High speed image acquisition for microelectronics inspection

Abstract

This invention is a high speed illumination apparatus and technique which isolates bond wires, ball bonds, bond wedges and microcircuit chips exclusively for manual or high speed automatic inspection of microelectronics assemblies. This system consists of multiple concentric rings of illumination, which are focused towards the center of the rings, but from different angles of incident. Light from these angles reflect off the different specular surfaces of the bond wires, wire bonds, and bond wedges, providing background contrast. Light projected on the flat surfaces of microchip bodies tends to be absorbed, producing a negative contrast shadow if the other elements are illuminated in parallel. Unique angles of incidence provide substantial illumination contrasts between the areas of interest and its neighboring surfaces. The reflections provide unique signatures which are easily distinguishable by an image processing system. Alternating the transmission of light through each of the rings at high speed using electronic shutters, contrasted images with unique features can be highlighted exclusively in milliseconds. These contrasted images are then captured by a light responsive transducer such as a video camera for further fault determination.