So what's the truth about lead-free solder ? - Page 14

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Re: So what's the truth about lead-free solder ?
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charged as
useful data.
bait.
reliability of
equipment

I think I'll make up a tool for mechanically scraping this "tin-plating" off
the next power tranny.
My first idea is two back to back Skarsten scrapper blades to scrape back 2
sides at one time.



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

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You might find that a tool is already available which works for this
purpose.  I'm thinking of the things for scraping the enamel off
transformer winding wire:
http://www.buerklin.com/gruppen/KapL/L115880.asp

Chris




Re: So what's the truth about lead-free solder ?
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controller
back



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

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But those are RoHS compliant.

More to the point, for removing laquer , not hard tin , from round surface.
I just tried a Skarstan blade , singly, in its normal wooden handle and it
scrapped the hard tin off some of the flat leads of the latest batch of
TIP35C/36C power trannies that I bought. Down to the copper with no
difficulty, I think I can ignore the tin-pest developinmg on the narrow
edges as long as the main surface contact areas are functionally solderable.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
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Re: So what's the truth about lead-free solder ?

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Ok, it was just a thought.  I was imagining the round pin of a T03 when I
thought of that.

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Do you mean tin pest or whiskers?  I would have thought that the edges would
be the worst place for whiskers to sprout from.

As for solderability, I would have thought that if the pins are exposed to a
sufficient quantity of sufficiently hot SnPb solder for a sufficient time,
then the tin would dissolve into the solder, like fine copper wire has an
annoying tendency to do.  If overheating of the semiconductor device is a
risk, then perhaps it could be done in a couple of goes, allowing to cool
in between.   The resulting tin-rich solder could either be removed and
replaced with fresh solder, or just diluted with more fresh solder.

I'm sure there would be plenty of people interested if you find a good
technique for small-scale use.

Chris


Re: So what's the truth about lead-free solder ?
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would
a

With the sort of stuff I deal with, geometry-wise, tin whiskers have no
relevance I would have thought.
It is that film of tin , all lovely mirror shiney when new turning to grotty
dusty grey (tin pest) , expanding in the process , and physically pushing
the solder away from any conduction maybe only 2 years down the road.
I am not sure just heating legs with solder would affect the integrity of
that initial tin film without some sort of mechanical intrusion while hot
and mixing.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
We've slightly trimmed the long signature. Click to see the full one.
Re: So what's the truth about lead-free solder ?



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charged as
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data.
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reliability of
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What's the application that requires this refinishing ?

Graham


Re: So what's the truth about lead-free solder ?
On Fri, 17 Aug 2007 23:15:39 +0100, Eeyore

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charged as
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data.
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reliability of
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equipment
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  High temp mag wire... not the shitty for high temp uses "Nyleeze" does
NOT burn off with the application of heat, and requires scraping to
remove the insulation.  Before Nyleeze, the requirement was the standard
for decades.

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

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Tin Whiskers:-

For those who though leaded solder was best.
Here is the problem with lead free solder.

 http://pubs.acs.org/cen/science/85/8529sci1.html

Colin



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

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Yes, a good write-up of the problems, and why leaded solder didn't suffer
from them.

Arfa



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