Emerald Group Publishing Limited
Copyright © 2006, Emerald Group Publishing Limited
EIPC summer conference – Venice 8-9 June 2006
EIPC summer conference – Venice 8-9 June 2006
Keywords: Conferences, Printed-circuit boards
Frank Smulders, Managing Director of EIPC, welcomed the delegates to a sunny and reasonably warm Venice (Plate 5). Not that the hotel was actually in Venice, it was probably nearer Milan, but in this day and age distance is not a problem; what's a few kilometres amongst friends.
Plate 5 Venice – setting of the 2006 EIPC conference
Walt Custer painted the backdrop to the conference by giving us some facts and figures, of which he had, as always, plenty. The 2006 world market for rigid and flex PCBs is $44 billion, of which Europe accounts for only 8 per cent against China's 26 per cent. The World GDP will be slowing over the next 2 years, with high energy costs and governments raising interest rates, and the US$ is very weak, which means that their exports are relatively cheaper. Inventory levels look high in the semi conductor field, which is slightly worrying what with a slowdown imminent. The continuing quest for low cost manufacturing centres continues, obviously China, but also India, Vietnam, central Europe and now back to Mexico. One did wonder when African countries might appear on the map, especially North Africa, but Walt says not. Military electronics grew 6 per cent in the first quarter of this year, as did medical electronics that were also up 6 per cent, these are world figures. The communications market grew 11 per cent, cell phone sales figures take some absorbing – 960 million to be made this year!! Nokia is the leader, Motorola number two. There is no growth in the PC market; here Dell is the leader, with Lenovo No. 3. Taiwan is the place for PC motherboards, with much higher levels than in previous years. Semi conductor sales are 9.8 per cent up this year, and there have been four years of double digit growth driven by consumer electronics in the Far East.
Japan PCB shipments have picked up with high end boards; in China rising material costs are giving them headaches, with the major Chinese companies being owned by Taiwan, Japan and US investment; Europe is flat, as is USA, with Germany slowing down in the second quarter; metal prices are rising sharply, copper tin silver and gold are all up, and likely to continue that way. Electronic equipment growth 8 per cent this year, PCB production will continue to grow, mainly in China, and overall this year there will be growth, but it is slowing. Thanks, Walt.
Flemming Boisen came from Texas Instruments in Denmark to talk about the difficulties with 0.4 mm pitch components. Here the precision needed in defining the solder mask edge definition is critical, where tracks pass between holes there might only be a tolerance of 10 μm. Flemming neatly encapsulated the problems that need to be addressed when transferring what is a relatively simple 400um BGA land pattern on a CAD system to a PCB fabrication where acceptable yields of a HDI-layer board are essential. He summarised the design rules which needed to be followed so that the manufacturer has the physical possibility of making the board, and at an acceptable price.
Wolfgang Alberth is the VP at Isola GmbH in Germany. HF applications for base materials include mobile, automotive, networking, above 4.5 GHz is high frequency. Low loss laminates are typically required for RF applications that transmit at higher frequency (> 800 MHz) and higher power (> 10 W)) or that receive at higher frequency (> 10 GHz). The greater the distance of transmission the greater the signal strength loss, so it is copper versus wireless. Wolfgang explained in layman's terms the definitions of the terminology – dielectric strength, dielectric constant, dielectric thickness, loss tangent dissipation factor, etc. which was very helpful. The requirements for high- speed laminates are complex, but the lower dielectric constant, lower dissipation factor compared to FR4, the material has to have process simplicity, be available world-wide, and lower cost of ownership. Isolas IS640 product family goes a long way to meeting all of these.
Giacomo Angeloni is the R&D Manager of Somacis in Italy, and they have actually been using the Isola HF materials so he spoke with the voice of experience. What convinced them IS620 is that it is close to the performance of FR4 and yet has the HF characteristics that were needed. The laminate is good for blind via drilling, through hole plating, drilling and routing is similar to FR4, it has an increased yield in production, it was robust, and it is possible to mix with different materials. On the downside, cost was a factor, and it is difficult to set up the right parameters for press cycles.
