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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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The debate about lead free solders seem to be nearly as politically charged as
that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham |
#2
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Eeyore wrote in
: The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham If it were better than lead solders there would not be any exemptions needed, every thing would be required to be lead free. Critical (Mil, Aero, etc)equipment gets an exemption though... ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#3
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me wrote in message
... Eeyore wrote in : The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham If it were better than lead solders there would not be any exemptions needed, every thing would be required to be lead free. Critical (Mil, Aero, etc)equipment gets an exemption though... ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- Follow the derogations/exemptions. Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. The suggestion from the following would be they are maverics putting themselves in an awkward position regarding spares etc. http://www.lboro.ac.uk/research/iemr...202015%20Makin g%20a%20Visible%20Difference%20EIGT%20Report.pdf "... Much equipment manufactured before the application of RoHS will suffer premature obsolescence, as component parts which have been modified to meet the RoHS requirement may not be compatible. Businesses supplying sectors such as defence, medical, instrumentation and control, currently have a derogation from the regulation in Europe. But this poses problems for the future availability of lead-free components. This issue has product lifetime implications for public sector purchases as well as business implications to those supplying export markets where RoHS standards do not yet apply. ..." The real conspiracy would be if it could be shown what manufacturing industries deliberately went with lead-free knowing that their products would fail due to that and not component failure, knowing they would sell more product. The engineers I have talked to in UK industry are genuinly unaware of in-service problems in electronic products, due to their enforced lead-free soldering. But the ones I know are in scientific/technical kit and instrumentation production so not subjected to vibrational environments. Do automotive electronics have a derogation ? as that would be an area that would soon show up lead-free solder problems. -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#4
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On Wed, 25 Jul 2007 08:42:50 +0100, "N Cook" wrote:
Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. Absolutely. Lead based solder alloys are ****ing superior, and Tin based, non-leaded alloys are inferior, and have VERY POOR reliability numbers. It is really quite simple math. A mission critical application REQUIRES a system where one does not have to expect some lame failure mode to creep in due to the utilization of a VERY POOR, failure mode prone device interconnection methodology. |
#5
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Spurious Response wrote in message
news ![]() On Wed, 25 Jul 2007 08:42:50 +0100, "N Cook" wrote: Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. Absolutely. Lead based solder alloys are ****ing superior, and Tin based, non-leaded alloys are inferior, and have VERY POOR reliability numbers. It is really quite simple math. A mission critical application REQUIRES a system where one does not have to expect some lame failure mode to creep in due to the utilization of a VERY POOR, failure mode prone device interconnection methodology. The next time I get a year or 2 year old 800 GBP/1500 USD combo in for repair with loose simple, thermally un-stressed,but vibrationally stressed components, I will actually measure the extraction force of the obviously suspect ones and some of the remaining ones, with a spring balance and a hook of wire. I would never have expected otherwise well-soldered (but obviously lead-free solder) very basic "components" like soldered wire links,1/3W resistors,TO92 transistors, to have solder failures after decades, let alone a couple of years. Some more relevant background text from http://www.lboro.ac.uk/research/iemr...202015%20Makin g%20a%20Visible%20Difference%20EIGT%20Report.pdf nothing about failure rates in the bullet-points though "..... The lead-free solder proposal was introduced at short notice by the EU in 1998 as a revision to the WEEE Directive under Article 175 (environment), and is the subject of qualified majority voting, so the UK has no power of veto. The UK was the only member state represented by its industry ministry, and other member states were represented by environmental ministries. No rigorous fiche d'impact was undertaken. The proposals take effect from 1 July 2006. Subsequently, the Removal of Hazardous Substances (RoHS) provisions, which deal with other hazardous substances, were made under Article 95 (single market). So interdependent legislation will be introduced under different agreement arrangements. Unintended consequences include: * Increased material and component costs because some PCB material and some components cannot be used with higher temperature solder; * Re-certification costs for safety critical products; * Damage to soldering equipment from electrochemical corrosion, following use of tin-rich solder in machines previously used with lead- based solder; * Increased capital equipment cost as equipment life shortens; * Increased costs associated with inspection, testing and tracking to demonstrate compliance; * Training and retraining costs for staff working with new materials; * Increased capital and inventory costs as manufacturers keep separate lines and stocks for defence and exempt products. ....." -- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net/ |
