Review of the IeMRC's First Annual Conference

Citation

Starkey, P. and Goosey, M. (2007), "Review of the IeMRC's First Annual Conference", Circuit World, Vol. 33 No. 1. https://doi.org/10.1108/cw.2007.21733aac.002

Review of the IeMRC's First Annual Conference

Review of the IeMRC's First Annual Conference

20 September 2006

The Henry Ford College at Loughborough University (Figure 1) was the venue for the first Annual Conference of the Innovative Electronics Manufacturing Research Centre, an initiative funded by the Engineering and Physical Sciences Research Council as a Centre of Expertise, through which UK industry could access and influence research in electronics manufacturing. A large audience, including many well-known faces and a balanced representation of academic and industrial interests, was welcomed by Professor Martin Goosey, the IeMRC's Industrial Director.

Figure 1 The Henry Ford College at Loughborough University

Dr Kathryn Walsh, Director of the Electronics-Enabled Products Knowledge Transfer Network, presented the opening paper: “Electronics manufacturing, the hidden sector” by referring to the report of the Department of Trade and Industry's (DTI's) Electronics Innovation and Growth Team which had remarked that, although the electronics industry was a cornerstone of modern society and an enabler in most emerging technologies, the sector was largely invisible to itself, to Government and to other key movers and shakers. It was proud and confident about its technical capability, but lacked confidence in its ability to exploit that capability, and had been trying to solve its problems through unfocused initiatives which lacked critical mass. It was a value chain of highly interdependent sub-sectors with fragmented and under-resourced representation which lacked the vision and leadership and needed to improve both its visibility and its ability to transfer knowledge and best practice in order to innovate and grow. Knowledge Transfer Networks (KTNs) were part of the DTI's Technology Programme whose purpose was to provide funding to facilitate further investment in science, engineering and technology with the active participation of business and industry. Dr Walsh commented that significant innovations in both automotive and aerospace electronics continued to originate in the UK, and at an increasing rate as measured by patent registrations. But in terms of public perception, it tended to be the failures which hit the headlines, whereas the successes of smaller companies went largely un-noticed.

Figure 2 Left to right: Gary Stephens, Kathryn Walsh and Arnold Black

Pursuing the theme of sustainable use of materials, against a legislative background of WEEE, RoHS, EuP and REACH, Professor Gary Stevens (Figure 2) of University of Surrey described a technique for the rapid assessment of electronic product enclosure plastics for manufacturing support and end-of-life management. End-of-life polymer management was historically poor with over 1 million tonnes being wasted annually in the UK, and there were opportunities to retrieve more value and to reuse materials through multiple life-cycles. A wide-wavelength spectroscopic probing method that used both visible and near-infra red radiation coupled with multivariable statistical analysis had been developed to rapidly identify and qualify plastic enclosure materials used in electrical and electronic products, both at the manufacturing stage and at end-of-life. For ABS and ABS/PC blends it was possible to determine the polymer concentration in the blends. It was also possible to determine the polymer type and grade, as well as any influences of UV exposure on the materials. The portable and robust equipment could be used for quality assurance measurements on incoming virgin materials and for evaluation of materials for end-of-life identification, classification and qualification, particularly for predicting the aged condition of materials at end- of-life and after multiple reprocessing operations. Further work was required to obtain more data on the influence of weathering, injection moulding and reprocessing effects. Problems had been encountered with the characterisation of materials containing carbon black and the intention was to evaluate high intensity near infra red and Raman spectroscopy with these types of materials. This short project had been very successful and offered some potential solutions for recyclers wishing to recover and reuse polymers found in end-of-life electronics applications.

A practical example of a KTN in action was described by Arnold Black, Operations Director of the Resource Efficiency KTN, which was tasked with supporting the better use of material and energy resources by UK business and commerce. Dr Black had led delegations to Japan and to Europe to observe how recycling companies and electronics manufacturers were meeting their waste recycling targets and to benchmark the UK's performance against them. As a result of the KTN's feedback, the UK Government was in a better position to consult properly with major UK stakeholders before fully implementing the WEEE www.engineeringtalk.com/guides/weee.html Directive. It appeared that although metals recovery from end-of-life electronics was well understood, probably because metals gave the best revenue, the recovery of plastics still presented big challenges. Several proprietary techniques had been developed to extract ABS and high- impact polystyrene, and although the principles of some of these had not been disclosed, the selective solvent extraction CreaSolv Process developed by the Fraunhofer Institute and which was in commercial use in Germany, was described in some detail. A key problem was the recycling of polymers containing brominated flame retardants and this could be addressed by the CreaSolv Process. Arnold described how there was a need to recycle more polymers from end-of-life electronics and also a need to encourage manufacturers to use fewer different types of polymer materials. Catalytic depolymerisation was also described and details were given of a process that could convert polymers into biodiesel fuel. The process, developed by Dr Christian Koch and operated by Hamos in Germany, could take an infeed of any type of polymer (including car tyres) and convert them into diesel with a Cetan number of >56. It was stated that this fuel was suitable for normal car engines and that a large plant was also operational in the USA.

