Forum for Science, Industry and Business

Cladding gold contacts with a laser

Electroplating is the conventional method used for this purpose, but scientists have now developed a novel laser-based method which involves laser cladding gold contact spots instead of applying the gold in a thin layer on the whole surface. This new technique is fast and offers the potential to cut up to 90 percent of the amount of gold used.

Gold contact spots on a snap dome.
Source: INOVAN

Keys and keyboards have become a common sight in today’s world, both in our personal lives (cars, phones, computers) and in industrial settings. Users expect keys to operate with 100 percent reliability regardless of how many times they are pressed. At the same time, manufacturers are seeking cheaper production methods and new ways of making more efficient use of expensive, high-quality materials.

Snap domes comprise small contact springs which are used to make electrical contact and provide tactile feedback in a wide range of keyboard designs. They generally consist of high-quality spring steel which is typically gold-plated or modified in some other way in order to achieve better contact and more reliable switching. As well as having low contact resistance, gold also boasts outstanding resistance to corrosion.

The new method replaces the conventional large gold surfaces with small contact spots which are cladded by a fiber laser. Using gold powder with grain diameters smaller than 10 µm, the fiber laser takes advantage of its beam diameter of less than 100 µm to create contact spots with a diameter and height of less than 100 µm. This micro laser cladding uses a nozzle to feed the gold powder into the interaction zone of the laser beam and the substrate material (e.g. stainless steel, nickel alloy). The laser energy melts both the gold powder and a thin surface layer of the substrate to create a welded spot which is metallurgical bonded to the substrate.

Significant reduction in material consumption

One of the biggest advantages of this new method is its material efficiency. To replace the thin gold layer deposited on snap domes by conventional methods, you need just five selectively welded gold contact spots – and initial calculations suggest that this slashes the amount of material required to make the gold contact by between 50 and 90 percent. Preliminary tests carried out by INOVAN comprising 100,000 switching operations demonstrate that this new approach does not measurably affect switch service life. In addition, the electrical properties of the gold contact spots correspond to the results obtained from electroplating.

Integrated production

The laser-based method also makes it possible to integrate the fabrication of the gold contact spots into the production of the switch components themselves. This enables rolls of material to be processed and facilitates the efficient production of short run batches and prototypes. Cladding a single point takes approximately 50 milliseconds. Researchers are currently investigating how to accelerate the process; experts consider that it should be possible to weld 20 contact spots simultaneously in the future by splitting the laser beam.

Using laser cladding to produce contacts from precious metals is a method that, in principle, is suitable for all metal parts which currently rely on plating techniques to make electrical contacts. Examples include the switches used in cell phones as well as bipolar plates for fuel cells.

Axel Bauer | Fraunhofer-Institut
Further information:
http://www.ilt.fraunhofer.de

Im Focus: Better thermal conductivity by adjusting the arrangement of atoms

Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.

In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...

Im Focus: First-ever visualizations of electrical gating effects on electronic structure

Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.

Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...

Im Focus: Megakaryocytes act as „bouncers“ restraining cell migration in the bone marrow

Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.

Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...

Im Focus: Artificial neural network resolves puzzles from condensed matter physics: Which is the perfect quantum theory?

For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.

Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...

Im Focus: Extremely hard yet metallically conductive: Bayreuth researchers develop novel material with high-tech prospects

An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".

The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...