Three-dimensional interconnect for multilayer module packages with selectively anodised aluminium substrate

It is reported that 3-D interconnects fabricated with a selectively anodised aluminium process for a multilayer module package can be used to evaluate high-frequency performance. The proposed method of fabricating vertical interconnects is easier and more cost-effective than other RF MEMS processes. To transfer RF signals vertically, coaxial hermetic seal vias with characteristic 50 Omega impedances and embedded anodised aluminium vias with a solder ball attachment and flip-chip bonding were used. The optimised interconnect structure demonstrated RF characteristics with an insertion loss of less than 1.55 OmegadB and a return loss of less than 12.25 OmegadB over a broad bandwidth ranging from 0.1 to 10 OmegaGHz. Experimental results suggest that the developed technology, which is based on selectively anodised aluminium, can be applied to new 3-D packaging solutions.