Venue for the 2018 EIPC Winter Conference was the splendid new Alstom Transport Information Solutions facility in Villeurbanne, in the Lyon metropolitan area of the Auvergne-Rhône-Alpes region in eastern France.
An extremely popular event—117 delegates represented a total of 20 countries, unprecedented in recent years, and only just fitted into Alstom’s conference suite. Indeed, some were even standing at the back!
A packed programme with an early start— 8:00 a.m. registration, and considerably earlier than that for most of the delegates who were staying in downtown hotels and enjoyed a 40-minute bus ride through a cold, dark, rainy morning rush-hour—the conference was opened by EIPC chairman Alun Morgan. Welcoming all present, he particularly thanked Alstom for their generous hospitality and the sponsors for their support.
Morgan gave an entertaining introductory presentation describing the evolution of robots, from his childhood science-fiction hero Robbie, through the first Unimate industrial robot working on automotive assembly in 1961, to the autonomous self-learning Knightscope K5 security robot patrolling a Silicon Valley parking lot. His replay of the 1979 “Hand-built by robots” TV advertising video for the Fiat Strada evoked some nostalgia, followed by considerable amusement when he played the “Driven by Italians!” spoof sequel (with due apology to his Italian delegates).
Discussing the implications of the 4th industrial revolution, and the profound effect it would have on our lives, he asked the rhetorical question “Will robots replace us?” and answered it with reference to the derivation of the word “robot” from an old Slavonic word meaning servitude, forced labour or drudgery—these were the jobs that would be lost, but a whole spectrum of new ones would be created as a direct result of automation and artificial intelligence.
Morgan was delighted to introduce Christian Roth, director of the System and Product Development Centre at Alstom Transport, who welcomed all guests to the Villeurbanne facility and gave a brief overview of the Alstom organisation. With headquarters in France, the company was already a world leader in integrated transport systems, with a presence in over 60 countries and employing over 30,000 people, before its recent announcement of a merger of rail operations with Siemens to create a European champion capable of better withstanding Chinese competition.
Alun Morgan moderated the keynote session on business, technology and new developments, with Walt Custer as his first speaker.
“Things are pretty good right now!” It was a welcome change for Custer not to offer the usual choice between “unpleasant truth” and “comforting lies” in his business outlook for the global electronics industry. His leading indicators showed that all major areas were in growth, and that most sectors of the world electronic supply chain were expanding, although currency exchange rates could distort apparent growth rates. Semiconductor sales were at record highs, driven particularly by the demand for memory, and shortages were resulting in price increases. Automotive and the Internet of Things were currently the main growth drivers; 5G would be the next substantial volume market and multiple disruptive technologies were emerging. However, geopolitical issues remained a significant area of concern.
Substantial manufacturing expansion was forecast for the European market, particularly in Germany. Developments in autonomous vehicles would lead to a massive restructuring of the industry and huge growth in automotive electronics which, although it would eliminate many existing jobs, would create many new ones in electronic systems. And the mil-aero sector was at an all-time high.
2017 figures for European PCB production showed a total of about 1880 million euro, of which Germany represented 43%, Austria and Switzerland 18%, Italy 10%, France 9% and UK 8%. There was a level of confidence in the German PCB industry that growth would continue into 2018, although shortfalls in component supply might cause problems later in the year. The French industry was benefiting from some long-term military programmes. The British PCB industry relied almost entirely on imported materials, and continued to suffer from the weakness of the pound and the uncertainties surrounding withdrawal from the European Union.
Thibault Buisson, business unit manager for advanced packaging and semiconductor manufacturing activities with Yole Développement, the specialist market research and strategy consulting company based locally in Villeurbanne, gave a presentation entitled “From Semiconductor Die to PCB: Changing Landscapes and Future Requirements.” He reviewed the revolution in microelectronics packaging, the dimension gap that remained between PCB design rules and wafer design rules, and discussed ways in which the gap might be bridged—there were opportunities for different business models.
A transition from subtractive to modified semi-additive processing (mSAP) was already evident in smartphone boards, and very optimistic growth was foreseen for substrate-like-PCB (SLP) technology, the next generation of HDI driven by large OEMs, with a forecast of more than $2.2Bn in 2022.
Embedded die packaging revenues were increasing, from $23M in 2015 to a forecast $50M in 2021, and the rationale for adopting embedded die packaging differed from application to application: for mobile devices it was mainly for miniaturisation, whereas for power and automotive applications an additional consideration was thermal management.
There were several business models around embedded die packaging, and substrate manufacturers were now offering packaging services by acting as outsourced semiconductor packaging and test (OSAT) suppliers. Several methods were available for manufacturing die-in-laminate packages. Many of the companies had developed their own techniques but others had decided to licence, and this might help some technologies become established as industry-standard.
The modified semi-additive (mSAP) process and embedded component packaging (ECP) technologies previously referred to by Thibault Buisson were explored in greater depth in the final presentation of the keynote session, which came from Dr. Martin Schrems, director of strategy and business development with AT&S in Austria, who discussed present and future solutions for the electronics industry in Europe. He commented that although the European market was relatively small, there was substantial growth in advanced packaging. AT&S had extensive expertise in the areas of embedded component packaging, IC substrates and mSAP substrate-like printed circuits in their manufacturing plants in Austria and China, as well as microvia HDI, any-layer HDI, and a full suite of rigid, flex, flex-rigid and IMS PCB products.
Dr. Schrems described a series of examples of interconnect solutions for smart mobility, smart home, smart industry, smart traffic, smart city and smart energy applications. And all these smart products need smart production, with an IT-driven integrated manufacturing and supply chain. The trend was towards modularisation, driven by considerations of time-to-market and system cost reduction using tested modules containing multiple components to simplify the development of new electronic products. Added benefits included reduced footprint and z-height, reduced impedance, noise and transmission losses and shorter electrical connections, together with improved thermal management and electrical shielding.
