Using Electrically Conductive Inks and Adhesives as a Means to Satisfy European PCB Manufacturing Directives

Abstract

The European Union implemented the WEEE (Waste Electrical and Electronic Equipment) and RoHS (Restriction of Hazardous Substances) directives in July 2006. The aim of the WEEE directive is to reduce the quantity of electrical/electronic equipment being disposed of in landfill, by promoting reduction, reuse, and recycling of equipment/component parts; with the RoHS directive eliminating a number of hazardous substances from the manufacturing process of such equipment that may eventually end up in landfill. The main effect on the manufacture of Printed Circuit Boards has thus been to identify a drop-in replacement for leaded solders, and the replacement of other banned substances in the manufacturing process, i.e. compliance to the RoHS directive, with limited attention being paid to the WEEE directive. A system of manufacturing a PCB has been evolved by utilising the principle of reducing manufacturing processes in the development of the PCB substrate and the possibility of recovering components at end of life by degradation of the substrate. A test vehicle was developed based on a currently mass manufactured board, but using a substrate of paper card, with interconnecting tracks added using conductive inks via a printing process. Components were bonded to the tracks using electrically conductive adhesives via an industry based manufacturing line. The scope of this paper will be confined to the ability to utilise an ECA as the connecting medium for single sided boards with a paper card substrate, thus opening the possibility of producing a WEEE/RoHS compliant environment-friendly PCB.