EIPC Winter Conference Rotterdam – February 13 & 14, 2020
In mid-February 2020, there were two major attractions in the Blijdorp area of Rotterdam, the main port city in the Dutch province of South Holland – the Zoo and the EIPC Winter Conference. The Zoo is open every day of the year, but the premier event of the season was the EIPC Winter Conference, held on the 13th and 14th, attracting around 90 delegates from a dozen European countries, as well as a few from North America, to an outstanding learning and networking experience for members of the PCB Community. A programme of more than 20 presentations and panel discussions, together with a table-top and poster exhibition, on the theme: “The Needs for the Next-Generation Electronic Devices and Changes in Fabrication Solutions for PCBs, PCBAs, Materials and Technologies”
EIPC president Alun Morgan welcomed all to the conference and gratefully acknowledged the support of the sponsors. He invited members to adopt the revised statutes of the association, and these were received very positively. He also took the opportunity to remind everyone that the ECWC15 World Convention would be held at the end of November 2020 in Hong Kong and Shenzhen, and that there was scope for additional papers to be submitted.
“It’s 2020, what shall I talk about?” he continued. He reviewed some of the predictions that had been made 10 years previously, and some of the scientific discoveries and medical advances made during the last decade. Looking forward, it had been said that there would be no need for futurists to predict the future because progress in artificial intelligence would make them redundant!
Time-honoured as the opening presentation was Walt Custer’s eagerly-awaited Business Outlook on the Global Electronics Industry, with emphasis on Europe. Unfortunately, Walt was unable to travel to the conference but he sent his best regards and delegated the delivery to Alun Morgan, who did a fine job as his deputy.
Although this edition of Custer’s Business Outlook had been compiled before coronavirus had distorted the 2020 situation, the fact remained that global manufacturing growth has reached bottom based on data from Purchasing Managers’ Indices (PMIs); tariffs, trade disputes and the UK’s withdrawal from the European Union were key issues, and geopolitical concerns remained very significant. However, his observation that most sectors of the world electronic supply chain were now expanding slowly had to be qualified in the context of quarantine restrictions in China.
He considered the PMIs to be “useful but sobering leading indicators”, and figures for Europe had shown a continuing contraction towards the end of 2019, the only notable area of growth being in medical electronics. Production in the European automotive industry was down because of uncertainty about the future of diesel power and mil-aero revenues were flat, as were volume consumer-electronics markets. However, there were substantial growth forecasts for 5G handsets and infrastructure.
World PCB production had been almost static for the last three years. Based on 2018 figures, the $74.5 billion total, split by geographical area, was China 54%, Taiwan and South Korea 10% each. Europe only represented 3.1% against North America’s 4.2%. The number of PCB manufacturers in Europe had declined to 202, with the majority of the revenue being generated in the German-speaking countries. Michael Gasch had predicted that Europe would close 2019 with a loss of 10% against 2018. “Hope for the best, prepare for the worst!”
Hans Friedrichkeit believed that there was a glimmer of hope in the German industry because the downturn in incoming orders had slowed and the automotive industry was likely to stabilise. “It looks as if the bottom of the economic valley of tears has been passed.”
Custer’s opinion was that the world market had reached bottom and was beginning to improve, although the first quarter of 2020 could be significantly influenced by the consequences of coronavirus. Trade disputes had impacted long standing regional alliances and US-driven impulsive market actions remained as problems. He believed that electronic assembly might shift globally to countries less affected by tariffs, and that many good new electronic products were on the horizon. In particular, 5G offered exciting opportunities for the next decade.
The following presentation was Dr. Hayao Nakahara’s outlook on PCBs in automotive electronics. Dr Nakahara apologised that he was unable to attend in person, and had asked EIPC Technical Director Tarja Rapala-Virtanen to deliver it on his behalf.
There was a continuing steady 5-6% annual increase in PCB usage as a consequence of the increasing functionality of advanced driver-assistance systems (ADAS). The growth in electric-motor-driven cars was slower that had been predicted, and despite the hype about autonomous vehicles, it was unlikely that completely driver-less cars (“Level-5”) would be generally available before 2030. “How can Level-5 cars make decisions in the streets of Saigon, Hanoi and Jakarta where millions of motor bikes cut in front of you all the time?”
