EIPC Summer Conference Stockholm June 9th and 10th 2005

Circuit World

ISSN: 0305-6120

Article publication date: 1 January 2006



(2006), "EIPC Summer Conference Stockholm June 9th and 10th 2005", Circuit World, Vol. 32 No. 1. https://doi.org/10.1108/cw.2006.21732aac.004



Emerald Group Publishing Limited

Copyright © 2006, Emerald Group Publishing Limited

EIPC Summer Conference Stockholm June 9th and 10th 2005

EIPC Summer Conference Stockholm June 9th and 10th 2005

Keywords: Electronics industry, Conferences, Printed circuits

Day 1 – 9 June

EIPC Chairman Paul Waldner welcomed the many delegates to the 2005 Summer Conference. He maintains that conferences are about meeting people as much as they are about learning from people, so he got everyone on their feet to say hello to one another. That was the easy bit; getting them to sit down again was something else. Paul talked about the success of the recent Technology Trip to China for the CPCA show, and now the EIPC are doing the same thing in Hong Kong in conjunction with the HKPCA at the beginning of December. In October 27th and 28th, there is to be a joint IPC/EIPC TMRC in Berlin, and a Call for Papers has just been issued. He reminded everyone that EIPC has its bi-annual General Meeting coming up which will be held during Productronica, and a new board of directors will be elected, as well as a new Chairman. All members are most welcome. His recent trips to Korea and Japan showed that the technology there is outstanding, with FPC in a whole class of its own, when it comes to equipment and technology. The world is now flat, says Paul, when it comes to competitiveness; Europe no longer has the advantage; the use of call centres and other information tools makes it all possible for everyone to do anything, anywhere. That includes us all.

Walt Custer looked at the present business conditions, including the supply chain effect, and the shift to Asia; difficult times for us all. Sure, there is growth in electronic equipment, manufacturing has moved up from $1,218billion dollars in 2004 to $1,312billion in 2005; Europe makes 19 per cent of world electronic equipment, but the situation in the States is not so good. Happily inventory levels are now down to where they should be, with no huge stocks anywhere. The period 2005-2006 shows a slowing but not a disaster. In the telecom sector, the top six companies have shown 12 per cent growth over 2003-2004, Ericsson up 12 per cent but margins slim, and the cell' phone market will be some 750 million units this year. In market share, Nokia enjoy 30 per cent and continue to be aggressive, Motorola have 16.8 per cent, and they are the two giants. He showed us how SkyPe works, immediate free telephone access to your laptop. Wireless is getting faster, now there are air cards; Asia has about 45 per cent of the world's chip consumption, and the assembly market shifting worldwide with Asia growth in this sector of, again, 45 per cent. He mentioned Elcoteq in Finland as an EMS company that is going places. Of the 3,000 PCB companies in the world, 1,000 are in China, 400 in Europe, and 500 in the USA. Japan currently running flat, but of course China is showing linear growth. However, less than 10 per cent of companies in China are indigenous, the remainder are all there through foreign investment. Europe PCB production is led by companies such as AT&S, Aspocomp, and Eltek. Capital expenditure in the PCB industry will be negative for the next year, but interestingly Central Europe is emerging as a major EMS sector.

Mats Ehlin came over from Du Pont PCM in the USA, but as he was born in Stockholm he felt quite at home. He wanted to discuss dry film photoresist technology for profitable PCB production, and began by looking at the value of European PCB production. What are the value drivers? They include quick turnaround service, local military/defence, medical electronics, a need for high product mix, demand for local production, some design involvement, and applications with advanced intellectual property. Competing with China is not a recipe for success, to do this you have to be extremely capable. These attributes include production flexibility combined with a broad capability, a short set-up time, real processing, “zero” defects, a high resolution capability, use of thin materials, sound possess technology know-how, and an ability to make strong personal relationships and instil brand loyalty. He explained the QFD – quality function deployment – process where customers determine the relative importance of attributes, low cost and high yield being the outcome. Where should the focus of your offer be? Direct imaging resists are technologies that offer easy start-stop capability, and for the highest possible yields.

LDI is a reality; there are now100 systems operating worldwide at the leading companies. LDI offers production flexibility with yield improvement, and their Riston LDI500 is a product they have brought in to meet the demands for maximum benefit. Mats described the semi-additive process, where 15 mm lines and spaces after plating are obtainable with an accuracy of ±1 μm. Customers claim a 5 per cent reduction in yield loss with their products.

