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EXAMPLES FROM NATURE: HIGHSPEED LASER STRUCTURING FOR A NEW GENERATION OF ELECTRICAL CONTACTS

Steinbeis experts from Saarbrücken and TE Connectivity Germany use laser structuring to optimize surface processing

As nature already knows, all surfaces are structured geometrically on a variety of different microscopic scales, and thanks to evolution they are perfectly matched to perform the required function. Until now, technical surfaces have been classified mostly in terms of roughness, which highlights the enormous potential that must have been overlooked over the years. Enter Material Engineering Center Saarland (MECS), the Steinbeis Research Center, which has developed an innovative laser-based structuring method for quickly and efficiently treating almost any kind of surface. After many years of collaboration with TE Connectivity Germany, a global market leader in the field of electrical connectivity, the center’s approach has proven to be a disruptive innovation. The partnership earned the two project partners the 2019 Transfer Award from the Steinbeis Foundation.

How did the partnership come into existence? The number and complexity of onboard electronic systems contained in modern cars is intensifying, such that the average vehicle is now fitted with more than 2,500 electrical contacts, through over 250 connectors. The current visions of future car functions, such as those required for autonomous driving, are posing more and more challenges to industry. Of crucial importance in this respect are factors such as low electrical contact resistance and the need to minimize the required insertion force of the increasing number of connectors found in cars. The experts at Steinbeis and TE engaged in an ambitious project and decided to use a patented technique called direct laser interference patterning (DLIP). This makes it possible to significantly improve the contact properties of electrical connectors and thus manage increasing levels of electrification in cars.

Aside from the outstanding achievements that resulted from the long-standing partnership in technical terms, the collaboration between the Steinbeis Research Center Material Engineering Center Saarland and TE Connectivity is an ideal example of successful transfer – from initial, fundamental work carried out in the laboratory to optimizations made to specific products, and the construction of a pilot plant used in the high-speed laser structuring of electrical connectors suitable for use in serial production in industry. There could be no doubting that this successful partnership would result in acknowledgement from the Steinbeis Foundation through bestowal of the Transfer Award.


“THE COMBINATION OF GEOMETRIC PRECISION AND TECHNOLOGICALLY ECONOMICAL SPEEDS IS UNIQUE.” 

Prof. Dr.-Ing. Frank Mücklich and Dr.-Ing. Helge Schmidt speak to Transfer Magazine

Hello Professor Mücklich. You are conducting research into surface morphology with your Steinbeis Research Center colleagues at Material Engineering Center Saarland (MECS), going down to the micro- and nanometer range. Your project partner, TE Connectivity, is an international market leader in electrical connections. Could you set the ball rolling for us and explain what led to this outstanding project between the two of you?

The original starting point for the successful partnership between MECS Steinbeis Research Center and TE was two completely unconnected doctoral theses in the field of electrical connector contacts, written entirely independently of one another. There was Dr.-Ing. Michael Leidner working at TE Connectivity using simulation software to model the ideal structure of surfaces on electrical connectors, and at the same time there was Dr.-Ing. Kim Trinh, who was working at the MECS Steinbeis Research Center, looking into the experimental implementation of tiny, microscopically fine, periodically structured surfaces on electrical connector contacts using DLIP laser technology. Both researchers were analyzing electrical and tribological properties, each discovering astoundingly similar results, but using completely different approaches and working completely independently of one another – an impressive basis for an extraordinarily successful partnership. The key point of contact came when their results were presented at a conference in the United States.

Modern cars contain an increasing amount of electrical technology, which by default needs connectors – something you benefit from at TE Connectivity, Dr. Schmidt, but that also creates challenges in development. How specifically?

The increasing number and complexity of electronic systems in modern cars automatically raise the requirements that have to be met by components and structural elements in order for any future functions planned within the overall system to work. It has to be ensured that any electrical contacts established through connectors will last and work reliably, in dry or damp conditions, but also in cold and hot climates, despite engine and driving vibrations. Aside from remaining stable under these kinds of harsh conditions, because connectors include an increasing number of poles, it’s also necessary to reduce the friction coefficients of contacting surfaces – and with that, the insertion force. This has to be safeguarded under continual, longterm electrical contact resistance.

Professor Mücklich: You use direct laser interference patterning, or DLIP, when structuring connections. Was this technology predestined to be used for your project?

All surfaces in living nature are structured on a microscopic scale as a result of ingenious optimizations brought about by evolution, so as a result they’re adapted excellently for the function they’re required to perform. So why, until now, did we accept the roughness found on technical surfaces after manufacturing? One reason was that the methods that were available for structuring the surfaces we needed were insufficient on a universal level for designing microscopically accurate and geometrically adaptable surfaces – not in ways that were also quick and thus efficient in economic terms. DLIP now allows us – for the first time – to produce microscopically detailed periodic surface patterns, efficiently and on almost any kind of material. By using DLIP, not only can we produce micro-, sub-micro-, and nano-scale surface structures in a variety of forms, we can even do this at the kinds of conveyor belt speeds encountered in manufacturing, in record times, on several hundred connectors per minute. The combination of geometric precision and technologically economic speeds is unique among all other methods used to date.

You didn’t just stop at surface structuring for your transfer project. You also developed a pilot plant for serial production, which creates the impression that this partnership is by no means over yet. What are your plans for the future?

Our transfer achievements until now offer tremendous potential in technological and commercial terms. DLIP methods are totally inexpensive and because you can process materials without touching them, the laser technology is very gentle on resources. At the same time, the manufacturing costs are only marginally higher because of the tremendous production speeds, even though you drastically improve the tribological properties of the connector contacts. The technology should be ready after the twelvemonth validation phase in 2019 and 2020, so it should be integrated into serial production at TE in 2021. To support this process, we intend to launch a startup next year, which will focus on making DLIP machines available for automated industrial manufacturing, and then we want to use this highly innovative technology to enter further markets in the future.