Dr Andy West of Loughborough University reported progress on the DISCOVER Project, for design and simulation of complex low-volume electronics production, with aerospace companies Smiths and Goodrich, and specialist assembler STI as industrial partners. With high-volume, low complexity electronics manufacturing having now moved offshore, what remained in the UK was high- reliability, innovative, complex, safety- critical work, high-added-value but still required at minimum cost. Experience showed that such electronics products often demonstrated poor first time yields, the reasons for which were not fully understood. The DISCOVER Project set out to analyse the causes and to model the whole manufacturing line in order to predict yield and reliability contributions from each of the component steps in the process flow. Simulation of board and unit assemblies at the design stage could then be used to amend designs or define process options to optimise product yield and service reliability. Deliverables from the project included a methodology for capturing and describing the linkages between design, manufacturing process variables and yields. Comparisons were also being made with high volume electronics manufacturing and international standards were being examined. The key aim was to develop rule based software that could be used in industrial trials.

Professors Andrew Richardson of Lancaster University and Chris Bailey of Greenwich University described a project to develop a design-for- manufacture methodology for System- in-Package (SiP) technology, using modelling and simulation to enable the analysis of key manufacturing issues during the design process through a virtual prototyping environment. The two-year project had several important industrial partners including NXP (formerly Philips), Coventor, Selex and Flomerics and was also co funded via Framework 6. SiP was the preferred packaging solution for next-generation micro-electro-mechanical systems (MEMS) and manufacturability of SiP products depended heavily on testability, control of thermal behaviour, understanding of defect and degradation sources and tolerance to electromagnetic and electrostatic fields. Modelling techniques, together with physics-of-failure and root-cause analysis allowed fast prediction of such properties as solder joint reliability and enabled the rapid optimisation of underfill attributes. The concepts of embedded test for built-in monitoring at wafer level were being explored and the project was also addressing thermo mechanical and behavioural models of SiP functionality. Some of the other areas being studied included lead-free assembly and solder joint reliability in wafer scale CSP SiP modules, electromagnetic shielding of packages, thermal management, and thermal expansion mismatch related issues. Specific work packages included the study of failure modes in SAC alloys and the influence of underfill properties such as thermal expansion and Young's modulus on failure. Work was also being carried out on the reliability of solder balls and reliability models were being built using a Weibull analysis based approach. The influence of reflow times and temperatures on the formation of intermetallics was under investigation. The project was looking at potential opportunities for this type of technology in built in health monitoring devices and the integration of MEMS switching devices on the substrate. Opportunities for continuing the work in this project via a Framework 7 proposal were being explored with a French partner.

Of particular relevance to PCB manufacture was the presentation by Dr David Hutt from Loughborough University entitled “Micro-materials integration and evolution in digital electronics manufacturing”. Dr Hutt described a new approach to the concept of ink-jet imaging of printed circuits. Instead of printing traditional inks, the project explored the feasibility of the deposition of self-assembled monolayers (SAMs) by inkjet technology. SAMs were single- molecule-thick organic films which could spontaneously form an ordered array when deposited on metal surfaces from solution. Alkyl thiols had been found to offer potential as etch resists, plating resists and selective solderability protectives when ink-jetted on to copper. The initial surface condition of the copper, and the evaporation dynamics of the solvent, were critical in controlling wetting and spreading. The effects of print-head geometry and driver waveforms were being investigated in co-operation with Xaar, and the programme aimed to generate PCB features with sub-50m geometries. By using these new materials it had been possible to produce oxide-free copper surfaces that could be soldered without flux. Fluxless wave soldering had also been demonstrated.

The afternoon session began with an update on the IeMRC's Power Electronics flagship project, introduced by Principal Investigator, Professor Mark Johnson of University of Sheffield. He explained the significance of power electronics, which held the key to annual global energy savings of around $1 trillion, or 14 giga-tonnes of carbon dioxide, by the year 2020. Power electronics was an area in which the UK was still relatively strong, both in technology and manufacturing but one in which there were still many challenges for the future. These included the need for increased power densities, lower electromagnetic emissions, ability to operate in extreme environments and a desire for greater levels of integration. Current limitations included thermal cycling, power density and the performance limitations of existing capacitor technologies. The project involved five universities and many industrial partners, and addressed the challenges of designing power electronics modules (PEMs) by supporting a programme which would deliver a detailed survey of new materials and assembly technologies, a physics-of-failure based approach to the qualification of PEMs and an investigation of the manufacturability of selected PEM technologies. Colleagues Professor Chris Bailey, of University of Greenwich, and Dr Ian Cotton, of University of Manchester, reported the progress of reliability studies and risk-informed design and decision making, and the causes, effects and prevention of partial discharge phenomena. Work was being undertaken to study electrical breakdown in silicone gels/ encapsulants and at gel to substrate interfaces. Techniques had been identified that allowed a 50 per cent improvement in resistance to partial discharge. The focus at Greenwich had been on physics of failure and power module design and simulation. Test structures had been designed that enabled the study of wire bond behaviour in terms of the stresses involved in various packages. Mark Johnson concluded the power electronics presentation by describing some of the work on advanced packaging and detailing the contribution on pulsating heat pipes being made to the project by researchers at Oxford University. This work had demonstrated effective thermal conductivities several times greater than for silver and it was noted that thermal resistances decreased as heat inputs increased.

