Not so sticky
Stiction is an issue
“One factor that can have a significant detrimental impact on a seal’s performance is the inherent stickiness or stiction of elastomers, which means that seals tend to adhere to countersurfaces,” says Murat Gulcur, Technical Director for semiconductors.“In static sealing applications, elastomer parts that stick in grooves can result in prolonged downtime to clean off seal residues from sealing surfaces and to replace seals, disrupting preventative maintenance cycles and leading to a loss in productivity,” he continues. “In dynamic applications, elastomers sticking onto a countersurface can prevent moving parts from working efficiently, especially after periods of rest.”
Minimizing stiction
It is therefore important to minimize the stiction properties of elastomer seals to improve the productivity of semiconductor manufacturing equipment.Murat explains that Isolast® PureFab™ materials, the Trelleborg Sealing Solutions range of perfluoroelastomer (FFKM) compounds specifically developed for semiconductor applications, exhibit outstanding low stiction properties. “That means in many cases they operate at the optimum level for an application without further treatment. However, for applications that need extremely low stiction, our unique Seal-Glide® chemical vapor deposition treatment can lower stiction even further.”
Unique Seal-Glide surface treatment
Compared to other surface treatments, such as polytetrafluoroethylene (PTFE) coating and chlorination, Seal-Glide® is more sanitary, sustainable, and less chemically aggressive. It also applies more easily to components with complex geometries.
“It’s up to 50 times thinner than conventional coatings, meaning it does not negatively affect the physical properties of a seal,” Murat points out.
Aiming to understand the effectiveness of Seal-Glide® in reducing and limiting stiction, Trelleborg Sealing Solutions undertook in-house developed tests. “In these we used the Seal-Glide® surface treatment with a variety of our Isolast® PureFab™ FFKM materials and one FKM compound, all of which are commonly used for seals in semiconductor processing equipment,” continues Murat.
Tests prove a lowering of stiction
“Our tests demonstrated that the Seal-Glide® treatment could lower stiction between the seal and the countersurface by up to 85 percent. “This level of reduction gives major benefits in the performance of semiconductor manufacturing equipment, reducing planned and unplanned maintenance, leading to a lower total cost of ownership for FABs,” Murat concludes.
As elastomers inherently stick to countersurfaces they are prone to stiction, the friction which prevents stationary surfaces from setting in motion especially after periods of rest, both in static and in particular dynamic application. This can cause seal wear and inefficiency in energy use, as equipment requires more power to move components.
Designed to improve the friction performance of elastomer components, the application of Seal-Glide® on a seal is through an innovative process, whereby a gas mixture that comprises different ion species bombards the top layer of an elastomer surface.
The thickness of the modified surface is typically less than 450 nanometers, which is around 50 times thinner than conventional coatings. This means the treatment can provide major benefits without negatively affecting the properties of a seal.
Importantly, the treatment allows the surface preparation of components with complex geometries and features, something that is impossible with lacquer-based coatings.
For more information, please visit: Seal-Glide®