Packaging which directly determines the success or failure of the device has always been the major difficulty in MEMS devices.Effected by many factors such as cost,convenience,package performance,process complexity,device size,wafer level packaging using a cap becomes a wise,novel and popular way,and it is the inevitable trend of MEMS package.Due to the advantages of small parasitic capacitance,easy bonding and good thermal insulation performance,glass cap a popular MEMS package cap.Especially for high frequency RF sensor,glass cap is the best choice because of its good electrical isolation.However,the production of glass cap is very difficult.The traditional glass reflow process is the best way to block the glass nowadays,but there are still many shortcomings,such as polishing debris easily,long sintering time,restrictions of minimum line width,requirement of high vacuum anode bonding,etc.In this thesis,some problems of glass powder reflow process have been studied.In order to obtain nano glass powder,the behavior of high energy ball milling of Borosilicate 33 glass was studied by discrete element analysis software.Based on the study of the milling law,the factors such as the filling rate,the material of the milling ball and the number of milling balls were determined.The variation of the force and the number of particles collision with the ball milling speed and ball-glass ratio were analyzed.It is confirmed that the theoretical ball ratio of the ball mill and Borosilicate 33 glass is 40:1 to 80:1,the critical speed is about 1000 r/min.Based on the results of discrete element analysis.Orthogonal experiment was carried out to study the highest discharge rate of nanometer glass powder.The morphology,particle size and crystallinity of the samples were characterized by XRD,scanning electron microscopy and laser particle size analyzer.It not only explored the best ball milling technology of Borosilicate 33 glass,but also provided a systematic method for the study of ultrafine ball milling.By using the method of combining theory and simulation,the finite element simulation is combined with the knowledge of mechanics of materials,mechanics,electricity and so on.Finally,the total thickness of the glass cap,the thickness of the micro cavity and the size of the vertical interconnect electrode are obtained.Through the traditional MEMS processing technology,the processing of MEMS micro cavity was completed.Based on the analysis of the existing particle separation method,it is concluded that the centrifugal method is the most suitable for the separation n of nano glass powder.And to study the dry glass powder and glass powder filled with solvent properties,filling rate.The effect of glass powder in air and vacuum atmosphere melting;wettability of glass in the different substrate surface has also been studied.The surface energy of liquid glass was changed by adding different reagents.Finally the sintering behavior of glass powder has been studied. |