Stephen Street works for UL International in the UK, Environmental legislation world-wide is increasing, with WEEE, RoHS and ELV in Europe, the CA Prop 65b in the USA, the Asia Pacific Green programs, and corporate social responsibility. The power of green consumerism should not be underestimated. It all impacts upon information technology, telecommunications, consumer electronics, and domestic appliances. If your products are used in these applications then you need to know about the RoHS directive, which he went on to explain.

For the record the limits are:

  • Lead – MCV – 1,000 ppm.

  • MCV 21,000 ppm.

  • MCV – 100 ppm.

  • Hexavalent Chromium – MCV – 1,000 ppm.

  • PBB – MCV – 1,000 ppm.

  • PBDE – MCV – 1,000 ppm.

Homogenous materials are termed as materials which cannot be mechanically disjointed into different materials. As to who enforces it all, this should be announced shortly. It might be your competitors! He described test methods to detect restricted substances, and took a look at UL796, a test that, for a new laminate, takes a year and costs $40,000. The new designation for FR4-like materials is called IPC4101A, and the proposed groups are being classified as:

  • brominated epoxy laminates;

  • non-brominated epoxy laminates;

  • and

  • epoxy blend laminates.

The UL Restricted Substance Compliance Solution acts as type of buffer between the suppliers and the customer and the regulator and is where UL offers risk management, compliance and cost avoidance. This is a low cost single programme to meets the needs of producers and eliminates the need for suppliers to participate in many test programmes. Available at: www.iqdata.co.uk.

So begin thinking about making your products greener; use your environmentally friendly attitude as a selling tool, and always keep an eye open for new technologies;

Thomas Sutter is the R&D director at Rohm & Haas Electronic Materials, and presented his thoughts on advances in inkjet materials. R&H has several digital imaging programmes running, and are active in the graphic arts field. They have been busy looking at solder mask inkjet applications as well as etch resist. With solder mask they need fine pitch solder pads need to be defined, and to explain how this is important he made a comparison between hard tooling solutions against inkjet application of soldermask.

R&H have taken a different approach, with a hot melt water-dispersible process, and he explained how it works. The circuit board is pre-cleaned, then coated uniformly with solder mask and pre-dried. The vision system then captures the fiducials on the board, and coveys this data to the inkjet head which will then scan the board and apply U/V blocking solder mask to the desired SM openings. The board is then exposed and developed, so that you have a finished board with clean SM openings or pads. The advantages are that quite conventional coating can be jettable, and there is no need to re-qualify a “special” resist. The system is compatible with dry film or liquid solder mask. The Inkjet UV blocking mask has variable drop volume and shape, and the hot melt technology gives you great versatility. He showed the lab scale Spectra Galaxy print head, which had defined 500 mm pad width, with 200 mm dams. There is no image distortion under vacuum pressure in a PC printer; the first prototype will be ready for testing later this month, with optimisation of the process during the third quarter this year. They will therefore be demonstrating this exciting new system at Productronica.

Harri Latonen came down from Aspocomp. What are the drivers and trends in OSP surface finishes? There are several: reliability; repeated mechanical wear, all devices run the risk of handling, impact, etc. ergo solder joint failure. Then there is the environment, with RoHS; materials management, process management, and managing lead-free assembly, where solder joint reliability is critical. It is a complex situation with many different parameters, and surface finish options are many and varied. Most are good, some are limited, but none are perfect for all applications. At Aspocomp they have been producing selective finishes for the last 5 years, and whilst lead-free soldering reflow profiles depend on the application, typically they are 20-40°C higher than in normal soldering. In considering material selection, the parameters of laminates have to be taken into account, as are the processing aspects. Are they compatible? Most often the answer is yes, but you do need to specify your requirements, and not rely just upon manufacturer's claims. The thermal expansion of a laminate can impact upon component retention, and higher melting temperatures can cause higher DT. Reflow during the assembly processes can be as many as three times, all at higher temperatures, so much depends on application. At Aspocomp they use a copper-selective OSP process called Entek Cu 106A(X) HT. Field testing of soldered examples showed that up to four reflows could be performed without detriment. In conclusion he stated that both OSPs and NiAu can be used for reliable solder joints.

