X-ray Industrial Computed Laminography (ICL) Simulation Study of Planar Objects: Optimization of Laminographic Angle

X-ray Industrial Computed Laminography (ICL) is a non-destructive three-dimensional (3D) imaging technique for high aspect ratio planar objects such as printed circuit boards and stacked IC. Complementing to the established method of X-ray Industrial Computed Tomography (ICT), ICL is based on tilt orientation of the planar object with respect to incident X-ray beam by a defined angle.The tilt angle of the planar object is called laminographic angle. Knowledge about the laminographic angle is very important for optimizing reconstruction quality of planar objects.This paper presents optimization of laminographic angle using simulated planar object in cone-beam geometry. Root Mean Square (RMS) contrast is used to characterize the effect of the angle on reconstruction quality. Simulated cone-beam projections (radiographs) were generated from different angles by rotating tilted planar object. FDK (Feldkamp, Davis and Kress) reconstruction algorithm has been adapted to reconstruct the planar object from the radiographs. Best reconstruction results are obtained when an optimal laminographic angle of 45 degree is used for data acquisition. The simulation study can be employed for in situ testing of planar specimens.