점군의 기울기벡터 히스토그램에 의해 형성된 구속상자를 이용한 표면실장 솔더페이스트의 3차원 Metrology

Three Dimensional Metrology of Surface Mounted Solder Pastes Using Bounding Box Formed by Histogram of Gradient Vectors of Point Cloud

This work presents a method of point-to-surface assignment for 3D inspection of solder pastes on PCB. A bounding box enclosing the solder paste tightly on all sides is introduced to avoid incorrect point-to-surface assignment. The shape of bounding box for solder paste brick is variable according to geometry of measured points. The surface geometry of the bounding box is obtained by using five peaks selected from the histogram of normalized gradient vectors for measured points. By using the bounding box enclosing the solder paste. the task of point-to-surface assignment is successfully executed. Subsequently, the geometrical features are obtained via surface fitting.