Deposition of thin-layer barrier coating on plastics for barrier improvement.
To support online quality management of plasma processes, the Institute of Plastics Processing (IKV) at RWTH Aachen University is investigating the use of spectroscopic plasma monitoring.
Plasma emissions are strongly associated to process parameters such as pressure, applied power and gas flow. However, scientists at the IKV say when looking at complex or rapid processes there is still a lack of viable and reliable industrial quality management systems. In these cases, establishing a temporal link between process variables and plasma properties is a crucial factor in order to obtain quality-related data in real-time.
Based on the optical emission spectroscopy (OES) spectroscopic plasma monitoring can survey the plasma process in real-time and thus the treatment or coating processes. The advantage of this technique is its ability to monitor different process information, e.g., the condition of the processing chamber, like the degree of contamination the expected layer properties, such as barrier properties, scratch resistance or wettability or the reproducibility of batch processes.
With this in mind, a plant control system based on programmable logic controller (PLC) has been developed at IKV. In close collaboration with Plasus Ingenieurbüro, the ‘Plasus Emicon’ system was integrated into the plant control system via Profibus DP. IKV states all available process data can therefore be collected and analysed simultaneously along with the measured plasma emissions, so that preventive action can be taken even in complex and rapid processes. Time and expensive sample checks are reduced to a minimum by continuous in-process performance monitoring.
Further investigations on process monitoring, for example automatic acquisition of process homogeneity in large area coating processes, are in progress.