Development of 3D shadow mask using 3D printer

Recent emergence of 3D printing technology has made the fabrication of unconventional micron scale structures possible. The shadow mask is a typical high aspect ratio 3D structure used to deposit metal patterns. Shadow masks are generally laser drilled on metallic substrate or hard baked patterned resist. A novel method of shadow mask preparation using an educational Makerbot 3D printer is discussed and experimental results are analyzed in this paper. The shadow mask was effectively used in a high vacuum deposition unit to transfer copper patterns on glass substrate. The accuracy and deviations in the printed aperture size of shadow mask and copper patterns transferred on the glass substrate are demonstrated via experimental results. Three sets of aperture widths: 300, 350 and 400 µm were designed and printed into two plastic masks of 400 and 700 µm thickness. 350 µm aperture width in the mask demonstrated less variation and copper line width obtained from pattern transfer process was measured close to the designed width. High aspect ratio structures were difficult to print due to the additive nature of 3D printing process. Shadow deposition effect was reduced for deeper sidewalls based slots in the mask. The inter-slot study indicated that 3D printed effective mask spacing on either side of apertures increases for thicker mask. The yield of the ABS deposited mask is observed to be poorer for the thicker (700 um) mask as compared to thinner mask. In general it can be concluded that 350 µm width resolution masks can be reliably fabricated at 400 µm thickness using this method. The 3D printing method explained in this paper is a feasible and economically viable approach to develop shadow mask for organic and plastic electronics applications.