The Effect of Glass Frit Paste Levelling Property on Encapsulation

Laser-assisted glass frit bonding encapsulation (hereafter referred to as Laser bonding) is proposed for encapsulating air sensitive device that need a hermetic package with long-term stability. Laser bonding technology is a typical local non-contact heating technology, which allows temperature-sensitive devices to be used inside cell. With the excellent barrier performance, glass frit play an important role in encapsulation. Many factors such as the particles size, paste viscosity during process and unfairness of the surface morphology caused in screen printing process can cause the formation of defects in glass frit, weakening the barrier properties for blocking moisture and oxygen. We found that high saddle height difference comes out due to improper viscosity and improper printing process. In order to further verify the reliability of the glass laser encapsulation in the temperature output mode, the water vapor transmission rate (WVTR) of the encapsulated structure was tested using the active metal calcium electrical test method. Finally, we found that the lower saddle height difference is contributes to the smooth surface appearance. Furthermore the lower saddle height difference conducts to lower WVTR.