RF Plasma Surface Modification Of The Flexible Substrate

Flexible electronics based on polymer substrates technology such as poly (ethylene terephthalate)(PET)has been rapid development in recent years. However, due to the low surface energy of the polymer film, the bond between the surface of the flexible substrate and the conductive film will directly affect the quality of flexible electronic devices. The most simple and direct method for low-cost flexible substrates (such as PET) is surface modification. RF plasma has a high electron density, energy and prone to lead to the relevant physical chemical reactions, the use of RF plasma surface modification of the flexible substrate can improve the performance of its hydrophilic, adhesive, etc., or even replace the polymer conductive adhesive of traditional flexible touch screen and solar cell. Therefore, the RF plasma modification of the flexible substrate has important practical significance.In this paper, a systematic study of RF capacitive coupled plasma (RFCCP) surface modification of PET film and its surface physical and chemical changes were characterized. The results of contact angle tests, scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and peel test analysis show that the pure argon plasma ion etching on the surface of the PET film, it has a cleaning effect while changing the membrane surface roughness, increased surface area, thereby increasing the hydrophilic to enhance the mechanical bond strength of the PET film and the Au film. Argon-oxygen mixed plasma due to the chemical activity of oxygen, the plasma chemical reaction enhanced the hydrophilicity and bonding properties of PET film by a large number of oxygen functional groups, the polarity of the membrane surface, and with the metal to form C-O-metal chemical bonds.The different mixing ratio of argon oxygen plasma modification experiments found that when the oxygen content reaches a certain level, the hydrophilic and the adhesion of the metal will be weakened. In order to investigate the mechanism of oxygen in the plasma surface modification, optical and mass spectra diagnosis were used and found that oxygen reactive species is the dominant particles of mixed argon oxygen plasma modification of PET flim, but the oxygen due to its electronegativity, the adsorption of a large number of energetic electrons reduce the activity of the plasma particle energy. Experimental optimization of argon oxygen mixture ratio of10:1can maximize the bonding properties of the PET film.Change the processing time and power, large changes in contact angle was found in30seconds treatment, which conclude that the plasma surface modification is transient. When the power is low, the low plasma energy limited the impact of the PET film surface, and when the treatment time is short (30s), plasma dose not fully treat the PET film, when the processing time is long enough (150s), plasma has been adequate on the membrane surface processing to achieve the physical and chemical reaction balance, plasma will no longer have an impact on the surface of the PET film. According to the structural characteristics of the reaction chamber, the sample is placed between the RF-RF plates and RF-ground plates and the treatment effects of the former is better than the latter in the same experimental conditions. Optical spectroscopic diagnostics show that the plasma spectrum in the RF-RF plates is stronger than RF-ground plates.In this thesis, mass spectrometry and emission spectroscopic diagnostics, as well as the discharge electrode structure and surface modification process combining comprehensive analysis and evaluation of experimental results, the plasma surface treatment mechanism.Provide valuable information and reference for practical applications.