Leedus: a Micromachining Process for Die-scale Pattern Transfer in Ceramics with High Resolution and Throughput

While ceramics are important materials for electronic and microsystem packaging, they are difficult to pattern lithographically. LEEDUS, a fabrication process combining lithography, electroplating, batch mode micro electro-discharge machining (µEDM) and batch mode micro ultrasonic machining (µUSM), is presented in this paper. This technology provides die-scale pattern transfer capability from lithographic masks onto ceramics, glass or other brittle materials. This is done by using the photomask to create an electroplating mold, then using the electroplated pattern as an electrode to µEDM a hard metal tool, which is finally used in the µUSM of the ceramic substrate. A minimum feature size of 25µm has been demonstrated on the glass-mica (Macor TM) ceramic plate with a 4.5mm¥4.5mm die size and 34µm cutting depth using a stainless steel microtool. The machining rate in the demonstration was about 18µm/min, and the tool wear ratio for the microtool was 6%. The average surface roughness was Ra 0.55µm. Other process characteristics are also discussed.