Sales of electric vehicles were still constrained by the price and life expectancy of lithium batteries. Typical cost in 2018 was $200 per kilowatt-hour. It was forecast that this could be reduced to less than $100 by 2023, which would certainly stimulate the market.
The world sales of new light vehicles was 90.3 million units, but the world’s largest market, China, continued to shrink as a consequence of reduced tax rebates, a general economic downturn, and increasing sales of used cars.
Reliability of automotive electronics was a fundamental consideration, with 200-300 sensors per car, and security remained an important issue, particularly in the context of connected vehicle technologies
Dr Nakahara estimated the automotive share of world PCB output to be 11% in 2109. The value of PCBs per car ranged from $30-$40 at the low end to $100-$150 at the high end, averaging $50-70 per car, and it had been estimated that the electronics content of a car might rise to 50% of its total value. “To replace bumpers and headlamps will not be cheap anymore in the future”.
Mustafa Özkök, Global Product Manager with Atotech, discussed the manufacturing challenges that 5G and millimetre-wave technology imposed upon the PCB industry, in terms of materials, processes and design considerations. He explained that the main driver for 5G was the forecast massive increase in the number of connected devices and the quantity of mobile data. For example, an autonomous car was expected to create 4,000 GB per day. Millimetre-wave would drive new hardware and the wireless infrastructure would need enormous geographic density of small cells in order to achieve connectivity of everything. The move to 5G would enable high frequency, high speed data transfer, big volume data traffic and high density connection.
Investment in 5G infrastructure was forecast to exceed $300 billion by 2025 with a large proportion related to upgrades of data centres and public clouds, which would demand substantial growth in the production of servers, routers and switches. New-generation substrate materials would be required for PCBs and ICs, and designs would regard signal integrity, impedance and capacitance, thermal management and EMI shielding as critical issues.
Dielectrics formulated for high speed, high frequency operation, mixed dielectric builds and advanced adhesion promoters, would all contribute to minimising signal attenuation. Advances in metallisation and plating processes could offer compatibility with hybrid builds and give uniformity of copper distribution. Final finishes designed to minimise signal loss and withstand aggressive environments and extended storage would be required. Many of these materials attributes already existed or were in development. Thermal management and new options for EMI shielding were also important considerations.
The session on inkjet and other coating technologies was moderated by EIPC board member Emma Hudson.
Her first speaker was Dr.-Ing Andreas Albrecht, from Cicor Group in Switzerland, with an enlightening presentation entitled “Printed Electronics – Pushing the Limits”. Discussing the principles of fabricating printed electronics devices, Dr Albrecht described how a functional material, which might be a metal, a conductive polymer, a dielectric or a sensor material, was converted from the bulk state to nanoparticles dispersed in a solvent mixture or polymer lacquer to form a printable functional ink. He stressed that Cicor did not make inks themselves, but were happy to cooperate with several specialist ink manufacturers and to evaluate and select products to suit their own specific requirements.
Most delegates were familiar with ink-jet printing techniques, but aerosol jet printing was emerging as an alternative contactless direct-write method of producing fine features on a wide range of substrates, which could be used for creating conductors, active and passive components, actuators and sensors.
Dr Albrecht explained the basic procedure: Ultrasound was used to break the ink into droplets, the size of which was governed by ultrasonic power and temperature, and an add-back of solvent ensured stability. A deposition head focused a jet of droplets, carried as an aerosol in a stream of nitrogen, onto the workpiece at a separation between 1-5 mm, as a 10 micron spot. The workpiece was mounted on a stage capable of movement in up to 5 axes, and heated to dry the ink. The deposition head could itself be programmed for free-form writing if required. Pneumatic atomisation was a more complicated alternative to ultrasonic.
Compared with ink-jet printing, aerosol jet printing offered some technical advantages: higher resolution, higher printing thickness and a larger material portfolio. Because of the large and variable stand-off distance it was capable of printing increasingly complex devices on three-dimensional surfaces.
Dr Albrecht reported that Cicor had invested in a technology centre for printed electronics at their Bronschhofen site in Switzerland, where a team of application engineers was working on the development and industrialisation of new additive manufacturing processes and connection technologies.
