A new approach to translational laminographic method for PCB inspection

Abstract

X-ray laminography, a tomographic technique that can examine individual planes of focus within a 3-D structure, promises to be an excellent method of inspecting complicated circuit boards. The technique has accuracy appropriate for circuit board inspection, but the application has been limited by the requirements of synchronized motion of the source and detector, a sophisticated X-ray device and a huge image acquiring system. A new translational laminography system is presented. The X-ray source and detector described are stationary. Translation of the XY table is only the mechanical motion required to generate the laminographic image. Based on this system, a new image separation algorithm is also explained. This algorithm uses a recursive process with a simple mathematical function, which is derived analytically by the X-ray projection geometry. To evaluate the proposed method, an X-ray Imaging system has been constructed. From the test sample experiments, it is confirmed that the proposed algorithm allows cleanly separated images with fewer artifacts than the one obtained by conventional laminography.