SMART Group 7th Annual Lead Free Conference, High Wycombe, Buckinghamshire, 3 February 2005
SMART Group 7th Annual Lead Free Conference, High Wycombe, Buckinghamshire, 3 February 2005
Keywords: Conferences, Electronics industry
Over 200 delegates came to High Wycombe and were warmly welcomed by Peter Swanson, SMART Group Chairman. He outlined the days programme, and spoke briefly about the work of the LeadOut Project, a pan- European project helping companies move to lead-free. One of the members is ISQ, their Mrs Sandra Estanislau had flown in especially from Portugal where she heads up their lead-free team.
The first speaker was Nigel Burt, Production Engineering Manager at Dolby Labs in the UK. Nigel talked about the WEEE & RoHS legislation. The RoHS is a single market directive, which is binding on all member states. He reviewed the current status, and how to understand it all. From 1 July 2006, it will be the responsibility of the producer to ensure that only lead-free solder is used in the equipment. There are exemptions, which he listed, and these are currently being reviewed.
The WEEE directive is not a single market directive; there are different requirements in different member states. As a producer one will have to finance the end of life disposal costs, and be responsible for equipment already in existence. In this regard, the DTI has a good web site that is most helpful (www.dti.gov.uk/sustainability). The WEEE regulations will be incorporated into British law early this year 2005. Nigel explained about “maximum concentration values” and about“homogenous materials” (materials that are of uniform composition that cannot be separated by being cut, bent, abraded, etc.). You have to have a look at your own products and self-assess the situation. He also touched upon the work of the NCH, the National Clearance House, who offers a service to producers for their recycling targets. Refer to the Blue Book, he says, this lists all the definitions and explanations. Refer also, he commended, to the Envirowise guides, which are excellent.
As for other non-European countries, he stated that Canada now has similar legislation, and China is planning to implement legislation similar to RoHS and WEEE. Australia and the USA have taken a “voluntary” approach. Greece was the first European country to have adopted all the regulations into Greek law, but then Greece does not have a SMART Group, and nor do many other countries.
Bob Willis examined some design considerations for lead-free process compatibility issues. Bobs highly visual presentation highlighted many of the problems that designers face when creating boards for lead-free application. Boards deform, and they can sag and warp with the higher temperatures used for lead-free assembly. It can be a good idea to leave a 3 mm strip free of component (and therefore holes) to give a board better flatness. Copper absorption is another phenomenon, whilst there is an IPC which test allows for this, good design can help with fillet lifting, pad lifting, and tearing. Leaving some resist over the pads reduces lifting. Wave soldering can produce shorts, so it is important to consider pad pitch, and drainage for solders on pads. Via hole testing this has shown that 0.2 mm via holes do not give any problems in lead free. Bob also introduced the impact of circuit board finishes,since they can have an important influence on assembly yields and reliability.
Finally, he announced that there would be a SMART Group webcast on lead-free design for manufacture on 8 March, which will be sponsored by Indium Corporation.
Someone who knows about PCBs and finishes is Martin Goosey from Rohm &Haas Electronic Materials (formerly Shipley). Yes, the higher temperatures needed will impact on boards, and there are implications for solderable finish selection. The most popular alloys, SAC and Sn/Cu, both have higher melting points and thus require higher soldering temperatures. Laminates can be overcooked, and there are consequent problems; measling, a separation of glass fibres, blistering and delamination. Ionic contamination can also cause problems. One can use low-end materials, such as phenolics, and FR4 is generally OK. Higher Tg materials have better crosslink densities, and hence better stability, and FR4 laminates which incorporate phenolic cured resins are proving better for lead- free work. Interestingly, he said that there have been reports that 40 per cent of the boards coming out of China are halogen free.
Rework is important, so solderable finishes should be better than HASL, and have an ability to survive higher temperature soldering and multiple solder cycles. They should also be compatible with a wide range of solders. Other important considerations included solderabillty, shelf life, handling and cost. The popular finishes were OSP, immersion tin, nickel-gold, palladium and immersion silver. Martin believes that OSP and immersion tin and silver will predominate. Nicel-gold has the highest cost, while OSP is the cheapest, but immersion silver, the finish finding the most favour, is somewhere in between.
Vincent Synnot of the Flint Group commented that in the good old days soldering temperatures for tin-lead alloys with a melting point of about 1838C were fine, but now we are up to 2508C and above, and components can cook. The problem is not just the heat but also the absorption of moisture before the heat is applied. See IPC/ JEDEC j-STD-033A. Components should be stored properly or at least be dried before they are soldered. The transition to lead-free assembly is moving from a scientific and technological problem to one of logistics and inventory control. Do not underestimate the amount of work in the area, and bear in mind that some component manufactures will not have made the change to lead-free until mid- 2006. The industry will see accelerated obsolescence, some“grey” market alternatives and not surprisingly some counterfeit components.
This took us nicely on to Question Time. Here an august panel comprising all the days speakers fielded questions from the delegates.
Q. Are all other European countries taking it as seriously as we are?
A. Germany, France, Spain, Italy, Denmark, Holland, etc., are taking it seriously, Greece seems more relaxed, we do not know much about how they will enforce compliance. Most countries will comply, but there is no common “policing”. Large companies will enforce it, but not so sure about the little ones.