Dr Albrecht’s introduction to aerosol jet printing provided a fascinating vision of an alternative procedure, but ink-jet technology had become adopted as a selective digital imaging process in the printed circuit industry, and recently established as an effective means of applying solder mask. Chris Wall, Technical Director of Electra Polymers gave a detailed description of the development and processing of ink jettable soldermask and the benefits of its use in PCB manufacture.
He went through the logical sequence of stages in the development of a new ink: understanding the inkjet application process, identifying the formulation constraints for an inkjet soldermask, identifying and sourcing suitable candidate raw materials, and meeting soldermask performance requirements and external compliance requirements.
He summarised the types of head available: drop-on-demand piezo, recirculating and non-recirculating, with examples of each, and described how the head type influenced droplet size and resolution. He illustrated the way droplets were generated, their shape in flight, and the consequences of satellite formation.
When it came to formulating a jettable solder mask ink, he reviewed the constraints of raw material suitability, resin viscosity, pigment particle size and filler content, and discussed the effects of surface tension and contact angle of the resulting ink formulation. Curing mechanisms were generally a combination of preliminary UV pinning and a final thermal cure. He explained resin and photoinitiator chemistry in sufficient depth to convey the principles without confusing the non-chemists in the audience! He described how new products were formulated, evaluated and submitted for independent testing for compliance to standards such as UL 94V0, RoHS, IPC-SM840 and NASA Outgassing, as well as automotive standards and customer-specific requirements.
He reviewed the benefits of inkjet solder mask as compared with liquid photoimageable products, which lay principally in a shorter fully-additive process route and no solvent emissions or developer effluent, and discussed the characteristics of image edge-profiles. The inkjet process enabled custom print strategies for specific designs, such as selective thickness control, multilayer deposition, and different surface textures.
Recognised for his consistently informative and entertaining presentations, Don Monn from Taiyo America gave his update on the progress of inkjet soldermask over the five years since 2015, without standing still. He focused on practical aspects of image definition and geometry, with particular reference to solder dams and soldermask defined pads, using a whole series of “then” and “now” cross-section photographs of actual soldermask features.
He demonstrated how edge definition and flow-out could now be controlled to maintain the physical height of dams such that whereas a nominal 5 mil dam in 2015 would slump to a height of barely 0.5 mil and an effective width of almost 10 mil, the equivalent feature now would have a height of almost 2 mil, while maintaining a width of almost exactly 5 mil with a sharply defined edge.
Taiyo America had submitted samples of their inkjet-printed solder mask for third-party testing and measurement of thickness over copper and over laminate, adhesion of soldermask dams, of solder mask over copper and of legend over mask, resistance to electroless nickel immersion gold, to solvents and to solder, and for print quality and registration. Monn showed comprehensive test results confirming compliance with standards in all respects. Of particular note were thickness measurements proving that coating thickness was maintained at track edges, and the results of thermal cycling tests: 1000 cycles -40°C +125°C, 500 cycles -40°C +140°C and 100 cycles -65°C +125°C , with no deterioration of adhesion, surface hardness or dielectric strength.
“It’s a technology worth investigating!” was Don Monn’s closing comment.
Continuing on the ink-jet theme, Uwe Altmann reviewed the evolution of the technology within Orbotech, from their first inkjet for PCB applications in 1999, their joint venture with and subsequent acquisition of New System in 2007, to the present day with over 520 legend-printing machines installed world-wide. He discussed the key benefits of Orbotech’s patented DotStream Pro technology, which featured multi-LED based UV for perfect ink-drop pinning, and superior depth-of-focus for the best printing on challenging topographies.
Their NAT technology demonstrator had been used for several years in collaboration with a leading ink vendor to develop inkjet solder mask, resulting in the launch at the recent IPC APEX Expo of the new Orbotech NEOS solder mask inkjet printer, offering a shorter, simpler and eco-friendly alternative to traditional methods. In addition to their proven DotStream Pro technology, the NEOS featured Structural Printing Technology, which optimised feature sharpness with unique 3D algorithms and included automatic calibration processes and consistent drop volume control.
The afternoon session began with a round-table on roadmapping and standardisation, moderated by Tarja Rapala-Virtanen, with short presentations from Steve Payne, Alun Morgan and Emma Hudson followed by a panel discussion.
