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#175088 - 02/22/08 04:42 AM Looming on the horizon?  
trollog  Offline
Member
Joined: Oct 2004
Posts: 276
San Diego California USA
Read an interesting article tonight about the implications of removing lead from solder to keep it out of our landfills. It seems that lead was alloyed with tin in solder in the first place to prevent "whiskering", where small hairlike filaments naturally grow out from the surface of the soldered joint, similar to rust or other corrosion. It's not completely understood why tin and a few other metals used in soldering do this in the first place, but alloying the metals with lead eliminates the problem. When the whiskers grow long enough to come into contact with the nearest neighbor's soldered joint on a circuit board, it results in.. yep.. a dead short. Seems the problem affects most of the alternative alloys proposed or mandated by "green" legislation in various countries (including the United States, most recently). So the price goes up and the MTBF (mean time between failures) drops to half that of things made with lead based solder due to whiskering. Just a heads up- it will be interesting to see in the coming years how this affects the work we do .. commerical lighting control boards come to mind, as well as the myriad types of dimmers, photocells, and various other devices we work with. It will probably take a good year before the existing stock of products made with leaded solder are sold off the shelf and all that is left are products made with the new lead free alternatives. I suppose it will become a script we have to memorize, explaining to customers why their expensive electronic device failed so quickly. Whiskering also begins from the time of manufacture, so maybe we will need freshness dates on the things we buy, similar to milk, cheese or beer.

A link to a NASA article on problems they have had with whiskering
and some good pictures of what it is and what it looks like:

http://nepp.nasa.gov/WHISKER/

http://nepp.nasa.gov/WHISKER/reference/tech_papers/2007-brusse-metal-whiskers.pdf

Wikipedia article on whiskering, including what metals/alloys are most
afflicted by it:

http://en.wikipedia.org/wiki/Whisker_(metallurgy)


Last edited by trollog; 02/22/08 04:54 AM. Reason: added a link

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#175089 - 02/22/08 05:09 AM Re: Looming on the horizon? [Re: trollog]  
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,392
Vienna, Austria
Time will tell... leaded solder was banned from commercial use in the EU at least one year ago and so far I haven't heard of a spectacular rise in equipment failures. I do know development of new technologies was problematic at first, but it seems to have worked out by now (I know a bunch of people whe experimented with lead free soldering of photovoltaic cell and concluded proper flux is the key to success.)

Last edited by Texas_Ranger; 02/22/08 05:09 AM.

#175096 - 02/22/08 12:16 PM Re: Looming on the horizon? [Re: Texas_Ranger]  
NJwirenut  Offline
Member
Joined: Sep 2001
Posts: 806
Bergen County, NJ
Tin whiskering isn't the only problem with the new solder formulations. The lead-free alloys tend to be much more brittle than the standard Sn/Pb solder, and the joints tend to crack with repeated heat/cool cycles. The problem is exacerbated by the use of surface mount components, which have no wire leads to absorb the stress.

Microsoft is learning about this the hard way with massive field failures on their "X-box 360" videogame systems. The lead free solder joints are failing, prompting LOTS of warranty repairs.


#175183 - 02/24/08 05:07 AM Re: Looming on the horizon? [Re: NJwirenut]  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Conventional tin/lead solder can still be sold here for "special" purposes, so fortunately those of us who want to keep on using it for repairing vintage radio equipment are still O.K. for the moment. It's getting harder to find sources though.

If they ever decide to completely ban lead in solder, I think we'll be back to stockpiling as much as we can afford. Better make room alongside all those boxes of filament lamps!


#175185 - 02/24/08 12:03 PM Re: Looming on the horizon? [Re: pauluk]  
SolarPowered  Offline
Member
Joined: Jul 2004
Posts: 625
Palo Alto, CA, USA
Pardon my ignorance, but isn't lead found naturally in nature? It seems to me that there's no more or less lead around whether some of it's made into solder or not.


#175186 - 02/24/08 12:08 PM Re: Looming on the horizon? [Re: SolarPowered]  
sparkyinak  Offline
Member
Joined: Jul 2007
Posts: 1,313
Alaska
Public preception is more important then reality


"Live Awesome!" - Kevin Carosa

#175188 - 02/24/08 01:27 PM Re: Looming on the horizon? [Re: sparkyinak]  
Theelectrikid  Offline
Member
Joined: Apr 2004
Posts: 810
Levittown, PA
Originally Posted by sparkyinak
Public preception is more important then reality


Tell that to home inspectors and their clients...

Ian (Surrounded by asbestos) A.


Is there anyone on board who knows how to fly a plane?

#175190 - 02/24/08 01:56 PM Re: Looming on the horizon? [Re: Theelectrikid]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,057
Estero,Fl,usa
I think this became an issue when people started realizing the impact of throwaway electronics. Nobody fixes anything these days, you throw it away and buy a new one so a lot more lead is finding it's way into the waste stream. Unfortunately some of these widgets are not even lasting long enough to survive their short design life


Greg Fretwell

#175191 - 02/24/08 02:14 PM Re: Looming on the horizon? [Re: gfretwell]  
BigB  Offline
Member
Joined: Mar 2004
Posts: 719
Tucson, AZ USA
How many kids a year do they figure chew on circuit boards anyway?


#175194 - 02/24/08 04:26 PM Re: Looming on the horizon? [Re: BigB]  
NJwirenut  Offline
Member
Joined: Sep 2001
Posts: 806
Bergen County, NJ
Unfortunately, with the reliability problems caused by the lead-free solder, there will probably end up being even MORE junked electronics headed for landfills in the future. If the manufacturers can get the solder joints to hold together long enough to get through the 90 day warranty, then failures after that just help ensure the sale of MORE cheap Chinese TVs and DVD players. frown

Wait until analog TV goes dark in the US next year--the curbsides are going to be flooded with discarded sets...


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