A New Interlayer Interconnect Technology for

A novel approach to multilayer circuitry based on flexible substrates has been established with prototype manufacture of test vehicles. Comprising the multilayer circuitry are a new conductive bondply and layer pairs (ViaThinTM) based on 50 ym (2 mil) polyimide film. The bondply base film is patterned with 100 ym (4 mil) vias and filled with an organic-metallic composite material (Ormet@) used to interconnect the layer pairs. Circuit traces of 50 pm (2 mil) width, multilayer capture pads of 225 pm (9 mil) diameter, and integrally formed conductive vias of 25 pm (1 mil) diameter comprise the layer pairs in the work described. 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.