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

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

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.

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

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.

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

"Eeyore" wrote in message
...


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



I have just this minute finished repairing a Panasonic DAB / FM radio which
was dying as soon as it was switched on, with a "F76 Pdet" error in the
display. I took this to be "power detect", which seemed reasonable, given
the symptoms. When I took the main board out to have a look at the
underside, I found the power supply section riddled with poor and
'cracked-right-round' lead-free solder joints ( the board actually has
"PbF" silk-screened on it ). The poor joints were particularly well defined
on the main free-air cooled regulator transistor, which is obviously subject
to thermal cycling.

I reworked all the joints with lead-free, as that is what the RoHS
legislation legally charges me to do as a commercial repair outfit, but boy,
the temptation was strong to just reach for the leaded solder, and do the
job 'properly' ...

Arfa

Arfa Daily wrote:

"Eeyore" wrote
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.


I have just this minute finished repairing a Panasonic DAB / FM radio which
was dying as soon as it was switched on, with a "F76 Pdet" error in the
display. I took this to be "power detect", which seemed reasonable, given
the symptoms. When I took the main board out to have a look at the
underside, I found the power supply section riddled with poor and
'cracked-right-round' lead-free solder joints ( the board actually has
"PbF" silk-screened on it ). The poor joints were particularly well defined
on the main free-air cooled regulator transistor, which is obviously subject
to thermal cycling.

I reworked all the joints with lead-free, as that is what the RoHS
legislation legally charges me to do as a commercial repair outfit, but boy,
the temptation was strong to just reach for the leaded solder, and do the
job 'properly' ...

Have you considered documenting this stuff ? With a scan or a pic for example ?

What do you tell the customer ? That Greenpeace is to blame ?

Graham

Arfa Daily wrote in message
...

"Eeyore" wrote in message
...


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



I have just this minute finished repairing a Panasonic DAB / FM radio
which
was dying as soon as it was switched on, with a "F76 Pdet" error in the
display. I took this to be "power detect", which seemed reasonable, given
the symptoms. When I took the main board out to have a look at the
underside, I found the power supply section riddled with poor and
'cracked-right-round' lead-free solder joints ( the board actually has
"PbF" silk-screened on it ). The poor joints were particularly well
defined
on the main free-air cooled regulator transistor, which is obviously
subject
to thermal cycling.

I reworked all the joints with lead-free, as that is what the RoHS
legislation legally charges me to do as a commercial repair outfit, but
boy,
the temptation was strong to just reach for the leaded solder, and do the
job 'properly' ...

Arfa



What was the chipcode dates on that DAB ?
No more than 2 years old no doubt.

If you had not repaired it than also no doubt it would have ended in
landfill taking with it ,perhaps not lead, but antimony, bismuth, tin,
copper, barium , phthalates etc

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

I reworked all the joints with lead-free, as that is what the RoHS
legislation legally charges me to do as a commercial repair outfit, but boy,
the temptation was strong to just reach for the leaded solder, and do the
job 'properly' ...

If you use leadfree solder, remember that the temperature is a bit
higher, and this makes the fumes from resin much more dangerous to
YOU..
Second.. if the components is made for leadfree solder , it can happen
that the tin/lead solder wont make a good solder-joint. ( but I agree
that sometimes one is tempted )
Alex

"Arfa Daily" wrote in message
...

"Eeyore" wrote in message
...


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



I have just this minute finished repairing a Panasonic DAB / FM radio
which was dying as soon as it was switched on, with a "F76 Pdet" error in
the display. I took this to be "power detect", which seemed reasonable,
given the symptoms. When I took the main board out to have a look at the
underside, I found the power supply section riddled with poor and
'cracked-right-round' lead-free solder joints ( the board actually has
"PbF" silk-screened on it ). The poor joints were particularly well
defined on the main free-air cooled regulator transistor, which is
obviously subject to thermal cycling.

I reworked all the joints with lead-free, as that is what the RoHS
legislation legally charges me to do as a commercial repair outfit, but
boy, the temptation was strong to just reach for the leaded solder, and do
the job 'properly' ...

But we know which solder you really used. Of course, you have to pretend
you used the PbF stuff. Just be careful that the lead nazis don't audit
your purchasing of lead content...

Leonard

On Wed, 25 Jul 2007 10:43:08 +0100, Eeyore
wrote:



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.



If the water tables around an outdoor shooting range had any higher
levels of lead leeched into them, the whole world would know about it,
and that is what we call NEWS.

FACT is that there is no such lead level increase in such areas, and
they dump TONS of lead into the ground at popular ranges.

FACT is that I have been touching, rubbing, etc. lead alloy soldered
circuit card assemblies (as well as the solder itself) my entire adult
life, and my lead levels are lower than the doc had previously seen for
someone my age, the last time I had that test taken ( about four years
ago).

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****.

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.

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

On Wed, 25 Jul 2007 10:45:30 +0100, Eeyore
wrote:



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.

Fully operating incinerators are sprinkled all over this country. There
was even some twit on TV the other day claiming that their placement was
racist.

Actually, I'd expect a lot of solder to turn to oxides and go up the smoke stack if
subjected to high temps.

Do you know the rate that pure Lead oxidizes? Do you know the rate at
which 63/37 Tin Lead Solder oxidizes at?

Bullets are still being found in old US Civil War battle fields, and
they are practically pristine balls. No crust whatsoever.

What actually happens with pure Lead is that it's first few mils of
depth become "tempered", similar to aluminum anodization.

So it becomes harder, and would oxidize even less.

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?