Design And Development Of Micro Welding System For Dissimilar Materials Based On Nanosecond Pulse Laser

The connection of dissimilar materials is an important part of the packaging process of integrated circuits and microelectromechanical systems(MEMS).With the development of integrated circuit technology,the demand for metal-glass microwelding has increased substantially in recent years.The laser can directly act on the interface of the material through the glass and induce the material to melt to achieve transmission welding.It is one of the most suitable processing methods to realize the metal-glass micro-welding process.Nanosecond pulsed laser has many advantages such as high stability,high processing efficiency and low cost,which is very suitable for metal-glass micro welding.Therefore,this paper focuses on the research of metalglass micro-welding,and designs and develops a metal-glass micro-welding processing system based on nanosecond pulse laser.In order to clarify the mechanism of the nanosecond pulsed laser in the microwelding process of dissimilar materials,we first studied and analyzed the time-domain characteristics of the nanosecond pulsed laser and the substance.Then,based on the classic Fourier law of heat conduction,the process of nanosecond pulsed laser interaction with metal is simulated.The temperature response of different metal materials under the action of nanosecond pulse laser is analyzed.The nonlinear absorption effect of nanosecond pulsed laser on glass-like transparent materials is also studied.Finally,the research of the interface effect in the process of metal-glass welding with nanosecond pulsed laser is carried out.It provides theoretical guidance for metalglass micro-welding system based on nanosecond pulse laser.In order to meet the requirements of sub-millimeter and micron welding accuracy,this paper establishes laser beam transmission models under the two technological conditions of point scanning method and mask projection method based on diffraction theory,and the spatial distribution of welding laser energy under the two processing conditions is analyzed.On this basis,a metal-glass nanosecond pulse laser microwelding system is developed,which can meet the requirements of two welding processes simultaneously.In order to meet the demand for real-time monitoring of welding quality during the welding process of metal-glass dissimilar materials,this paper designs and develops a real-time monitoring system for microscopic imaging that can be coaxial with the projection processing optical path based on the principle of microscopic imaging.And according to the polarization principle and narrow-band filtering,the problem of the optical path of the projection processing interfering with the optical path of the microscopic imaging is solved,and the effect of real-time monitoring of the microscopic imaging of the processing process is achieved.In order to verify the processing performance of the system developed in this paper for the micro-welding of metal-glass dissimilar materials,a series of verification experiments were carried out.First,the experimental research on the response threshold of different materials to nanosecond pulsed lasers was carried out to provide the basis of process parameters for subsequent welding verification experiments.Then,the influence of different process parameters of the system on welding quality was studied experimentally,and the influence law of material type,material thickness and material roughness on welding quality of dissimilar materials was obtained.Finally,welding experiments were carried out under the two process conditions of the point scanning method and the mask projection method.The experiments proved that the processing resolution of this system can be better than 30μm.