Polymer Processing Techniques Used in Photovoltaic Packaging and Balance of Systems (BOS) Component Fabrication
Injection molding is the most common processing technique for photovoltaic (PV) module components. Lamination and adhesive dispense are processing techniques performed directly by the PV manufacturers. Adhesive dispense is a packaging process commonly optimized with shear rheology. Outside of this context, viscosity measurements have limited industrial value. Polymers used for adhesives and lamination have the highest melt flow index (MFI) and can easily flow with limited pressure. Injection molding is typically performed on thermoplastics with a low MFI, requiring high packing pressure and high temperatures to mold the polymer into the desired shape. Commercial laminators are divided into an upper and lower chamber, and both are connected to a vacuum pump and separated from each other by a flexible membrane. Lamination processing steps include module lay-up, evacuation, polymerization, cool down, repressurization and ejection. The gradient in temperature allows for the polymer to evenly flow into the mold, and it slowly begins to solidify prior to ejection.