Research And Design Of On-line Measurement System For Grinding Force Of Wafer Grinder

With the increasing of wafer diameter and the reducing of chip thickness, high machining efficiency and quality are required. In the process of wafer grinding, grinding force have direct influences on the quality and machining efficiency, so monitoring and control of it is considered as an important technique for processing wafers with high efficiency and free damage. Measurement system for grinding force of wafer grinder can give full play to grinder performance, improve reliability of the process of grinding, and establish application foundation to realize control force grinding. However, most of the existing wafer grinders haven't on-line measurement system, so it is necessary to carry out related research.Based upon the analysis of principle of wafer rotation grinding, the all-round force monitoring scheme is proposed, and the method of decomposition and measurement of grinding force is presented. The size, direction, functional point and moment of the component force are calculated by curvilinear integral. Then force transfer model is built, which provides references for forecasting grinding force. According to the direction of component force, the coordinate system of force-measuring platform is established, and the necessary condition of continuous monitoring for wafer grinder with two-spindle and three-working-position is analyzed. According to the measuring range, minimum pre-tightening force in assembly of the platform is calculated.Principle of measurement and composition of the piezo-quartz system are expounded, and reasonable crystal groups and test circuit are selected. Then on-line force-measuring platform of wafer grinder is designed. In order to guarantee the stiffness of machining system and the performance of dynamometer, axial stiffness and deformation of the platform under maximum work load are analyzed by static analysis, and the natural frequency is calculated by modal analysis. Furthermore, the structural dimension is optimized. In addition, methods of static and dynamic calibration are proposed, according to actual condition of the grinder.The effect of grinding force on material removal rate and surface layer quality is discussed. And some experiments are taken to research the influence of the parameters on grinding force. Based on analysis above, components of control force grinding system and process scheme of control force grinding are presented, which is a helpful exploration to the technique for processing wafers with high efficiency and free damage.