Vacuum aluminum plating process

Vacuum aluminum plating is under vacuum conditions, the aluminum metal is heated and melted to evaporation, and aluminum atoms condense on the surface of the polymer material to form a very thin aluminum layer. Vacuum aluminum plating requires that the substrate surface is smooth, even, and uniform in thickness; the stiffness and friction coefficient are appropriate; the surface tension is greater than 38dyn/cm2; the thermal performance is good, it can withstand the heat radiation and condensation heat of the evaporation source; the moisture content of the substrate Less than 0.1%. Commonly used aluminum-coated substrates include polyester (PET), polypropylene (PP), polyamide (PA), polyethylene (PE), and polyvinyl chloride (PVC) films, and the process requirements; the vacuum degree must not be lower than 103 Pa. In order to avoid brown stripes or uneven thickness of the aluminum layer; to control the system tension, open the cooling system to avoid tensile deformation of the film heat; precise control of the take-up speed (280 ~ 320m/min), aluminum delivery speed (0.4 ~ 0.7m /min2mm aluminum wire) and evaporation boat heating current to obtain the required aluminum layer thickness (100-300A°); pre-drying a certain amount of primer on the film, fully drying, and then vacuum aluminum plating, Can improve the adhesion of aluminum layer and film. A certain amount of protective resin is then applied to the aluminum film to prevent oxidation of the aluminum layer. The aluminum-plated film formed by this process is resistant to friction and is not easily degraded. Vacuum aluminum plating common quality problems and solutions are as follows:
1. Brown stripes appear on the surface of the film. Reasons: 1 Low vacuum solution: Clean the aluminum in the vacuum chamber, vapor deposition device, cooling system, unwind, take-up device, and guide roller; check the vacuum system; reduce the ambient humidity. 2 film releases gas. Solution: film pre-drying; extend the vacuum time. 3 too much aluminum spray. Solution: Increase the speed of the vehicle; reduce the evaporation boat current; reduce the speed of sending aluminum. 4 Evaporation boat contains impurities. Solution: Clean the boat and heat shield. 5 Evaporation boat aging. Solution: Replace the evaporation boat.
2. When the film is coated with aluminum, the hole causes: 1 The aluminum material in the evaporation boat is too full. Solution: Reduce the speed of aluminum delivery; increase the evaporation boat current. 2 Short circuit between evaporation boats in the vacuum chamber. Solution: Remove the short circuit. 3 Vacuum indoor impurity splash Solution: Clean the vacuum indoor wall, send aluminum evaporation device, cooling drum, unwinding, coiling device and each guide roller.
3, the phenomenon of stretching of the film when aluminum plating causes: 1 substrate tension is too large. Solution: Adjust the unwinding and take-up tension control system and reduce the tension appropriately. 2 The cooling system is malfunctioning. Solution: Check the cooling system and troubleshoot. 3 Evaporation boat temperature is too high. Solution: Reduce evaporation boat heating current; increase speed.