| Leading-Edge Developments in Electronics Manufacturing. Institute of Circuit Technology Winter Seminar. Hinckley, Leicestershire, UK. 3rd December 2025. |
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ICT chairman Mat Beadel welcomed delegates and introduced the first speaker, Jonathan Jones, process engineer with embedded-die packaging specialists RAM Innovations, who described the development of novel manufacturing technologies and the benefits of advanced embedded packaging for wide-band-gap semiconductors.
He demonstrated the benefits of RAM’s three-dimensional “heterogeneous integration” approach, with semiconductors and other components embedded within the printed circuit board. Compared with traditional two-dimensional surface-mounting of components, with limited opportunity for optimised placement resulting in longer routing of conductive paths and compromised symmetry, heterogeneous integration enabled shorter conductive paths, improved matched impedance, lower parasitics and higher efficiency. In the specific example of wide-band-gap devices, which offered significant benefits at high switching frequencies compared with equivalent silicon-based power converters, embedding gave an opportunity to reduce the size of filter capacitors and inductors, consequently reducing overall system size, weight and cost. Embedding achieved tighter power loops and allowed capacitors to be placed close to the die, whereas in conventional power converters these components were on the surface and connected with multiple wire bonds. Jones discussed the robustness and reliability of embedded assemblies, with particular reference to the results of thermal cycling on die-base and die-top sinter and silver epoxy connections, where their superior properties compared with conventional assemblies were clearly demonstrated. In high-power applications, embedded aluminium-nitride ceramic tiles ensured that the module was isolated whilst providing an excellent thermal path for efficient cooling. Material selection for embedded applications was a critical consideration. Structural integrity was paramount; some challenges currently being addressed related to material stability under thermal expansion and operational stress, and also to resin flow and encapsulation. Meticulous design-for-manufacture was fundamentally important. During the transition between R&D and medium-volume production, panel size was being increased from 12” x 9” to 18” x 12”, with typically 40 modules per panel, and the emphasis was on maintaining the same consistency and yield as had been achieved on smaller panels. It was an advantage that RAM had their own PCB manufacturing facility, with all of their development work being carried out on production-scale machinery. Jones showed examples of equipment and products. Dr Claypole began by reminding us that, of the 60 million tons of electronic waste generated last year, less than 20% was recycled. Indeed, in the case of printed electronics, less than 1% was recycled. Silver was the active component in many conductive inks; it was an expensive metal and its price continued to increase. So the development of an efficient reclaim and recycling technique was well justified. He reviewed the principal ingredients of a conductive ink: a resin consisting of solvent, polymers and modifiers, and conductive particles that could be silver, gold, carbon or an organic material. Because silver was typically in the form of metallic micro-flakes, conventional processes for reclaiming it faced a serious challenge in separating the metal from a dispersion of associated materials. Dr Claypole showed a video comparing existing technology with Ail Arian’s alternative, using printed RFID tags as the example and demonstrating how easily not only the uncontaminated silver but also the uncontaminated substrate material could be recovered. To close the loop, recovered silver had been reused to make new conductive inks and the first prints with 100% recycled conductive materials had been successfully achieved – a positive step towards the creation of circular electronics. Not all of the technology requirements could be met with glass-reinforced materials, and both the availability and the choice of ultra-thin glass fabrics were becoming limited by demand. So what glass-free alternative materials were available to support next-generation requirements? He went on to explain that resin-coated-copper bondply is an unreinforced adhesive system coated onto ultra-thin copper foil for use in high-performance and high-reliability multilayer PCB stack-ups. Similarly, resin-coated-foil bondply is an unreinforced adhesive system coated onto polyester film, offering design flexibility in high-performance multilayers. He described the technology of the horizontal coating process, capable of precise thickness control down to 15microns, and explained that, unlike traditional glass-reinforced prepregs, these glass-free materials eliminate micro-Dk variability from glass weave, ensuring signal integrity at high frequencies and in designs with extremely fine features. Typical resin chemistries are bismaleimide-triazine and halogen-free high-Tg epoxy and the resin-coated copper materials are particularly suitable for MSAP processing. Summarising the benefits to PCB designers and manufacturers, he mentioned lower dielectric thickness, good adhesion with metal, better laser drilling and better Dk skewness. He reviewed a long list of application examples, including “M+N” PCB stack-ups and embedded packages, concluding that these families of materials represent a leap in PCB bondply technology. The absence of glass reinforcement, combined with electrical precision and superior thermal management, result in properties that enable OEMs and manufacturers to build faster, cooler and more reliable electronics without adding manufacturing complexity. |
Early fog made the journey challenging for those travelling from afar, but it lifted to reveal a clear blue December sky over Hinckley, which is actually closer to the exact geographical centre of England than the familiar Meriden venue, for the Institute of Circuit Technology winter seminar. An intriguing programme, focused on some leading-edge developments in electronics manufacturing, more than justified the effort to attend.
Jones explained that RAM had established the capability to package multiple electronic components using PCB methodology, to produce circuits optimised for size, weight and power density, with a unique solution for high-current connect and thermal management.
ICT council member Steve Driver introduced the second speaker, Dr James Claypole, CEO and founder of Ail Arian in South Wales, with a presentation entitled “A silver lining for circular electronics”, pioneering a recycling approach that effectively created a circular ecosystem for printed electronics. Dr Claypole explained the derivation of the curious company name “Ail Arian” as a Welsh language term for recycled silver, although Google’s neural machine translation service informed me that it meant “second money”. Whatever, the process he described was certainly the basis of a clever recycling concept for silver conductive inks.
What if silver could be made magnetic? Dr Claypole’s team of materials scientists had developed a method of forming a “shell” of silver on a ferrite core. Very fine particles of this silver-coated ferrite had been demonstrated to be an excellent conductive ingredient in ink for printed electronics. There was a significant cost saving against pure silver and very little effective conductivity had been sacrificed because of the phenomenon of “edge effect conduction”. And the conductive particles were magnetic. Therefore their recovery from end-of-life printed electronics, smart packaging, biosensors, biodegradable electronics etcetera was greatly simplified.
ICT technical director Emma Hudson introduced the final presentation, delivered by ICT vice chairman Leigh Allinson who discussed next-generation substrate materials. Typical applications included 5G infrastructure, electric vehicles, high-performance computing and aerospace, and the driving factors included lower loss and stable dielectric constant, higher performance and thermal reliability, together with sustainability and cost reduction. From a development point of view, there was a need to “bridge the gap” between products based on standard glass-FR4 and those with increased functionality, smaller form factors and improved performance.
Allinson described how his company’s background in thermal management technology, designed resin flow and precise horizontal coating technology, combined with radio-frequency and microwave formulation technology, had enabled the development of a range of resin-coated-copper and resin-coated-foil bondply materials.