IPC LF & TN news from late September

Once again, I’m trying to catch up on my reading on the IPC Lead-Free & TechNet discussion lists. Right now, I’m about three months (!!) and 2000 e-mails (!!!!!). Here is some news dating from September 24 to September 29.

  • A couple of posters noted Ireland was the most likely country to initiate the first WEEE & RoHS enforcement actions, as it seemed Ireland was the most aggressive in identifying WEEE & RoHS enforcement as revenue streams.

    I sincerely hope this isn’t true, since Ireland was one of the shining examples of how well Europe could do if they were a bit more laissez-faire. This was so true that the EU was at one point discussing penalizing Ireland for having taxes that were too low and luring companies away from the rest of Europe.

    But I guess the pressure from the EU finally got to them ?

  • There is a note that Dr. Henning Leidecker at NASA is conducting a study on whether conformal coatings can mitigate tin whisker growth. I hope NASA gets good results, since everything I’ve seen up to this point says conformal coating doesn’t stop tin whiskers at all.

    There’s a very good presentation about that very topic located here. It was written by Thomas A. Woodrow & Eugene A. Ledbury, both from Boeing, and is titled “Evaluations of Conformal Coatings as a Tin Whisker Mitigation Strategy”. It was originally presented in April 2005 at the IPC/JEDEC 8th International Conference on Lead-Free Electronic Components and Assemblies.

  • A very helpful gentleman from NIST (National Institute of Standards & Technology) posted some information about using an XRF spectrometer to detect any of the substances banned by RoHS. The information was very helpful, and demonstrated that

    1. using an XRF to measure quantities of elements – as opposed to just detecting their presence – is a very tricky task, as some elements will absorb the X-rays given off by other elements, and

    2. if you are going to use an XRF machine to measure quantities, be very consistent about frequently calibrating the XRF machine with known standards.

  • There is a very large report on RoHS exemption requests, located here. It is 148 pages long and is written by the Institute for Applied Ecology, who was commissioned by the European Union to evaluate the exemption requests.

    Specifically, pages 35-41 describe the evaluation & discussion regarding cadmium in relay contacts. I am not going to quote the pages here, as they are definitely worth reading in their entirety. However, I will provide a summary, which is that the relay & switch manufacturers admitted they do not understand some or even most of their customers’ end-product applications; while there are some applications that definitely need the increased life-span of Cadmium Oxide contacts, the relay & switch manufacturers could not immediately name those applications; and the consultants’ final recommendation was that the exemption for cadmium in electrical contacts be re-evaluated in three years time.

  • Also, John Burke’s arguments regarding the banning of lead under RoHS were not even dealt with, as this would require evaluation not just of the technical aspects but also of the political aspects which resulted in lead being a banned substance under RoHS in the first place. While I can sympathize with the consultants’ statement that such an evaluation of the overall rationale for RoHS was beyond the scope of this study, I also feel that that consultant’s ducked the issue and that John Burke’s arguments did have sufficient technical merit that they should have been evaluated (and not just avoided).

  • There is ongoing discussion regarding which lead-free PCB finish is best. This discussion has been goning on for a while, and I’m not going to go into much detail here except to say that the answer depends very much on the environment the PCB is going to see during shipping, storage, soldering, and use in the end product. All of the finishes have their pros & cons. If you can get good product & good reliability out of a particular finish, then that finish works for you.

  • I saw an interesting note about military & high-reliability applications not allowing more than 500 volts between surface traces & the layers below if the PCB is made out of FR-4. The poster said that as you get into higher voltages, you have more chances of migration and other issues. At 1500 Volts, his industry would use PTFE as a PCB laminate.

  • There was an interesting reference to a way to reduce silver that involves baking soda, warm water & aluminum foil. (??)

  • BAE Systems, a European defense company, is developing lead-free ammunition. The story is on Sky news here. While this may be new for some types of munitions, some localities have been requiring lead-free shotgun pellets for years now.

  • There was also a link posted to a study on lead alternatives, carried out by the Toxics Use Reduction Institute. Interestingly, the study focused on ammunition used at shooting ranges, weights used for things such a fishing sinkers & tire weights, and heat stabilizers used for PVC wire & cable coatings. Lead in solder was not studied, partly since there are already a number of studies going on due to RoHS, but also because lead in solder only accounts for 0.5% of overall lead use, and TURI wanted to focus on applications that would have more immediate results. The study can be found here.

  • A question came up regarding whether banning of lead shot had actually been empirically shown to reduce lead levels in water. The response was that the deciding factor in the legislation had not been human consumption of lead. Concern was actually for other wildlife, such as predators (especially bald eagles) who would eat waterfowl that had been shot with lead shot, bottom feeders who would eat shot that had sunk to the bottom of lakes or streams, and waterfowl that would eat shot that was lying on the bottom of shallow ponds. One poster who is an avid sportsman said the Minnesota Department of Natural Resources, as well as similar agencies in other states, try to record all wild animals who are found to have died of lead poisoning, including birds, fish & mammals. That poster also said that lead shot has been shown to affect ducks, eagles, loons, terns, and other birds, with loons being especially vulnerable.

    Greg Morose, project manager at the Massachusetts Toxics Reduction Institute, noted that evironmental concerns for lead containing products are waterfowl ingesting fishing sinkers, indoor shooters being exposed to airborne lead particles in indoor shooting ranges, & soil contamination and sewer runoff from wheel weights. TURI’s report addresses alternative materials for all of those applications.

  • There was some discussion about the use of “patent pending”. When something is marked “patent pending”, that means a patent has been applied for, but it does not tell you if the patent has been granted, or if the patent was for a specific method, device, idea, or what. This link was posted for those looking for more information.

  • It is an interesting side note that lead shot in water may increase the lead levels in creatures living in the water, and may cause some health problems down the line, but silver powder thrown into a lake or pond will kill large parts of the ecosystem, as silver kills many of the small single-celled organisms that make up the bottom of the food chain. This observation has been pointed out by more than one of my colleagues.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s