铝合金镀银表面粗糙化处理方法及其SEY抑制机理

Roughening Method and SEY Inhibition Mechanism of Aluminium Alloy Silver Plated Surface

目的为了有效降低空间大功率微波器件铝合金镀银表面的电子发射系数,提高空间大功率微波器件的微放电阈值。方法研究了铝基体上电化学镀银平板试样表面的两种粗糙化处理方法——微图形光刻法和直接湿化学腐蚀法,利用扫描电子显微镜和激光扫描显微镜对两类表面处理得到的多孔平板样品的粗糙形貌进行了表征,利用电流法对其表面二次电子发射(SEY)特性进行了测试分析。结果所获得的规则阵列圆孔表面和大深宽比及随机分布的粗糙表面均能够显著降低镀银表面SEY,并且工艺重复性好。与平滑银表面相比,抑制效果最好的圆孔阵列样品表面能将SEY的最大值从2.2降到1.3,E1值从50 e V增加到100e V;随机刻蚀结构能将平滑银表面SEY的最大值从2.2降至1.1,E1提升至300 e V。基于孔隙内二次电子轨迹追踪的蒙特卡洛理论模拟方法,对两种典型样品的表面二次电子陷阱效应进行了理论分析,表面SEY特性模拟规律与测试数据一致。结论光刻和湿化学刻蚀工艺制备的银表面微形貌均能有效降低镀银表面的SEY,镀银表面粗糙化处理方法能够提高卫星大功率微波部件的微放电可靠性,并不会显著增加其插损。

The work aims to effectively lower the secondary electron yield（SEY） on silver plated surfaces of aluminum alloy of space high power microwave components and improve the corresponding multipactor threshold value. Two roughening methods were studied for surface of silver electroplated plate specimen on aluminum substrate： Micrographic lithography method and direct wet chemical etching method. Scanning electron microscope and laser scanning microscope were adopted to characterize the rough morphology of porous plate specimen through two surface treatment methods. The current method was utilized to test and analyze the SEY characteristics. The obtained surface of regular array round hole, high aspect ratio and randomly distributed rough surfaces could lower SEY on plated silver surface obviously, and the repeatability of process was good. Compared with the smooth silver surface, the round hole array specimen with the best inhibition effects could reduce the maximum value of SEY from 2.2 to 1.3 and increase E1 from 50 eV to 100 eV. The randomly etched structure could decrease the maximum value of SEY on smooth silver surface from 2.2 to 1.1 and improve E1 to 300 e V. The theory of secondary electron trap effects on surfaces of two typical specimens was analyzed based on Monte-Carlo simulation. The simulation rules of surface SEY characteristics were in consistent with the test data. Both micro morphology of silver plated surface prepared by photoetching and wet chemical etching processes can lower SEY on silver plated surface and the roughening treatment of silver plated surface can effectively improve the reliability of micro discharge of satellite power microwave components and avoid increasing the insertion loss.