Cleaning thin films and addressing the impact of debris on yields, production, and quality. Highly engineered thin film is increasingly used in flat panel displays (FPD), touch panels, automotive applications, and thin film solar panels. In all these sectors there is a zero tolerance policy to defects, and the presence of foreign particles in the production process leads to high reject rates.
The solution is the Ultracleen® range of contact cleaning roller by Teknek. Particles on a surface are held by several forces which make it difficult to remove them. Although the forces are small, in relation to the particles they are comparatively large. The main forces involved are static charge and Van der Vaals forces. Static charge is often induced in surfaces when they touch each other, especially if they are far apart on the tribo-electric scale. Van der Waals forces are typically seen when two very flat surfaces come in contact with each other (e.g. two sheets of glass) the sheets appear to be stuck together.
It is normal to incorporate static elimination on a surface after it has been cleaned. The surface energy of a pick-up roller has to be sufficient to overcome the static attractive forces and any Van der Waals forces. By breaking through the boundary layer and coming into direct contact with the particles, pick-up rollers can more easily overcome the forces keeping the particles tied to a surface.
Unlike vacuum systems that clean without touching the surface, contact cleaners use a system of special rollers in contact with a surface to pick up particles and transfer them to an adhesive roll. Contact cleaners break down to two main categories, sheet cleaners and web cleaners. Cleaning can be either single or double sided.
Contact cleaners use high energy pick up rollers which come in contact with the particles being cleaned. The particles form a temporary bond with the rubber pick up roller and then get transferred to an adhesive roll where they are permanently captured. The rubber rollers have more surface energy than the substrate being cleaned. The adhesive roll has higher surface energy than the rubber rollers so the pick up (rubber roller) cleans the substrate and the adhesive roller cleans the rubber roll. After the adhesive is fully loaded it must be replaced.
In a contact cleaning system the pick-up roller penetrates the boundary layers that make vacuum systems less efficient at removing small particles. For this reason contact cleaning is a much more efficient way of removing small particles from sheets or webs. Contact cleaning can be used before many critical processes such as printing, laminating, coating, packaging, and stacking.
For further information, visit Teknek www.teknek.com.