Transferable Redistribution Layers (TRDL)

Since the early 1990's, redistribution layers (RDL) have been used to relocate and change the pattern of the bond pads on die. RDL allows legacy parts that were designed as wirebond die to be flip-chip soldered to Printed Wiring Boards (PWBs). The flip-chip soldering technology shrinks overall board size as well as shortening electrical connection lengths. Since the introduction of this technology a couple decades ago, RDL has been performed at the wafer level through a back end of line (BEOL) process performed directly on the active surface of the wafer. Transferable redistribution layers (TRDL) may become the next evolutionary step for RDL and provide a viable solution to complex RDL. The TRDL technology allows for multi-layer RDL to be transferred from a non-active surface to an active one. TRDL is particularly important for prototyping and quick-react situations. The TRDL wafers can be processed in parallel with obtaining the active components, thereby drastically reducing the time from design to completed components.