#6
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![]() N Cook wrote: The next time I get a year or 2 year old 800 GBP/1500 USD combo in for repair with loose simple, thermally un-stressed,but vibrationally stressed components, I will actually measure the extraction force of the obviously suspect ones and some of the remaining ones, with a spring balance and a hook of wire. I would never have expected otherwise well-soldered (but obviously lead-free solder) very basic "components" like soldered wire links,1/3W resistors,TO92 transistors, to have solder failures after decades, let alone a couple of years. I agree. I imagine you've seen a number of these then ? Do you tell your customers about the lead-free thing and its consequences ? Graham |
#7
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On Wed, 25 Jul 2007 10:41:01 +0100, "N Cook" wrote:
Spurious Response wrote in message news ![]() On Wed, 25 Jul 2007 08:42:50 +0100, "N Cook" wrote: Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. Absolutely. Lead based solder alloys are ****ing superior, and Tin based, non-leaded alloys are inferior, and have VERY POOR reliability numbers. It is really quite simple math. A mission critical application REQUIRES a system where one does not have to expect some lame failure mode to creep in due to the utilization of a VERY POOR, failure mode prone device interconnection methodology. The next time I get a year or 2 year old 800 GBP/1500 USD combo in for repair with loose simple, thermally un-stressed,but vibrationally stressed components, I will actually measure the extraction force of the obviously suspect ones and some of the remaining ones, with a spring balance and a hook of wire. I would never have expected otherwise well-soldered (but obviously lead-free solder) very basic "components" like soldered wire links,1/3W resistors,TO92 transistors, to have solder failures after decades, let alone a couple of years. Most "solder creep" (the expression which describes your scenario) failures can be tracked back to a poor design as it relates to fixturing large masses or "tugged on" components or interconnects. Such elements should be fixtured by means other than the soldered leads. It was unclear to me whether your situation was a remark about how quickly a lead free assembly exhibits such failure, or about older. leaded solder alloys in assemblies. Some more relevant background text from http://www.lboro.ac.uk/research/iemr...202015%20Makin g%20a%20Visible%20Difference%20EIGT%20Report.pd f nothing about failure rates in the bullet-points though Cool. "..... The lead-free solder proposal was introduced at short notice by the EU in 1998 as a revision to the WEEE Directive under Article 175 (environment), and is the subject of qualified majority voting, so the UK has no power of veto. The UK was the only member state represented by its industry ministry, and other member states were represented by environmental ministries. No rigorous fiche d'impact was undertaken. The proposals take effect from 1 July 2006. Yep. Subsequently, the Removal of Hazardous Substances (RoHS) provisions, which deal with other hazardous substances, were made under Article 95 (single market). So interdependent legislation will be introduced under different agreement arrangements. Unintended consequences include: * Increased material and component costs because some PCB material and some components cannot be used with higher temperature solder; * Re-certification costs for safety critical products; * Damage to soldering equipment from electrochemical corrosion, following use of tin-rich solder in machines previously used with lead- based solder; * Increased capital equipment cost as equipment life shortens; * Increased costs associated with inspection, testing and tracking to demonstrate compliance; * Training and retraining costs for staff working with new materials; * Increased capital and inventory costs as manufacturers keep separate lines and stocks for defence and exempt products. ....." And for solder, it was entirely NOT necessary. The other substances perhaps, but not for solder. |
#8
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![]() Spurious Response wrote: "N Cook" wrote: Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. Absolutely. Lead based solder alloys are ****ing superior, and Tin based, non-leaded alloys are inferior, and have VERY POOR reliability numbers. It is really quite simple math. A mission critical application REQUIRES a system where one does not have to expect some lame failure mode to creep in due to the utilization of a VERY POOR, failure mode prone device interconnection methodology. So pony up your data ! Graham |
#9
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On Wed, 25 Jul 2007 10:41:13 +0100, Eeyore
wrote: Spurious Response wrote: "N Cook" wrote: Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. Absolutely. Lead based solder alloys are ****ing superior, and Tin based, non-leaded alloys are inferior, and have VERY POOR reliability numbers. It is really quite simple math. A mission critical application REQUIRES a system where one does not have to expect some lame failure mode to creep in due to the utilization of a VERY POOR, failure mode prone device interconnection methodology. So pony up your data ! "Data" is a collection of values or attributes for a given observation. "Information" is processed data. What you are looking for is information. |