Q. Will anyone cheat?
A. No one is naming names! In the UK compliance is a big issue. The key thing is the ability of different sized companies to comply, where the small ones are not sure if they comply or not. Certainly there is a difference in interpretation between the EU member states. From a recyclers perspective, there are a great number of requests from overseas companies asking for help.
Q. All companies, especially SMEs, who are dedicated to meeting RoHS,deserve assurance from HM Government that competitive imports, the mass importation of goods, will also comply?
A. “Imports and their compliance are the responsibility of the company putting them on the market.”
Q. What would the panel consider as good practical advice to a PCB supplier on surface finishes.
A. Much depends on application. All finishes have good points and bad points, but do not refer to them as lead-free finishes, they are RoHS compliant finishes. ENIG is not necessarily RoHS compliant. Immersion silver is generally a good all-round finish.
Q. In the RoHS directive, what does homogeneous mean?
A. A uniform product that cannot be mechanically disjointed into different materials. It is not applied at a component level, but to individual plastics, to alloys, and even to coatings. The NPL web site is ideal for answers to such questions.
After an excellent lunch, the theme of the afternoon was Materials &Equipment.
Steve Dowds is the global product manager at Henkel. Such nostalgic names as Dexter Hysol, Loctite and Multicore all come under the Henkel name. But now its Henkel, and Steve looked at Reflow 230, alloys such as SnAgCu in its various forms, SAC 405, 387, 357, 305. The IPC – SPVC Report is awaited in which four alloys were tested, and analysed by Andrews Corporation, they found that in processability there was no difference. Thermal shock and thermal recycling results to be published in the next few weeks.
Is lead-free solder as reliable as Sn/ Pb? In bulk testing – yes; on real assemblies – ... At low temperature ranges and strain rate –yes. Under high temperature ranges and strain rate – no. Work continues in finding high reliability lead-free alloys for the automotive industry. CAVE– Innolot looking at lead-free for automotive application. Steve also talked about lead-free wetting, flow out, and spread. In the field of solderable finishes Steve likes immersion silver.
Steve highlighted the problems with CSPs. Mainly it is thermal stress, there is a high CTE mismatch. Testing for mechanical failure (i.e. drop tests) has shown that the reduction in solder joint surface area leads to a weakening of solder joint, and the smaller solder ball diameter and surface area gives weakness as the lead-free alloys less ductile. The use of an underfill is generally good and can help avoid some of these issues.
Gerjan Diepstraten of Vitonics Soltec come on afterwards, and took a long and detailed look at wave and reflow soldering. They have installed wire supports on their equipment to prevent boards sagging; however, the titanium fingers tend to pick up lead- free solders. His company prefers spray fluxing of VOC fluxes. In the preheating, one forced convection heater is good for VOC if reflow profile is to be followed and maintained. Gerjan went through all the materials, the product process and the solder equipment, with all the features and benefits explained. Good man is Gerjan, there is lots of help available.
Alan Brewin of NPL is always easy listening. He described the new work being done at NPL on the fatigue of lead-free solders. It is the CTE mismatch that causes fatigue failures, and they have spent 9 years of work to try and understand where the failures take place. Tests are made by applying known forces to solder joints, then examining the side view of test pieces, testing solder as they use it. SAC and SnPb are different animals when it comes to sheer strength. NPL has a huge number of members working on the lead-free transition project, and are looking at the effect on reliability of PCB structures with tin as opposed to lead-free processing.
Alan Dukinfield knows about waste. He runs RID UK, and he offered some practical solutions to compliance. Alan painted a less than rosy picture of recycling in Europe; the Netherlands recycle 50 per cent of their waste, the UK a pathetic 13 per cent. Under the new Landfill Directive, whereas there were 239 sites before, now there are 10- 15. Given that we fill the equivalent of a Royal Albert Hall a day, we have a problem. This is where companies such as his come into play, and Alan took some time to explain how one needed to register with an environment agency for waste disposal. He painted a very clear and detailed picture of a WEEE Structure. RID can help companies who have to register, and who have waste to dispose of. The process is complicated, it is the CENELEC Standard has to be obtained, and that is a lengthy process. Producers will be responsible for all new goods that have to conform to the WEEE directive which go on the market after August 2005. The last holder of an item will be responsible for all WEEE wastes, and users themselves will have to segregate all wastes and disposes it separately. Much work to be done, it all lies ahead.
For more information, visit the web site: www.smartgroup.org
In the afternoon there was a further Question & Answer session, which proved that whilst there were too many questions to be posed in the time, there was no shortage of expert response from the professionals on the panel. Good to know that this wealth of expertise exists. Let us hope that it is fully appreciated (Plate 2).
Plate 2Speakers at the SMART Group Conference
One of the speakers at the Seminar said that there were now another 18 months to go to 1 July 2006. He had become involved in lead-free 7 years ago, and thought that there was plenty of time. Now there isnt, which is probably why the room was full to bursting (Plate 3). Much to do, so little time to do it in. But the UK has the SMART Group, so there is no excuse for anyone being not up to the mark on the day. For the next annual conference they may have to find a larger venue. The Royal Albert Hall, possibly?
Plate 3The event was well attended
