Study on the effect of laser pre-sintering in laser-assisted glass frit bonding

With the rapid development of laser technology, laser-assisted glass frit bonding technology has been widely used in the packaging process of photoelectric devices. Despite its popularity, there still be some defects to affect the bonding performance, such as pores, cracks, non-fusion, and low joint strength. The glass frit should be pre-sintered by furnace or laser before laser-assisted bonding process. The behavior of the glass frit during the laser pre-sintering and laser bonding was studied in detail. It was found that the traditional pre-sintering process by a furnace can be replaced by laser pre-sintering when the thickness of glass frit layer was ca.3 μm. For the glass frit layers with thickness of ca.8 μm, a furnace should be used for pre-sintering firstly, and then the laser was used for re-sintering. The pre-sintering and re-sintering by laser can effectively inhibit the formation of pores in the following bonding process. The joined interfaces were inspected through a digital microscope and energy dispersive spectrometer (EDS). When the glass frit layer was re-sintered by laser, more penetration and less porosity was observed. It was found that the treatment of re-sintering by laser could improve the bonding strength obviously, the maximum bonding energy was 1.1 J/m2. It can conclude that the laser plays a positive role in the pre-sintering process, and the bonding quality is improved fundamentally.