#10
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On Jul 25, 3:42?am, "N Cook" wrote:
Follow the derogations/exemptions. Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. I suspect it is because these fields are considered "life-safety" fields. Even ordinance, when you think of it in terms of friendly fire incidents. They probably just don't want to recertify their processes, or don't have the time to do it right. But the "Truth"? That's much more elusive. Does RoHS result in a better environment? I don't know, but I doubt it. The sheer number of TV sets that will be obsoleted in the coming years due to the migration to Digital Television will probably swamp the RoHS "gains" by orders of magnitude. Ditto for the batteries used in some electric cars, and the US's (likely?) ultimate reliance on it's vast coal reserves to power all this crap. And that's if Global Warming doesn't get us first... Bottom line: I don't think the environment gives a sh^t about RoHS, or WEEE. I think we need fewer people, and less "disposable" crap from China. -mpm |
#11
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On a sunny day (Wed, 25 Jul 2007 08:33:12 -0700) it happened mpm
wrote in .com: On Jul 25, 3:42?am, "N Cook" wrote: Follow the derogations/exemptions. Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. I suspect it is because these fields are considered "life-safety" fields. Even ordinance, when you think of it in terms of friendly fire incidents. They probably just don't want to recertify their processes, or don't have the time to do it right. But the "Truth"? That's much more elusive. Does RoHS result in a better environment? I don't know, but I doubt it. The sheer number of TV sets that will be obsoleted in the coming years due to the migration to Digital Television will probably swamp the RoHS "gains" by orders of magnitude. Right, I turned in a portable TV last week. This one was about 30 years old (seventies), and was still working OK, but no analog transmissions here anymore, all you get is nice equal distributed noise when tuning in to a digital station. |
#12
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On Wed, 25 Jul 2007 15:57:34 GMT, Jan Panteltje
wrote: On a sunny day (Wed, 25 Jul 2007 08:33:12 -0700) it happened mpm wrote in s.com: On Jul 25, 3:42?am, "N Cook" wrote: Follow the derogations/exemptions. Military , aerospace & medical do have derogation from WEEE and RoSH, but can anyone nail down precisely why they are exempted. I suspect it is because these fields are considered "life-safety" fields. Even ordinance, when you think of it in terms of friendly fire incidents. They probably just don't want to recertify their processes, or don't have the time to do it right. But the "Truth"? That's much more elusive. Does RoHS result in a better environment? I don't know, but I doubt it. The sheer number of TV sets that will be obsoleted in the coming years due to the migration to Digital Television will probably swamp the RoHS "gains" by orders of magnitude. Right, I turned in a portable TV last week. This one was about 30 years old (seventies), and was still working OK, but no analog transmissions here anymore, all you get is nice equal distributed noise when tuning in to a digital station. There are SEVERAL HDTV set top tuners out there that will pipe the finished signal into a standard TV. What is nice about digital broadcasts is that when you have the signal, you have it all. No snow, No herringbone patterns. Crisp and clean, with no caffeine. |
#13
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![]() "mpm" wrote in message oups.com... And that's if Global Warming doesn't get us first... If you believe that to be a possibility, are you not concerned about the additional carbon based fuels used to heat these lead free solders to the higher temperatures that they require? Leonard |
#14
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On Wed, 25 Jul 2007 19:47:40 -0400, "Leonard Caillouet"
wrote: "mpm" wrote in message roups.com... And that's if Global Warming doesn't get us first... If you believe that to be a possibility, are you not concerned about the additional carbon based fuels used to heat these lead free solders to the higher temperatures that they require? Good one. |
#15
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It is really application and chip package specific, and even makes a big
difference on where the chip is mounted on the board. It also makes a big difference on the various lead finishes, process steps and how they are done, and which of the common 23 lead-free mixes you use. Would you believe ENIG finishes can even cause issues with lead-free? Personally, if you look there is a consortium lead by Boeing, of areospace industries, who have been doing a lot of testing on the subject, and ended up settling on just 1 or 2 alloys that perform the best in the early phases, to pick out which ones to run thru the gauntlet- with control subject of regular leaded solder. If you do searches on key documents/terms listed within these, you will find more than you ever wanted to know: http://www.aciusa.org/leadfree/LFS_S...P_WG_Brief.pdf http://www.calce.umd.edu/lead-free/SMTAExemptMay8.pdf http://www.jgpp.com/projects/lead_fr...entations.html - a whole list of documents