A new interlayer interconnect technology for multilayer fabrication

A novel approach to multilayered circuitry based on flexible substrates has been established by prototype manufacture of test vehicles. The multilayered circuitry is comprised of new conductive bondply and layer pairs (ViaThin^TM) based on 50 μm (2 mil) polyimide film. The bondply base film is patterned with 100 μm (4 mil) vias and filled with an organic-metallic composite material (Ormeto ^R) used to interconnect the layer pairs. Circuit traces of 50 μm (2 mil) width, multilayered capture pads of 225 μm (9 mil) diameter, and integrally formed conductive vias of 25 μm (1 mil) diameter comprise the layer pairs in the work described here. The bondply vertically interconnects the layer pairs using a lamination process common in the printed circuit board industry. Eight-layer circuits have been fabricated, employing four circuit layer pairs and three bondply interlayers. The multilayer technology presented was developed within the DARPA-funded MCM-L consortium