He concluded that although there was still a significant footprint of the European electronics industry including PCB manufacturing, global cooperation was needed for providing the full interconnect solutions for a global customer base. Modularisation was expected to become a disruptive change in the global electronics industry and offered both opportunities and risks for European and global manufacturers.
The first technical session was introduced and moderated by Martyn Gaudion, CEO of Polar Instruments, on the theme of trends and capabilities in PCB fabrication. First to present was Dr. Christian Klein, section manager for PCB development for automotive electronics, with Robert Bosch, who gave his perspective on future automotive requirements for PCBs.
As one of the world's largest automotive equipment suppliers, Bosch had developed an enormous variety of electronics solutions for applications. For example, connected mobility: connection from the vehicle to the internet and to other vehicles. Automated mobility: giving the driver various levels of assistance from partial to full automation, and powertrain systems for internal combustion, hybrid and full-electric vehicles. In all these applications, the over-riding focus was on reliability.
Dr. Klein made a comprehensive analysis of the possible failure modes associated with environmental stresses, including temperature cycling and storage, bending, vibration and humidity, separately and in combination, and assembly stresses on the PCB related to reflow soldering, selective soldering and press-fit technology.
Increasing environmental loads required adaptation of materials and concepts for automotive electronics, together with a very good understanding of cause-and-effect relationships. In particular, trends to plastic housings, longer operational times and hotter applications led to increased humidity load, increased temperature and temperature-cycle load and longer temperature-humidity-bias impact on the PCB.
New functional requirements, for example the trend to higher operating voltages in small enclosures, finer-pitch, higher I/O components, power electronics on organic substrates, and high-speed applications in radar and image processing, required new PCB concepts such as power PCBs and highly integrated logic PCBs.
The effects of humidity, both on the surface and within the structure of the PCBs were areas of critical concern, and the possible failure modes had been studied in great detail. Humidity on the surface, either as water vapour or condensed in the form of dew, in combination with ionic contamination and voltage bias, could lead to material degradation or material diffusion followed by electrochemical migration and dendrite growth. The mechanisms had been modelled so that electrochemical failure could be predicted, and all new components and materials were subject to standard qualification tests. Ongoing, the features of the test board were being adapted to reflect miniaturisation, and work was proceeding to correlate results with surface insulation resistance and ion chromatography measurements.
Humidity within the PCB led to a different class of failure modes resulting from electrochemical migration: conductive anodic filamentation and failures associated with hollow fibres and organic fibre contamination. Cracks in the resin could result from temperature degradation, high pressure, bending and mechanical load. The mechanism of CAF formation was understood and qualification methods for cracks were being developed to enable more effective material selection.
Finally, with the increase in high-speed applications, particularly in automotive radar systems, power integrity, signal integrity and electromagnetic compatibility, became significant considerations in PCB design rules and material selection, and inevitably the most cost-effective solution was sought.
As we experience the beginnings of Industry 4.0, the fourth industrial revolution, development continues in PCB materials and imaging processes. So it was perhaps logical that solder mask technology would enter its fourth generation: two-pack screen-printed, single-pack UV-cured, liquid photoimageable. What next? Andreas Dreher from Würth Elektronik introduced the concept of “solder mask 4.0” with his presentation on a technology branded “s.mask,” the outcome of a collaboration between two PCB manufacturers, Würth Elektronik and FELA, both from Baden-Württemberg in Germany, with the cooperation of solder mask manufacturer Taiyo, using digital 3D printing techniques.
Dreher described the inkjet printing process and how it had been adapted and optimised for applying solder mask exactly where it was wanted, at high resolution and precise registration and with the capability to vary the deposit thickness on different features of the PCB as required. A particular attribute was its ability to form solder dams and solder-mask-defined pads without solder mask on pad and without any undercut edges to trap process contaminants. It also avoided unwanted mask in via holes.
Würth Elektronik were conducting an extensive programme of compatibility and solderability testing, together with measurements of surface insulation resistance, ionic contamination, long-term temperature cycling and hot storage operational life testing. Initial results were all good and it was clear that s.mask met all the typical performance requirements for solder masks. And the exercise was a splendid example of PCB shops combining their resources to advance the technology.
A thermoplastic dielectric with some unique properties, liquid crystal polymer (LCP) had been employed as a flexible substrate and encapsulating material for a range of miniaturised hermetic modules for sensor integration, the subject of an informative presentation from Dr. Marc Hauer, R&D Manager and Engineering Manager at Dyconex in Switzerland.
He explained that liquid crystal polymer was a partially crystalline aromatic polyester that demonstrated a combination of excellent electrical, thermal and mechanical properties, and was fully compatible with PCB and thin film technologies. Being thermoplastic, it did not require any additional bonding material to make embedded or multilayered structures, and because of its extremely low water absorption and chemical inertness, it was ideal for biomedical applications. Compared with conventional flexible circuits, liquid crystal polymer structures had no interfaces; therefore, there was no possibility of diffusion along interfaces.
He showed examples of implantable devices in which plated or sputtered metals could be used as simple conductors or in combination as integrated resistors, thermocouples, thermistors or heaters, and thinned semiconductor components could be embedded for additional functionality.
The capability of liquid crystal polymer to encapsulate devices in harsh environments, was demonstrated by embedding moisture-sensitive silicon chips in LCP substrates and subjecting them to long-term immersion in phosphate buffered saline solution and concentrated sulphuric acid at elevated temperatures. No failures had been observed.
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