http://www.jgpp.com/projects/lead_fr...M-0409-991.pdf http://www.jgpp.com/projects/lead_fr...ll%20Voids.pdf http://www.jgpp.com/projects/lead_fr...404Woodrow.pdf http://www.jgpp.com/projects/lead_fr...up_3_16_05.pdf Another key term to search for is Thomas Woodrow, who has dedicated years attempting to unravel this puzzle for best practices. When looking at these presentations, it is important to look hard into the nitty gritty of the source references, or you will easily end up with the wrong conclusions. Things like a good number of the tests were done with immersion silver, and ENIG (gold) and other board finishes can have a big impact on the results of the test. ENIG has it's own issues, such as a big increase in what is becomming known as "black pad" failures when lead-free solders are used with it. As I recall, it had something to do with the ENIG process steps, which vary from board house to board house. In the second one, several working groups have found the failure shown in page 33 of the document( pdf page 33), where you can see cracks running all through the BGA ball, and a rather clear separation off the pad. Caused by temperature cycling, and failures in less than 150 thermal cycles! Tin Whiskers Theory and Mitigation Practices Guideline: http://www.jedec.org/DOWNLOAD/search/JP002.pdf "The amount of damage required for a BGA to fail on an assembly was used to predict lifetimes for other BGAs, at other locations, on the same board. They tested: Sn3.9Ag0.6 for reflow soldering, Sn3.4Ag1.0Cu3.3Bi for reflow, Sn0.7Cu0.05Ni for wave, and 63Sn37Pb for reflow and wave. The surprising part is that BGAs using tin/lead will outlast SAC BGAs by a factor of 20x. Thus, SAC BGAs in high-reliability electronics could be problematic in high-vibration environments. .... There has been no other transition to affect all aspects of our industry as fundamentally as lead-free. Predicting reliability will prevent future disasters, and that's the best reason to glean information from all approaches. There's still so much we need to know." http://listserv.ipc.org/scripts/wa.e...eadfree&P=1444 ----- Original Message ----- From: "Eeyore" Newsgroups: sci.electronics.design,sci.electronics.repair Sent: Tuesday, July 24, 2007 3:42 PM Subject: So what's the truth about lead-free solder ? The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham "Eeyore" wrote in message ... The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham |
#16
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![]() Tin Whiskers Theory and Mitigation Practices Guideline: http://www.jedec.org/DOWNLOAD/search/JP002.pdf "The amount of damage required for a BGA to fail on an assembly was used to predict lifetimes for other BGAs, at other locations, on the same board. They tested: Sn3.9Ag0.6 for reflow soldering, Sn3.4Ag1.0Cu3.3Bi for reflow, Sn0.7Cu0.05Ni for wave, and 63Sn37Pb for reflow and wave. The surprising part is that BGAs using tin/lead will outlast SAC BGAs by a factor of 20x. Thus, SAC BGAs in high-reliability electronics could be problematic in high-vibration environments. I'm not sure that I would find this "surprising", having seen the general performance of lead-free from a service angle, for several years now. At the end of the day, like several other technologies we have been forced to ditch as a result of dubious science and conclusions, lead-based soldering was a mature, proven, and above all *reliable* way to construct electronic equipment. If Boeing Corporation are really leading research into the performance of this hateful material, then I hope that it is with a view to reinforcing the avionics industry's opinion that this stuff has no right to up be in the sky, and responsible for getting 450 people safely to their destination. If they are researching with the intention of determining the best compromise alloy to use in place of conventional solder, then I believe that is indeed a worrying development ... It would be interesting to know from someone directly involved in avionics or avionics service, how many in-service equipment failures are currently as a result of bad joints, and what sorts of levels of failures are being recorded in the vibration tests that must be being done on evaluation sample pieces, constructed with lead-free. Arfa |
#17
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On Tue, 24 Jul 2007 23:08:51 -0700, "Leeper" wrote:
t is really application and chip package specific, Bull****. Lead based solder alloys are superior in damn near all electronic realms, and there is no configuration where they would not be other than high end commercial and military applications, and they certainly do not include Tin. RoHS is a Euro-ploy to boost the Euro-dollar, and there is no health problem surrounding lead alloyed solders. It is all bull****, and it was all bull**** when it was started. We already had regulations in place for such matters for DECADES. Get a clue. |
#18
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![]() Spurious Response wrote: "Leeper" wrote: t is really application and chip package specific, Bull****. Lead based solder alloys are superior in damn near all electronic realms, and there is no configuration where they would not be other than high end commercial and military applications, and they certainly do not include Tin. Whilst I don't disagree with you, where's the hard comparative data ? RoHS is a Euro-ploy to boost the Euro-dollar, and there is no health problem surrounding lead alloyed solders. I only wish it was just the EU. It is all bull****, and it was all bull**** when it was started. We already had regulations in place for such matters for DECADES. FYI, the idea(l) behind RoHS is to encourage recycling by removing elements that would be troublesome otherwise. Personally, I can think of no good reason to attempt to 'recycle' old printed circuit boards. For example it appears to be both uneconomic and likely energy wasteful too. Graham |
