The Smart Group 8th Annual Leadfree Seminar – February 16, 2006

Citation

(2006), "The Smart Group 8th Annual Leadfree Seminar – February 16, 2006", Soldering & Surface Mount Technology, Vol. 18 No. 2. https://doi.org/10.1108/ssmt.2006.21918bac.002

The Smart Group 8th Annual Leadfree Seminar – February 16, 2006

The Smart Group 8th Annual Leadfree Seminar – February 16, 2006

Keywords: Conferences, Surface mount technology

At the customary venue of the Wycombe Wanderers Football Club ground, Bob Willis welcomed the 160+ delegates to the seminar, and mentioned that he will once again be running the lead-free experience at Nepcon. Just making sure everyone is on the ball.

Routes to RoHS compliance was the title of the first paper, given by Neil Stanton of BSI Product Services who talked about his involvement with the IPC610 kitemark, and the RoHS kitemark. The end product must comply after July 1st, and we know the maximum concentration values, do not we? We know, do not we, the eight product categories, and the six substances and we know that the Statutory Instrument 2005 is No. 2748. We may also know by now that NWML are the “enforcers”. BUT we do not yet know the full list of exemptions, the full definitions of exemptions, and, furthermore, can we believe suppliers declarations? Do our customers want compliant products? So, how to ensure compliance? Possibilities include the following:

• Believe all declarations? Complex issue, no certain answers here.

• Take random samples? How many, and are they representative? Which test method do you use? Many will slip through the net.

• Trace every component to source? Prohibitively expensive, and very time consuming.

The best course of action is to take all reasonable steps, use reliable and trusted suppliers wherever possible, evaluate all suppliers, and ensure they understand what RoHS means.

File documented evidence to show the enforcement body. Undertake risk assessments on all components backed up with analysis where appropriate. Ensure process and controls are in place. Communicate with your customers, always a vital strategy, and always review, update and improve. www.rohs-kitemark.com is a good web site. www.rohs.gov.uk is another one.

RoHS readiness – a progress report on suppliers & customers was given by Alan Lund, of RS Components. His company manages 250,000 lines that are sold in the UK, where they are strong in the R&D, maintenance and repair fields. Their web site accounts for 35 per cent of sales, which is interesting. They sell 220,000 components, which have had to comply, from 800 suppliers, Inc. semiconductors, connectors, cables and fixings. The role of the distributor is to:

• alert customers to RoHS;

• obtain and disseminate compliance information; and

• “cleanse” and maintain the integrity of the supply chain.

They have run several RoHS events, and they have a very good web site which covers the subject, and which permits customers to raise questions and receive answers. Their RoHS Guide has been very successful in the UK and has been translated into 12 languages for use around the world by demand. 830,000 copies have been sent out so far.

They have also published the status of every component, in all eight defined scenarios. They have a dedicated team within RS, handling huge number of enquires from all over the world, especially Japan. Customer concerns include:

• Part number changes.

• Compliance information, where and how to get it, and confidence in these statements.

• Availability – compliant components, and non-complaint components.

• Enforcement and due diligence.

• Costs of change – administration, process, materials, stock write-off.

• Where is the hype? Will everyone else be ready?

Component availability is key to achieving RoHS compliance. Changing a part number is not the panacea. In conclusion – RoHS is as much a logistical issue as a technical one.

Lead-free user experience. Nigel Burtt is the Production Engineering Manager at Dolby Laboratories, who make electronic equipment for the music and entertainment industry, and they are very active in meeting the deadline by converting all their equipment over to lead-free. They have a very well equipped own in- house SMT line, All products manufactured in the UK and, placed on the market after July 1, must comply with the directive. BUT if it is manufactured in the USA and is to be used as part of a UK manufacturing operation it does not have to. Part numbers are a pain, of course. The Dolby Part Number system was explained. Components such as zinc- passivated screws contain hexavalent chromium, so even screws now have to comply. Written evidence from a supplier is insisted upon. For SMT part numbers they need details such as max lead-free reflow temperatures, and moisture sensitive levels, with one or two exemptions. In the States, they are worried about reliability in lead-free component populated boards.

