Surface activation is the process of altering the chemical and / or mechanical properties of a product surface via the bombardment with ions generated inside a plasma. While sometimes there are chemical processes which can achieve the same or at least similar surfaces properties, surface activation via plasma treatment offers a number of important advantages, e.g. shorter treatment times, easier process control, no exposure to hazardous or poisonous substances, no or strongly reduced cleaning cycles and, last but not least, considerably reduced treatment cost. Some typical applications for plasma surface activation include:
Rendering a surface hydrophilic makes it easily wettable, meaning that a fluid will cover the surface and stick to it. Please note that the term "hydrophilic" itself refers to the behaviour of a surface towards water, and hydrophilic surfaces are usually generated via oxidation in order to form hydroxyl (OH) groups. However, depending on the process gas or gas mixture plasma treatment can increase the wettability of surfaces for many other liquids, e.g. hydrocarbons, acids, solvents etc. Parts with hydrophilic or easily wetted surfaces are typically used in the household / white-ware industry, automotive industry, machine tool manufacturing and other industries.
Rendering a surface hydrophobic will achieve the opposite effect of rendering it hydrophilic, i.e. the surface will repel a liquid and is therefore difficult to wet. As with hydrophilic, "hydrophobic" itself refers to the behaviour of a surface towards water, and hydrophobic surfaces are usually generated by implanting carbon-fluorines like CF, CF₂ and CF₃ into the surface. However, by selecting the proper process gas or gas mixture the same effect can be achieved for other liquids as well. Industries making use of parts with hydrophobic surfaces are basically the same as above.
Many parts made from polymers / plastics do not reach optimum cross-linking of the molecules during the initial manufacturing process. With plasma surface activation, unlinked molecules on the surfaces of these parts can be linked together, which improves the surface hardness / abrasion resistance and also reduces the permeability of the surface for specific chemical compounds, making the whole part more resistant to ageing and other negative effects.
Without a suitable activation / modification of the surface, many polymers and other materials are difficult or almost impossible to bond, a typical example is PTFE (Polytetrafluoroethylene, better known as Teflon). With plasma surface activation, the surfaces of these parts are chemically and / or mechanically modified so that they will accept and bond to the adhesive used, without the need to treat them with often hazardous mixtures of chemicals.
For more information about plasma surface activation and suitable systems please contact us.