#19
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On Wed, 25 Jul 2007 10:27:43 +0100, Eeyore
wrote: "Leeper" wrote: t is really application and chip package specific, Bull****. Lead based solder alloys are superior in damn near all electronic realms, and there is no configuration where they would not be other than high end commercial and military applications, and they certainly do not include Tin. Whilst I don't disagree with you, where's the hard comparative data ? Considering the fact that we have 5 decade old circuit cards still operating perfectly, and that we already know what alloys containing Tin which is not bound by Lead do over time and temperature cycling, I do not think that precise numerical analysis is even needed on such a profoundly lopsided issue. |
#20
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![]() Spurious Response wrote: Eeyore wrote: "Leeper" wrote: t is really application and chip package specific, Bull****. Lead based solder alloys are superior in damn near all electronic realms, and there is no configuration where they would not be other than high end commercial and military applications, and they certainly do not include Tin. Whilst I don't disagree with you, where's the hard comparative data ? Considering the fact that we have 5 decade old circuit cards still operating perfectly, and that we already know what alloys containing Tin which is not bound by Lead do over time and temperature cycling, I do not think that precise numerical analysis is even needed on such a profoundly lopsided issue. Whilst I agree with you, bureacrats tend not to be very receptive to anecdotal comment. And make no mistake, the bureacrats are the ones in control of this. Graham |
#21
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On Wed, 25 Jul 2007 10:27:43 +0100, Eeyore
wrote: FYI, the idea(l) behind RoHS is to encourage recycling by removing elements that would be troublesome otherwise. Lead alloy solders in discarded circuit assemblies does NOT pose any "troublesome" issues for the environment. Fact: Metallic form lead solder alloys, or even raw metallic form Lead does NOT pose a problem for water tables or land fills. Aside from the polymer materials provided for in the "regulation", RoHS is total bull****. |
#22
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On Wed, 25 Jul 2007 10:27:43 +0100, Eeyore
wrote: Personally, I can think of no good reason to attempt to 'recycle' old printed circuit boards. For example it appears to be both uneconomic and likely energy wasteful too. If one (read a business) had an incinerator for refuse, which is common in the US, one could very easily have enough heat energy "left over" to reflow, and "Smack and Gather" soldered assemblies after they reach reflow temperatures. It would not take long to gather a ton of "solder". A ton is a ton is a ton, and gathering several grams from each assembly one has for salvage makes the planet more "green", because reprocessing lead, and lead alloys is far easier and less costly than mining it. |
#23
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![]() Spurious Response wrote: Eeyore wrote: Personally, I can think of no good reason to attempt to 'recycle' old printed circuit boards. For example it appears to be both uneconomic and likely energy wasteful too. If one (read a business) had an incinerator for refuse, which is common in the US, one could very easily have enough heat energy "left over" to reflow, and "Smack and Gather" soldered assemblies after they reach reflow temperatures. It would not take long to gather a ton of "solder". A ton is a ton is a ton, and gathering several grams from each assembly one has for salvage makes the planet more "green", because reprocessing lead, and lead alloys is far easier and less costly than mining it. Incinerators are now deprecated since the greenies say they make dioxins. Actually, I'd expect a lot of solder to turn to oxides and go up the smoke stack if subjected to high temps. Graham |
#24
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![]() Spurious Response wrote: reprocessing lead, and lead alloys is far easier and less costly than mining it. So all those owners of lead mines are wasting all that money doing things the more expensive way as a public service? |
#25
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![]() I dunno, but soluble core solder Rocks ![]() |
#26
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On Tue, 24 Jul 2007 23:42:47 +0100, Eeyore
wrote: The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham Don't look to this newsgroup for factual info on lead free! Instead look at actual test results in the trade publications such as SMT magazine: http://smt.pennnet.com/home.cfm They have published numerous tests comparing various lead free materials and processes with tin-lead. Some lead free materials and processes are better than others (no surprise) and picking the best one for your situation is non-trivial. My nutshell summary of the published test results is that lead free is significantly harder to do right than tin-lead, requiring tighter process controls, but if done right it can be more reliable than tin-lead for non-shock situations. Lead free is harder, stronger and more brittle than tin-lead so tin-lead will deform plastically under high shock when lead free will break, however lead free will withstand more hot-cold cycles than before failure than tin-lead (better fatigue resistance). So you need to know what the significant failure mechanisms are in your design to pick the most reliable materials. Glen |