Dolby have moved from FR4, on to Isola FR408. They have found that yellow legend ink is more popular than white and that peelable resists have their place, too. They are mostly using SAC387, also playing around with aperture designs, which for lead-free have to be specific. They introduced the process in 2005, and were running with lead-free in summer last year. They employ separate benches and tools for lead, and lead-free areas. Nigel imparted a lot of useful information covering experience with soldering irons, and the complete assembly and rework process. All metal objects have been subjected to the salt spray test and all have passed quite happily. They have designed a custom test vehicle with Topline, so far all appears to be going well.

Complying with international patent obligations was the subject of a paper from Steve Brown, of Cookson Electronics. Cookson have devoted much time to considering which alloy to use. Tin/Silver/Copper alloys in the end tend to fit the bill for most people, but they are three times as expensive. Considerations included melting point, wetting speed and force, thermal fatigue resistance, mechanical strength, fluidity, and raw material cost have to be accommodated. Happily most companies have concluded that the SAC alloy was the favourite. The SAC alloys, 405, 396, 387 and 305 have varied origins, but it is SAC305 which is gaining the highest usage.

Intellectual Property Rights are going to be vigorously challenged in the USA, and Iowa State University have the patent for SAC for solder joints in the USA, and for solder Senju in Japan. Royalty payment requirements apply in both cases. On a DVD writer with a hard drive, as an example, the finished product may cost some £250. There is a Royalty cost at 5 per cent, which has to be paid once. But if you pay at the soldering stage, and not at the finished goods stage, it is but a fraction of the cost. However, if you do not know where the product are gong to end up, how do you determine which royalties are payable?

Steve said that you should show, if challenged, who supplied the solder materials,. Compliance with IP is required at the point of sale of the finished products – solder material in Japan, and electronic devices in the USA. An interesting situation.

IPC-SPVC Comparison of SAC Solder Compositions was made by the avuncular figure of Steve Dowds, from Henkel.

SPVC aims to reduce the confusion regarding alloy choice and is devoted to achieving a worldwide consensus on the issue. As a general rule, the Japanese have focused on 3 per cent silver alloys, Europeans on 3.8 per cent and the States on 3.5-4.0 per cent alloys. Steve described the test vehicles, and their suppliers. No significant difference in assembly performance, no difference in assembly was noted. Good wetting for all alloys, with no difference in size and shape of solder joints, but there are more voids in SAC alloys than in SnPb. In thermal cycling, thermal shock exposure all showed no significant difference based on silver content. No evidence that solder joint voiding contributes to solder joint failure. BUT does void size contribute to failure, or the number of voids? No, was the answer. But some lessons were learned.

Lead-free assembly does require extra effort but is entirely “do-able”. Immersion solder finish OK, FR4 OK. Packages susceptible to CTE stress tend to fail earlier. IPC SAC 305 is their solder of choice.

There followed a Q&A Session, at which various questions were posed to the panel of the speakers. One question, should the audit trail be on paper or may it be electronically written? Either would be acceptable. Another – what Tg-based FR4 materials were tested at Dolby? High end product was tested. Another – what is the trend with vapour phase soldering? About 5 per cent but less than 10 per cent. On eof the Panelists said that the RoHS is a single market directive, and if member states give a national interpretation to that then the EU Commission will take action. But it has been difficult to get precise answers. Really?

After lunch, the papers were aimed at bringing people up to date with technologies involved with lead-free. Alistair Watson from Seho talked on soldering equipment in use today. Is lead-free soldering a capable process, or just a problematic one? Well, there are about eight common problems with solder joint reliability, for starters. Fast de-alloying of various elements, wettability, then there is the flux – higher temperatures, a sustained activity, a wider process window is required, are just some of the problems. Solder temperature is now run at 2608C as a compromise, but can components withstand higher than that? But at 260 you need a higher contact time, and here quartz shortwave IR make good heaters, and lead-free solder needs nozzle geometries with higher velocity and turbulence, which give good wetting properties, a reduction in solder balls, and improved heat transfer. Remember that nitrogen will reduce the dross at higher temperatures, but the higher amount of tin can attack the solder pot. Cast iron is back in fashion here.