Katsumasa Suyama hails from the Espec Corporation in Japan, Well ahead of the European RoHS directive, they have been using Sn-Ag-Cu (SAC) solder alloy since 2001. However, aware of the difficulties placed upon assembly by the higher temperatures, they have been running tests with Tin-Zinc-Bismuth lead-free solder, on an OSP surface finish. In a detailed presentation, Mr Suyama he concluded that in high temperature testing Tin-Zinc-Bismuth showed a lack of joint strength against SAC, with Sn-Zn-Bi resistance decreasing after 530 cycles, and failing after 650 cycles, whereas others passed 1,000 cycles. SAC cracked after 1,000 cycles, and SZB peeled at toe. It was Ni-Pd-Au that looked good for intermetallic compound (IMC), and is much better for solder joint strength.

Orbotech-Schuh GmbH sent along Harald Eppinger to tell us about how they test lead-free soldering with AOI. Reflection values can change with changes in process, brightness of solder joint, etc. so they needed to create a “model” which would give them a comparison between lead- containing and lead-free solder joints. Orbotech tested component presence, position of solder joints, and focused on BGAs on their test panel, being able to look under the BGA, In lead-containing and lead-free solder joint comparisons, solder joints looked more matt, were darker, and more grainy. Lead-free soldering can be astonishingly good, with the differences in reflection due to Pb-Sn being only small recognising problems in advance. The differences between Pb-Sn and SAC are hardly visible, but tests have shown that with 3D AOI on reflow solder joints there are no problems, on wave soldering no problems, and with pick and place there are no problems, either. Their technology can live with the lead-free requirement.

Jurgen Friedrich of ERSA talked about lead-free flip-chip and chip scale packaging designs, which require a new inspection technique. The tiny solder joints for CSPs always crack on the component side, not on board side. Why? Well, different materials have different thermal expansion characteristics (CTE), with huge differences, up to six times that of the component that sits on the board. It is that CTE mismatch that leads to shear strain at corners of solder-joints. So how does lead-free change anything? The process temperatures are higher; the lead-free solder joint solidifies at a higher temperature. Is there an alternative to a non-destructive test? Yes, happily there are now some new microscopes available on the market that allow inspection of bottom joint, and look up at the top joint, which is more important. Problems come with not the heating up, it is the cooling down, you get just as much stress during cooling as you do in heating, so the risk of component side ball delamination will increase with a lead free process. To see is to survive. As the saying goes, you want your customer to come back, not your boards.

The man from Nokia Technology Platforms, Finland came to tell us about how they manage data flow for PCB design. His name is Tero Kärkkäinen. They use Gerber RS274X or RS274D, Excellon NC and design rules check (DRC). For embedded resistors, they use thin film technology, such as Ohmega Ply, and thick film polymers. For embedded resistors they have to bear in mind space saving on the surface of the PCB, there are potentially better signal integrity costs savings (resistor density is the factor here) and improved application reliability, i.e. fewer solder joints. We are now seeing a new kind of detailed information for PCB manufacturing, which includes resistor value, resistor tolerance, material definition and power handling capabilities.

Data flow automation is therefore needed to avoid human error, and whilst what we have now is an old format such as IPC-2581, happily this will lead to a new standard called IPC 2584, which although not ready yet, is needed before embedded resistor technology production can enter mass production. The way forward is for embedded capacitors, embedded active components, and embedded optics, and all of these are setting up new challenges for design data infrastructure, so there is a need for better data transfer between OEMs and PCB manufacturers.

Martin Cotton is a designer, too. If he was not in circuits he should be in haute couture, such is his style. Sanmina-SCI has this concept about RFID. By replacing bar codes with RFID means that you are adding value to the chip, and thereby you remove price pressure from the system. If companies such as Flextronics are starting to look at RFID, then we should be looking at it too. If you bury an RFID into an item, it cannot be removed, which offers great security. This “label” could be mounted on a PCB type laminate. There is no connection to the PCB; the PCB is the carrier. RFID can “revolutionise the pipeline”. By embedding the RFID system into the product, you can offer “tracking” through the whole manufacturing process, through assembly sub-assembly, shipping, retail sales and consumption (purchase). The RFID chip can act as a sensor, and you can have it as an active, or passive component. RFID can be used during the product manufacturing process or through the product lifecycle. It can be used as a third party interrogator, using wireless. It changes the PCB supplier from a service provider to a product developer; it is both a production device, and a security. We are not talking labels; here we are talking PCB opportunity. RFID is part of a LAN matrix, like the internet. Needless to say a lot of questions to a lot of interesting ideas.

