Large-area flexible printed circuits for automotive applications

To meet the demands for safety and passenger comfort, modem passenger cars offer more and increasingly sophisticated electrical and electronic systems. The wiring harnesses that support such systems become too large, complex and heavy, when designed for a conventional electrical architecture based on 14 volts, posing several challenges to automotive manufacturers. Alternative electrical architectures based on 42 volts and in-vehicle multiplexing promise to reduce the size and weight of the wiring harness, but these architectures are yet to be fully developed and standardized. In the near term, alternative wiring solutions have gained the interest of automotive manufacturers. Small flexible printed circuits (FPCs) have previously been integrated into automotive instrument clusters. The benefits of reduced weight and space requirements of such FPCs compared to a wire harness has fuelled an interest in much larger FPCs as substitutes for the Instrument Panel and door harnesses in high-volume production cars. This research investigates the materials typically used in FPC manufacture, for applicability within a passenger car. [Continues.

Electromagnetic compatibility performance of large area flexible printed circuit automotive harness

Electrical interconnection is increasingly important to the functionality of modern vehicles. At the same time the drive within the industry to reduce costs and improve fuel efficiency requires the reduction of the weight of vehicles wherever possible. It is in this context that the possibility of using large-area flexible printed circuits (FPCs) in place of wiring harnesses is receiving strong interest from manufacturers. An FPC harness offers a substantial weight reduction over wire, improved reliability and quality control, and enhanced functionality. Since good electromagnetic compatibility (EMC) design and performance is necessary for the safe and proper functioning of a vehicle, it is important to know if the EMC performance of a vehicle is likely to be compromised by the incorporation of an FPC harness. This question is addressed in this work by comparing the performance of wire and FPC structures in a standard EMC test. The cost implications of anti-interference measures for mass production of FPC harnesses are also assessed. It is found that relatively cheap and simple to implement track structures can significantly reduce the amount of coupling to a large-area FPC automotive harness from an external electromagnetic field

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

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