title: Image matching technology in high power LED's eutectic welding.
abstract: As the integration packaging density of high-power LED (Light Emitting Diode) chip modules become higher and higher, the accuracy and speed of visual inspection require higher demands correspondingly. The accurate position matching of substrates and flip-chip LEDs is one of the key technologies in the automatic eutectic welding process. In this paper we propose a method based on image features to complete the matching of the substrates and the flip-chip LEDs. Firstly, the substrate images and the flip-chip images are pre-processed respectively to obtain binary images. Then we apply Hough transformation to detect straight lines on the binary images, and find out the main linear directions to trigger the mechanical arms to adjust the positions of the substrate and the chip initially. Thirdly, we use eight neighbors interconnected domain algorithm for the first time to locate notable features of the substrate, and pass the located information to the control system to trigger the mechanical arm to adjust the substrate for the second time. At the same time, projection algorithm is applied to locate the anode of the flip-chip to drive the mechanical arm to adjust the position of the flip-chip again. Finally, the position information is used to trigger the mechanical arm to accomplish the matching of the substrate and the flip-chip. The proposed method improves the speed of matching on the basis of the accuracy of matching, which achieves these requirements of real-time and high accuracy applications.
authors.forename: Peng
authors.initials: P
authors.lastname: Ge
authors.forename: Peipei
authors.initials: P
authors.lastname: Yin
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Tianhai
authors.initials: T
authors.lastname: Chang