In response to the market demand and technology changes of flexible printed circuit board (FPC), ITRI Mechanical and Mechatronics Systems Research Laboratories (MMSL) has developed additive processes for double-sided FPC processes to improve the technical capabilities and product value for domestic FPC vendors. The additive processes combined with ultra-fine conductive-line printing technology, precision positioning printing technology and roll-to-roll processes possess the advantages of green manufacturing, simplified fabrication process, and low cost production; allowing to increase production throughput and yield. This technology can also be applied to advanced electronic devices such as sensors, high frequency antenna, and battery, etc. In this paper, the additive processes and equipment for double-sided FPC are discussed in depth.