Chemically Polished Quartz

Abstract

Abstract : Etching in a saturated solution of ammonium bifluoride is shown to be capable of producing chemically polished AT-cut quartz surfaces over a broad range of conditions. The quality of chemical polish depends primarily on the surface finish prior to etching, the depth of etch and the quality of quartz used. The speed of polishing depends primarily on the temperature of the etching bath. In an 88 degree C etching bath, starting with 3 micrometers lapped blanks, chemically polished blanks with a surface roughness of 0.1 micrometer and a roughness angle of 1 degree can be produced in 15 minutes. Starting with a finer surface finish can produce a smoother chemically polished surface. Chemically polished blanks are shown to be extremely strong. Fundamental mode 20 MHz resonators made with chemically polished natural quartz blanks showed no Q degradation with increasing depth of etch.