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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Old July 24th 07, 11:42 PM posted to sci.electronics.design,sci.electronics.repair
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Default 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



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Old July 25th 07, 06:12 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?

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...

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Old July 25th 07, 07:08 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?

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




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Old July 25th 07, 07:14 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?


I dunno, but soluble core solder Rocks
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Old July 25th 07, 08:42 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?

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...

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News==----
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Newsgroups
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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/




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Old July 25th 07, 09:16 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?



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


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Old July 25th 07, 10:15 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?

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.
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Old July 25th 07, 10:19 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?

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.
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Old July 25th 07, 10:27 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?



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

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Old July 25th 07, 10:31 AM posted to sci.electronics.design,sci.electronics.repair
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Default So what's the truth about lead-free solder ?

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.


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