Design and construction of large-area flexible printed-circuit automotive electrical interconnection harnesses

Abstract

The replacement of automotive wiring harnesses with large-area flexible printed circuits (FPCs) would help to reduce the vehicle weight and emissions. To help clarify what a future large-area FPC interconnection harness should be capable of, a detailed design exercise to meet the engineering specification of the instrument panel wiring harness of a specific midrange passenger car was carried out. To demonstrate the added value of using an FPC, intelligence in the form of active circuitry was incorporated in the designs. Two generic architectural concepts were pursued. The first, a single large-area FPC, supported the wire harness geometry, all point-to-point interconnections, and current ratings up to 4 A. However, the panel size was too large to be manufactured on existing automotive FPC process lines. The second, intended to be a collection of smaller FPCs that could be manufactured on existing automotive FPC process lines, was found not to be practical as originally conceived. A physical implementation of the single large-area FPC design was made in stages at different company sites using various pieces of equipment, some of which are not normally used for FPC or electrical circuit manufacture. Modified versions of the equipment could be used to create a large-area automotive FPC manufacturing line.