Study Of Suppressing Micro-discharges By Preparing Insulating Siloxane Film Using AP-PECVD

In order to suppress micro-discharges,the preparation of an insulating siloxane film onthe conductor surface using Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition(AP-PECVD)and its effect for micro-discharge suppression was studied in this paper.Firstly,two kinds of AP-PECVD experiment system respectively based on the atmospheric pressure diffuse discharge and the atmospheric pressure dielectric barrier discharge were set up for insulating siloxane films preparation.The electrical and optical characteristics during AP-PECVD process as well as the chemical composition,the hydropathy property and the insulating stability of prepared films were emphatically studied,and the optimal experimental parameter was determined from the point of preparing reliable insulating siloxane film.Finally,based on the dielectric property tesing results of the optimal insulating siloxane film,electric field simulation and experimental research were combine used to verify the effect of suppressing micro-discharges from the point of improving the distorted electric field in cables and restraining the rising of metal particles.The experiment results showed that the discharge power,the film preparing efficiency and the film oxidation degree in the AP-PECVD experiment based on the atmospheric pressure diffuse discharge were significantly influenced by the discharge gas,and a siloxane film(Si O2-like)with the largest aera and the highest oxidation degree was obtained under the condition of 700 sccm air/500 sccm Ar.But for the sake of the relatively low trigger frequency of the microsecond pulse power supply,all the obatained siloxane films cound't reach the insulating effect for their relatively small thickness.However,in the AP-PECVD experiment based on the atmospheric pressure dielectric barrier discharge,a relatively homogeneous “multi-glow discharge” was obtained on the condition of 3 slm Ar/500 sccm Ar(TEOS),and a reliable insulating siloxane film was also prepared.Moreover,the air aging testing experiment results indicated that this insulating siloxane film characterized a great insualting statbility and could be an optimal choice for the study of suppressing micro-discharges.The dielectric property tesing results showed that the prepared insulating siloxane film of15 min processing time featured a thickness of 2.07 ?m,a relative dielectric constant of 3.96 and a volume resistivity of 6.55×1013?/cm.The COMSOL simulation results indicated that after the insualting siloxane film covering the distorted electric field in cables reduced from1.22×105V/cm to 8.87×104V/cm,and the workfucntion value of the copper surface also increased from 4.65 e V to 4.78 e V.From this,it can be concluded that the happening condition of micro-discharges is restrained.Moreover,the rising voltage measurement results showed that the rising voltage of metal particles had been improved about 32% after the insulating siloxane film covering,and this indicate that micro-discharges resulting from the metal particle rising could be suppressed.