Marcus Bärtele is the man from EADS who came to talk about embedded passives in BGA interposer structures for avionic applications. He described the differences between avionics equipment, which in its overall format demands include very high density for assembly, high data rates, minimum weight, operates in harsh environment, has to be highly reliable, and has to have a long life, more than 25 years. It will be maintained over long periods, it must include state of the art manufacturing technologies; there are a wide variety of them, with low volumes per lot sometimes. System considerations include thermal a management, manufacturing technologies, miniaturisation, embedded components in interposer PCBs. It is with these BGA interposer structures that bow and twist is one of the problems that are encountered, Before balling it is stable between -50 μm to +150 μm, and the assembly process of double pack (IP and BGA) does not negatively influence the component. Mr Bärtele explained the steps for the assembly process of a Double (Interposer) Pack, and it is by this means that they have created a balanced CTE between the BGA and the PCB. They have, of course, used lead-free solder between the two interposers,

Frando van der Pas is the face of Enthone, and looked at the new reliable generation of PCB surface finishes for lead-free soldering applications, a subject about which he is obviously passionate. He stated that HASL really is not a starter, and of the other processes the usage is currently as follows: immersion Silver 63.3 per cent, Immersion Silver 31.1 per cent, ENIG only 3.5 per cent and OSP 19.0 per cent. He claims that immersion silver and OSP will grow at HASL's expense, and HASL will decline, as it is a difficult alloy to control, and lacks the capability of providing a planer finish.

ENIG has many advantages, including a durable finish, with good shelf life. It is wire bondable, and easy to test, but it does have relatively high costs and is not reworkable, important in the lead-free solder field, but on the other hand it does demonstrate inconsistent solder joint strengths.

Immersion tin is relatively low cost, good solderability, is compatible with lead and lead-free solders. Tin whiskers are of course a major limitation, and horizontal process equipment is expensive. Furthermore, the process is difficult to control.

So, on to immersion silver – and a new generation. What are the advantages? It has relatively low cost, is a highly solderable finish, it does not affect solder joint reliability, and is already in use in some lead-free pastes. It is compatible with solder resists, and all “no clean” assemblies, is wire bondable and has good colour. Limitations might include silver electromigration, but it is, however, readily oxidised. He explained how Cookson have improved bath life and stability, deposition speed, thickness deposit rate and have reduced sensitivity to drag-in contamination, etc. Performance has been improved for SMT reflow, wave soldering, and wetting balance, and it is highly compatible with SAC. The electromigration figures looked good, tarnish resistance was much improved, even after 6 pb-free reflows. Cases of galvanic attack were examined, where solder mask undercut and poor side mask adhesion, corrosive environments such as etching. They have developed a new chemistry that minimises solder mask undercut, with a milder pH, called Entek plus HT for Pb-free. They also have a new Organic Solderability Preservative (OSP) for lead-free, where the advantages include the highest joint strengths, with good solderability. But it is not wire bondable and there are some contact resistance properties. Less robust than thick metal coatings, this new OSP give a PCB a 12-month shelf life, and by careful consideration of parameters it will be perfect for SAC adhesion.

Next on was Hiroshi Otake is from Uyemura who knew about final surface finishing for lead-free material solder joint applications. The process ENIG and ENEPIG were described, the latter is ideally suited for SAC alloy solder materials in which higher solder joint reliability was recorded. ENEPIG showed continuously good test results whereas ENIG did not, when under extreme conditions of frequency of application and high temperatures during multiple reflow. ENEPIG gives a uniform, thin and even IMC layer with SAC, giving better adhesion, bond integrity. ENEPIG is very good for solder reliability where SAC alloys are used in continuous high volume production.

Don Cullen is from MacDermid in Connecticut. He discussed the effect of lead-free surface finishes on solder joint microvoids. The use of a powerful X- ray will always show where you have voids, but how are they caused? You have different finishes, at different temperatures, for a start. Microvoids are usually seen along the foot of the solder ball where it sits on the conductor, and can be caused by insufficient temperature during solder reflows, by oxides on sliver underneath, by solder mask contamination, by tin contamination, machine oils, foams, etc. It came down to cleanliness, surface preparation, and surface finish. Flux gassing on Ag showed higher outgassing than with gold. The causes and creation of microvoids was explained at length and in detail, it has much to do with processing, the creation of microvoids can be minimised by running thinner film of solder, from 0.15 to 0.45 μm. No one simple answer to a complex problem, as Don told us.

