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.
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.The Fraunhofer Institute for Laser Technology ILT in Aachen has developed a method of producing keys on an industrial scale which fulfills both these requirements. Within the scope of the Mifulas 2 project funded by Germany’s Federal Ministry of Education and Research (BMBF), researchers at Fraunhofer ILT – working in collaboration with their project partner INOVAN – have been drawing on their experience in laser cladding to replace the electroplated gold layers on switch contacts known as ‘snap domes’ with small welded gold spots.
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.
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.Your contacts at Fraunhofer ILT
Axel Bauer | Fraunhofer-Institut
Copper oxide photocathodes: laser experiment reveals location of efficiency loss
10.05.2019 | Helmholtz-Zentrum Berlin für Materialien und Energie
NIST research sparks new insights on laser welding
02.05.2019 | National Institute of Standards and Technology (NIST)
Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.
Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...
Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.
The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...
Discovery by Brazilian and US researchers could change the classification of two species, which appear more akin to jellyfish than was thought.
The tube anemone Isarachnanthus nocturnus is only 15 cm long but has the largest mitochondrial genome of any animal sequenced to date, with 80,923 base pairs....
Researchers at Chalmers University of Technology, Sweden, have discovered a completely new way of capturing, amplifying and linking light to matter at the nanolevel. Using a tiny box, built from stacked atomically thin material, they have succeeded in creating a type of feedback loop in which light and matter become one. The discovery, which was recently published in Nature Nanotechnology, opens up new possibilities in the world of nanophotonics.
Photonics is concerned with various means of using light. Fibre-optic communication is an example of photonics, as is the technology behind photodetectors and...
Fraunhofer IZM is joining the EUROPRACTICE IC Service platform. Together, the partners are making fan-out wafer level packaging (FOWLP) for electronic devices available and affordable even in small batches – and thus of interest to research institutes, universities, and SMEs. Costs can be significantly reduced by up to ten customers implementing individual fan-out wafer level packaging for their ICs or other components on a multi-project wafer. The target group includes any organization that does not produce in large quantities, but requires prototypes.
Research always means trying things out and daring to do new things. Research institutes, universities, and SMEs do not produce in large batches, but rather...
29.04.2019 | Event News
17.04.2019 | Event News
15.04.2019 | Event News
14.06.2019 | Information Technology
14.06.2019 | Materials Sciences
14.06.2019 | Medical Engineering