US Patent 7772109 Manufacturing method of multilayer wiring substrate

A first multilayer wiring structural body 16 and a second multilayer wiring structural body 56 are simultaneously formed on both surfaces 101A, 101B of a substrate 101 and thereafter the portion of a structural body 120 corresponding to a third region C1 is folded so as to oppose a second structural body 22 to a second structural body 62 and the first multilayer wiring structural body 16 is electrically connected to the second multilayer wiring structural body 56.