Dr Terenzio Faccinetti is an Italian living in Germany, and working for UL, and i/c compliance in Europe. He explained the RoHS Directive, arguably the most expensive piece of legislation to impact the European electronics industry ever issued by those non-elected officials in Brussels. He said that there was a balance between compliances, costs, benefits and image. How do I know if something I buy is compliant? You may well ask. Due diligence, chemical analysis, and surveillance and audit are the tools to be used. You can audit the supply chain. There are more than a few challenges for those wishing to meet the new directive, needless to say all of them cost money. You will need to obtain and accumulate environmental expertise, material expertise, chemical expertise, and regulatory knowledge, and you will need to consider alternative manufacturing processes, new investments (in equipment) personnel training and information, long term assurance and RoHS audits. Phew. OK, much of that can come from consultancies such as the SMART Group in the UK, and others in Europe, but that is just the start, and you have now less than three weeks in which to make sure that you are compliant. For those present this was a useful paper in box-ticking where RoHS compliance was essential, and of great interest for those who have a part to play in the whole process of electronic equipment manufacture.
Inkjet Printing – a subject of eternal interest was aired by three speakers. Legend Printing was discussed by Hans Fritz, of SAT Electronic, who look after Printar in Germany. He maintains that inkjet printing will eventually replace most conventional PCB imaging methods for legend inks, solder mask and embedded components. Solder mask application is now possible with 100 μ definition. It may also be used for BGA and inkjet applied solder mask on conductors gives good coverage. Inkjet printing now has much improved registration, high printing accuracy and quality, and inkjet can be used for traceability, where the data related to the PCB can be stored as a complete manufacturing history as a barcode. This can be a 1D and 2D barcode, as well as flat text, but advanced product traceability is best in a 2D format.
Ing. Adriano Blason from New System srl came on to join in the discussion on inkjet in the PCB industry. Only since the mid-90s have printer heads been able to produce drop on demand technology, 30-40 pl, making legend ink application possible. Their first machine was introduced at Productronica back in 1999, so they have a bit of experience under their belt. Adriano was able to provide some useful advantages of inkjet printing against screen printing, which have been apparent for some time. Resolution is 70-100 μm, good enough for legend printing, and they now have 6pl heads which can give 50 μm lines, with UV curable inks, initially with white inks now but black and yellow are possible. Inks have to meet IPC-TM- 650 standards, and here New System is involved with Sericol, Coates, Peters & Electra as ink makers. For the future they will be looking at high speed machines using very high speed and grey scale printer heads, printing down to 100 μm with a 3pl head.
Inkjet in the field of etch resist application was also covered by Adriano. It's a single step; there are huge savings to be made on materials costs, capital costs against LDI are massively less, you can define 100 μm gaps and tracks now, 60 μm possible soon. Solder mask application is another thing altogether, where the printed resists has to meet known standards, and must be applicable to both rigid and flex. Perhaps this is a subject that should be serialised in EIPC conferences.
Dr Christian Buchner of Schmid Systems Technologies in Germany was concerned on the accuracy aspects. Their DirectMask DoD 800 system was described, with a production speed of 30s per side, a 760 × 760 mm print area, which can accommodate up to 12 heads, any make of print head can be used, and temperature controlled ink reservoirs (affecting viscosity control) are integral. Accuracy – alignment is done “on the fly”, and the system can accommodate all head makes, all ink applications. Working with Rohm & Haas, they looked at the requirements for solder mask. They have developed a hot melt black ink which replaces film artwork. The board is fully coated with solder mask, dried, and then the black ink or mask is inkjet printed on to the board where the image is required. The board is then exposed, and the black ink or mask and the solder mask beneath is developed off in a normal aqueous solution, the edge definition is excellent, with no undercut, no over or under-exposure, with resolution down to 50 μm.
