| CAI Ya-hui,WANG Dan,ZHANG Wen,HE Yong-ning.Electron Emission Characteristics and Discharge Suppression of PTFE-SiO2 Composite Coating[J],52(6):369-376 |
| Electron Emission Characteristics and Discharge Suppression of PTFE-SiO2 Composite Coating |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.06.033 |
| KeyWord:space electronics electrostatic discharge SiO2 PTFE composite coating secondary electron yield |
| Author | Institution |
| CAI Ya-hui |
School of Microelectronics, Faculty of Electronic and Information Engineering, Xi'an , China;The Key Lab of Micro-nano Electronics and System Integration of Xi'an City,Xi'an , China |
| WANG Dan |
School of Microelectronics, Faculty of Electronic and Information Engineering, Xi'an , China;The Key Lab of Micro-nano Electronics and System Integration of Xi'an City,Xi'an , China |
| ZHANG Wen |
School of Science, Xi'an Jiaotong University, Xi'an , China |
| HE Yong-ning |
School of Microelectronics, Faculty of Electronic and Information Engineering, Xi'an , China;The Key Lab of Micro-nano Electronics and System Integration of Xi'an City,Xi'an , China |
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| Abstract: |
| Polytetrafluoroethylene (PTFE) is widely used in spacecraft, but charge accumulation occurs when PTFE is irradiated by plasma because of its poor electrical conductivity, which is harmful to the device. To reduce the rate of surface charge accumulation and the occurrence of electrostatic discharge (ESD), in this paper, PTFE-SiO2 composite coatings were prepared by magnetic stirring, regulating the secondary electron yield (SEY) of PTFE close to 1 over a wide energy range. The PTFE dispersion and SiO2 powder were mixed by magnetic stirring, and the mixed solutions were spin-coated on the copper-clad plate, which was used to simulate a space electronics device environment. Then the composite coatings were obtained by heating at 80 ℃ for 4 h, and their morphologies were studied with a scanning electron microscopy (SEM). Their secondary electron emission (SEY) properties were measured through the local leakage current method in the SEM. The surface potential was calculated by MATLAB and the discharge characteristics were tested in the SEM. The morphology of composite coatings showed that the surface roughness increased with the increase of SiO2 concentration, and the SiO2 particles were only partially exposed at low concentration. As the SiO2 concentration increased, the SiO2 particles changed from the tilt to the horizontality and then covered the PTFE. At the energy where SEY was greater than 1, the shading effect of SiO2 particles made the SEY of the composite coating decrease with the increase of SiO2 concentration when the concentration of SiO2 was less than 15%. When the concentration of SiO2 was greater than 15%, the shading effect was weakened due to the decrease of the tilt angle, which made the SEY no longer change with the concentration. At the energy where SEY was less than 1, the high SEY property of SiO2 made the SEY of the composite coating increase with the increase of SiO2 concentration when the SiO2 concentration was less than 15%. When the concentration of SiO2 was greater than 15%, the SEY decreased with the increase of concentration due to the decrease of the tilt angle and the shading effect, and finally tended to be the intrinsic SYE of flat SiO2. The calculation results of surface potential showed that the balance potential of negative charge was much larger than that of the positive charge, and was approximately equal to the difference between the incident electron energy and Ep2. When the SiO2 concentration was 15%, the equilibrium potential and the charge accumulation rate were the lowest, which were correlated with the maximum values of σ10 and Ep2. The test of discharge showed that the composite coating could effectively reduce the surface charge deposition rate and increase the discharge threshold. In conclusion, the composite coating can regulate the SEY of PTFE close to 1 over a wide energy range and increase the Ep2 of PTFE coating. The high SEY property of SiO2 and the shading effect play a major role in modulating the SEY. The modulation effect of SEY is the most obvious when the concentration of SiO2 is 15%. The maximum SEY value changes from 2.0 to 1.6, and the SEY at 10 keV changes from 0.6 to 0.8. The composite coating can effectively improve the discharge threshold, and reduce the charge accumulation rate and the occurrence of ESD. Therefore, it is a very processing way to improve the reliability and service time of spacecraft electronic devices. |
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