双源激励DBD表面改性PET薄膜电荷耗散及沿面闪络特性

Charge Dissipation and Surface Flashover Characteristics of Surface Modified PET Film by a Dual-power Driven DBD Source

PET薄膜表面积聚的大量电荷是发生闪络的重要因素,采用表面处理可以加快电荷耗散以提高闪络电压。为此设计了一种脉冲与射频电源协同激励的双层DBD装置,并将其应用于PET薄膜的Ar/CF_(4)等离子体表面改性中,就表面改性对PET薄膜沿面闪络场强的影响进行了研究。结果表明:文中提出的双电源协同激励DBD装置能够显著降低放电起始电压、促进放电弥散均匀性,进而提高表面改性的均匀性;经该装置处理后,PET薄膜的沿面闪络场强显著提高。辐射光谱诊断和材料表面分析的结果进一步表明,在改性过程中CF_(4)裂解产生的氟化物对薄膜表面刻蚀起到重要作用,而装置中射频DBD能够促进CF_(4)的裂解,显著增加下层材料处理区中的氟化物,进一步强化蚀刻作用。另外,还基于电荷陷阱理论对表面改性提高闪络电压的原理进行了分析,结果表明:等离子体刻蚀能够增加样品表面浅陷阱密度,从而提高电荷耗散率,进而提高沿面闪络强度。

The accumulated charge on the surface of PET film is an important factor for flashover.Surface modification can accelerate charge dissipation and improve flashover voltage.Consequently,a double-layer dielectric barrier discharge(DBD)device co-excited by pulse and rf power supply was designed,and was applied to Ar/CF_(4) plasma surface modification of PET film.The effect of surface modification on the surface flashover electric field intensity of PET film was studied.The results show that the proposed device can significantly reduce the breakdown voltage,promote the dispersion uniformity of discharge,and improve the uniformity of surface modification.The flashover field intensity of PET film is significantly increased when modified by the device.The results of radiation spectrum diagnosis and material surface analysis further show that the fluoride produced from the cracking of CF_(4) plays an important role in the surface etching during the modification process,and the RF DBD in the device can promote CF_(4) cracking,which increases the fluoride in the treatment area of the lower material significantly,and further enhances the etching effect.In addition,the principle of improving flashover voltage by surface modification was also analyzed based on the charge trap theory.The results show that plasma etching can increase the shallow trap density on the surface of the sample,increasing the charge dissipation rate and improving the flashover field intensity along the surface.