Research And Parameter Optimization Of Laser-assisted Glass Bonding Process Based On Glass Frit

Glass has excellent thermal stability,insulation,high light transmittance and low water vapor permeability,and is widely applied to the field of electronic component packaging.However,due to the high sensitivity of core components to oxygen,moisture and temperature,traditional glass packaging methods are difficult to meet.The laser-assisted packaging method based on low melting point glass frit can realize local bonding,which belongs to non-contact heating,small heat affected zone and is not easy to damage electronic components.At the same time,this method has fast bonding speed and high precision.So it can be widely used in the field of packaging.However,after laser-assisted glass bonding,pores and cracks are easy to occur in the weld,resulting in low bonding strength.Therefore,it is urgent to further optimize the process.In view of this situation,this paper built laser-assisted glass bonding test platform,using a single-channel welding method to bond glass.and conducted a systematic study on the laser-assisted glass bonding process.The content first analyzed the bonding mechanism and law,then explored the influence trend of different process parameters on weld morphology and weld strength,and finally optimized the process parameters to improve the bonding quality.The purpose is to provide some process guidance for laser-assisted packaging glass based on low melting point frit,and promote the further application of this method in the field of electronic component packaging.The research contents are as follows:（1）The weld forming process of laser-assisted glass bonding was observed by coaxial observation system,and the weld forming mechanism was revealed.Some common defects were analyzed,including the bulge of the weld edge,the non bonding of the weld,pores and cracks.The temperature field simulation model of laser-assisted glass bonding was established by using COMSOL software,and the temperature distribution law in the connection process was studied.The temperature at 1mm away from the weld was measured by thermocouple,and the model was verified by comparing with the simulation results.（2）This paper studied silk screen printing quality and weld forming law about 3μm、8μm、14μm three kinds of thickness glass frit under different laser power.A single factor study was conducted using samples with a frit thickness of about 8μm,and the influence of bonding speed and fixture pressure on weld surface morphology were analyzed.It was found that the laser-assisted glass bonding weld can be divided into three types according to the surface morphology:unmelted on both sides of the glass frit,molten and molten diffusion.The bonding properties of the samples with three morphologies were analyzed by scanning electron microscope,energy dispersive spectrometer and stress meter.The results showed that the boundary between glass and frit was obvious,the elements diffused each other,and the stress increased gradually.（3）Taked the weld width and weld strength as the response values,the three key process parameters of laser power,connection speed and defocus were selected,and the mathematical model was established by response surface method.The interaction trend was analyzed by the model,and the reliability of the mathematical model was verified by experiments.Then the correlation between weld width and weld strength was explored.It was found that the weld strength first increases and then decreases according to the power function with the increase of weld width.Finally,the optimized process parameters were obtained through the established mathematical model.The optimized parameters were used for laser-assisted galss square bonding.The results showed that the weld morphology was good,there was no crack,and the leakage rate was less than 5×10^-3pa·cm³/s,with good sealing performance.