Rapid realization of ultra-high vacuum packaging of atomic chips by thick film technology

Abstract

This research is an attempt to apply the silver thick-film metallization and the soft soldering process to the ultra-high vacuum packaging of atom chips with through silicon via (TSV). During the packaging process, a vacuum environment is used to avoid oxidation of the Cu layer on the chip during heating. At the same time, tin foil is used to protect the inner wall of the glass cell to prevent the gas emitted by the solder from polluting the inner wall. In general, by the adoption of screen printing, sintered surface metallization at a constant temperature of 450–500 °C for 5 min, combined with soft soldering, the packaging of an atom chip with TSV and a silica glass cell is realized. The weld gap is less than 50 μm, the airtightness can reach 8.5 × 10−13 Pa m3/s, and the vacuum degree can reach 2.18 × 10−8 Pa. That can meet the requirements of cold atom experiment for light path and vacuum degree.