EIPC Summer Conference, Berlin: Day 1

Estimated reading time: 16 minutes

Dr. Boaz Nitzan, VP of functional inkjet technology at Camtek, in Israel, gave a detailed description of the recently introduced Gryphon SL, described as a full digital manufacturing station for PCB solder mask and legend by ink-jet technology. The equipment represented the latest innovation in Camtek’s 3D functional inkjet system and offered a “one-stop-shop” for solder mask and legend deposition by 3D inkjet technology, replacing both the traditional solder mask and the legend application and imaging processes in PCB manufacturing. It was designed to enhance production by improving accuracy, reliability and yield, whilst reducing manpower demand and eliminating the need to treat waste products from the process.

The system used real-time alignment and built-in AOI to match the image to the actual panel, and the print-head recognised and followed the 3D topography of the PCB surface. The ink was immediately tack-dried with a built-in UV curing system. From a process point of view, the system had the advantages of reducing the number of stages from seven to three and the capability to print solder mask and legend consecutively from a single alignment, with consequent reduction in process cycle time. It occupied very little floor space and required only a single operator. Technical benefits included the ability to achieve zero clearance, to print different thicknesses in different areas, and to print gloss, semi-matte or matte from the same ink. Total cost savings of almost 50% per panel could be achieved compared with photoimaging processes.

Don Monn, European sales and new product development manager for Taiyo America, took the published theme of the conference: “Improve profitability through technical leadership and innovation to meet future market requirements,” as the basis for a thought-provoking debate on the question: “Inkjet soldermask: Is it right for you?” delivered in his distinctive animated style, with the underlying message of getting things right first time. He went to great lengths to determine the real costs of rework and scrap—going far beyond those immediately visible, then analysed to the same level of detail the actual costs of the photoimageable solder mask process in a typical high-mix PCB fabrication shop manufacturing 3,500 panels per month, 50% screen-coated, 50% spray-coated. Not just the prime costs of materials and tooling, operator costs and equipment running costs but all of the peripheral consumables, down to squeegee rubber and sticky tape—amazing how all of these seemingly trivial costs added up to a substantial total! Returning to the keyword in the conference theme, he remarked: “Profitability is not a dirty word where I come from!” and reiterated the “Do it once, do it right” message as a preface to the fast-approaching point in time when technology, in the shape of production-proven ink-jet equipment and end-user qualified inks, would help the industry increase its profit margins.

This session provoked more interactive dialogue than any other in the conference programme. Dr. Nitzan in particular was inundated with requests for additional information and explanation on equipment capability and material performance, and delegates would have missed a substantial proportion of their lunchtime break if I had not reluctantly brought the discussion to a close.

Theme of the afternoon session was the evaluation of new materials, processes, packaging and PCBs for the next generation of electronics “Made in Europe,” and was focused on the work of the Fraunhofer Institute for Reliability and Microintegration IZM in Berlin, with three technical presentations, moderated by Fraunhofer’s Dr. Michael Töpper, followed by a visit to the Fraunhofer IZM laboratories in Berlin Mitte.

Dr. Ivan Ndip, head of the department of RF & Smart Sensor Systems, examined the demands on the PCB for future RF applications, with particular reference to the role of RF systems in the Internet of Things. IoT had a layered architecture: a device layer with RFID and RF sensor systems, a network layer of high-speed optical communication systems, a service and applications support layer with cloud computing systems for Big Data, and an applications layer, with RF wireless communication systems. System-integration technologies were the fundamental building blocks of RF systems, and for future RF applications the PCB could be considered either a key enabler or a bottleneck, it needed to ensure signal and power integrity whilst minimising electromagnetic interference. Critical material parameters were surface roughness and surface finish of the metallisation, and homogeneous permittivity, low moisture absorption, wide frequency range stable over a wide temperature range and low-loss tangent of the dielectric. Fraunhofer had developed a holistic and systematic approach to testing and evaluating PCB materials, in cooperation with manufacturers like Isola and Corning, and were now able to predict the issues at PCB level that could compromise RF performance, through 3D full-wave simulation, layout, fabrication, test structure design and RF measurement. Dr. Ndip discussed the RF design of interconnects in multilayer PCBs, gave examples of RPD problems and how new design measures could optimise the electromagnetic performance of vias without using decoupling capacitors. He then considered the design, simulation and measurement of integrated antennas, showed the correlation between simulated and measured values, and demonstrated how a 77 GHz antenna could be completely de-tuned as a consequence of typical PCB manufacturing tolerances.

Lars Böttcher, project manager, embedded die technologies at Fraunhofer IZM gave a fascinating insight into next-generation PCB and panel-based packages using embedding technologies. He explained that cost reduction in semiconductor packaging could be achieved by an increase in production format size, and PCB embedding technology offered a potential solution, although for next-generation panel-level packaging, advanced processes and materials would be needed, together with improvements in resolution and accuracy. Warpage remained a major challenge, and polymer materials with controlled CTE and modulus, together with low shrinkage, were required, with designs optimised in terms of layer sequence and build-up. However, the production of embedded packages was ramping up rapidly. Already established in power and logic applications, growth would be seen in the smartphone and computer markets, and embedding technology would soon be implemented at PCB manufacturers, semiconductor manufacturers and outsourced assembly and test (OSAT) companies. Fraunhofer IZM had already established a complete PCB manufacture and assembly line for substrate integration on 24” x 18” panels, and Böttcher described process sequences for embedding bare chips, packaged components and passive components using solder or adhesive interconnects or alternatively direct copper interconnects, with examples of applications in modular systems.

Böttcher discussed Fraunhofer’s collaboration in the EmPower Project which had been referenced in the earlier presentation of Mike Morianz from AT&S. The project aimed to industrialise double-sided copper plating on wafer level as a route to industrialising next-generation automotive power modules, and to combine high-performance with small form factor. The process concept was based on epoxy coated foil or prepreg and copper foil with direct microvia connection from top and bottom side, which required double-sided copper metallization of the semiconductor. No soldering or sintering was used for die-attach, which was achieved by hot-bonding to B-stage epoxy resin. Power cores fabricated using the process were bonded to an IMS substrate with thermally conductive prepreg, and high-current connections were made by silver sintering. A 500-Watt demonstrator had been produced and it was forecast that power devices based on this technology would soon be in volume production.

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