Development of an inspection process for ball-grid-array technology using scanned-beam X-ray laminography

An inspection process based on scanned-beam X-ray laminography (SBXLAM) is proposed herein for quantitatively monitoring the quality of ball-grid-array (BGA) joints. The long-term reliability of the BGA joints depends on the component-assembly process producing joints with sufficient solder volume and proper alignment. Inspection algorithms were developed to measure the critical BGA-joint characteristics, including the alignment between the ball and the PCB pad, the solder thickness, and the average joint-diameter, and thus, determine whether the joints are defective. The performance of the inspection algorithms was evaluated by inspecting samples with defects that were independently verified.