Conductive Inkjet Technology sent along Mike Johnson to talk about inkjet metallisation technology. He said it's a new process – a solid inkjet system, an additive process, using standard digital inkjet printing, but now with a prior processing beforehand to put down a seed layer for plating with copper as an additive process. It can be used in all manner of applications. A UV curable non-conductive ink for piezo-electric jet has a dual role; it provides adhesion to the substrate, and provides an image. Resolution is now at the 50 μm line width barrier, but the system currently operates at 100 μm now which is fine. They are working with Preco and are using their expertise is in web-handling, on a system running at 30 m/min. Uniform film thickness with a smooth top layer surface is being achieved on their prototype machine which is up and running, providing a PET of 50- 200 μm thick, with 100um lines and gaps, and at a cost of one US cent for 10cm2.
But what about inkjet for flexible circuitry? This is a nice concept, nice to do but difficult. This is a two stage process. Initially, a digitally printed catalytic ink is applied, which gives the adhesion to the substrate; this is UV cured, then it is electroplated by immersion in metal ions, which puts pure metal down, and being metal it is stable, tarnish resistant, and you can solder directly onto the surface. Purely additive technology, it is inexpensive, but can be printed onto 3D parts, and it can be used as a reel-to-reel process. It is a digital process, perfect for prototype printing. Standard print heads – limited to 50 μm. Print a thin line; use a laser to cure what is wanted, down to 2.5 μm lines. Invisible conductors!
Paul Waldner of MIE knows a bit about the difficulties of resolution versus registration. This is economically important for obvious reasons. Smaller is finer, finer is demanding. Some clever stuff such as fully flexible multilayers for mobile phones turned out to be too expensive. So where is the middle line? You can go for finer gaps and tracks, or you can add more layers. Smaller gaps and tracks are fine, but how to do you hold registration AND resolution? Paul explained.
Customers want more quality for less money, and quicker. Paul opts for higher layer counts versus finer lines, and he gave to the delegates his argument for the economic advantages of more layers by an evaluation of various multi-layer constructions. The LDI process measures distortions, and offers great registration accuracy.
Frédéric Baradel is the Sales & Marketing Director at Automa-Tech who export 95 per cent of what they make, which is very healthy. What they make is automatic exposure machines, and for that they are probably one of the best in the world. The main drawback of exposure systems is the artwork. To find the best alignment between the panel and the artwork is an art form. You can use cameras, with a back-light system for inner layers, also for outer layers but with associated software. Frederic explained the coordination systems and how they work, with all the different parameters, dX, dY dT and dD. And then there is dE. Artwork, design, drilling – all are contributors (distance measurement). Glass artwork is the best way of obviating problems of temperature and hygrometry, you can control both in their machines using air on the glass. Cleanliness is of course next to godliness, always has been but always worth repeating. Exposing flex circuits is another “art” he said, and went on to explain the many considerations. In conclusion, their new UV printers are still taking significant steps to improving registration capability, their use is still continuing, and he sees their use continuing for the next 10 years. We'll see.
Anders Ekman from Huntsman talked about Probelec® dielectric and lamination technique for flex-rigid and rigid PCBs. They are used for an adhesive for bonding flex to flex or flex to rigid typically 2-030 μm after drying and also for use as a build-up material. A full epoxy 2-componment system, it has good shelf life/storage life can be used for laser drilling, good electrical and mechanical properties, LD180 cures at 180°C and LD 150 curing at 150°C. LD150 uses brominated flame retardants. Application is by vertical roller coater, or by screen printing (vertical or horizontal). Highly suitable materials for CO2 laser ablation speed.
