μAXI - HIGH PRECISION AUTOMATIC X-RAY SOLDERED JOINT INSPECTION TECHNOLOGY TO MEET ZERO DEFECT QUALITY STANDARDS

摘要

For BGA, CSP and flip-chip-applications, automated X-ray inspection (AXI) is an accepted and particularly standardised quality-control procedure. Its use has increased for hidden characteristics of other SMD-solder joints such as QFP-and QFN-elements. Any defects caused by a difference in thickness or material can be detected by X-ray analysis. To ensure the product quality of quality-sensitive electronic assemblies hitting actual and future zero defect quality requirements, the inspection strategy for a minimised escape and pseudo defect rate should determine the inspection time - not the line throughput. With common in-line AXI, the inspection depth is normally determined by the throughput of the SMT line. Principally, X-ray inspection takes much more time than optical AOI, and the higher the defect coverage, the more inspection time is required. For zero defect production, inspection with small fields of view with micrometer resolution, 360° rotation and oblique viewing up to 70° is required: μAXI. To guarantee these higher defect coverage requirements, μAXI takes more time than common inline AXI and has to be performed beside the production line. The first realised μAXI system is a phoenix|x-ray 180 kV / 20 W microme|x X-ray inspection system with a typical position accuracy of only a few microns which is equipped with the new x|act software platform. To minimise programming time, x|act is using CAD import of component and pad information instead of more complicate and less exact view based programming. The operator simply links specific inspection strategies from a library to each pad type like BGA, QFP, PTH etc. The x|act software then automatically creates the inspection views. Due to CAD-based programming and the precise μAXI system, inspection programs can be generated offline and are portable to all systems of the same type. The x|act software provides a live overlay of the CAD-information in the X-ray image. This allows the user to have the complete sample data available at all times, even when using oblique views (tilt and rota- tion). Not only the pad ID is visible at any time: In addition, even the pad specific inspection results are accessible simple by mouse over. The overlay technique is very convenient for the operator for perfect orientation at any time and reliable identification of detected defects for rework - which might be very time consuming on a board with thousands of solder joints. The new x|act software is the first solution for highest resolution μAXI to ensure a minimised pseudo defect and escape rate for highest reliability of electronic products.