A New Automatic Testing System Based on Image Processing and Microprobes for IC-Testing

Abstract

In order to develop integrated circuit (IC) testing, a new system was suggested using a microprobe array, a four-wire tester, machine vision, and motion control technology. The microprobe array can be automatically aligned with the IC die by an image-processing program in the system. It was found that the operating efficiency of the algorithm was improved by six times by extracting the rectangular edge contour. Several image-processing methods were combined and optimized to calculate the deflection angle, and the linear fitting method was improved. Inaccurate fitting was eliminated by the modified fitting method, and the alignment error was significantly reduced. Although IC electrodes were precisely aligned with the microprobe tips, the compressive displacement of the microprobe also has a greater influence on the electrical testing. The testing resistance was not a stable value until the compressive displacement exceeded 100 $\mu \text{m}$ . Finally, the effectiveness of the microprobe automatic testing approach was confirmed. The open circuits of the ICs can be detected, and the resistance of the circuits, which are not open circuits, can be automatically measured and evaluated.