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So what's the truth about lead-free solder ?

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:

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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

Reply to
Glen Walpert
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So all those owners of lead mines are wasting all that money doing things the more expensive way as a public service?

Reply to
Guy Macon

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

Reply to
mpm

On a sunny day (Wed, 25 Jul 2007 08:33:12 -0700) it happened mpm wrote in :

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.

Reply to
Jan Panteltje

Dr Howard Johnson (High Speed Digital Design) had this article in his email newsletter (and posted on his site). Interesting read. Rollback RoHS:

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--
Joe Chisolm
Marble Falls, TX
Reply to
Joe Chisolm

On a sunny day (Wed, 25 Jul 2007 12:29:00 -0500) it happened Joe Chisolm wrote in :

Well seems [all] we have to [do is] make some traces .65mm apart :-)

Reply to
Jan Panteltje

The main issue for lead free in military and aerospace electronics is tin whiskers. Tin solder will grow conductive whiskers that even penetrate conformal coatings. In low power circuit, the whisker will short something out. In a high power circuit, it might burn up like a fuse, but if it happens in a satellite (no atmospheric pressure) the little whisker will cause a plasma arc capable of passing huge amounts of current.

We in the defense electonics industry fight with this issue every day and the information is very confusing. Parts turn lead free midstream in production and seems impossible to keep tack of it. Every company is dealing with it differently. We stay away from certain finishes like bright tin and look at the spacing of components and coatings on our boards. This can mitigate some of the reliability risks of lead free.

If high-rel is of upmost importance, we struggle to find tin-lead parts.

Reply to
Traver

Some ? ALL !

Goodbye microelectronics.

I just came across this too.

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" At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure tin transforms from the (silvery, ductile) allotrope of beta-modification white tin to brittle, alpha-modification grey tin. Eventually it decomposes into powder, hence the name tin pest."

Graham

Reply to
Eeyore

More than political -- the subject could easily be viewed as troll bait. It's been 'discussed' many times in ser.

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Reply to
Allodoxaphobia

AFAIK this exemption only applies to component lead finishes.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

On a sunny day (Wed, 25 Jul 2007 14:47:25 -0400) it happened Spehro Pefhany wrote in :

Too bad.... How about conductive glue replacing solder? Na, will have to wait until the first EU politician's cellphone fails in some emergency.

Reply to
Jan Panteltje

as

data.

It's not a troll.

New data ought be available as to the effects on actual in-service reliability of lead-free by now. It seems as I expected, anecdotally, that musical equipment products that tend to see high levels of vibration are suffering.

Graham

Reply to
Eeyore

What ever happened to 'multiwire' (or some such trade name)? It was a multilayered weld-bonded wiring alternative to multilayer PCBs in the '60s and '70s and was very rugged, easily implemented with NC technology, and used no solder of course.

Since each layer is built up in succession, between power and ground planes, even BGAs can be accomodated.

Regards,

Michael

Reply to
msg

How about getting a clue ? You can get conductive epoxy adhesive btw. It's loaded with silver particles and is ridiculously expensive.

Graham

Reply to
Eeyore

Gone the same way as wire wrap it seems.

Graham

Reply to
Eeyore

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

Reply to
Alex

No, that's not true AIUI. It's the other way round.

Graham

Reply to
Eeyore

tin

white tin

powder,

So when I pull , with just finger tension, a component lead through what was a lead-free solder joint only a year or so before and there is a grey powdery looking surface to the lead where it had been inside the solder joint - is that "tin pest" ?

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N Cook

It could well be I suppose. Here's the problem, we're in 'uncharted territory' here because the EU insisted on going down this path before the science was well-established. Document it. It has serious implications for the classic practice of keeping MI gear in the van / truck, in the (unheated) garage etc.

I'd love to see the idiots at the Commision in Brussels forced to eat humble pie. It's about time that Emperor Barroso's new clothes were seen for what they are.

Graham

Reply to
Eeyore

Do you always talk shit ?

Graham

Reply to
Eeyore

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