducing the equipment cost and saving energy;