Automatic Optical Inspection of Bump Offsets in Flex-on-Glass Bonding Using Differential Interference Contrast Imaging

Bump offsets have harmful effects on the quality of flex-on-glass (FOG) bonding in liquid crystal display (LCD) module industry. Here we report a novel automatic optical inspection (AOI) method to achieve fast inspecting FOG bonding bump offsets. Overcoming difficulties to image targets at different depths in light absorption medium when using ultra-short-exposure and high-speed imaging, the proposed method innovatively achieves inspecting FOG bonding bump offsets using differential interference contrast imaging based on spatial Poisson point process approximation. Theoretical analysis proves that the proposed method has high reliability in FOG bonding bump offset AOI inspection. Experimental results show missed detection rate of the inspection algorithm is 0.01%, and false rate is 0.1%, and verify the accuracy and validity of the proposed method, all of which are significant for guiding practice in LCD module industry.