The present invention discloses the structure and process for fabrication of an electronic package to contain and protect Package-to-Package (P2P) stacked module of integrated circuit (IC) chips. The process includes a step of providing an interposer that includes conductive traces interconnected between pre-designated contact pads disposed on a top and/or bottom surfaces for mounting at least a top or bottom packages of the IC chips with electric terminals contacting the contact pads disposed on the top and/or bottom surface of the interposer. Standoffs and passive components can also be added onto interposer in order to improve solder joints reliability, electrical performance and main board density at the same time. The inclusion of passive components on the interposer could enhance the electrical performance and the testability of the finished package stack.