DAMN!!! I was sitting here chewing on a big chunk of it! :-0 >>> KD5NWA <[EMAIL PROTECTED]> 05/02/06 10:26AM >>> Be careful, a metal compound and the metal itself behave totally different. Metallic Bismuth will cause kidney damage among many other issues. It is not a safe metal to ingest.
At 10:11 AM 5/2/2006, Bill Guyger wrote: >Hi All > >This is totlly off topic, but the Bismuth - Lead connection caused >me to remember that there was a company in the building I work in >that was developing Bismuth Shot Gun Shells. Their theory which >seemed to be logical is that Bismuth being heavy like lead, would >create shot that behaves more like lead shot from a ballistic stand >point than did steel shot. And.........if you happened to consume a >pellet eating the game you brought down with the Bismuth shot, it >wouldn't be toxic like Lead. After all, What's Pepto Bismol made of >but Bismuth? > >Bill (the other one) AD5OL > > >>> "Ahti Aintila" <[EMAIL PROTECTED]> 05/01/06 10:49PM >>> >Bill, > >A minor correction to your statement: "Another posting by Ahti Aintila >to the reflected has suggested an alternative, but if the components >are tin plated only, then the formation of tin whiskers will occur." > >Actually I suggested bismuth as the alloying material for replacing >poisonous lead, preventing tin whisker growth and lowering the process >temperature. The problem with eutectic Sn-Bi is the low melting >temperature (+139 deg C). That is the reason for the separate Bi layer >over tin and a new soldering process that Prof. Kivilahti is calling >Transfusion Bonding. > >I completely agree with you that the present lead-free solder alloys >with Sn, Ag, Zn and Cu DO NOT completely eliminate the whisker risk. > >73, Ahti OH2RZ > > >On 02/05/06, William Bordy <[EMAIL PROTECTED]> wrote: > > >>Problems with tin whiskers have been around a lot longer than RoHS > > >>(perhaps > > >>as far back as WW II?). It presents a problem with reliability of > > >>equipment > > >>designed for low cost production, with no budget for > re-engineering, sure. > > > > >>But for the rest, it's not so clear. > > > > Yes, as the listed WEB explains, tin whiskers have been around a lot longer > > than RoHS. But, as the below excerpt from the WEB site, > > http://nepp.nasa.gov/WHISKER/background/index.htm , explains, it is > > believed that no-lead solders will increase the risk of tin whiskers. > > > > " > > Why the Recent Attention to Tin Whiskers? > > The current worldwide initiative to reduce the use of potentially hazardous > > materials such as lead (Pb) is driving the electronics industry to consider > > alternatives to the widely used tin-lead alloys used for plating. For > > example, the European Union has enacted legislation known as the > Restriction > > of certain Hazardous Substances (RoHS) and Waste Electrical and Electronic > > Equipment (WEEE) Directives which have set June 2006 as deadlines for > > electronic equipment suppliers to eliminate most uses of Pb from their > > products. It is widely believed (though reasons remain somewhat of a > > mystery) that Pb when alloyed with tin imparts whisker-inhibiting > attributes > > to the final finish. > > > > With respect to factors such as solderability, ease of manufacture and > > compatibility with existing assembly methods, pure tin plating is seen by > > the industry as a potentially simple and cost effective alternative. In > > fact, many manufacturers have been offering pure tin plated components as a > > standard commercial (and in some cases high reliability) product for years > > while others are exploring pure tin alternatives for the very first time. > > Many electronics manufacturers have never heard of the phenomenon of tin > > whiskers and therefore, may not consider the risks of tin whisker growth > > during the validation of new plating systems. > > > > Continuing reports of tin whisker-induced failures coupled with the lack of > > an industry accepted understanding of tin whisker growth factors > and/or test > > methods to identify whisker-prone products has made a blanket acceptance of > > pure tin plating a risky proposition for high reliability systems. Still, > > organizations such as NASA and the DoD may soon be faced with few options > > other than pure tin plating since the desires of the commercial market for > > environmentally friendly components carry far more weight than the > > infinitesimally small market share of the high reliability user. > > " > > > > There is a wealth of information on the tin whiskers problem at > the NASA URL > > I listed. I won't repeat it here, but I would suggest that those, > (I suggest > > anyone who buys consumer electronics should be), who are > interested read the > > information at the URL and resources suggested. > > > > To simply say it has existed, does not resolve the believed increase of tin > > whiskers due to the use tin plated only components and the use of no-lead > > solder. > > > > Another posting by Ahti Aintila to the reflected has suggested an > > alternative, but if the components are tin plated