Dr Peter Meeh of MacDermid GmbH spoke to the conference about the application of test methods and comparative results for immersion tin, immersion silver and ENIG. Another MacDermid man, but this time from Germany. They are using a MUST II solder wetting balance from Concoat in the UK and a test coupon for measurements with the solder globule method. He demonstrated how they run their test methodology, and described what they were looking for and what they had found. All three surfaces are compatible with lead-free solders. The solder globule method is a sensitive method for the examination of surface finishes with lead free solders, and he concluded that ENIG, immersion silver and immersion tin are compatible with lead-free solders; all of them have their own characteristics. However, all the samples were made under production conditions so this is not just another laboratory report.

Day 2 – 10 June

Markus Willie of Ruwel AG told us that his company has been making flex-rigid boards for 30 years now, and whereas before the application was for the military and avionic industries, now it is for the automotive and communication sectors as well, the more so. Schoeller Elektronik started it all in 1974, they are now part of Ruwel. Flex-rigid boards can eliminate many connector or solder joints that are potential sources of failure, and a complete wiring system can be replaced by a single flex-rigid board. They weigh less and occupy less space, and have uniform properties. Flex-rigid also allows for a decreasing amount of space being used to best effect.

Ruwel have “Multiflex” which are hybrid constructions consisting of flexible and rigid substrates laminate together in layer counts of choice. Interconnect is through plated via holes, you do, however, have to have a symmetrical build-up to minimise bow and twist. Some panels are best constructed during manufacture with a rigid layer which contains a snap-out section that can be removed after assembly. Multiflex boards can be made in sequential build-up and high-density interconnect techniques, so an 18-layer flex board is possible, “Semiflex” is another possibility, which is where the flex element is only required for installation, rework or maintenance. Only ten bend cycles are allowed, but this is usually enough. Finally, he came to “Yellowflex”, which is something new – a halfway house between the two former concepts. Instead of using a flexible copper clad polyimide foil (or similar) they use a copper sheet selectively coated with a flexible polymer material, which is laminated onto the rigid board material. This build-up can then be processed as a normal PCB.

Daniel Kush of Pacothane Technologies was another American who came across from New York to bring us up to speed with the problems encountered with the use of coverlay films in flexible circuitry. It is the squeeze-out of adhesive that takes place during lamination that causes problems, and with increasing circuit density the mount of surface area lost to accommodate adhesive squeeze-out is pushing current materials and processes to the point of failure.

His company had embarked upon a test programme incorporating all known materials, through set test conditions, but with a number of material combinations, and had concluded that the best of these was to use 1.5 mm reinforced red rubber with optimised conformal-release film 125 μ thick.

Giacomo Angeloni is the R&D Director at Somacis in Italy. In what might arguably be rated as the most inconclusive paper of the conference he went into some detail about the complexity of obtaining accuracy and reference for laser hole drilling in SBU boards. Not his fault, of course, it is the nature of the beast, there are so many different factors that can influence the accuracy that the mind boggles, and the enormity of the problem is not confined to any one phenomenon. The warp and the weft of the material used in the substrate, during both C-stage and B-stage, the Z registration, the X-Y registration, all contribute, in varying percentages, and of course the larger the panel the more the problems are magnified. How best to deal with these problems? Pray for more stable materials, or go and play football if all else fails.

Marc Hüske of LPKF Laser and Electronics AG brought the question of laser cutting flex and rigid PCB materials to the conference, and when one considers the diversity of shapes manifested in hand-held electronic devices, you can see why such a method is gaining increasing popularity. However, it is not without its problems. Laser cutting offers great advantages, you can cut assembled boards, you do not need tools to cut coverlays, and you can cut any shape you wish, out of any material. However, you do tend to get carbonisation during cutting, which gives conductivity problems, and you will get loss of definition.

Wolfgang Alberth of Isola GmbH reminded us that we need to find niche markets, and here it is the flex and semi-flexible markets. Flex has a growth rate of 12 per cent per annum. Really something to be looked at in Europe. Main sector is computers, then display, then communication, etc. A $6billion market in 2004. By region Asia produces 56 per cent, Europe only 3 per cent, Japan 32 per cent. One interesting market sector is automotive, and maybe European companies should now be putting more R&D effort into this sector. Ninety per cent of the materials used in flex is polyimide, which might a little bit “over the top” for some applications. Using an alternative film would be more cost effective. Perhaps what we want is a semi-dynamic film. After all, polyimide was not exactly easy to buy last year, was it? This new material has to be double-sided, based on epoxy, and would allow freedom of design. The good news is that this product exists; it is called Duraflex and is produced in some volume at the Isola plant at Bottegone in Italy. Good news all round. It has a Tg of 1508C, cu peel strength of 1.3, and can be used for reel-to-reel production. Thank you, Isola.

