Laser dambar and flash removal for plastic molded surface mount components with lead spacing under 20 mils

National Semiconductor´s Advanced Packaging Equipment Group set out to apply lasers to the problem of leadframe feature removal in fine pitch packages. The system developed is fully automated with a high-resolution parallel-processing vision system, and magazine-to-magazine material handling. The limits of laser accuracy are far from being exceeded. With one mil kerf width on high-power lasers the limitation will not be the laser but the system. Although it has never been tested, it is estimated that dambars associated with lead spacings of 2.0 mils could be removed by the method described. This is the resolution that will be required for small-geometry interconnects at the silicon level which are headed towards 4 mil center lines.<>