Development of paper membrane switches for fully featured computer keyboards

This paper documents the successful development and evaluation of a novel membrane switch. The process results in lower environmental burdens and manufacturing costs than current screen-printed polyester solutions. Detailed is the evaluation of offset lithographically printed conductive tracks on paper substrates for application in computer keyboard assemblies. Offset lithographic printing of conductive tracks is an emerging fabrication technique finding application in low-cost, high volume, flexible circuitry applications. Several fully featured demonstration keyboards and switch membranes have been constructed and tested. These are currently in use in office environments and are presented

Low cost patterning of thin film

A novel route for the low-cost patterning of electrical thin films has been established. The process has been developed principally for the manufacture of thermocouples using high-speed reel-to-reel industrial techniques, but could be applied to the manufacture of a wide range of electronic devices including radio frequency identification (RFID) antennae, electrical interconnect, and passive electronic components. The procedure exploits high-volume processes directly to print self-removing masking layers. The process offers substantial advantages over traditional thin-film patterning methods including faster, cheaper production runs. Raw material use and wastage are greatly reduced, affording environmental benefits

Fabrication of bifunctional membrane electrode assemblies for unitised regenerative polymer electrolyte fuel cells

Bifunctional membrane electrode assemblies have been fabricated using a screen printing technique, which demonstrate a repeatable and stable operation to cell current and voltages. This approach lends itself to a rapid, low-cost and repeatable fabrication process for bifunctional catalytic electrodes in polymer electrolyte membrane fuel cells and electrolysers

A review of developments in electrodes for regenerative polymer electrolyte fuel cells

The design of electrodes for unitised regenerative polymer electrolyte fuel cells (URFC) requires a delicate balancing of transport media. Gas transport, electrons and protons must be carefully optimised to provide efficient transport to and from the electrochemical reaction sites. This review is a survey of recent literature with the objective to identify common components and design and assembly methods for URFC electrodes, focusing primarily on the development of a better performing bifunctional electrocatalyst for the oxygen reduction and water oxidation. Advances in unitised regenerative fuel cells research have yielded better performing oxygen electrocatalysts capable of improving energy efficiency with longer endurance and less performance degradation over time. Fuel cells using these electrocatalyst have a possible future as a source of energy

Printed thick-film thermocouple sensors

Thermocouples have been printed using thick-film processes, which demonstrate a repeatable and stable reaction to temperature and a potential difference per degree temperature change comparable to conventional commercial couples. The potential for this novel approach is to offer a rapid, low-cost, low-temperature manufacturing process for electrical temperature monitoring

An initial investigation into the low-cost manufacture of diffracting objects

In this letter we report on an initial investigation into the printing of diffracting objects via the high-speed, low-cost, printing process of offset-lithography, a method more commonly used in the printing of books and newspapers. A series of diffracting objects were printed onto clear substrates and evaluated with a coherent light source. The diffraction patterns generated correlate well with the Fourier transform of the printed image

Conductive lithographic films

This paper reports progress in the development of a novel fabrication technique for printing circuit board designs directly onto suitable substrates. Circuit tracks can be formed on organic or synthetic substrates by depositing films of a metal-loaded ink via a standard lithographic printing process. The application of this work is in substitutes for conventional (copper-clad resin/laminate) circuit boards where, for low complexity circuits, directly printed substrates offer cost advantages and environmental benefits. The paper is a resume of work and results, including; ink formulation, environmental test, circuit modelling and life cycle analysis. Conductive lithographic films have now been successfully demonstrated in a telephone handset developed in conjunction with Nortel, microprocessor and microwave stripline applications. Whilst developed primarily as a low cost, low environmental impact alternative to subtractive PCB manufacture, other potential advantages such as flexibility and environmental robustness are apparent

Lithographic technology for microwave integrated circuits

Conductive lithographic films (CLFs) have been developed primarily as substitutes for resin/laminate boards, which share properties with the metallisation patterns used in planar microwave integrated circuits (MICs). The authors examine the microwave properties of the films and show that, although the losses are greater, they have potential as an alternative to the traditional manufacturing process of MICs

Printed thermocouple devices

A novel process for the fabrication of thermocouples using thick-film techniques has been developed. Thermoelectric reactions of 22 μV/°C per couple have been observed which are comparable to those of conventional thermocouples. This work outlines the potential for a rapid, lowcost, low temperature manufacturing solution for the production of electrical temperature sensors

Test structures to characterise a novel circuit fabrication technique that uses offset lithography

This paper reports on the use of microelectronic test structures to characterise a novel fabrication technique for thin-film electronic circuit boards. In this technology, circuit tracks are formed on paper-like substrates by depositing films of a metal-loaded ink via a standard lithographic printing process. Sheet resistance and line width are electrically evaluated and these quantities are compared with optical and surface profiling measurements