Halogen-free laminates – worldwide trends, driving forces, and state of play was presented by Dr Adrian Beard of Clariant GmbH. Oem strategies, environmental concerns, flame retardants, all pay a part, FR plastics are used in 30 per cent of all plastic production, less than half is halogenated. BFR is the main plastic used in electronics. There is balance between safety (flame retardants) and the environment, the traces of PBDE in breast milk has been alarming, and flame retardants have been banned in certain applications. Brominated flame retardants have been found in farmed salmon, but where does it come from? Risk assessment on TBBPA is expected by the end of 2005. End of life, scrap, waste, etc. what are the options? Recycling is something of a cottage industry in China, but the impact on the environment is of somewhat larger significance. Environmental discussions have resulted in legislation which has been brought into effect in Europe (WEEE/RoHS) but the situation re Deca-BDE is blurred. WEEE 2002/96/EC demand separation of plastics containing brominated flame retardants. But discussions which are driven by a mixture of scientific and emotional behaviour are rarely conclusive (the use of nuclear energy in the UK for the generation of electricity as a case in point) so the industry has had to take the initiative and has moved towards halogen free options. However, a study on these for the PCB industry was inconclusive. Companies do tend to abide by legislation, however, not only from motives of social responsibility but also to preserve their good name. Many of the world's leading OEMs have now committed to going down the halogen-free route, there are developments in new halogen-free raw materials, Clariant have Exolit OP, as do Chemtura, Supresta, and new halogen free resins are available from Huntsman, Dow, Bakelite, etc. Park, Matsushita have halogen-free laminates for PCBs available, and 20 per cent of Chinese PCB exports are now halogen-free. The USA is now beginning to consider halogen-free products, but in Europe there is little activity. Halogen-free is a market, so halogen-free PCBs should account for 3-4 per cent of the market. Perhaps we should be getting on with it.

Erik Bergum is VP Sales for Polyclad in Europe and was on next. How to chose laminates for lead-free was the subject of his paper. Not all laminates are suitable for lead-free. With the higher temperatures that pertain to lead-free, thermal stress is a factor. Whilst a higher Tg is generally better for lead-free assembly, that is not in itself sufficient. It is the Td, the decomposition temperature that is getting increasing attention.

Polyclad put together a team of nine people from all over the world to look at what laminate would “do the trick” and simplify the process. They have colour coded, so that an immediate “go-nogo” guide is available. Within that guide lies a range of variables, such as surface finish, lamination cycles, layer count, blind and buried vias, etc.

There are five different materials, with a Tg ranging from 140 to 180°C, and a Td ranging from 320 to 350°C. Erik showed how each laminate fitted into the possible specification on the colour chart, and it all made perfect sense.

Young Gao is a market development manager at the Advanced Circuit Materials Division of the Rogers Corporation. His paper was based upon the impact of PCB material dielectric properties on high-speed digital systems, from a designer's perspective. He drew our attention to the laminate material possibilities, and which ones might suit the designer. High-speed digital transmission is rated at 2.5 Gb/s, and most now run at 5 Gb/s, but systems operating at 10 Gb/s and higher are on the horizon. Whatever the transmission medium, signal distortion exists. This can be due to amplitude reduction and dispersion. The former is measured in dB, and the rise time in picoseconds (ps). So, for better transmission, you need better signal integrity. The “eye” diagram shows both time and amplitude, from which you can see that the wider the eye, the better the signal. Signals have formerly been in analogue format, up to 2 GHz, and microwave .2 GHz, but now digital transmission gives better band width, and is more tolerant of distortion. In the selection of a laminate you have to bear in mind that signal loss can be traced to dielectric and the conductor. So, low loss material is important. Thus a laminate with 59 ps and 472 mV is superior to one with 112 ps and 208 mV, it has a wider “eye” but with the same input. As an example, Rogers RO4350 without a connector has this wide eye, the same laminate without a connector is has a narrow eye.

EIPC chose the gleaming tower of the Scandic Infra City Hotel at Väsby, where inside all was light, air and open space. The facilities were excellent, and the Dinner and Tour of Stockholm gave the delegates a welcome break for an evening of relaxation and an excellent dinner at the Wärdshuset Godthem restaurant, followed by a look at the city by night, all memorable experiences. Another high-quality EIPC event, and maybe, just maybe, the word is getting out – a 30 per cent increase in the number of delegates is not happenchance.