Thermal stress cracking can be completely avoided by CO2 laser cutting thin alumina sheets underwater.  I also show how to formulate and apply silver paste, then sinter in a kiln to produce double-sided ceramic printed circuit boards with conductive vias.

60W CW CO2 laser at 80% power.  10mm/sec.  Standard lens focal length (50mm).  2mm water above ceramic.  180 passes to cut through 0.75mm thick alumina.  

Silver paste: 97% silver powder, 3% glass powder by mass.  Particle size 1 micron or less. Add poly vinyl alcohol mold release until desired consistency reached.

Paste applied with 4 mil thick vinyl stencil.  Dried in air 10 minutes, then rapidly brought up to 900*C, held for 10 minutes, then rapidly brought back down to room temperature.  Total cycle about 45 minutes.

I measured electrical conductivity of the finished traces from my process with vinyl stencils: 4 milliohms per square at 10 micron final thickness.  This is pretty close to the Dupont published spec ( less than 2 milliohm/sq at 16 micron…