In this paper, we develop a low-cost manufacturing technology for RF substrate and a high-performance process technology for integrated passive devices by electrochemically forming thick oxide on Si wafer and processing Cu thick metal and BCB. Several integrated passive devices such as LPF, BPF, and balun are,fabricated using this technology and they show good RF performance in spite of their small chip size. (C) 2003 Wiley Periodicals, Inc.