Helium Permeation Performance Study of a Permeable Standard Leak Element Based on Transfer-free PMMA and PI
A standard leak element based on transfer-free polymethylmethacrylate(PMMA)or polyimide(PI)was developed.The fabrication process involved spin-coating PMMA or PI on a copper foil,followed by spin-coating photoresist on the opposite side,and subsequently creating small holes of different arrays with a diameter of about 10 μm on the copper foil using UV lithography.The flow conductance of helium through the leak element was measured by the differential pressure method.The results show that the samples all exhibite a molecular flow regime within the pressure range from 5 kPa to 105 Pa.The flow conductance of transfer-free PMMA or PI shows a linear relationship with the effective permeation area,and the effective permeability area of PMMA or PI can be controlled by controlling the number of small holes,thereby obtaining different flow conductance.The transfer-free PMMA or PI materials developed in this study are ideal for low-permeation leak elements.
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维普
