EIPC winter conference

EIPC winter conference

EIPC winter conference

Cannes, 12-13 February 2004

Keywords: EIPC, Conferences, Printed-circuit boards, Electronics industry

EIPC Chairman Paul Waldner welcomed over 100 delegates to the EIPC Winter Conference. Not that it felt like winter, Cannes drummed up some nice warm sunshine for the 2 days such that coffee and a chat could be taken on the hotel terrace underneath the palm trees. Inside the Montfleury Hotel Conference room the programme unfolded to help delegates adapt to a changing PCB world.

Thursday, 12 February

The first session, chaired by Paul Waldner of mie (Plate 1), was entitled Management Overview, which covered a rather wide range of topics.

Plate 1 Paul Waldner receives a gift

The first speaker was Walt Custer (Plate 2), who tends to look at the industry from the top down, which gives him a pretty good view. Reflecting that 2002 was a year of massive change, with a major shift to Asia, a huge build-up in China, and a strong dollar, change in the world was hardly a surprise 2 years later. That China was 18 percent up in a year back in industrial growth would startle no one, but there were certain industry sectors that merited comment.

Plate 2 Walt Custer

The automotive field grew, and continues to grow, predictably. The Government and military sector was bolstered by events in the Middle East, so the 12 month aggregate is OK. The electro- medical sector, including measurement and control, is a good business to focus on, it has kept going and companies in it have done reasonably well.

As for communications, well, the bottom fell out of the market in November and December last year and Walt does not know why – this sector includes mobiles and data comm. so there may have an overestimate in usage, he confessed. The cellular phone market is booming, computers are booming, replacing notebooks especially, and the market growth is back in double figures. In the EMS field Jabil were up 39 percent Solectron down 9 percent. Celestica down 19 percent, but the overall growth is 9 percent. EMS revenues up to $170 billion, Asia has 43 percent of that, and North America has lost the most.

In the PCB field, Taiwan is now back to 2000 levels, and the projected growth in China is massive. The industry is starting to climb out of recession, the good technology companies are doing well, and demand is for a lot of high-end boards. Happily, nurturing suppliers is now fashionable, and you could not say that 6 months back.

Cef Gonzales presented a paper from Du Pont entitled "Changing the business model to compete with Asian suppliers" and he illustrated the beginning of his talk with examples of the "bully boy" tactics pursued by OEMs. It was important to know who you will not deal with, and pick the right market segment. You also need to have a contingency plan. The reasons why companies failed were examined – poor market intelligence, reacting too late, poor or wrong business plan in place, also denial "this can't be happening"! With the PCB now regarded as a commodity, i.e. it is no longer strategic, and with PCB sourcing migrating at China, you need to define what will go and what will not. In Europe's favour in this changing world lie several factors – communication, language, time, short supply lines, local knowledge and culture and the same or similar cultures. So, for those who might be pondering the problem of a shifting market, the five-letter acronym DMAIC would be useful – define the problem, measure data, analyse data, improve and control. Or in the words of some business manager – change the business model but move to China!

Tarja Rapala-Virtanen from Aspocomp then spoke about the trends in build-up board technology, the drivers and the trends. The drivers were coming from the semiconductor side with conductor widths and/or pad sizes of 10 μm. The trends since 1970s have moved from any layer count to any layer construction with embedded components. Such that we are now into the fourth generation of board design with via in pad and 75-80 μm lines and spaces with 0.20 mm buried holes. Design freedom is possible, with microvia on microvia. There used to be many process steps for conventional 8-layer boards, but now process flow only adds one step. Experiences at Aspocomp with any layer build up boards have only been possible with supply-side partnership, and in such manner is the challenge of microvia technology met.

Advanced HDI PCB design inspection and plugging was the title of the next session, chaired by Joachim Zimmermann from Robert Bosch

Flemming Boisen had come all the way from Texas Instruments in Denmark and looked at advanced micro-via PCB design. The requirements for this included a low count of components, low cost of components including the PCB, the need to avoid long lead times for components, and an ease of change – most mobile phone designs take place when one model is in production. Just too late, not just in time!

Embedded components may also be another way to reduce material costs, RF parameters and impedance needs, where using Via-in-Pad minimises the loss factor, track width and height tolerance. Dielectric thickness tolerance is important; we need it to be ±5 μm, with good via hole inductance, essential for large ground plane cutouts. Materials can include FR4 (Laser drilling type) as well as RCC and some advanced materials to include flexible laminate.