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![]() "Glen Walpert" wrote in message ... On Tue, 24 Jul 2007 23:42:47 +0100, Eeyore wrote: The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham Don't look to this newsgroup for factual info on lead free! Instead look at actual test results in the trade publications such as SMT magazine: http://smt.pennnet.com/home.cfm They have published numerous tests comparing various lead free materials and processes with tin-lead. Some lead free materials and processes are better than others (no surprise) and picking the best one for your situation is non-trivial. My nutshell summary of the published test results is that lead free is significantly harder to do right than tin-lead, requiring tighter process controls, but if done right it can be more reliable than tin-lead for non-shock situations. Lead free is harder, stronger and more brittle than tin-lead so tin-lead will deform plastically under high shock when lead free will break, however lead free will withstand more hot-cold cycles than before failure than tin-lead (better fatigue resistance). So you need to know what the significant failure mechanisms are in your design to pick the most reliable materials. Glen And in the meantime whilst smaller manufacturers who don't have the resources of the big boys to research this crap in sufficient detail to find the 'correct' process to replace the previously utterly reliable and simple leaded soldering that they were using, cartloads of electronic equipment are failing as a result of the bad joints that the experimentation or 'best fit' replacement alloys are causing. I wonder what qualifies you to make that remark at the beginning of your post, telling people not to look to this group for 'factual' information on lead-free ? When I tell you that I work day in day out with equipment from major manufacturers that uses the stuff, and that since they have been using it, I have seen the incidence of bad joints in places that would never previously have suffered, skyrocket, do you consider that to not be 'factual' ? Am I lying perhaps ? There are many good engineers that contribute to this group, and most have reported seeing an increase in such bad joints. Are they all being less than 'factual' ? When push comes to shove, this is an electronic repair group, frequented by, amongst others, repair professionals who have to deal with the effects of legislation such as RoHS, and its implications, at the sharp end, which is more than the manufacturers and political activists / pseudo scientists responsible for creating these situations, do. As such, I feel that it is therefore rather presumptuous of you to suggest that opinions voiced on this group, are not based in fact, and thus not valid. Arfa |
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Glen Walpert wrote:
On Tue, 24 Jul 2007 23:42:47 +0100, Eeyore wrote: The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham Don't look to this newsgroup for factual info on lead free! Instead look at actual test results in the trade publications such as SMT magazine: http://smt.pennnet.com/home.cfm They have published numerous tests comparing various lead free materials and processes with tin-lead. Some lead free materials and processes are better than others (no surprise) and picking the best one for your situation is non-trivial. My nutshell summary of the published test results is that lead free is significantly harder to do right than tin-lead, requiring tighter process controls, but if done right it can be more reliable than tin-lead for non-shock situations. Lead free is harder, stronger and more brittle than tin-lead so tin-lead will deform plastically under high shock when lead free will break, however lead free will withstand more hot-cold cycles than before failure than tin-lead (better fatigue resistance). So you need to know what the significant failure mechanisms are in your design to pick the most reliable materials. Glen Another major issue is tin whiskers. We have hard evidence at $WeBuildAvionics (where I am currently consluting) that the current Pb Free / RoHS solder mixes have significant problems with growing whiskers, leading to wonderful issues such as short circuits developing under BGAs a few months after production. In a Flight control computer (don't laugh - in a fly by wire environment it's the ONLY flight control and virtually all late model airliners use it) this is Not a Good Thing [tm]. The whole RoHS / Pb free thing is a political issue - the processes for Pb Free use more hazardous substances than they get rid of. Typical EU beauraucrats - unelected, overpaid and have to find something to regulate to justify their existence. [1] Cheers PeteS [1] Their existence, even from birth, might not be justifiable. |
#29
