The Study On The Surface Wettability And Water Vapor Barrier Property Of Poly(Chloro-P-Xylylene) Film

Poly?chloro-p-xylylene??PPXC?film has been extensively applied in many fields such as semiconductor devices,microelectronics and material moisture protection because of its good mechanical properties,dielectric properties,solvent resistance moisture resistance and so on.However,due to the increasing requirements of moisture barrier properties of electronic devices and the low hydrophobicity of the PPXC film,its further application is limited.Therefore,it is meaningful to explore how to improve the surface hydrophobicity and water vapor barrier properties of PPXC films,so as to prevent the corrosion of water droplets on the devices.In this thesis,the surface morphology and wettability of PPXC films coated with different hydrophobic coatings were studied systematically,and the relationship between surface hydrophobicity and water vapor barrier property was studied.The results are shown below:?1?Nano-silica?Si O₂?was coated on the surface of PPXC film,and the effects of different kind of nano-Si O₂ particles with different particle size and hydrophilic/hydrophobic on the surface morphology and wettability of the film were investigated.The results shown that compared with Si O₂ particles with a particle size of 500 nm,the effect of Si O₂ particles with a particle size of 20 nm on the hydrophobicity of the coating surface is more pronounced.As the particle size of the added Si O₂ particles decreases,the water contact angle?WCA?of the coating can be increased from 128°to 154°.Hydrophobic nano-Si O₂ particles were more favorable for improving the uniformity of the surface morphology of the coating.?2?Thermal cured polydimethylsiloxane?PDMS?and nano-Si O₂ particles were coated on PPXC films,then the effect of nano-Si O₂ content,curing temperature and humidity on the surface morphology of the films were investigated,and the evolution of the surface morphology of the films under different conditions were summarized.The results shown that three different types of pattern structures?Raised Bowl-shaped Structure,Traditional Porous Structure and Nanoparticle Aggregation Structure?can be obtained on the surface of PPXC films by controlling the content of nano-Si O₂ particles,cross-linking curing temperature and humidity.The number,distribution and size of the three structures can be regulated by different experimental conditions.With the evolution of the surface morphology of PPXC film,its surface wettability ca n be improved from weak hydrophobic to super-hydrophobic.The WCA increased from 84°to 168°,with the water droplets on the surface of the sample shift from the"Wenzel"state to the"Cassie"state.?3?The thermal curing polymer PDMS was introduced on the PPXC film,then the surface wettability of the film was regulated by the concentration of solution and the relative humidity?RH?of the environment,to investigating the relationship between the surface hydrophobicity and the water vapor barrier property of the PPXC film.The results shown that when the curing temperature was 60 ^oC,the RH was 55%and the PDMS content was 0.5 wt%,the WCA of the sample can be increased from 84°to 142°.Compared with the pure PPXC film,the water vapor barrier performance?WVBP?of this sample has been significantly improved,and its water vapor transmission rate?WVTR?can be reduced from5.26 g·m^-2 per day to 1.58 g·m^-2 per day.In this thesis,the surface morphology,surface wettability and water vapor barrier property of PPXC films were studied.It was proved that the increase of the hydrophobicity of PPXC film was beneficial to improve the WVBP.The results show that by controlling the surface morphology of the film,the hydrophobicity and WVBP of the PPXC film can be improved.The improvement of surface hydrophobicity and water vapor barrier properties of PPXC films is beneficial to further expand its practical application.