ENHANCED THICKNESS CALIBRATION AND SHADING CORRECTION FOR AUTOMATIC X-RAY INSPECTION

An X-ray inspection system incorporates an improved technique for determining, in an X-ray image of a multilayered assembly, the gray level component of a first material in the presence of a second material. The total gray level of the image is dependent upon the physical characteristics of each material comprising the assembly. The present invention accurately determines the component of the total image gray level due to the first material. In the case of circuit board inspections using X-ray images of solder connections, a calibration procedure facilitates the direct conversion of the gray level component due to the solder connection to the thickness of the solder connection.