Uwe Altmann is the LDI specialist at Orbotech, and he has been doing it since the technology first began at Orbotech. As a result they have a lot field experience, and he summarised their discoveries. Advantages were many. Yield improvement, better layer to layer registration, cost and time saving on photo tools; less plots, higher throughput and higher yields photo tool defects eliminated, better line quality due to better UV light uniformity, artwork costs reduced substantially; the process can be integrated with little disruption; better line width control. On rigid-flex, yields were up; getting rid of films helped speed up deliveries as film registration was no longer an issue; no dust, no defects on the layout, so yield increased. Definition was much improved also, with better accuracy of registration, 0.4mm pitch possible, against 0.6mm with film. No more photo plotting is obviously attractive, and registration of outer layers is much better, with tools that are efficient.
Werner Liebsch of Du Pont Electronic Technologies wanted to talk about something that is not yet available in Europe, so there's an appetite whether if ever one heard it. DMD, Digital Micro mirror Device. It's a new way of imaging, and with it you can image anything. 405nm is the operating wavelength. LDI eliminates non- repeating defects, and thus raises yields. For high speed production and for fine lines, they have produced two parallel systems – 355 and 405nm – LDI 500 is what it is called.
Manfred Suppa of Lackwerke Peters knows about solder masks, and obviously their reliability when exposed to contumelious thermal stress and thermal shock. In this regard the automotive application was illustrated, where a temperature range of –40- +150°C is experienced over 15 years, in some 240,000kms of driving, and about 6,000h lifetime for the electronics. So you need stability in 500-3,000 cycles of –40- + 140°C. Failure on account of thermal degradation is measured by the Arrhenius equation. Failure on account of thermo-mechanical failure is due to:
ageing process of the polymers;
loss in volatile components; and
The test criteria then becomes apparent. Peters have a LPISM that meets the demands, it is polyalcohol- developable, titled SD2469, and can be curtain coated.
Dieter Link of Huntsman was also concerned about soldermask usage in a hot area. Reliability is the key. The growth rate of electronics in automobiles is three times higher than the growth in car manufacture itself, so solder masks are a critical component. Probimer®65 halogen-free solder mask was developed to respond to these requirements, and has been tested for 3,000 and 33,000h at –40- +140°C. In addition to the demands of lead-free soldering (tested to 290°C for 90s), and consequent higher temperatures, the solder mask has to resist oils, solvents, aggressive fluids, and moisture resistance, has to be developed in biodegradable and recyclable solvents, and has to have high electrical values. It should not be affected by the freezing of trapped water, and adhesion must be good after 3,000h at 140°C. Chemical tinning also had no effect, and one pass on a curtain coater can give 6um edge coverage. For boards with higher than 250um track height they have gap filling system, applicable in one pass. It is solvent free, and will give a DFT of 400um in one pass.
Day 2 – Friday 9 June
Alfred Kaiserman is the AOI Products Manager at Orbotech, Belgium and started the day in the test and repair vein. There is a new generation of AOI, it seems, one in which the equipment is not so relatively expensive, and where much of the work formerly done by the operator is now done by the software. There are no more geometric false alarms as there once were; traditional AOI used the same sensitivity all over the panel which means that element functionality is ignored, and defects are missed. The latest systems decide if a defect is critical based on full multilayer panel understanding, so non-critical faults are ignored; there is no trade off. The new AOI systems understand the layout of the panel, based on CAD software, and assigns only suitable algorithms to the inspection process, called 3D logic. It analyses a wider area, not only the contour, and compensates for the traditional image acquisition limitation.
Richard Frisk is the President of Lloyd Doyle, a company known for innovation, and their application of optical test experience to 3D solder bump inspection caused a real stir at Productronica last year. Since then things have moved rather fast, and the system can now be used for a number of applications. Printed component inspection, microvia hole inspection and 2D and 3D bump inspection. The next generation of PCBs will have some form of active or passive component built into the printed circuit. Resistor printing will incorporate inspection to determine trimming, with the system predicting values accurately by developing algorithms which will detect faults in printed resistors, aerials, etc. Boards with 100,000 75um holes in them were often seen back in 2004, but now these boards will have 350,000 microvia holes with 40 um holes, even down to 20 um by the end of this year. So this calls for a different approach to inspection – buried viahole inspection; and outer layer controlled depth holes. The Lloyd Doyle AOI system is configured for high resolution for targets the attach side of the chip carriers as their first application, but this is scalable to wafer bump inspection by design. Richard described the workings of the interferometer which measures the height of the solder bumps, with 100 per cent accuracy. Lloyd Doyle has called this the IBIS – Interferometric Bump Inspection System.
