Development of Solder Joint Inspection Method Using Air Stimulation Speckle Vibration Detection Method and Fluorescence Detection Method

b fast and highly reliable method of inspecting minule solder joints of high-density rnouaed devices hns been dcveloperl. It uses two techniques to detect all types of defects, such as unsoldered leads. solder bridges. and mis-aligned leads. One applieszxternal Form to solder joints with an air jet. which vibrates w shifts unsoldered leads. The vibration and shift is detected as a change in the speckle pattern produced by laser ilIumination of the solder joints. The other uses fluoresoenoe from PC (Printed circuit) boards gcnwrrmed by shon wavelength laser illumination. A silhouene image of the solder joint is detected and processed to extracts defects. The experimental results show that this new inspection method detects all types of defects accurately with a very low false alarm rate.