01 Nov 2006
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Printed-on wiring
Electronic circuits can now be directly written onto surfaces without the need for printed circuit boards or connecting wires. Advanced ink technologies combined with computer controlled pens have been used by the ATC to wire together sensors as part of the BAE Systems and Team McLaren Mercedes partnership.
Trials to monitor the suspension of a Formula 1 car have been successful with the ATC circuits clocking up over 5,000 km of flawless operation.
Wiring and connections are often a weak link in electronic systems and frequently need manual skills to assemble and place them in equipment. New direct writing techniques are now being developed that allow electrical conductors and even simple electronic components to be printed as thin films of special ink directly on almost any surface. Technologists at the ATC have been perfecting the techniques of ink deposition using programmable pens for a range of BAE Systems applications including antennae devices, displays, stealth materials, packaging and wiring harnesses.
"Direct Write technology deposits electrical wires, resistors, capacitors and other electrical components in 3 dimensions onto complex surfaces." says Jagjit Sidhu, Project leader at the ATC. "The micropen system can write lines from 1/20th mm to over 1mm wide on virtually any surface. Many types of material can be deposited including conducting, insulating, magnetic, dielectric and optical materials." he says.
The completely flat and nonintrusive nature of the painted features makes them ideal for applications involving smooth, aerodynamic surfaces and Team McLaren Mercedes spotted the potential for making load measurements on their car suspension components.
It is vital to the Formula 1 engineer to understand the forces that keep the car in contact with the track especially during high speed cornering. The racing car team glean this information from load sensors attached to the car but the impracticalities of fixing such devices directly to suspension components has limited the accuracy of measurements in the past. The environment near the suspension is extremely harsh involving aerodynamic forces, wide temperature ranges and humidity. Conventional wiring would interfere with the airflow across components and would not endure under these conditions. Team McLaren Mercedes saw the ATC's printed-on wiring as a potential solution to these problems and as a result, a set of suspension items were given the direct write treatment.
Load cells interconnected using this technology have been evaluated on Team McLaren Mercedes' cars during track trials, and after 5,000km of wet and dry testing there was no degradation in the performance of the interconnects.
The work with Formula 1 team has allowed Jagjit and his team to evolve the technology in some vital respects: "This project has enabled us to demonstrate how well the direct write techniques work in a harsh environment. It also allowed us to develop new tools to meet the fast turnaround times needed by Team McLaren Mercedes. As part of this, we developed a means of linking Computer Aided Design information with our micropen controller: speeding up the whole process of design and fabrication." he says. The success of this work prompted Jonathan Neale, Managing Director of McLaren Racing to say: "Over the past 10 years BAE Systems' technologies have benefited almost every aspect of our Formula 1 racing car. We're anticipating that in time, Direct Write could make a significant difference in reducing the weight and complexity of wiring on the car, thus improving reliability and performance, and ultimately race results."
This joint work with the Formula 1 industry has significantly advanced the maturity of the technology in a short period and has allowed the ATC to speculate with confidence on a number of defence applications such as air land and sea vehicles where durability to harsh environments is essential.