Steve Payne, Manager of European Operations for iNEMI, introduced the organisation as an industry-led research and development consortium that road-mapped the future technology requirements of the global electronics industry. He explained that the iNEMI roadmap had become recognised as an important tool for defining the state-of-the-art in the electronics industry as well as identifying emerging and disruptive technologies. There were 500 participants globally. The Organic PCB Chapter drew on information from Product Emulator chapters, which defined the future needs for high-end system, aerospace, automotive, office and computer, and portable and wireless. It had identified development needs in HDI technology, microvia plating, modelling tools for embedded active and passive components, improved layer registration, fine-line imaging, alternatives to back-drilling, cycle time reduction for rigid and flexible circuits, and Industry 4.0 adoption. Key drivers were miniaturisation with increased functionality, increasing data volumes and transfer speeds, higher-speed processors, increasing complexity of components, form and flexibility of interconnects, and environmental considerations.
He listed current collaborative projects aimed at eliminating gaps in the technology evolution to satisfy product sector needs, commenting that, ten years hence, 5G would probably have been superseded by 6G and that artificial intelligence might be the next boundary to cross.
Alun Morgan, Technology Ambassador for Ventec International Group, suggested revising the ANSI grade definitions for thermosetting laminates as used by UL, IEC and IPC. The current grading system was based on the NEMA LI 1 Standard, first published in 1965, which classified materials based on their chemistry.
Morgan commented that, in the modern world of electronics, the performance of the printed circuit board and the printed circuit assembly was all that mattered, that much of the performance was contributed by the base material, and that the designer only cared about the performance. The varnish building block definitions used in the current UL 746E standard requested that they be listed by chemistry. In fact, the building blocks were not defined as to allowable chemistries, and some building blocks fell into multiple categories which led to confusion. And the building blocks were not defined as to minimum and maximum loadings.
The way forward he proposed was to define base materials less on what they were made of but more on their performance. He gave as an example IPC-4103, which characterised materials only on their Dk and Df performance at certain frequencies without a concern for the chemical composition. He recommended that once UL listed as to their safety characteristics, the base materials be put in common categories where the printed board shop must test one material out of the same group for PCB approval. And if the base material qualified as FR-4.1, it no longer mattered that a secondary resin was present from the board point of view.
Technical consultant and expert on electronics industry standards and certification, Emma Hudson summarised the current and recent standards development work of IEC TC 91, and the upcoming proposals from UL, particularly those related to solder limits, which were recognised parameters for PCBs, solder resists and metal-clad laminates. Solder limits were meant to represent the soldering processes the PCB would be exposed to during component assembly operations. UL were looking to change the term to “Assembly Soldering Process” to provide a better description of what was meant by the parameter. The proposed default condition would be 6-cycles of IPC-TM-2.6.27 T260 reflow, and the reflow profile would be considered representative of wave and selective soldering. Follow-up Service inspectors would check the maximum reflow temperature and the number of soldering cycles that the printed circuit assembly was exposed to, but would not be checking any other details of the reflow profile.
There was no plan to apply the new Assembly Soldering Process limits to existing board types, but only to new evaluations, once the proposal had been accepted by the UL Standards Technical Panel and added to UL 796, UL 746E, UL 796F, and UL 746F. Hudson stressed that there was no guarantee at this stage that the proposal would be accepted.
Not surprisingly, it was Emma Hudson’s topic that attracted the majority of questions from the audience!
The session on reliability and environmental technology was moderated by EIPC board member John Fix, Director of Marketing and Sales with Taiyo America.
His first presenter was Martin Cotton, HDP User Group, UK The session on reliability and environmental technology was moderated by EIPC board member John Fix, Director of Marketing and Sales with Taiyo America.
His first presenter was Martin Cotton, Project Facilitator with the HDP User Group, discussing the final report of the project evaluating the effect of moisture conditioning on several high frequency Dk and Df test methods using a variety of laminate materials. Earlier work had found that differences in moisture conditioning contributed up to a 43 percent difference in measured Df values, for the same laminate material, depending upon the test method used.
The objective of the final phase of the project had been to evaluate the effect of varying moisture conditioning on Df and Dk measurements for a series of different low-Df, mid-Df and high-Df laminate materials, half of which were halogen-free, to determine the sensitivity of each test method to different moisture levels, and to determine what test frequency range or ranges were most affected by the moisture present within a laminate material.
