Research On Measuring Device And Method Of Griding Force In Wafer Griding Process

Grinding force is an important index to characterize the grinding state in the process of wafer grinding.Grinding force not only affects the quality of wafer grinding,but also reflects the wear of grinding wheel.With the rapid development of electronic products,the demand for wafer is increasing and the quality of wafer grinding is also put forward higher requirements.Grinding force is mainly determined by grinding parameters(spindle speed,feed rate,wafer speed,etc.),besides it is also affected by the flow of grinding fluid,the wear of grinding wheel,etc.The real-time monitoring of grinding force is very important for the fast and efficient grinding of wafer.In this thesis,a set of grinding force measuring device is built,which can monitor grinding force in real time,including force sensor module,signal collector module and signal transmission module.In order to ensure that the grinding force measuring device can meet the working requirements,ANSYS is used to simulate the thickness of the worktable of the grinding force measuring device.The results show that the maximum pressure and the maximum Z-direction displacement of the worktable decrease with the increase of the thickness of the worktable.When the thickness of the worktable of the grinding force measuring device exceeds 20 mm,the measurement results will not be affected.In this thesis,a calibration scheme of membrane pressure sensor is designed to calibrate the membrane pressure sensor.In order to ensure the rationality of calibration of the membrane pressure sensor,this thesis uses ANSYS to simulate the transfer law of the normal grinding force applied on the wafer.It is found that when the normal grinding force is transferred downward,it will all act on the membrane pressure sensor,within the measurement range of the membrane pressure sensor.After that,the static calibration of the membrane pressure sensor is carried out in the way of loading step by step,and the research shows that the linearity and repeatability of the membrane pressure sensor are good;the dynamic calibration of the membrane pressure sensor is carried out by setting the cyclic loading mode,and the research shows that the time response of the membrane pressure sensor is good,and the relationship between pressure and voltage is obtained.In this thesis,the normal grinding force in wafer grinding process is measured.The experimental results show that the grinding process of wafer can be divided into three stages,namely,the start grinding stage,the stable grinding stage and the end grinding stage.At the beginning of grinding,the normal grinding force increases slowly,but at the end of grinding,the normal grinding force returns to zero rapidly.In the stable grinding stage,the normal grinding force increases along the radial distance of the wafer.When grinding the grinding wheel teeth with the wafer,the grinding teeth first contact with the edge of the wafer,then slowly approach the center of the wafer,and the grinding teeth are in contact with the center of the wafer all the time.