EVA Encapsulation Film

EVA encapsulation film is one of the most critical encapsulation materials in the production process of solar modules, which covers the top and bottom of the cell in the middle, playing the role of protecting the cell; EVA has a high transmittance after melting, which can improve the incidence of light and increase the output power of the module; in addition, in the process of module production, the lamination is a key link, and the parameter settings of the laminating machine basically revolve around the characteristics of EVA. The parameters of the laminator are basically set around the characteristics of EVA, so EVA is crucial to the production of modules.

The main component of EVA is a copolymer of ethylene and vinyl acetate, plus various additives such as crosslinking agents, thickeners, antioxidants, light stabilisers and so on.

EVA has excellent flexibility, impact resistance, elasticity, optical transparency, low-temperature bending, adhesion, environmental stress cracking resistance, weather resistance, corrosion resistance, heat sealing and electrical properties.

EVA is a hot melt adhesive, at room temperature, EVA is solid, non-adhesive, and has poor light transmission. When EVA is heated to a certain temperature, EVA will melt and bond to the object it is in contact with. EVA used for solar cell encapsulation is specially designed as a thermosetting hot melt adhesive, i.e., a cross-linking reaction occurs when it is heated and melted. When the temperature is low, the cross-linking reaction occurs slowly and it takes longer to complete the curing, and vice versa for a shorter period of time. Therefore, it is important to select a suitable lamination temperature so that the EVA gains mobility in the melt and the curing reaction occurs at the same time. As the reaction proceeds, the degree of cross-linking increases and the EVA loses its fluidity, acting as an encapsulant.