"N Cook" wrote in message
...
Arfa Daily wrote in message
...
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automotive electronics industries currently enjoy, never get rescinded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



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
http://home.graffiti.net/diverse:graffiti.net/

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