…or “Let there be light” for those who prefer English (or missed the Latin class in school). The heart of an Optical Inspection System is obviously the camera, but without the proper lighting and the resulting reflections even the best camera won’t allow a dependable fault detection. Especially with today’s challenges, like the use of 01005 packages or the switch to lead-free soldering, the good old days of a simple top illumination with white light in combination with a 1 Megapixel camera are definitely over.
GOEPEL electronics with its 15+ years experience in Automated Optical Inspection (AOI) offers “Flexible Spectral Illumination” in all Opticon systems - from bench-top to in-line machines.
The illumination modules in Opticon AOI systems are now able to emit light at any frequency – from infra-red to ultra-violet, freely controllable by the user. But not only the wave length, also the intensity and the direction of the light can be adjusted, allowing the reliable detection of low-contrast components, varying polarity marks, fluctuating material reflections, and impurities. The result is a higher detection reliability of real failures and a lower false-call rate. In order to help the end-user to find the right wave-length and angle, all illumination variants are predefined as presets in Opticon systems, implemented in the standard library and ready to use.
One very common problem is the detection of low-contrast components, such as SOTs, which reflect light very similar to the PCB background. The image below shows how infra-red light can help to increase the contrast and guarantee a dependable detection of faults.
Fiducial-marks are usually very easy to detect by any AOI system. Sometimes they get tinned , for example when they need to be used by X-ray systems, and the reflection of the solder can vary dramatically. Ultra-violet light would be the solution and the example below shows the difference.