A Spatial-Constraint-Based Feature Point Matching Algorithm for the Positioning of Multiple IC Instances

With the development of integrated circuit (IC) chips, the semiconductor industry has begun using many ultrathin chips. To prevent cracking when they are picked up by the machinery, the precise pose of every chip must be provided using the image matching approach. Traditional feature point matching methods are robust to the pose changes of a single chip, but they are not effective for positioning multiple IC instances in one image. To solve this problem, a novel spatial-constraint-based feature point matching algorithm that uses both local information and the spatial topological relationship between feature points to divide the feature points among different IC instances is proposed. Various experiments using images captured of RFID chip pick-up equipment demonstrate that our algorithm results in correct positioning for multiple IC chips; is robust to translation, rotation, scaling, shearing and perspective transformation; and is not sensitive to occlusion and clutter. This algorithm may have many applications in the field of IC manufacturing and packaging.