Strip Lasermarking Offset Marking Defect Improvement For Small Outline Packages

Strip-level laser marking is an assembly process to mark the units with product codes. This helps to eliminate mixed device issues. Offset marking is a defect of the laser marking process where the marked product code is shifted from the designated location on the units. This paper will address the issue of offset marking by doing improvement of the marking stage and clamper design to mitigate the lead frame warpage issue which causes the offset marking defect. Besides, this paper will also seek to eliminate the laser mark machine sequence in which, track motor homes when a different recipe is selected as the machine sequence indirectly contributes to the offset marking issue. After completion of the improvement actions, distance between the package edge to the marked alphabet on both sides of the units are measured by using microscope under 5x magnification. Then, the marking offset measurement is calculated by averaging the difference between both distances. Based on the data, it’s observed that mean and max measurement of offset marking have improved by 72 % 64% for the small outline packages. Conclusion, overall yield loss on offset marking is improved and defect was eliminated.