Fabrication of metal micro-precision sieves with high open areas using UV-LIGA process

The manufacture of thick micro-precision sieve-sheets with high open areas is a key technical challenge. After analysis on the process limitations existing in three manufacturing methods for metal micro-precision sieves, an optimized UV-LIGA technique based on SU-8 photoresist is presented to manufacture the micromesh nickel sieve-sheets. Operational parameters of some key process steps for fabricating micro-precision sieve-sheets are determined experimentally, and morphological characteristics of electroformed hexagon micromesh nickel sieves are evaluated using a SEM and an optical profiler. Experimental results show that, using the UV-LIGA process, hexagon micromesh nickel sieves (200 μm in side length, 50 mm in diameter and 120 μm in thickness) with an open-area percent of 88% and a sheet-thickness of 120 μm, which can hardly be achieved by the conventional machining methods, are successfully machined. The machined sieves are characterized by their smooth surfaces and aperture walls, high precision sizes as well as rigid and homogeneous structures. These results show that the UV-LIGA is an excellent method for fabricating micro-precision metal sieves.