Nano-device Connections Use Nickel
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THE MAGAZINE DEVOTED TO NICKEL AND ITS APPLICATIONS |
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Imprint patterning is a new technique for making high-density electrical circuits in nickel. |
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Using nickel instead of silicon to make ultra-fine micro parts has many advantages. Nickel is less
brittle, more flexible, and has a higher electrical conductivity than silicon. |
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Micro parts can be reproduced with a high degree of accuracy using nickel electroforming. |
Nickel winning favour as a substitute for silicon.
By Virginia Heffernan
Nickel Magazine, November 2004 -- As a low-cost alternative to silicon, nickel continues to make inroads into microstructure applications such as high-density circuit manufacturing.
Traditionally, micro-electromechanical systems (MEMs) have been manufactured in silicon using technology borrowed from the semiconductor industry. But Tecan, a U.K.-based manufacturer of precision metal parts and tooling, has opened a dedicated facility to produce both highly accurate micro parts and larger parts with ultra-fine features by electroforming in nickel and other materials.
The company is particularly enthusiastic about a technique called imprint patterning, a new approach developed for high-density circuit manufacturing.
"We’ve had a mini-frenzy [over the technology]," says Noel Cherowbrier, vice-president of international development for Tecan Inc. "Customers are coming to us with all sorts of different applications where they want to have an imprint tool made."
Based on the microreplication techniques used to make compact disks and reflective road signs, imprint patterning produces a high-density metal stamp or "tool foil" made of nickel. Using an ordinary laminating press, an image of the stamp can be imprinted directly on to a substrate, producing circuit traces and vias (small holes that connect the wires on different layers of a circuit board). The substrate can then be metallized to ensure accurate high-density circuitry.
The new technique, a high-volume, precision embossing technology, allows silicon originals to be kept as perfect masters from which an infinite number of replicas can be produced at relatively low cost.
Imprint patterning has advantages over the standard approach to high-density circuit fabrication based on photo imaging and laser drilling. Because the approach is padless, real-estate savings can be significant. In addition, full vias can be produced across the whole surface of the metal stamp in a single operation. The stamp can be used repeatedly.
"This new technology may revolutionize the manufacture of high-density and microvia-based printed circuit boards, as it is significantly faster, less expensive and has the capability of providing finer pitches and vias than current technology," writes Cherowbrier in an article for Circuits Assembly entitled MEMs: A Nickel for Your Thoughts. "The process involves no drilling, no photo tools and no registration issues and the plating procedures are reduced."
The benefits of using nickel instead of silicon in microstructures, including high-density circuitry, are many. The main benefit is that it is cheaper. But nickel is also less brittle, more flexible, and has a higher electrical conductivity than silicon. Because it has good optical properties and can be made into smooth mirrors, it is ideally suited for optical applications.
Component manufacturers using nickel can also work with larger substrates than are possible with silicon, allowing them to produce large parts with fine features or a number of parts with tight tolerances. And they can produce those parts in less time because making nickel-based systems is much simpler than making silicon products.
"The silicon approach has dominated because of its familiarity with designers and the availability of suppliers," says Cherowbrier. "However, it is not necessarily the best approach, particularly with regards to cost, application and time to market."
So far, nickel-based technology has been used to make products ranging from hearing aids to micro-lenses. Because it can be used for manufacturing to such extremely small scales, future applications are virtually limitless.
Virginia Heffernan is a Toronto-based freelance writer.
PHOTOS: Tecan Inc.
 Noel Cherowbrier |