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![]() Another major issue is tin whiskers. We have hard evidence at $WeBuildAvionics (where I am currently consluting) that the current Pb Free / RoHS solder mixes have significant problems with growing whiskers, leading to wonderful issues such as short circuits developing under BGAs a few months after production. In a Flight control computer (don't laugh - in a fly by wire environment it's the ONLY flight control and virtually all late model airliners use it) this is Not a Good Thing [tm]. The whole RoHS / Pb free thing is a political issue - the processes for Pb Free use more hazardous substances than they get rid of. Typical EU beauraucrats - unelected, overpaid and have to find something to regulate to justify their existence. [1] Cheers PeteS [1] Their existence, even from birth, might not be justifiable. It's good to hear at last from someone involved in the avionics industry, and it's also good to hear that this particular industry is identifying serious problems with the technology, as that might at least help to maintain their exemption for some years to come. I really hope that the industry has sufficient strength to stand up to this legislation, and to continue to maintain their position of refusing to use it on safety / reliability grounds. With my daily dealings with lead-free solder, and all of the problems that it has brought to consumer electronics, the thought of being held seven miles up in the sky by equipment using the same technology, is truly worrying to me. I cannot agree more that this whole thing is a poorly thought through example of 'bandwagon politics' and job justification. I would be interested in hearing any other input that you may have on the subject, with regard to the avionics industry. Both anecdotal and factual would be welcome, and I am sure that Graham (who started this thread) would like see more from you, as well. Arfa |
#30
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On Thu, 26 Jul 2007 19:56:31 -0400, PeteS wrote:
Glen Walpert wrote: On Tue, 24 Jul 2007 23:42:47 +0100, Eeyore wrote: The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham Don't look to this newsgroup for factual info on lead free! Instead look at actual test results in the trade publications such as SMT magazine: http://smt.pennnet.com/home.cfm They have published numerous tests comparing various lead free materials and processes with tin-lead. Some lead free materials and processes are better than others (no surprise) and picking the best one for your situation is non-trivial. My nutshell summary of the published test results is that lead free is significantly harder to do right than tin-lead, requiring tighter process controls, but if done right it can be more reliable than tin-lead for non-shock situations. Lead free is harder, stronger and more brittle than tin-lead so tin-lead will deform plastically under high shock when lead free will break, however lead free will withstand more hot-cold cycles than before failure than tin-lead (better fatigue resistance). So you need to know what the significant failure mechanisms are in your design to pick the most reliable materials. Glen Another major issue is tin whiskers. We have hard evidence at $WeBuildAvionics (where I am currently consluting) that the current Pb Free / RoHS solder mixes have significant problems with growing whiskers, leading to wonderful issues such as short circuits developing under BGAs a few months after production. In a Flight control computer (don't laugh - in a fly by wire environment it's the ONLY flight control and virtually all late model airliners use it) this is Not a Good Thing [tm]. The whole RoHS / Pb free thing is a political issue - the processes for Pb Free use more hazardous substances than they get rid of. Typical EU beauraucrats - unelected, overpaid and have to find something to regulate to justify their existence. [1] Cheers PeteS [1] Their existence, even from birth, might not be justifiable. Damn. You actually made a post that I agree with 100%. Seems one must fully encapsulate a finished assembly in transformer varnish under vacuum to lock out the whisker growth. Serviceability... right out the door. Stink factor... worse than it was. The whole ****ing thing stinks. |
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![]() Spurious Response wrote: Damn. You actually made a post that I agree with 100%. Can you please detonate yourself in that case ? Graham |
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On Fri, 27 Jul 2007 03:42:53 +0100, Eeyore
wrote: Spurious Response wrote: Damn. You actually made a post that I agree with 100%. Can you please detonate yourself in that case ? **** off, troll. |
#33
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Spurious Response wrote:
On Thu, 26 Jul 2007 19:56:31 -0400, PeteS wrote: Glen Walpert wrote: On Tue, 24 Jul 2007 23:42:47 +0100, Eeyore wrote: The debate about lead free solders seem to be nearly as politically charged as that about anthropogenic global warming and a casualty seems to be useful data. I've read plenty of comments to the effect that lead-free is less reliable in the long term (vibration seems to be a key weakness AIUI - maybe also thermal cycling) which presumably explains the exemptions for certain categories, yet I've also seen some studies that claim it can out-perform lead containing solders. Is there any real hard and fast information out there that one can rely on ? Graham Don't look to this newsgroup for factual info on lead free! Instead look at actual test results in the trade publications such as SMT magazine: http://smt.pennnet.com/home.cfm They have published numerous tests comparing various lead free materials and processes with tin-lead. Some lead free materials and processes are better than others (no surprise) and picking the best one for your situation is non-trivial. My nutshell summary of the published test results is that lead free is significantly harder to do right than tin-lead, requiring tighter