A new method for image separation of overlapped images from a two-layered printed circuit board (PCB)

Conventional laminography provides cross-sectional X-ray imaging which separates the top and bottom sides, or any other layer of the printed circuit board (PCB), into separated images. However, only an image on the focal plane is obtained by a set of projections. Furthermore, the image is blurred by superimpositions of the out-of-focus structures. This paper presents a new method for image separation via object translation with a moving X-Y table instead of synchronously rotating or translating two components, i.e. a source and detector. This method uses a recursive process with a simple mathematical function which is derived analytically by the X-ray projection geometry. An X-ray imaging system has been constructed for the purpose of evaluating the proposed method, and was used for the test sample experiments. The experimental results confirm that the method is a powerful tool for separating objects from overlapped X-ray images.