Marc Hüske is the Innovation Manager at LPKF Laser & Electronics AG, Germany. Laser-based repair of circuit boards will be of huge interest; lasers are already widely used in the circuit world, for laser direct imaging, for laser trimming, in metrology, for laser direct structuring, and now laser based repair. Very thin lines and spaces make it more difficult to carry out repairs; mechanical tools are not suitable here, so their laser repair station is for manual use, it is easy in operation, is safe and clean, and has a “plug & play” system. You have to choose the right wavelength for repairs, of course, because you are repairing copper, which has a different absorption characteristic than the insulator. 1,064wavelength of the YAG laser appears to be the best frequency, and high pulse peak power is needed for ablation. The whole system is neatly encapsulated into housing, and the repair substrate is monitored by a CCTV and the laser by a joystick. Obviously a very effective production tool. It is called the Laser Scalpel. In conclusion he convinced us all that their ProtoLaser 100 is a good way of creating a prototype.
Acronyms abounded when Veronique Steukers of EBFRIP brought us up-to- date on TBBPA, the flame-retardant of choice for FR4 materials. Risk Assessment in the EU has an uncertain pedigree at the best of times, but Veronique explained how the system works (in theory at least) and how they had concluded that there were no risks to human health. Good news. One new FLA is REACH, a new one for us to learn, and an important one, too. It stands for Registration, Evaluation & Authorisation of Chemicals, and one that will affect anyone making circuit boards with effect from next year. Every single substance you use will have to go through REACH, but only once. Veronique told us that this is the responsibility of the manufacturer using the products, not the product manufacturer.
VECAP – Voluntary Emission Control and Action Programme – is designed to control the emission of chemical substances to the atmosphere. Chemicals may not belong in the environment, but they do belong in industry, but only someone who is the Head of the Competitiveness Aspects of Sustainable Development Unit, DG Enterprise, in the European Commission could run such a programme.
Jérôme De Boysère is the Marketing Manager of Clariant Produkte in Germany. Halogen-free PCBs are close to his heart, and they are important, with green electronics currently limited to consumer electronics items such as TVs, DVDs, PCs., etc. In Japan it is growing at 15 per cent p.a. in Europe 3- 5 per cent (no growth) in the States only 1 per cent but growing, Taiwan and China 6 per cent. Marked differences here. iNEMI have started a halogen-free Initiative, and the High Density Packaging User Group (HdPUG) has an update to their report on the environmental assessment of halogen-free PCBs. Jérôme discussed what “halogen-free” really means, and it turns out to be not quite what one thought, it's far more complex than that.
Neil Patton is the PTH Product Manager at Atotech Deutschland GmbH was concerned with the combination of halogen-free with lead- free PCB production. Listening to his paper one could understand why. It is a minefield. All laminates suitable for lead-free have phenolics in them, which gives a few problems in the processing. To assess if these materials were suitable, work has to be done; just saying “High Tg” is not enough. Neil listed the laminates which meet IPC 4101B specifications, but lead-free materials have less good copper adhesion, peel strengths are 25 per cent less than with normal laminates. For desmear, one needs to know the effect of phosphor, novolac, and fillers. There is quite a bit of resistance to desmear in laminates anyway but when you get to lead-free laminates the situation gets worse. High Tg = hard to desmear. Halogen-free laminates give a slightly higher Tg than FR4, but it is clear that environmental legislation has had a profound effect on the raw materials used in the industry, and PCB manufacturers have to take the testing of these new materials seriously, working with the manufacturers to obtain the optimum results.