Can you use FR4 for high-frequency? Yes, you need to use 1,800 MHz material. PCB assembly line needs include dimensional stability during component placement, no delamination during multiple soldering operations, and must be compatible with lead-free soldering operations.

Richard Frisk, president of Lloyd Doyle, discussed the optical inspection of micro-via holes. Over the past 22 years, Lloyd Doyle had been developing AOI equipment for bare board, and he looked at where the product is today. There were many different analysis methods, and if you bore in mind the fact that there were 100,000 holes in the average 450×650 panel, that meant that there were 200,000 holes that need to be correctly formed and correctly inspected. This also applied to filled microvias as well as. Holes could be oversized, undersized, misaligned, grossly misaligned, blocked or missing altogether. Looking for these holes in a new MVI system was achieved using different analysis methods from conventional circuit optical test but incorporating pixel-counting algorithms in designated areas. Three different fault criteria are used for determining faults:

1. 1.

   Offset – positional defect outside an operator defined limit;

2. 2.

   Likeness – similarity to a "known good hole";

3. 3.

   Contrast – the contrast of all samples to "known good hole". If contrast values change, then the variation is beyond the operator set limit.

One wonders why there is no AOI certification already as a standard. It sounds essential.

Mark Lefebvre, Research Manager of Shipley LLC looked at the Periodic Pulse Reverse acid copper plating technology and described a model for PPR throwing power which included a brightener deficient surface, a brightener rich hole, and a combination of high throwing power with bath stability. Work is in hand to improve PPR bath stability, and improve thick panel throwing power (for boards up to 8 mm thick). Their approach to product development included a modified additive and waveform. Stability improvement was achieved with a modified additive package, clever bath analysis and by- product management. Mark showed many examples of the by-product effects, with 92 percent throwing power – the results were very good, with a stability index of over 10. A thicker panel is more difficult to plate, he said, but the next generation of PPR exhibits excellent thermal shock and cycling performance. Given the familiar problem with corner cracking, he noted that no barrel cracking was experienced with a test of 6×10 s at 288°C.

Bert Reents of Atotech Deutschland was on next to talk about production processes in horizontal and vertical technology for blind micro-via filling.... He has been with them since 1996, and has been working on the production processes and parameters for copper plating blind micro-vias since 1997. They are looking for higher reliability, smaller dimensions and better thermal management. The different non-plating parameters can have a significant influence on filling quality, such as the size, the aspect ratio and the shape itself, drilling quality; base material – always a problem; PTH – poor. Surface distribution is the most important factor. Most of the DC and standard electrolytes with soluble anodes have a lifetime problem, the root cause being the breakdown of brightener products. He went on to look at the horizontal Inpulse process that minimised the breakdown products of anodes. Inpulse 2 is for horizontal plating and filling of BMVs, and for vertical plating and filling of BMVs it is applicable for pattern, semi-additive plating and panel plating and through holes with gold. Conveyorised lines have better distribution but here, naturally, some investment is needed.

Friday, 13 February

The first session of the day was entitled Progress in PCB Imaging Technology and was chaired by Giovanni Tridenti, MD of Somacis

The first speaker was the energetic Frédéric Baradel, the sales and marketing director at Automa-tech. Automa-tech has been going since 1991 and employs 135 people in the manufacture and sales of a unique range of exposure units, LDI, both automatic and semi-auto. They have 350 automatic exposure units installed worldwide. Of manufacture in France, 95 percent is for export of which 86 percent is for the Asian market. Mr Baradel explained all about which was the best imaging technology for a particular product. He compared the various light sources – scattered, direct, collimated etc – and moved on in a highly professional delivery to an investigation on how laser direct imaging energy was released. He told us about the process influences on inner layers, outer layers, solder mask and conformal mask, the need for cleanliness and good housekeeping in an area of paramount importance, not only for quality, but also for yield.

That led to Hans Fitz from his company SAT talking about inkjet technologies in the PCB industry. He said that as batches are getting smaller and smaller, and quantities too, cutting tooling costs is important. Digital printing is applicable in many manufacturing steps. He told us that Legend ink printing accounts for 2-3 percent of production costs and the application of and processing of LPISM accounts for 10 percent. Solder mask printing is the real challenge to the industry. Hans showed how ink jet works how inks behave, how the interchange between drop size and velocity is critical. There is a delicate balance between negative pressure and the miniscus formed within the nozzle so stationary heads are better than moving ones, given that satellite drops follow the main drop anyway and you needed to avoid ink wander. A thorough and interesting look at ink-jet application.

