Structural study of hermetic seal formed by water glass at low temperature when trapped between glass plates

Abstract

Abstract Hermetic sealing is an important technology in applications such as packaging of MEMS, sensors and vacuum glazing. Hydrocarbon materials like cyanoacrylate “super glue” have been used for convenient sealing. However, it is known that cyanoacrylate and other hydrocarbon glues are permeable to water vapour and do not act as a hermetic seal. On the other hand, there are some hermetic sealing techniques such as anodic bonding, ultrasonic solder bonding, solder glass bonding with or without laser assistance that require high process temperatures and are of high cost. In this paper, we assess water glass for low-cost hermetic sealing of soda lime glass at low temperatures of less than 100 °C. The vacuum level in a sample encapsulation was measured by means of a spinning rotor gauge which showed no pressure increase for one year. In addition, the bonding strength was also measured, showing that the 80 °C annealing process is the best process temperature for the highest adhesion strength.