only, then the formation > > of tin whiskers will occur. The NASA WEB site does not propose a sure fire > > solution and in fact, exceptions are made for mission critical systems to > > meet RoHS by the EU. > > > > Obviously, the removal of lead is a good thing, but the introduction of a > > new problem without a known solution is short sighted. > > > > I discussed RoHS with a US distributor representative expressing > my concerns > > of product reliability. His response was products are obsolete in a few > > years anyhow. My response is I really wouldn't like to replace a > $3000 piece > > of consumer electronics equipment in 2 years or less. > > > > I have discussed this with manufacturers also. They are concerned with the > > shelve life of products, as tin whiskers are a result of time, not > > environment. In fact, one has mentioned changing his warrantee to reflect > > time from factory shipment. > > > > Although goods sold in the US do not currently require no-lead components, > > the EU RoHS requirements are rippling into the distribution chains. > > > > Regardless, tin whiskers appear to be a real problem that is being sweep > > under the rug in the rush to no-lead solutions. > > > > 73, > > Bill Bordy > > NJ1H > > > > > > > > -----Original Message----- > > From: Jim Lux [mailto:[EMAIL PROTECTED] > > Sent: Monday, May 01, 2006 1:40 PM > > To: William Bordy; 'Lyle Johnson' > > Cc: 'FlexRadio' > > Subject: RE: [Flexradio] RoHS & Tin Whiskers was Re: July 1 > > > > At 09:28 AM 5/1/2006, William Bordy wrote: > > >I have been following the RoHS requirements and one issue I see rarely > > >discussed is the "Tin Whiskers" issue. For those that are not > familiar with > > >it please see the following WEB site: > > > > > >http://nepp.nasa.gov/WHISKER/background/index.htm > > > > > >It appears that with the switch to no-lead that the reliability of the > > >equipment will be substantially reduced. > > > > Problems with tin whiskers have been around a lot longer than RoHS (perhaps > > as far back as WW II?). It presents a problem with reliability of equipment > > designed for low cost production, with no budget for re-engineering, sure. > > But for the rest, it's not so clear. > > > > > > > > >This appears to be what happens > > >when politics drive science. > > > > No science involved here. Lead has been known as a toxin for centuries. > > It's just that society, as a whole, has decided that it's worth reducing > > the amount being discarded, much as they've decided that the societal costs > > of air pollution or persistent pesticides were greater than the cost of > > reducing it. In general, reducing waste in any form has a long term > > benefit because it provides more efficient resource utilization: in the > > sense that more of the value goes into the eventual product use, as opposed > > to being discarded during manufacturing or at product EOL. > > > > Not so much politics, but the race to the bottom for low cost production, > > driven by the capital market's expectations of short term returns on > > investment. > > > > In the long run, we DO benefit, even if we suffer from short term > > fixes. Consider, for instance, emissions controls on cars. The "quick > > fixes" of the 70s were pretty lame. Today, however, cars are more > > efficient, less expensive (in constant dollars), and last a lot longer, and > > run a lot better (because of electronic engine controls). Back in the 60s & > > 70s, a car that lasted more than 100k miles was unusual, and a car that > > went 200k miles was something special (remember a print ad campaign about a > > VW or Toyota that had 250+k miles... the distance to the moon). Today, > > there's lots and lots of cars with more than 100,000 miles running just > > fine. And, what about muffler replacement (unleaded gas required reducing > > the sulfur in gasoline, which in turn reduced the amount of sulfuric acid > > that accumulated in the muffler.. further, the requirement that exhaust > > systems not leak for 50,000 miles prompted improvements in design to make > > them last longer) > > > > > > >73, > > >Bill Bordy > > >NJ1H > > > > James Lux, P.E. > > Spacecraft Radio Frequency Subsystems Group > > Flight Communications Systems Section > > Jet Propulsion Laboratory, Mail Stop 161-213 > > 4800 Oak Grove Drive > > Pasadena CA 91109 > > tel: (818)354-2075 > > fax: (818)393-6875 > > > > > > > > > > > >_______________________________________________ >FlexRadio mailing list >[EMAIL PROTECTED] >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ >FlexRadio Homepage: http://www.flex-radio.com > >_______________________________________________ >FlexRadio mailing list >[EMAIL PROTECTED] >http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz >Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ >FlexRadio Homepage: http://www.flex-radio.com Cecil Bayona KD5NWA www.qrpradio.com I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ... _______________________________________________ FlexRadio mailing list [EMAIL PROTECTED] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