However, Stephen Jones at Invotec knows a thing or two about high resolution inkjet printing for HDI PCB manufacture. He has been doing it for some time now, and his paper took us through the process. Stephen Jones dislikes artwork; he dislikes its' instability, says it is creepy stuff. LDI, he said, gets rid of artwork. Conventional photo tooling and imaging processes are at the boundaries of their capability. But LDI is not being accepted as fast as it should due to ownership costs. Inkjet printing is a conceptual alternative with the potential of substantial process cost reductions. Inkjet printing is a direct CAM to image on-panel, and that is what is needed. Here was the voice of experience speaking, with a lot of practical hands-on and highly detailed analysis of what is needed to make the system work. For imaging it is good, for ident it is OK, for solder mask it is some way off and as for inner layers they still have a long way to go.

On the other hand Russ Crockett from Du Pont wondered why LDI imaging continues to expand and he explained that as the industry is driven to more and more complex circuitry, so is the relative speed at which LDI is penetrating the Asia/Pacific market. It does offer some cost reduction combined with yield improvement, production flexibility, and waste reduction. Fundamentally, it meant no phototools, and Russ looked at the pros and cons. There is no faster way from CAD to image, and accuracy and finer lines are all part of a first-pass- yield utopia that LDI brings to those who see the system as one which gives them a competitive advantage. LDI is the ultimate registration tool.

In last session of the morning, entitled Developments in PCB laminates

It was Sylvia Ehrler from Multek in Boblingen, Germany who explained to the conference the lengths that her company goes to, to ensure that the laminate they purchase is the laminate that does the job they want it to. She took us through the study that she had made of high frequency base materials, and showed a comparison of their thermomechanical properties. Customers need higher T_g materials, and some of the new "high frequency" or "low loss" materials were put to the test at Multek, with some interesting results. In a maze of test results it became clear that they had identified two out of ten samples submitted as being "fit for use" after testing for peel strength, time to delamination, solder shock, and pressure cooker. Somehow one felt rather sorry for Sample H, it had been tough.

Dr Manfred Cygon expounded on a new base material for high-speed digital and RF applications from Isola AG, through a detailed presentation he demonstrated that by skilful molecular modelling, it had been possible to develop a base material for high frequency circuits which not only had a very good price/performance ratio, but which also had superior signal integrity, a low loss factor, outstanding dielectric properties, tack free prepregs and could be processsed using conventional FR4 technology.

John Andresakis from Oak Mitsui Technologies said that work at his company on materials for embedded capacitor applications had been proceeding very much with lead-free in mind, given that solder float tests were now running at 288°C >200s. There was no one material that meets all demands placed upon it, but he presented a comparison of the results obtained with filled and unfilled systems using ferroelectric particles in polymeric ultra-thin substrates. The result has been the production of a material, close to the ideal price, which has a flat loss factor, excellent impedence, and very good damping and low noise levels, with superior signal integrity. It appears that unfilled thin substrates are what are required for embedded capacitors.

Rogers Corporations' Cliff Roseen discussed the suitability of their LCP laminates in sequentially built additive multilayer circuits. This technique favours chip packaging substrates and HDI flexible circuits, though higher thin layer count constructions using the excellent properties of the LCP dielectric. Radar and MEMS applications also benefit from increased multilayer capability. LCP laminates exhibit good SAC soldering, can be recycled, have gone as high as ten layers and have a 290°C melt range.

The final session, chaired by Paul Comer, of Graphic Plc, covered lead-free challenges and PCB surface finishes

Ed Greenwood, who runs the Alchemetal Corporation, peered over the lectern to tell us all about a wunderkind product called AC78. This is a nickel-loaded polymer that you can print on to any substrate you can think of (provided it tolerates the cure cycle, presumably). Once cured it is electrically conductive, can be electroplated, can be soldered to, and acts as an RFI shield on non- metallic surfaces. With this product, he claims, you do not need solder to make your connections, you can get rid of the lead and meet all the deadlines for lead elimination. Yes, well. AC78 has been evaluated by the US Navy who found that it met all the key objectives that were set out, with good adhesion, a dry film surface resistivity of 0.65 Ω/sq/mil and 1000 h rust protection. Solderless attachments can be achieved by marrying components with the coated substrate and curing them simultaneously, but we were not sure about temperatures here. AC78 is currently being evaluated for multilayering, and we await further news with interest.

