Institute of Circuit Technology Harrogate Christmas Seminar 2018

Estimated reading time: 10 minutes

The Institute of Circuit Technology returned to the fading Victorian splendour of the palatial and stately Majestic Hotel in the North Yorkshire town of Harrogate for its 2018 Christmas seminar, an intense programme of five excellent technical presentations, impeccably organised and moderated by Technical Director Bill Wilkie and generously supported by GSPK Circuits.

Introducing Martin Cotton as the keynote speaker, Wilkie called upon ICT Chairman Professor Andy Cobley to present him with an inscribed tankard as a token of appreciation for all the support he had given the Institute over many years on the occasion of his retirement from the position of director of OEM projects at Ventec: “The last great adventure for me in the PCB world.”

In his keynote presentation, Cotton challenged his audience to consider laminate dielectric properties in a context of power and cost in a presentation entitled “The Effect of the Dk of a PCB Laminate on the Cost-effectiveness of Office Rental Space. Intrigued?”

Reflecting on a career spanning over half a century, Cotton recalled a conversation with Steve Lloyd, managing director of GSPK Circuits, that had resulted in him offering to demonstrate that the dielectric constant of a material could affect rental costs and power bills as a farewell address to his friends and colleagues in the ICT.

The details of this presentation are reported separately, but suffice it to say that Cotton spoke as an engineer fully trained in value analysis, value engineering, and kaizen, and admitted that although he had rounded, abbreviated, and made shortcuts to show a good story, the outcome held true. No-one disagreed with him.

David Shaw, account manager of semiconductor technologies with A-Gas Electronic Materials, gave an update on the Maturolife project, a European Horizon 2020 funded project aimed at coupling design with advanced materials innovations to produce high added value and aesthetically pleasing and functional products for assistive technology, making urban living for older people easier and more independent. The Maturolife acronym translated as “Metallisation of Textiles to Make Urban Living for Older People More Independent and Fashionable.”

The project consortium had 20 partners in nine countries, and the work was divided into two main streams: design and materials science. The design objectives were to embed wants, desires, and aesthetic and emotional responses, ensuring that the end users of the product were engaged in the design process. The material science objectives, as discussed in detail by Shaw, were to develop techniques for the metallisation of textiles based on electroless plating and printed circuit manufacturing processes. At a later stage of the programme, work would be focused on integration of sensors and electronics, production of prototypes, and industrial scalability.

Shaw described a programme designed to achieve sustainable selective metallisation of textiles based on a functionalised copper nanoparticle catalyst and electroless plating to produce superior smart textiles and final finishes to improve the life expectancy of the conductive textile. To enable process development, it was planned to build a pilot line to run in semi-production mode, and eventually to manufacture and validate three assistive technology demonstrators.

Work on test patterns had demonstrated the feasibility of high-resolution metallisation using printed patterns with palladium and silver catalysts as a reference baseline while development of the copper nanoparticle catalyst continued. Significant progress had been made with the copper catalyst, and it was now close to matching the capability of its palladium and silver equivalents.

Programme Manager Dr. Darren Cadman from Loughborough University gave an update on the SYMETA project “Synthesizing 3D Metamaterials for RF, Microwave, and THz Applications,” now into its third year. The SYMETA consortium comprised five universities, led by Loughborough and funded by the Engineering and Physical Sciences Research Council. Dr. Cadman explained that the project focus was to create novel, multi-functional 3D metamaterials using emerging additive manufacturing techniques. Metamaterials were materials engineered to have properties not found in naturally occurring materials and were made from assemblies of multiple elements fashioned from composite materials such as metals or plastics. The project aimed to compile a palette of meta-atoms, the basic building blocks of metamaterials, and then to organise these systematically to ensure that the metamaterials demonstrated the required properties.

He reviewed various available additive manufacturing processes—extrusion, jetting, laser sintering, and stereolithography—but commented that these all used single materials, and the project required the use of mixed materials to realise its objectives. He made specific mention of proprietary 3D printing equipment from Nano Dimension and nScrypt, which could work with multiple materials, although the types of UV-curable dielectrics employed tended to exhibit high dielectric loss.

Examples of available dielectric materials for fused filament fabrication (FFF) included FFF PLA (polylactic acid), FFF ABS (acrylonitrile butadiene styrene), FFF PreMix, FFF barium titanate loaded ABS, and PolyJet polymer. And there was a selection of inks available for building conductors including silver pastes, reactive silver inks, reactive organometallics, proprietary silver inks from SunTronic, and Electrifi conductive filament. Copper inks were also available.

The selection of materials for additive manufacturing of microwave devices had to take including their processability in terms of viscosity and flow, curing temperature and adhesion, their reliability in terms of temperature and chemical compatibility, and very importantly, their respective dielectric loss characteristics or electrical conductivity.

Dr. Cadman discussed the synthesis of artificial dielectrics as a means of achieving additional degrees of freedom of material choice and gave examples of various 3D cellular geometries with tailored electromagnetic properties that could be rapidly and straightforwardly fabricated by additive manufacturing. The introduction of metallic inclusions could increase capacitance, at the expense of reducing permittivity. PREPERM had developed a new range of ultra-low-loss thermoplastic materials specifically for improved antenna efficiencies at millimetre-wave frequencies, and these were available in filament form for FFF techniques.

He showed examples of components for X-Band waveguides, prepared on a Voxel8 dual-material printer and demonstrated how relative permeability could be managed by controlling the relative proportions of air-infill and metal-infill. High-dielectric-permeability low-loss ceramic materials were in development at the University of Sheffield, with sintering temperatures below the melting point of silver. Work continued on the optimisation of multimedia extrusion, and it was planned to create microwave demonstrators for operation at frequencies between 10 and 100 GHz.Page 1 of 2

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