The results were presented as an extensive series of scatter-plots and graphs which demonstrated that the test method coupon design had a significant impact on the measured results. Trace-Conductor coupons with plane layers on both sides showed no detectable difference in Dk and Df that might be correlated with moisture conditioning. The moisture conditioning methodology used for the Z-axis and in-plane test methods was sufficient to show a significant impact on loss due to moisture conditioning. The effect of moisture conditioning on the Dk and Df of laminate materials was shown to vary depending upon the specific laminate material being tested, and the HDP User Group recommended that users of these high frequency test methods include in their test runs a base-line laminate material as a control. The test results showed that the Dk and Df values for the as-received and dry baked samples with internal plane layers were not always very close, mainly because of uncertainties in measuring the exact moisture content in such samples.
Dr. Anna Graf, OEM Marketing and Application Engineering specialist with Isola in Germany, discussed high temperature stable base materials for e-mobility applications. She commented that there were still several challenges to be addressed, specifically driving range, charging time and high battery cost. How could the challenges be approached? Dr Graf explored the basic electrical architecture of electric and hybrid-electric vehicles and concluded that improvements were needed in system efficiency, power density and miniaturisation.
New materials were required for power electronics. Silicon carbide was a more effective material than silicon, but operated at higher temperatures. Ceramic-based direct bonded copper substrates had excellent thermal properties but were expensive and required specialist fabrication techniques. A high-temperature-stable FR4-like laminate could provide a cost-effective alternative.
Dr Graf described a German government BMBF-funded project named HELP, with fifteen collaborating companies working to develop reliable and cost-effective high-temperature electronics for e-mobility based on printed circuit boards made from high temperature resistant resin systems. The objective was an organic-based printed circuit material capable of operating at 175°C with a peak temperature of 200°C and increased temperature cycling resistance. In collaboration with the consortium, Isola had developed a halogen-free, next-generation automotive high-reliability laminate solution for high power and voltage applications that required extreme thermal stability. It was a glass-reinforced material with very low thermal expansion. Dr Graf did not disclose the resin chemistry, but made it clear that it was not epoxy. The material had processing characteristics similar to FR4, and properties similar to polyimide.
Additional information and further discussion of base materials with high temperature reliability came from Volker Klafki of Technolam in Germany. He began with a review of laminate developments and reliability expectations since the 1990s, up to recently emerging requirements in connection with e-mobility when extreme anti-CAF performance and resistance to thermal ageing were demanded. The ongoing theme appeared to be: “What is sufficient now will very likely be insufficient in the future”
He summarised the criteria currently used to classify reliability: withstanding the thermal stresses of assembly, reliability during thermal cycling and no degradation under high temperature storage, defining end-of-life as the point at which electrical and mechanical properties had declined by 50 % from their initial values. He discussed the significance of relative thermal index with reference to UL standards, and CAF resistance at high temperatures.
He described qualification procedures, properties and process guidelines for two high-reliability proprietary laminates developed for high-temperature applications, with very low thermal expansion and superior CAF resistance.
“Quo vadis flame retardants? How can we meet ever more stringent performance and sustainability demands?” were questions posed by Dr Adrian Beard from Clariant in Switzerland, and discussed in detail in his presentation which gave an overview of the many challenges facing the flame retardants industry and some solutions that were in the pipeline.
He explained that the regulatory and environmental pressure on halogenated flame retardants continued to grow, and flame retardants continued to be added to the candidate list for “substances of high concern”. The RoHS directive was once again under revision and more substance restrictions might happen. The European Ecodesign Directive would restrict the use of halogenated flame retardants in electronic displays as of 2021. In Sweden, a tax on household appliances and electronics, clearly not based on science, penalised not only halogenated flame retardants, but also additive phosphorus flame retardants that had good environmental and health profiles. It was clear that not only stricter chemical legislation but also the trend to non-chemical legislation could drive transition to halogen free flame retardants in many areas.
