The company E + E Elektronik manufactures a new kind of humidity sensors on 8 "silicon wafers.
In this case about 90,000 sensors are placed on a single wafer. As part of the quality control, the sensors also are visually checked. Only human control is no longer possible with this huge number of sensors. The dwh GmbH has equipped an existing microscope from Olympus with a camera and a motorized stage as an interim solution and has written a control software that automatically scans the wafers.
First the exact location and rotation of the wafer is determined , then it is uniquely identified by a data matrix code. Based on existing CAD data, the optimum scan path is calculated and the wafer is scanned stepwise while the focus is constantly monitored and adjusted for preserving image sharpness.
The resulting images are stored and automatically checked for errors - according to predetermined criteria - by a second software which has been developed by us. The entire process is coupled with the company's own database. This way, uninterrupted monitoring is possible.