Back grinding of wafer with outer rim (BGWOR) is a new method for carrier-less thinning of silicon wafers.At present,the effects of process parameters on the grinding force remain debatable.Therefore,a BGWOR normal grinding force model based on grain depth-of-cut was established,and the relationship between grinding parameters (wheel infeed rate,wheel rotational speed,and chuck rotational speed) and normal grinding force was discussed.Further,a series of experiments were performed to verify the BGWOR normal grinding force model.This study proves that the BGWOR normal grinding force is related to the rotational direction of the wheel and chuck,and the effect of grinding mark density on the BGWOR normal grinding force cannot be ignored.Moreover,this study provides methods for reducing the grinding force and optimizing the back thinning process of the silicon wafer.