Dr Beard explained that Clariant were members of PINFA, the Phosphorus, Inorganic and Nitrogen Flame Retardants Association, a group of global flame retardant manufacturers and users committed to fire safety and improving the health and environmental profiles of their products. Clariant themselves produced a range of flame retardants based on aluminium diethylphosphinate for advanced electronic materials, and these had achieved the highest sustainability standards.
“Be prepared! Flame retardants under scrutiny usually do not come as surprises!”
The subject of brominated flame retardants continues to be a matter of regulatory controversy! Tetra-bromo-bisphenol-A (TBBPA) has traditionally been used as a reactive component in the manufacture of brominated epoxy resins. Product designers have long presumed that TBBPA is fully reacted in laminates although, there has been little public data documenting this or defining potential “free TBBPA” within the epoxy polymer. Sergei Levchik, New Product Development Manager at ICL-IP America, a member of North America Flame Retardant Alliance, reported a study to analyse commercial laminates to determine the concentration unreacted TBBPA flame retardant in printed wiring boards
Laminate samples, selected to cover a wide Tg range from 140°C to 200°C, were obtained from major suppliers to the electronics supply chain. In addition, halogen-free laminates were tested as controls.
Samples were prepared according to EPA Method 3545A (Pressurized Fluid Extraction), and EPA Method 8321B (High-performance liquid chromatography, coupled with thermospray-mass spectrometry and ultraviolet detector). The test method was independently validated with respect to TBBPA detection and quantification, and two control samples of TBBPA-free laminates were used.
It was shown that representative set of FR-4 laminates provided by three suppliers did not contain free TBBPA after curing. It was also shown that high-end laminates did not contain free TBBPA
These analyses demonstrated that TBBPA can be used effectively and safely to enhance the flame retardant performance of printed wiring boards.
This concluded the first day’s conference session, and delegates boarded buses for a lesson in automated logistics and Smart Technology in a tour of Hutchison Ports Europe Container Terminal (ECT) Rotterdam, one of the most advanced container terminals in Europe, situated at the Maasvlakte, directly on the North Sea. Approaching 20 million twenty-foot equivalent container units are handled every year, with most of the loading and stacking done by autonomous robotic cranes and computer-controlled automated guided vehicles. An enormous and amazing operation!
The final event of a long day was a splendid networking dinner at “The Castle” pavilion in the Sparta Stadium, home of the oldest football club in the Netherlands. After the meal, a great many would-be football stars invaded the pitch for team photographs in the goal-mouth, before returning to the conference hotel for rest and relaxation in preparation for the second day’s programme.
Rested and refreshed, delegates returned to the conference room for the second day of the 2020 EIPC Winter Conference in Blijdorp, Rotterdam, South Holland.
The first session, on new technologies and design, was moderated by EIPC board member Martyn Gaudion from Polar Instruments. He was delighted to welcome back Dr Despina Moschou , assistant professor at the University of Bath in the UK, for her update on recent developments in design and manufacture of Lab-on-PCB devices.
Dr Moschou gave a brief introduction to the University of Bath, a centre for biosensors, bioelectronics and biodevices, developing technologies to improve biomedical diagnosis, environmental monitoring, industrial bio-processes and the understanding of biological functions.
“Lab-on-Chip technology is no longer science fiction – it’s actually happening!” She drew a parallel with the progress of the development from the old fashioned computer to present-day “system-on-a-chip” integrated circuits.
The Lab-on-Chip micro-total-analysis-system (μTAS) offered unique advantages in miniaturization, low reagent volumes, rapid analysis time for early detection, together with automation and portability. But economic manufacture of integrated smart microsystems on silicon relied on economies of scale and there was no established commercial manufacturing technology. The Lab-on-PCB approach had emerged as a very strong candidate, owing to its inherent upscaling potential: the PCB industry being well-established world-wide, with standardised fabrication facilities and processes. Many material and process options were currently available commercially, and prototypes compatible with Lab-on-Chip dimensions and requirements had been demonstrated for various applications. Dr Moschou showed many examples of Lab-on-PCB devices and reviewed some of the challenges that had been encountered and overcome. The concept was truly cost effective in mass production and work was continuing on standardization and engagement.
