Lead-free Solder ( continued ... )

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Hi all

Friend of mine also in the electronic service business just called me to
tell of a conversation he had in the pub last night with one of his friends.
Turns out this guy is a washing machine service engineer with his own
business of many years. He told my friend that from a business point of
view, he is delighted with lead-free solder, because in the last year or so
it has boosted his profits significantly. This is because of the number of
bad joints that he now sees on items such as solenoids. He is firmly
convinced that the lead-free solder, being a harder material that doesn't
stick well in the first place to items with a large thermal inertia, cannot
take the vibration that a washing machine subjects it to. This seems
altogether reasonable to me.

Just this morning, I have repaired a NAD CD player that would play for
anything between 5 and 45 minutes, before randomly failing. No amount of
physical provocation would bring on the fault, nor correct it when it
occured. It would need to be left off for about a half hour before it would
play again. Just for sport, I tried a laser, but of course, that wasn't it.
I then took the board out, and went over it with a headband magnifier. I
then found two perfect cracked-right-round joints on a connector. The joints
had that traditional lead-free straight-sided volcano like shape. Once these
had been attended to, and the original laser put back in, everything was
fine.

Is it just me, or does anyone else have concerns for the wider implications
of this nonsense technology that has replaced a mature and reliable
technology in the dubious name of that new great ( and some would say false
... ) god, "Green" ? If washing machines can vibrate these joints into
submission, I sincerely hope that the exemptions that the avionics and
automotive electronics industries currently enjoy, never get rescinded ...

Arfa



Re: Lead-free Solder ( continued ... )
I see it as another example of well-meaning people effecting change about
that which they know not.  The consequence is that a few people feel they
have saved the world, and everyone else suffers.  Mr. Common Sense has once
again died and gone to hell.

 WT

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Well meaning nothing! - many of these so called "green" initiatives are led
by anarchists hoping to destroy capitalism, although they do seem to have
shot themselves in the foot with this one as washing machines have a much
shorter life span and the capitalists sell more washing machines.



Re: Lead-free Solder ( continued ... )
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Interesting view of the EU bureaucrats. Anarchists. One who believes in
the abolishment of law and order and or government. ;-)

--
*Life is hard; then you nap

    Dave Plowman         snipped-for-privacy@davenoise.co.uk           London SW
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Who said anything about EU beaurocrats? - They've simply passes popularist
legislation on things they know absolutely nothing about!

You'd have to be blind (or never watch the news) to miss the crowds of kooks
that riot every time there's a political summit, the EU beaurocrats see
large crowds rioting and decide that many people must all be right - eat
shit, 2 000 000 000 000 flies can't be wrong!



Re: Lead-free Solder ( continued ... )
I have worked with it and have concluded that it is different, but not
neccesarrily that big a deal.  Some of it is much harder to work with than
others and I suspect that just like the early days of circuit board
automated production, we will see the manufacturers go through a learning
curve with respect to how to use it properly.  Lead definitely has its
advantages, and I think the environmental impact is minimal for now, but
what about hundreds of years from now?  Who knows what those lead containing
boards will be subjected to in time?  It is a change that I suspect will not
be reversed, so I see no reason to do anything but get used to it and
happily accept any repairs that it brings me.  No different from all those
hundreds of LA7838s that did not have enough solder deposited on the joints.
We ain't going back to manual inseertion and soldering in production lines
either.

Leonard

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Re: Lead-free Solder ( continued ... )
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friends.
so
cannot
would
it.
joints
these
implications
false

But you can get that sort of failure with Pb/Sn if the flow soldering is not
hand redone for the large metalic heatsinky pins etc, combined with a blunt
post soldering leg/pin-cropper straining the joint before it comes out of
the factory.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
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Granted, you can. But this guy saw it as enough of a difference from what he
has seen over the years with traditional lead-based solder, as to be worth
commenting about. Where the problem comes about, is with the higher temps
required to flow this stuff. The manufacturers dare not go up too high for
fear of damaging both semiconductor components, and the board substrate ( to
say nothing of their bank account from the higher energy costs associated
with having to use the stuff - green? - Ha! ). This leads to them going
*just* high enough to solder those components, which leaves them well short
of enough temperature to get a really good joint at high thermal inertia
components like connectors and power devices. Certainly, I see a lot more
bad joints now than we had become used to with lead-based solder, and by far
and away, the majority are on connectors and similar that would not have
been giving the same trouble a few years back. I also see a higher number
than would be expected, of bad joints on fine pin-pitch LSIs, often along
one side only, which I'm guessing is the side away from the solder
wavefront. From the time that the techniques were first developed to
production-solder these devices, the soldering has been very reliable, but
not any more ...

Arfa



Re: Lead-free Solder ( continued ... )
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to
or
doesn't
of
I
was
of
he
 to
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short
far

I'd not realised it was a hiding to nothing play off between
temperature/wave speed/heat capicity/heat transfer rate. Heatsinky
components/mechanically streesed ones should still be redone by hand surely.



Re: Lead-free Solder ( continued ... )

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As long as the manufacturers can (only just) get the product to out live the
warranty they're very happy. Most electronic components generate heat so the
temperature cycles up/down every time its used. The expansion/contraction
breaks lead free solder pretty quickly so the production lines are busier
than ever turning out replacement equipment.



