Development of precision inspection system for 3D micro system packaging using the projected grid pattern distortions method

Recently rapid development in electronics and informational technology makes the electronic devices more powerful and smaller. To manufacture such device that integrate the powerful functions within the restricted small size of device, precise and rapid inspection of the packaging including mounting and soldering is needed. In this paper, such a inspection method has been studied. Using phase shift profilometry methods, based on projection of structured moire-like light pattern on object´s surface and measurement of the resultant phase shift, more efficient, precise and robust inspection measurement can be made. To ensure these method´s precision it is necessary to make the projected pattern perfectly sinusoidal and also having predefined grid pitch (period). This phase shift based inspection and measurement method and systems developed by authors allow high speed 3D inspection of micro system packaging of the electronic components like wafers. Experiments, which were carried out with special target gage block and real PCB samples, showed repeatability of measurement results with less than 0.3 mum standard deviation and better than 1 mum absolute accuracy within wide working range.