John Swanson from MacDermid in the States came on next to talk about OSP coating selectivity. He described key coating and process characteristics in a lead-free OSP process, where performance expectations include durability in a high temperature lead- free environment. OSPs are popular because they are relatively low cost materials, but changes to the formulations of late due to the higher temperature requirements have led MacDermid to evaluate the way in which the OSP sits on the surface of the copper and their conclusion from their experiments is that the coatings with BZIM and metal compound 1 showed much less permeability to oxygen and thus better protection with superior solderability results.
Carmen Arribas came from Ormecon International in Germany, and they have a new OSP which she described to the delegates. Called Nanofinish®, it uses the properties of the organic metal polyaniline on copper surfaces, and produces an ultra-thin (50-100nm) uniform and planar surface coating using an environmentally friendly product technology. The product gives a clean layer, which has very low ionic contamination and supports fine-pitch device assembly. No formic or acetic acid is used and thus no odour is, nor harmful emissions are, given off; the process is extremely easy and offers a broad process window.
Grazyna Koziol coordinates matters at the Advance Technology Centre of the Tele and Radio Research Institute in Poland where they have been extremely busy working on lead-free PCB finishes in the lead-free soldering process. They chose the most popular finishes on the market, ENIG, immersion silver and immersion tin, as well as lead-free HASL. They used three SAC alloys, and three fluxes, one of them VOC free. They used circuit boards as received and some which had some heat-aging. By and large they got some pretty good results, and a more active flux appeared to give better soldering, and was better for solder joint integrity. The different lead-free finishes had no effect on shear strength, but there was some decreasing shear strength when the second side was soldered at 250°C. No doubt a huge amount of work had taken place over a long period of time, and the results were definitely worth listening to. Like many others she proved that a nitrogen environment gave better results.
Dagmar Metzger from Robert Bürkle told us all about their Quick Cycle Lamination process for lamination of circuit boards which she compared to a conventional process. Energy consuming process, the QCL lasts 25-30 min, 80 per cent of the curing is done in the press line and the rest in the curing oven. Loading and unloading can be done manually or automatically. QCL is a conveyorised system, with a temperature ramp-up of 100°C per minute against a conventional process where 3-5° per minute is normal, so it is obviously much faster, with a cycle time of 90s, which means 40 panels per hour versus a conventional press capacity of 10m2 per hour. Each panel is processed individually but with repeatable process conditions for each panel, individual panel tracking is possible, and throughput times are short. Quality is also improved, and thickness tolerance is ±3 per cent.
We had the pleasure of listening to Giacomo Angeloni from Somacis again as he stepped in on behalf of a colleague to give the final paper of the conference, which was an absorbing and detailed presentation on their experimental work with ion sputtering. There are two methods – there is physical vapour deposition, or chemical vapour deposition, both can offer a DFT of 0.5-3 μm, the key point is copper elongation – copper with low elongation is more susceptible to cracks and lower peel strength – but sputtering simplifies the deposition of thin films with uniform thickness over large surfaces, such thickness being easily controlled. His conclusion was to explain that whilst sputtering is as yet not 100 per cent effective, and is still hugely expensive, such that chemistry suppliers can sleep well at night, it is a methodology that has to be continuously evaluated as demands for pattern accuracy increase.
EIPC had organised a evening expedition to the ancient city of Venice, which allowed the delegates and their wives/girlfriends to hear from excellent guides much about the history, and even more about how the city survives in the modern age, with environmental pressures from both natural and man-made sources alike. In warm evening sunshine the guest bobbed across the lagoon in a chartered boat armed with glasses of prosecco, and later bobbed their way back whilst being served with a what seemed like an endless meal of sound Venetian cooking, with endless supplies of yet more prosecco. All very jolly, and only one guest hinted at a touch of mal de mer.
Another cracking EIPC Conference – an as-always sound technical content to the programme, always with excellent speakers throughout, held in a first-class venue. Congratulations to all concerned.
J.H. LingAssociate Editor