Re: Lead-free Solder ( continued ... )

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well, i do use it and i don't like the finish i get from it how ever,
  we do like using it on repairing old electronic boards that have high
wattage R's on the board that create cracks when hot. I find in those
cases you can increase the heat on the tip and force it to flow nicely
which gives a good bond on those hot running components.


--
"I'm never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
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Trouble with that philosophy, is that the jury is still out on whether you
can reliably mix leaded and non-leaded solder. Some solder manufacturers say
that you can, whilst others say that you can't. A number of independant
metalurgical experts are of the opinion that by mixing the two solders, the
long term integrity of the joint will be compromised. There is actually no
requirement in the legislation to repair equipment that was originally
manufactured with leaded solder, with anything other than leaded solder.
Somewhere around the shop, I have an old reel of leaded high melting point
solder that I used to use for that sort of thing, but haven't in a long
time. It was originally for resoldering those spring-off resistors -
remember them ?

Just as an aside, after this morning's NAD, this afternoon I had a Sony home
cinema - one of the DAV series - I dunno, a 300 or 500 or some such. It had
the usual problem of thinking that it was in headphone mode, but instead of
the common bad connector, this time, it was yet more lead-free bad joints on
the power amp PCB. As well as the ones on the bottom of the connector that
were causing the headphone problem, it also had cracked-around joints on
just about all of the six channels' output filter chokes, a problem which
you've probably all seen more than once on these, and also on the output
relays. Now these are problems that have developed, as the boards are old
enough that if they were original production drys, they would have showed
long ago. I accept that drys also 'develop' with leaded solder on certain
components that suffer high levels of thermal cycling in use, but the amount
of drys on this one board, all on components that are either fairly large,
or subject to mechanical vibration stress ( the relays ) rather than thermal
issues, leads me to believe that there is a different failure mechanism at
work here, possibly related to the lack of ductility of lead-free compared
to leaded solder.

As far as the suggestion of manufacturers having to hand work bunches of
components as the boards roll off the line, I can't imagine any way that
this could be accomplished in a practical or cost-effective way.

Arfa



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Who are these experts and where are the links to the info on this?  I would
be curious what testing they have done and on what formulations.  The
vendors that have been willing to comment to me off the record say that
there is no problem and that they are just political CYAing when they say to
use lead free to repair lead free boards.

Leonard

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Re: Lead-free Solder ( continued ... )

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Hi Leonard

I came across several on the net saying much the same thing, when I was
researching an article on the stuff a couple of years back, when everyone in
the business thought that it was suddenly going to be "illegal" to use
leaded solder after the RoHS directive came in, and that if you did, the
solder police in their green uniforms would come rushing round to arrest you
before beating you up and throwing you in Eurojail for 20 years. I've
cleaned up the PC since then, but have found the following link to an
article written by a Dr Paul Goodman, who works for a well respected
institution who provide help and advice to industry on the technicalities of
this directive and associated issues. I had a number of direct conversations
with Paul to make sure that I was correctly understanding comments that he
had made in his document on the subject, and came to the conclusion that he
knew what he was talking about. The bit that refers to mixing solder types
is under the heading "REWORK"

http://documents.rs-components.com/EITC/UK/generalFiles/soldering_and_RoHS.pdf

I'm sure with a bit of time spent, other similar comments could be found
again, unless there has been a serious genuine ( or politically motivated )
change of opinion by those that agreed with Paul, in the intervening couple
of years. The document I have referred to is still live - I've just checked.
In case that long link embedded in a news post gives any trouble, the gap
either side of the word "and" is filled with an underscore.

Arfa



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Most of the far-eastern manufacturers were years ahead of the RoHS deadline
and a huge number failed due to faulty soldering, as it was before the
deadline I used lead/tin solder - most of my monitor customers were regulars
so if mixing solder types had been any less reliable than the original
lead-free, I would have soon found out!



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message
say
the
home
had
of
on
amount
thermal

Another failure mode I've come across ove rthe years is where the component
sourcing changes, but the board layout/drilling remains the same and the new
comps have smaller diameter pins. The solder bridges the gap ok for a few
years and then cracks, not even heat stressed, just room temp changes
probably. How would the non Pb/Sn stuff fare with that situation in
comparison.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
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Re: Lead-free Solder ( continued ... )

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..................after less than a years use you'd be able to pull most of
the components out without heating the solder!



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Here's another interesting and related piece that arrived on my computer
today

http://uk.farnell.com/jsp/bespoke/bespoke7.jsp?ATT=whiskers_text&CMP=NLC-Findings&bespokepage=farnell/en/ed_world/news/latest_news/2006/tin_whiskers.jsp

Arfa



Re: Lead-free Solder ( continued ... )
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friends.
so
cannot
would
it.
joints
these
implications
false

Perhaps we should offer the following service. What would it be called ?
From after day one, after expiry of warranty, while fully working order, go
inside any kit at owner's request and pre-emptively rework the usual
suspects.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
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Sounds like a recipe for disaster if you ask me! If it aint broke, fix
it till it is broke.

Ron(UK)

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