Semikron (SEMIKRON International GmbH) manufactures components and systems for power electronics. In order to guarantee a consistent, faultless connection of the electrical contacts, the company has decided on an automatic optical wirebond inspection system from Viscom.
Dr. Weidner is responsible for the optical inspection of a wide range of completely different products at Semikron’s Nuremberg location. Dr. Weidner commented, “We have simple circuit boards that can be inspected very well with a human visual inspection as well as products that are clearly more complex and on which the many wire bond connections cannot be sufficiently checked with the human eye alone.” Above and beyond straight defect detection, she sees further advantages in the investment of a wirebond AOI system. “With the straight visual inspection, we have no statistical data for an evaluation. Thus, we do not know when and where which defects occur. Therefore, we have decided on an inspection system. With it, we also can analyze and rectify the causes for defects. The upstream processes are improved.”
The S6056BO inspection system is equipped with two identical camera heads working in parallel. These have LED illumination units that can be controlled as groups to generate an illumination specifically for wire bonds, and are capable of seeking out defects on the complex reflective wires. For high-throughput requirements, the system is laid out with two tracks. The inspection cradles of the two tracks are loaded by internal shuttles. Since the lots are manufactured per order on several bonders, after they are manufactured, they run through the wirebond inspection.
Defects detected by the automatic bond AOI include missing bonds, flatly drawn loops or damaged bond feet. These defects cannot be detected with the naked eye. For the S6056BO, with the appropriate illumination and camera layout this is not a problem. Thanks to high-performance image processing algorithms, a very high inspection depth is achieved.
In addition to the standard tasks, Viscom also takes on customer-specific assignments. Thus, for example, software for lot number management was implemented with the help of a solution for individual barcode reading. A multi-stitch analysis that guarantees the robust separation of wires from inhomogeneous backgrounds also was developed. All wedges and loops can be reliably inspected with just one image, without multiple captures. Ultimately, this means simplified inspection program generation and reduced cycle time.