IC leadframe inspection system using multiple thread on the Windows NT

In this paper we propose an automatic IC leadframe inspection system to inspect major defects in lead spacing, pad shift, tape position and punching defect. This system is composed of an image acquisition part and an inspection part for improvement of inspection speed and flexible inspection environment. We adopted Windows NT operating system in consideration of stability and compatibility of the system. The system has these 2 separate parts so that the image may be refreshed continually during inspection; hence, the whole system's performance was improved. A subpixel method using a high-resolution camera is adopted because the spacing inspection requires very high accuracy and this made it possible stably to maintain an accuracy of about one third of a pixel. Tape inspection is performed by using the mutual relation of the positions of the tape boundary lines. We developed an algorithm which can shrink and expand any polygon efficiently to inspect tapes of arbitrary shapes. By experiment using above inspection method, our inspection system was confirmed as high speed and high accuracy inspection system that can inspect about five leadframe units per second.