Imaging Geometry
Spatial gaps between the X-ray emission point and the printed circuit board determine the magnification level of the inspection system. The source-to-object distance is the primary variable used to zoom in on specific solder joints or internal component features. Bringing the object closer to the source increases the size of the image on the detector.
Calculation Method
Calculation of geometric magnification is the ratio of the source-to-detector distance to the source-to-object distance. As the source-to-object distance decreases, the magnification increases, allowing for the inspection of tiny features like bond wires or microvias. However, moving the board very close to the X-ray tube increases the risk of collision and can lead to image blurring if the focal spot is not sufficiently small.
Professional systems use motorized stages to precisely control this gap and maintain focus. The operator must select a distance that provides enough detail without sacrificing too much of the field of view. This trade-off is central to the setup of any high-resolution X-ray inspection process.
Minimizing Gap
Minimizing the source-to-object distance is the most effective way to improve the resolution of the X-ray system. This technique is used to find microscopic defects that are invisible at lower zoom levels.
