Abstract
LED chips position is of crucial significance in chip testing, scribing, die spreading, and die bonding. It’s a great solution to indicate electrical characteristics of chips, examine whether the chip pins are up to the standard, and distinguish LED chip quality. Concerning this, an LED chip positioning method based on wavelet transform is proposed in this paper. Firstly, CCD, light and motion control module are adopted to construct and acquire the visual system of LED chip images. Then the images are processed with lowpass filtering and normalization to obtain Hi-Q chips image, and image features are extracted by further using multi-scale wavelet transform. Lastly, high accuracy positioning of LED chips is achieved by employing high-accuracy point pattern matching algorithm. Experimental results show that the LED chip image positioning error is less than 1μm and the position speed is faster than 5 particles per second, which offer new approaches for high-accuracy chip positioning system of detection machines, sorting machines, die bonders, etc.
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