Everything in view with VERSAEYE

For this reason, there is a simple procedure for program creation. Two different methods of image processing are possible for the inspection. The first is “Pattern Matching”. A positive example of an image is taught in here, and the system then searches for exactly this image on every further printed circuit board. If the taught-in image is found, the inspection result is “good”. This works reliably with SMD assemblies, but has a serious disadvantage with THT solder joints: SMD components always have the same geometry and dimensions of the same body. With a THT solder joint, on the other hand, the pin can move freely depending on the hole diameter and is normally not centered. Therefore, there is the second possibility of image processing – the so-called “histogram”, in which colored pixels are searched for in an inspection area determined by the operator. The tolerance limits for image processing can be narrowly set for the histogram and are therefore not based on taught-in images, but on a condition-oriented decision. If there are enough pixels in the selected tolerance range in a defined inspection area, the result is saved as “good”. Irrespective of the direction in which the pin is located. A remarkable feature of the histogram is the 24-bit color depth, which reproduces a true-to-detail image and thus enables an extremely differentiated inspection.

For the first time, the inspection program is created on a non-populated and non-soldered PCB. Here all necessary information such as pad and hole size can be seen directly. After all tolerance sizes for classifying the good or bad parts have been entered into the program, it is time for a first inspection run with a fully assembled and soldered PCB. Normally, the defects are reliably distinguished from the good solder joints without the need for tedious finding and reworking of the test samples. This saves time and nerves. The program is created directly at the system. From practical experience it is known that at high production pressure not so much time can be spent at the system. Therefore, a complete AOI inspection program can be created offline, completely without the system. This ensures that production is not delayed at any time.

The “good” and “NG” results of the inspection are sent to the customer via a possible MES connection and can then be viewed for tracking and follow-up processes. In any case, traceability via the repair workstation is possible. The DataMatrix code (DMC) is read into the software by a hand-held scanner and the associated result is retrieved directly from the database. The operator is most pleased about a “good”, but even a NG (not good) is easily traceable. With the help of a crosshair, the operator is shown the position of the supposed error. A 360° panoramic view can then be viewed directly through the special view of the eight side cameras. The fault can be reliably located without having to inspect the printed circuit board with a magnifying glass.

Ersa: Krisztian, after the five-day AOI training you can now operate everything (AOI, offline programming, repair workstation) independently – how do you feel about the operation?

Krisztian Kuzma: In my experience the hardware is robust, easy to maintain and seems to easily identify errors. I think it will help us a lot in the future. The software looks intuitive, which is confirmed by the programming. I understand how the system works – only the process of debugging is complicated at the moment. That will subside with increasing experience. It´s also helpful that we have access to all data at all times when we have questions about the PCB later on.