Thursday, November 29, 2012

The Transparency Principle

The Wolfson Center and the Zisapel Center and CPC to develop together an innovative technology for printing ultra-thin conductors on convex lenses


The Wolfson Microelectronic research and teaching Center in conjunction with the Sara & Moshe Zisapel Nano-Electronics Center at the Technion will develop, together with CPC Hi Technologies Ltd. of Yokneam, technology for printing ultra-thin conductors on transparent curved surfaces. The thickness of the conductors -only 50 microns – will leave the surfaces transparent to short wavelengths.

"This agreement is a highly important step for us, as a center which is a national infrastructure in both the nano and micro fields," says the Head of the Wolfson and Zisapel Centers, Prof. Nir Tessler. "The technology we will develop over the next two years is relevant and applicable to a wide variety of areas and products, and will promote a significant expansion of our activity in the field of printing on rigid and flexible surfaces."

The story began when a security company approached CPC with a request to print ultra-thin metal strips on concave and convex surfaces. "This is actually quite a rare request, because it is usually customary to print conductive metal strips on flat surfaces. The added challenge was that this customer wanted especially thin strips – 50 microns, compared to the 150 microns that CPC manufactures."

CPC approached the management of the Wolfson and Zisapel Centers following previous projects conducted with Technion researchers, and because of its familiarity with the Center's knowledge and equipment. The joint project, launched on October 1, received financing of over NIS 3 million from the MAGNET Program in the Ministry of Industry, Trade and Labor.

"The project is scheduled to end within two years, which is a very short period of time," says Yakov Schneider, Chief Engineer of the Wolfson Microelectronic Center. "This is why we recruited several 'heavy guns' from the Technion. Four engineers and two technicians will work on the project on a regular basis, but they will of course receive peripheral support from the Center's team."

The project will focus on developing a conducting grid printed on a non-standard surface, such as in the shape of a 'lens'. The grid will protect the device behind the 'lens' from harmful electro-magnetic radiation, but will not impair the transparency of the surface to visible light and to heat radiation.

Contrary to commonly used technology in the field (screen printing), the Center's team suggested that CPC should work using a special mold – as is done when using simple stamps. "It is of course far from simple with the dimensions involved," says Prof. Tessler, "but the basic principle is the same – a mold using which the metal strips will be printed on the concave surface. Unlike regular stamps, our mold is made of soft silicon that is reminiscent of rubber, and instead of ink we have color that is based on silver particles. The product is a grid of very thin, and very accurate silver strips, on the concave surfaces."

The Center assesses that this specific development, which is designed to answer a very specific need, will serve as a basis for many other products. "We are actually developing here an innovative printing technology, that may be used in all fields currently at the forefront – printing of biological molecules for electronic needs, printing of solar cells, nano-metric sensor systems, etc."

National Infrastructure

Prof. Tessler clarifies that the "mandate" of the Wolfson Center extends also to the Zisapel Center and is academic research, "but we perceive it also as a national infrastructure. There is a technological infrastructure here that does not exist anywhere else in the Israeli academia, with high-level clean rooms and advanced know-how, especially in the field of structure manufacturing and treatment of intermediate layers (interfaces).  Keeping all this to ourselves - is simply out of the question. That is why this center is open to anyone who is interested, and we invite researchers and hi-tech companies and anyone who needs our equipment and knowledge. In many cases, we are the ones who initiate contact with the industry, but in this case the industry came to us, and you could say that it is approaching us from places we did not expect. The Center is already interacting regularly with 15 to 20 industrial companies, but a level of cooperation as in the project with CPC is a significant precedent, that is expected to be followed by many other companies."

"We have selected the Wolfson and Zisapel Centers as our partner in this project because the Center's team has developed highly innovative methods for printing in unconventional conditions," explains Ludmila Abezgauz, the technologist in CPC who is in charge of external relations and collaborations. Ludmila has a Ph.D. from the Technion in Biotechnology and Food Engineering, under Prof. Dganit Danino, and is currently working part time, concurrent with her work at CPC, as a researcher in the same lab.

"When we think about the equipment required to realize the project, clearly the Technion's mechanical engineering knowledge will be extremely helpful to us. There was also a geographic consideration – our proximity to the Technion – but this is of course merely a bonus. The decisive consideration was knowledge and technology, and the motivation of the Wolfson and Zisapel Center's people to cooperate with industry in applied research."

Established in Yokneam in 1984, CPC is the first Israeli company to print conductors. At the beginning the company focused on "regular" graphic printing, such as on signs and stickers, and later specialized in printing flexible electronic circuits, switches, light bulbs and sensors, and flexible heating elements.

"The company provides solutions at the development level of systems and assemblies, from the design and concept stage through the feasibility check, mechanical and electronic development, and planning and production of a prototype. With the new company it has purchased in Carmiel, CPC will be able to provide serial production solutions for any complex medical and military system."

"In the present case, our customer requested that we print on a curved, transparent surface, while at the same time substantially decreasing the thickness and density of the conductor. Each of these requirements is far from a simple challenge, and clearly their combination creates a highly complex project."

"With the tools we have at our disposal – screen printing and process printing – these requirements, which include printing conductors at a thickness that does not exceed 50 microns, cannot be filled.  We could develop a basic solution ourselves, but it would not have been suitable for the customer's commercial requirements: commercial production of an inexpensive 'shelf product'. It was clear to us that we would have to rely on raw materials currently existing in the market, and to find a solution that does not require building a new facility."

"Fortunately, our meetings with the Wolfson and Zisapel Centers have led to an agreement, and over the next two years we will work on this project together. This is a highly application-oriented project, which is based on the integration of substantial existing knowledge. This integration creates a whole new technology – printing ultra-thin conductors on a curved surface – which could be used by us in additional projects."

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