Dr Patrick Webb of Loughborough University reviewed the challenges for electronics manufacturing posed by new surface-contamination-related failure modes in the context of the recent exponential growth in the market volume of wireless-enabled devices. Concurrently with the expansion of the wireless market, assembly processes based on no-clean fluxes had been widely adopted in order to reduce the use of environmentally damaging cleaning solvents, and conformally coated wireless products assembled with no-clean or low-solids solder pastes had shown some unexpected failure modes. It had been suggested that failure was related to ionic flux residues being trapped under conformal coatings and subsequently reacting with water vapour to form leakage paths which caused degradation of performance. The project aimed to reproduce failures under controlled conditions, correlate them with the levels and locations of organic and ionic contamination and confirm the exact failure mechanisms.

Returning to a subject area with relevance to PCB fabrication, Sam Duby of the Cleaner Electronics Research Group at Brunel University reported a collaboration with the Laser Group at the University of Hull to assess laser patterning of thin films for high volume manufacture of electrical structures. Their specific focus was the manufacture of low-cost thermoelectric devices, and a novel production technique had been devised which allowed the manufacture of complete bi-material thermocouple arrays in one non-stop reel-to-reel process. There were many potential uses for low-cost thermocouples but a particularly attractive one was for thermoelectric power generation from low-grade heat sources which would otherwise be wasted – cooling towers and automotive exhausts being good examples. Advantages of the process included the fact that no wet chemistry was used in the fabrication process and no liquid waste was generated. It was possible to manufacture thermopiles that could be folded up and another potential application area was in the harvesting of power from waste heat in solar panels.

With relevance to assembly-soldering, there was significant interest in the potential of nano-composite solders for use in harsh environments, because of their improved creep resistance compared with conventional solders. However, the challenge remained to devise techniques for preparing suitable nano-particles and incorporating them into solder paste. Dr Roya Ashayer of Kings College, London presented a study exploring the feasibility of using microemulsion techniques to fabricate tailored nano-particles. She described the chemical processes used to successfully prepare 90nm nano-silica, functionalise it with a silane, then attach 2 to 3nm gold nano-particles to its surface and grow a nanoshell to a thickness of 60nm. Work was continuing to reduce the tendency for nano-particles to be expelled from the solder during reflow.

The final part of the conference included an interactive session led by Professor Paul Conway in which the conference attendees were given an overview of the IeMRC's future plans and invited to discuss these and to offer suggestions and questions. Finally, the last presentation was given by David Topham, who gave an overview of the 3D-Mintegration Grand Challenge Project. This four year, £9.2 million, multi-disciplinary programme currently involved seven research institutes and 20 companies. It had the objective of creating a paradigm shift in manufacturing by developing the technologies and strategic approaches required for the production of highly integrated, cost-effective and reliable multi-functional 3D miniaturised devices. Efforts were being applied not only to manufacturing processes, but also to the end-to-end design, assembly, packaging and testing of complete systems.

The IeMRC Conference was being run in conjunction with the 3D- Mintegration Conference, which was taking place the following day. Many of the delegates attended both conferences and were thus able to benefit from an excellent evening drinks reception, networking event and dinner that took place in the college following the close of the Conference.

As a diversion from the formal presentations, Electronics Yorkshire (Figure 3) brought their mobile soldering training unit to the venue and parked it outside the college so that delegates could experience the hands- on realities of soldering in a practical workshop setting. Also, there were two large poster (Figure 4) and display areas set up outside the main conference rooms where researchers from both the IeMRC and 3D-Mintegrtation were able to display details of their projects and to network (Figure 5). These were complemented by displays from various other organisations including the Resource Efficiency KTN, British Aerospace and Plestech (Figure 6).

Figure 3 Electronics Yorkshire Mobile training unit

Figure 4 Left to Right: Dr Samjid Mannan, Dr Roya Ashayer and Professor Chris Bailey

Figure 5 Left to right: Dr Andy Cobley and Professor Paul Conway

Figure 6 Left to right: Steve Payne (Cirflex) and Rob Harvey (Xaar)

The first IeMRC Conference was a great success, providing an in depth and detailed review of some of the important research work that was being supported in the UK. The conference very effectively demonstrated the action going on behind the scenes of what had been fairly accurately described at the outset as a fragmented and under-resourced industry, characterised by a lack of critical mass and focus. It was clear that the UK Government did indeed recognise the significance of the country's electronics industry and was prepared to help secure its future by funding and encouraging the sharing of knowledge and expertise, and by encouraging cooperation between academia and industry. Not least, the event presented a very effective networking opportunity: many new potential partnerships and areas of collaboration will surely result. We look forward to next year's conference. Further details of the IeMRC can be found at www.lboro.ac.uk/research/iemrc

This article is based on an earlier version that was prepared by Pete Starkey for Circuitree. Thanks are due to Pete and the publishers of Circuitree for permission to use the original article as the basis of this one.

Pete Starkey and Martin GooseyOctober 2006