High density electronic packaging applications will benefit by utilizing this very thin multilayer interconnect construction. Specific advantages include higher packaging density, thinner composite profiles, and flexibility for installation. Especially useful for automotive multiplexing applications is the ability to readily combine high density signal carrying capability with high current carrying capacity all in the same compact package. This paper describes an approach to building ultra-thin multilayer circuits in a repeatable high volume production process. Properties evaluated include dielectric strength between layers, current carrying capacity, and ability to withstand tight folds in flex-to-install applications. Also included is data on electrical performance after high temperature and humidity exposure, and a discussion of minimum pad and via size limitations. The methods described in this paper provide meaningful improvements in achieving higher density interconnect packaging.