The paper describes the newly development technology of 3D stacking packaging by introducing laser-drilled through silicon interconnect (LTSI). Compared to the recently abundant researches of 3D chip-to-wafer or wafer-to-wafer stacking, it demonstrated a more reliable and practical process flow to achieve the 3D stacking technology. The investigation of thermal effect and electrical properties on LTSI confirm that this newly low-cost interconnect technology could be a good candidate for both wafer stacking application and 3D SiP module.