How the advantages of using vapour phase for lead-free reflow can impact your production was demonstrated by Joachim Krause, of IBL.

IBL recognised the importance of nitrogen in reflow soldering, and they have been at it for over 20 years now. The changes taking place in solder alloys has led his company to examine the difficulties in applying them, both in thermal terms, and with wetting. If you compare convection reflow to vapour phase reflow, you see the heat transfer is more effective in the vapour phase system, with good heat transfer through out the whole assembly. There are no CFCs, it is not dangerous, it is non-combustible, and there is less risk of pop-corning with BGAs. Vapour phase soldering is now available for producers of large boards, and the gas atmosphere guarantees the best possible soldering with lead-free.

Max temperatures needed are at 2308C. There is no overheating of assemblies; best possible wetting, larger process window, uniform temperature distribution; excellent heat transfer, with no CFCs and repair of BGA is easy.

Advantages of Nitrogen for lead-free were indicated by Paul Stratton, BOC. Nitrogen is probably the most cost effective solution to lead-free soldering. Nitrogen reduces drossing, and it is that reduction in dross that is sufficient to pay for the nitrogen. There is a lot of bonus here – better yields, as nitrogen improves wetting, with less solder balling. Nitrogen wave soldering is very popular in the Far East. It improves wetting, pad coverage, can reduce the soldering temperature, improves second pass solderability (no oxygen) you get cleaner, shinier joints, and it improves the pullback of misaligned components. In tests they were getting 0.875 per cent defect rate, in a case study. A clear winner, it seems.

RoHS – 5 months to implementation was the firm reminder served by Abigail Cottrell, from the DTI who came along to bring the delegates up to speed with the developments taking place between now and the dreaded date. There have been 50 exemption requests, and the results will be given by the TAC (Technical Adaptation Committee) meetings on web site by the end of the month. ERA Technology were asked to bring out an interim report in the Spring on exemptions in Categories 8 and 9. No measures before 2009. There is an informal network of EU RoHS Enforcement Bodies, with 14 countries now involved, working together on a uniform approach. They have produced a guidance document.

What happens on July 1st? Producers will have to “self-declare” which means that by placing your products on the market you are saying “ I comply” and it will be assumed you do. But if you do not then beware. The NWML will be after you – www.rohs.gov.uk is an invaluable document to make sure that you sleep well at night, and that everything is ticketyboo in the factory. If you have sub-assemblies which are not yet compliant, but which are going into the EU, they have to be compliant. If they are going into equipment that is not to be sold in the EU, then they do not have to be RoHS compliant.

Analytical Test Protocols for ensuring compliance with the EU RoHS Directive. Paul Cusack, Soldertec Global. Paul ran through the background to it all, and spent a little time looking at where lead, mercury, cadmium, and hexavelent chromiums are used, PBBs and PBDEs as well. Sampling considerations are screen tests, pre-treatment and verification tests. First line of testing includes X- ray fluorescence, which can determine levels of banned substances contained in the sample. But if you have a problem, then ring Paul, as his company offer a RoHS compliance analytical service which will reveal all.

A final Q&A Session saw out the meeting until tea-time. The SMART Group ran a survey during the day where the delegates were asked to complete a form in which various questions were asked. The response was revealing.

The following questions were asked and 69 delegates responded to the questions:

1. Do you believe you are exempt from the Directive?

Yes=37

No=24

Uncertain=8

2. Will all your products be compliant by July 1st ?

Yes=15

No=22

Uncertain=14

3. If “No” or “Uncertain” what percentage of product do you estimate will be compliant by July 1

< 10%=12

10%=4

20%=1

30%=4

40%=1

50%=7

60%=1

70%=3

80%=5

90%=7

4. What is your greatest challenge in being non-compliance by July 1?

Availability of lead-free and tin/lead components=27

Compliance issues=10

Cost of stock to support spares=5

Customers=4

Transition to lead-free=3

Reliability=3

Moisture sensitive devices=2

Rework and repair=1

Comment not classifiable=3

A reminder, if needed, of the next major lead-free event=the IPC/SolderTec Global Joint Lead-Free Conference, 25/27 April – Malmö, Sweden. For more information, please visit the web site: www.lead-free.org.