Ultra-thinning Processing of Dielectric Substrates by Precision Abrasive Machining

The ultra-thin dielectric substrate was obtained by precision grinding and lapping/polishing. In the precision grinding, the substrate was thinned until 50 μm in thickness using fine-grained diamond wheels and a polishing pad. The substrates in the lapping and polishing were thinned to 17 μm in thickness with good flatness. The good flatness was produced by hard polishing pad made of polyvinyl chloride resin owing to their mechanical properties of high fixed grain density. These were confirmed by detailed AFM observations. Finally, the substrates were segmentalized to produce five thousand small tips (2 mm × 0.4 mm) by a precision dicing device.