process controls, but if done right it can be more reliable than tin-lead for non-shock situations. Lead free is harder, stronger and more brittle than tin-lead so tin-lead will deform plastically under high shock when lead free will break, however lead free will withstand more hot-cold cycles than before failure than tin-lead (better fatigue resistance). So you need to know what the significant failure mechanisms are in your design to pick the most reliable materials. Glen Another major issue is tin whiskers. We have hard evidence at $WeBuildAvionics (where I am currently consluting) that the current Pb Free / RoHS solder mixes have significant problems with growing whiskers, leading to wonderful issues such as short circuits developing under BGAs a few months after production. In a Flight control computer (don't laugh - in a fly by wire environment it's the ONLY flight control and virtually all late model airliners use it) this is Not a Good Thing [tm]. The whole RoHS / Pb free thing is a political issue - the processes for Pb Free use more hazardous substances than they get rid of. Typical EU beauraucrats - unelected, overpaid and have to find something to regulate to justify their existence. [1] Cheers PeteS [1] Their existence, even from birth, might not be justifiable. Damn. You actually made a post that I agree with 100%. Seems one must fully encapsulate a finished assembly in transformer varnish under vacuum .... Sorry, I wasn't concentrating and I thought you were still talking about the bureaucrats, I thought that would be a very effective solution. to lock out the whisker growth. Oh.. well can we still do the bureaucrats afterwards? ?? Chris |
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![]() Spurious Response wrote: Seems one must fully encapsulate a finished assembly in transformer varnish under vacuum to lock out the whisker growth. Tin whiskers will grow through conformal coatings. Graham |
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On Fri, 27 Jul 2007 22:22:16 +0100, Eeyore
wrote: Spurious Response wrote: Seems one must fully encapsulate a finished assembly in transformer varnish under vacuum to lock out the whisker growth. Tin whiskers will grow through conformal coatings. Graham This dude has real problems along those lines: http://tinyurl.com/27xc98 Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com |
#36
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Glen Walpert wrote:
My nutshell summary of the published test results is that lead free is significantly harder to do right than tin-lead, requiring tighter process controls, but if done right it can be more reliable than tin-lead for non-shock situations. MORE reliable? Please elaborate. -- "Liberals used to be the ones who argued that sending U.S. troops abroad was a small price to pay to stop genocide; now they argue that genocide is a small price to pay to bring U.S. troops home." -- Jonah Goldberg |
#37
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![]() "clifto" wrote in message ... Glen Walpert wrote: My nutshell summary of the published test results is that lead free is significantly harder to do right than tin-lead, requiring tighter process controls, but if done right it can be more reliable than tin-lead for non-shock situations. MORE reliable? Please elaborate. The reason that one might speculate this is that PbF solder has a higher melting point and is harder, thus perhaps less prone to thermal damaged due to cycling. This might be the case IF done right, but there are so many variables that it is impossible to generalize this. The fact is that most in the field realize that it is much easier to get it right with leaded solder, and it is generally considered to be more reliable for most applications. In fact, there are exemptions for critical applications that allow leaded solder, even in the EU. The biggest problem that I have seen in consumer electronics with PbF is that not enough solder is deposited in the automated process of making the boards. This aften leads to an unreliable joint. It is also harder to get good results in repairs with PbF, as it requires higher temperatures and even the most freindly formulations do not wet and flow as well. Leonard |
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On Thu, 26 Jul 2007 18:14:20 -0400 in sci.electronics.design, "Leonard
Caillouet" wrote, The reason that one might speculate this is that PbF solder has a higher melting point and is harder, thus perhaps less prone to thermal damaged due Lead Fluoride??? |
#39
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David Harmon wrote:
On Thu, 26 Jul 2007 18:14:20 -0400 in sci.electronics.design, "Leonard Caillouet" wrote, The reason that one might speculate this is that PbF solder has a higher melting point and is harder, thus perhaps less prone to thermal damaged due Lead Fluoride??? It's for brushing your mercury fillings. -- "Liberals used to be the ones who argued that sending U.S. troops abroad was a small price to pay to stop genocide; now they argue that genocide is a small price to pay to bring U.S. troops home." -- Jonah Goldberg |
#40
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On Thu, 26 Jul 2007 16:39:50 -0500, clifto wrote:
Glen Walpert wrote: My nutshell summary of the published test results is that lead free is significantly harder to do right than tin-lead, requiring tighter process controls, but if done right it can be more reliable than tin-lead for non-shock situations. MORE reliable? Please elaborate. SHOCK.... and AWE! |
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