COATING TECHNOLOGY
PLASMA W
Problem-solving
Overcoming complex adhesion challenges via the use of plasma-enhanced chemical vapour deposition coatings
PVA TePla has its own lab for designing and manufacturing plasma systems
hen traditional chemical adhesives fail to suffi ciently bond dissimilar types of materials,
engineers often turn to plasma treatments to solve complex adhesion problems. Whether bonding metal to plastic,
silicone to glass, polymers to other polymers of diff erent durometers, biological content to polymeric microtiter plates or even bonding to polytetrafl uoroethylene (PTFE), plasma can be used to promote adhesion. Adhesion promotion can be
achieved by increasing the surface free energy through several mechanisms,
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a solid, liquid or gas. When enough energy is added to a gas it becomes ionised into a plasma state. The
including precision cleaning, chemically or physically modifying the surface, increasing surface area by roughening and primer coatings, according to Michael Barden of PVA TePla, a company that designs and manufactures plasma systems. “It is not a question of whether
plasma is eff ective or not,” says Barden. “Plasma is the king of surface activation and the best technology available. It just depends on the circumstances of the application.” Plasma is a state of matter, like
collective properties of ions, electrons and radicals can be controlled to change the properties of surfaces without aff ecting the bulk material. In this way, plasma is a powerful tool in solving surface preparation problems such as precision cleaning and decontamination, increasing surface wettability and adhesion promotion. In addition, plasma can also be used to polymerise monomers onto surfaces through plasma-enhanced chemical vapour deposition (PECVD) to provide thin fi lm coatings. The net eff ect is a tremendous improvement in bonding – in some cases up to a 50 times bond strength improvement can be achieved.
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