Jean-Paul Birraux, sales & marketing manager for First EIE in Switzerland, discussed direct imaging, versatile automation and data format management, remarking that First EIE had more than one thousand installations of imaging equipment world-wide. He referred to the acquisition of the company in 2015 by Inspec in Japan, commenting that the strong synergy and complementary product portfolio extended their range from imaging to include automatic optical and visual inspection, automation and roll-to-roll technology.
He went on to describe First EIE’s latest CFX-compliant direct imaging system, which could be configured in several configurations from a single stand-alone machine to a fully automatic line. They continued to use their proven mercury UV light source, which gave a full spectrum from 350 to 465 nanometre wavelength. The system was capable of accepting all data formats, and resolving 20 micron features. A new glass-mask-imaging system had been developed, capable of resolving 15 micron features on large-format chrome masks for applications including LCD, TFT, OLED and touch panel manufacture.
Hans Fritz, owner of SAT Electronic in Germany, described a new innovation for PCB registration improvement developed by InPeKo and launched at productronica: a multilayer ultrasonic welder. With videos, he demonstrated how two cameras detected layers and prevented incorrect layer build-up. Accuracy was better than 10 microns. There were four welding heads and the actual welding process took less than one second for stack heights up to 9.5mm. The very small weld area saved space on the outer border of the layer, which could be as narrow as 6mm. The major benefit of the ultrasonic welding process was that heating was very localised, generated only in the prepreg. Therefore there was no thermal distortion of the material beyond the welding point. An added capability was “aufslippen”, meaning that prepreg could be welded to the external surfaces of the stack if necessary.
The concept of the machine was flexible and modular, with options from semi-automatic to fully-automatic, and it could be adapted to provide customer-specific solutions. In its standard format it could handle panel sizes from 500 x 330mm to 700 x 800mm with real-time control of temperature, time and energy.
The final session, on manufacturing technologies and new processes, was moderated by EIPC board member Oldrich Simek, owner of Pragoboard in the Czech Republic, and his first presenter was Joan Tourné, CEO of NextGIn technology in the Netherlands.
Tourné explained the concept of “vertical conductive structures” (VeCS) as a means of increasing the efficiency of high density interconnect, in terms of increasing the connection density, simplifying the laminating process and reducing signal distortion. He clearly demonstrated the principles using x-ray and microsection photographs of actual VeCS interconnections. There were two classifications: VeCS 1 used all through-slots, VeCS 2 used multiple depths of blind slot. In either case, the slots were formed by routing or peck-drilling, then metallised and plated, then drilled over-size at intervals to leave a series of vertical conductors on the walls of the original slots. He stressed that any board shop with the capability to produce high-end circuits could manufacture VeCS with no additional investment in equipment or process.
He showed many examples of VeCS designs, discussed how detail process improvements had been made and reviewed the results of reliability testing. He explained how VeCS 2 could be used to produce separate circuits on top and bottom of the panel, to increase density and make better utilisation of routing space without vias penetration through the board, and with no sequential lamination being required. Connections could be created for power-hungry power and ground applications, and stub-less connections made to internal layers without back-drilling. He acknowledged the development and evaluation work carried out in China by WUS PCB on real-life product.
Horizontal plating lines have been in operation for many years, but traditional transport systems are not ideal for the thinner panels and delicate fine-line photoresist patterns associated with modified semi-additive processing (mSAP) and advanced modified semi-additive processing (amSAP) technologies. Atotech had recognised the need to develop a non-contact transport system to handle these challenges, and Global Product Manager Mustafa Özkök described the features of their latest horizontal copper plating equipment.
In their new system, mechanical damage to fine pattern features was avoided by using fluid streams instead of wheels to guide the panel and to support it between the anodes, so that the pattern area of the panel had no contact with any mechanical components. Özkök showed a video to demonstrate the system in operation. The clamping mechanism for providing cathode connection had been redesigned to avoid panel bending and optimised transportation, the latest pulse plating technology has been incorporated and the software and control system were ready for Industry 4.0 integration. The patented anode design gave very uniform plating distribution.
