Study of the fine line process and signal integrity for packaging substrate

This paper presents the forming mechanism of fine line (less than 50 mum) in manufacture of packaging substrate. Both subtractive and semi-additive lamination processes were applied for finer pitch substrate manufacture. In addition, signal integrity of the finer traces made on different types of material was tested. Based on these studies, design guidance of fabrication process, materials selection and layout design rule were established for high quality signal integrity applications. Control points of key processes in substrate fine traces manufacture were also described in details, such as choices of surface finish, image transfer, etch resist, foil, etc. Furthermore, the key significant technology in fine traces manufacture was analyzed particularly, and process control technique for improving the yield was obtained.