Charlie Kerr hails from Tin Technology in the UK and told us about a project carried out as part of the Sustainable Technology Initiative funded by the DTI. The Tin Strip Project, as it is known, showed that the UK PCB industry produces significant volumes of waste tin in stripping solutions. This waste tin is consigned to landfill; however, landfill is not desirable and there is a need for more sustainable chemistry and recovery technologies. The landfill directive in the UK (originating, of course, from Brussels) means that the number of landfill sites in the UK will reduce from 218 to 34, and at present there is insufficient waste treatment capacity and a dearth of waste treatment companies in the UK. Moreover, the landfill tax, currently £15per tonne, will rise to £35 per tonne from next year. Against that cheerful background Charlie Kerr went into a look at all the potential recycling technologies that are available, including acid reclamation, tin oxide removal, and membrane filtration. Much work is needed before any system becomes commercially available, and when it does it is likely to be expensive. Happily a good number of dedicated people are currently working towards a truly sustainable tin stripping process.

Dr Martin Bayes works with Rohm & Haas Electronic Materials, and thus was perfectly placed to inform the delegates about the effects of electroless nickel deposit composition on Electroless Nickel-Immersion Gold (ENIG) process performance. The ENIG process has grown significantly over recent years, and it is well placed to continue the growth path with the advent of led-free soldering. However, one of the problems associated with the ENIG process is a solder joint failure in which defective solder joints exhibit substantially reduced strength. The failure occurs at the solder-electroless nickel interface, revealing a darkened nickel surface, which is now referred to as "black nickel". Dr Bayes showed how, with an increase in the phosphorous content to 8-10 percent in the nickel layer, the gold coverage uniformity improves significantly, such that oxidation is impaired. It is this oxidation that is the root cause of the problem. Thus, by increasing phosphorous content in the immersion gold process, using a stabiliser system that allows for consistent performance and good bath control, black nickel defects are substantially reduced.

Dr Peter Meeh came to Cannes from MacDermid GmbH, and put up a very good case for the use of immersion tin as a proven final finish for circuit boards. Immersion tin provides for reliable soldering, and only a marginal formation of tin whiskers. No one wants tin whiskers, but there are preventative measures that can be taken in the immersion tin process. In a most comprehensive and detailed presentation Dr Meeh showed how the employment of the MACstand HSR/3 process for immersion tin now gives excellent corrosion protection of copper for long periods of storage (3 years+) yet lends itself to component soldering with both conventional and lead-free solders.

Still in the chemistry session, Sven Lamprecht from Atotech Deutschland pursued a topical theme with his presentation on the relationship between immersion tin thickness for lead-free soldering and solderability. SnAgCu (SAC) alloys are set to become the alloy of choice in the lead-free soldering world. The higher temperatures that SAC alloys require means that there needs to be a thicker tin layer, otherwise if the tin available is converted into the Sn/Cu intermetallic compound, such that no pure tin is left as a solderable layer, the wetting behaviour will dramatically decrease. For multiple soldering processes this is vitally important. Sven's detailed presentation showed precisely why the required tin thickness for multiple reflow soldering should be 1.2 μm for good pad wettability.

A final paper, from Michel Brizoux of Thales Research and Technology in France showed the experiences of a company working in the military electronics field with tin finishing to replace nickel-gold. Tin is a good challenger, mainly because of flatness, press-fit compatibility, it is lead-free, has low cost, and gives good solder joints. Michel looked back at their experiences with HASL, ENIG, and OSP, and their work with immersion tin, which, he maintained, should soon become a good alternative. It meets all their criteria, there is no "black nickel" and it is brittle- fracture free. However, whisker prevention is still an issue, and ionic contamination (fixed at 0.3 μg eq. NaCl/cm²) as a Thales standard is more difficult to reach because of contamination entrapped in holes and under the solder resist, and this is difficult to remove in a standard process. However, technical specifications have been established for the use of Sn finish on Thales circuit boards, and this confirms the move towards this particular metallisation process.

This had been a comprehensive, well-considered conference, with the world-class papers taking the many delegates through the key stages of new PCB technologies, as well as giving a view of the state of the industry and how it should react to the changes taking place (Plate 3).

Plate 3 Delegates at the EIPC winter conference

Plate 4 Delegates enjoy a social evening at a local Cannes restaurant

EIPC have proved once again that their reputation for hosting first-class conferences is entirely deserved (Plate 4). Contrary to some misconceptions, Cannes in February is in fact an ideal venue, and the arrangements made by EIPC for the many delegates who came were flawless.

John LingAssociate Editor