The equipment could be configured for panel plating, mSAP or amSAP processing, and Atotech had developed appropriate specialist chemistry and a new copper electrolyte. Özkök explained the principal process differences between mSAP and amSAP. The sequence for mSAP was to use a substrate with very thin copper cladding, less than 5 microns, electroless copper approximately 0.4 microns, followed by 1-3 microns strike copper plate, photoimaging, pattern plating with blind-microvia filling, then resist stripping and differential etching to achieve line and space of better than 30 microns. amSAP followed a similar sequence but with thinner substrate copper, typically 3 microns, and relied on heavier electroless copper, up to 1 micron, so that strike plating could be eliminated. Better than 20 microns line and space could be achieved with amSAP, and it gave better capture-pad cleanliness. Özkök showed microsections of blind microvias produced in the new equipment with the new copper electrolyte. The first installation of the new system had been completed and qualification was ongoing at a customer in Europe.
Excessive heat is increasingly a major cause of failure in electronic assemblies, especially those with high power electronic devices, and system reliability can be critically dependent on efficient thermal management. Mike Tucker, Field Applications Engineering Manager for Kinwong Electronic, gave a comprehensive review of thermal management solutions using PCBs. He first discussed options based on FR-4 PCBs: thermal vias, copper coins and metal cores, then explored those based on insulated metal substrate (IMS) PCBs: metal-clad PCBs (MCPCB), copper-base pedestals, and flexible IMS PCBs.
He demonstrated the effect of hole-wall copper thickness on the efficiency of thermal vias, and explained how selective plating methods could be used to increase the hole-wall thickness and hence improve heat dissipation.
Copper coins of various shapes could be embedded inside FR-4 boards to act as efficient local heat sinks. Alternatively a metal core could be incorporated between the inner layers of an FR-4 board and used not only for lateral heat spreading, but optionally as a bus-bar for high current applications.
Insulated metal substrates were widely used for heat dissipation, the simplest construction being a single-layer circuit etched on a copper-clad, aluminium-based IMS. Tucker showed examples of more complex multilayer interconnects on IMS, and some typical design rules. When the metal base of the IMS was copper rather than aluminium, copper-base-pedestal techniques could be used for heavy-duty LED lighting and power-train systems, enabling the heat-generating component to be soldered directly to the copper base to give a shorter heat dissipation path with less thermal resistance. Flexible (probably better termed “bendable”) IMS substrates with good thermal characteristics could be formed into three-dimensional shapes after assembly.
Heiko Lang, Sales Director of the Electronics business unit in the Schmid Group introduced Schmid’s “Green Fab Concept” on behalf of his colleague Laurent Nicolet who was stranded Hong Kong as a consequence of CoronaVirus.
He remarked that global development was revealing new challenges for the PCB and substrate industry. 5G, high frequency applications, embedding, high power applications and new materials were pushing the industry in the direction of the integration of new processes and production solutions. Schmid’s objective was to work towards increasing technical capabilities but with a green approach and an optimized cost structure. They had recognised technical challenges in general process technology, particularly in metallisation, subtractive mSAP, SAP and embedded traces, in production concepts such as automation and greener production, design requirements and new materials
Schmid’s development was all driven by intensive cost analysis, because only by efficient process technology could they offer added value to their customers. They had carried out in-depth research on chemical consumption and utility data in cooperation with customers and chemical suppliers.
An example, he discussed in detail was their modular in-line plasma system for touch-free, simultaneous single-sided or double-sided vertical processing of high end PCBs and IC substrates. The system could be configured flexibly by combining etch and sputtering process modules. The first installation was running successfully in Switzerland. Compared with traditional permanganate wet-processing, it had been demonstrated that the system could make savings of nearly 80% in electricity consumption, 70% in water consumption, 46% in chemical consumption, and reduce CO2 emissions by 35%
Their wet process lines for mSAP technology offered higher flexibility, higher yield and substantial improvements in total cost of ownership. Their high-end vertical process line had the capability to run thinnest flex-material down to 25mµ touch free. And all of Schmid’s equipment was Industry 4.0 ready and capable of being integrated and automated.
At the conclusion of the conference programme, Alun Morgan made his closing remarks, once again acknowledging the support of the sponsors, thanking all of the speakers for so generously sharing their knowledge and experience, the moderators for keeping good time and good order, and the delegates for their interest and attention. Particular thanks from all present went to EIPC Executive Director Kirsten Smit-Westenberg and Project Manager Carol Pelzers for their flawless organisation and administration of another immaculate event.
The 2020 EIPC Summer Conference will be on 16th and 17th June in Sweden.