The latest casualty of lead free solder: Titan super computer

[Ferzerp]

I found this amusing for some reason.

http://oakridgetoday.com/2013/03/13...y-cray-re-soldering-supercomputer-connectors/

How many years, and we still can't make reliable solders now?

The fluff story seems to concentrate on "too much gold", but it's more of a gold-tin alloy issue that wouldn't be present with lead if I understnad correctly. I'm sure someone like IDC can correct me.

Wasn't sure which forum this fit in, but CPU is close enough because it's a super computer! (Even if its superness is via GPUs)

 

[Idontcare]

Given the little info they provide regarding the solder issues the possibilities are just too wide open to really attempt to discuss what the root cause could be. It could range from tin whisker formation to Au-Sn interstitial compound formation, any of which would be bad.

Would have been ironic if the issue was with the Nvidia cards and not the CPU sockets as it were (bumpgate and all).

 

[Ajay]

Too much Gold in the connectors probably just created a poor bond, probably too many voids. Correcting the gold contacts too more closely match amalgam in the solder. Tin will reflow best with Tin and Gold with Gold.

 

[Ferzerp]

Other stories suggest that the solder is too brittle (the same thing we saw right after the switch over to lead-free is it not?)

http://blogs.knoxnews.com/munger/2013/02/more-details-on-titans-trouble.html

 

[Ajay]

Other stories suggest that the solder is too brittle (the same thing we saw right after the switch over to lead-free is it not?)

http://blogs.knoxnews.com/munger/2013/02/more-details-on-titans-trouble.html

So it appears, though I'm not sure how reducing the Gold in the contacts will help this

 

[Ferzerp]

http://www.semlab.com/goldembrittlementofsolderjoints.pdf

?

 

[AtenRa]

I had a long time to read about metallurgy, nice links thx

 

[Vinwiesel]

Lead free solder is definitely more brittle. It is much easier to fracture a lead-free solder joint than an old tin/lead one. With the old tin/lead soldered boards, often times if a component was physically damaged it would rip the land/pad off the circuit board, or rip the leads off the component. With the new lead-free solder, the fracture typically occurs at the solder joint.

For soldered wires that are subject to movement, I used to see the wire flex until it broke. Now, I sometimes see where the wire has flexed, and broken free of the solder still intact. The lead solder cools into a smooth malleable blob, where the lead-free solder is almost crystalline. Think of it as flexing aluminum vs flexing steel. You can bend steel many many times before it snaps, but aluminum will snap after only a few bends.

The gold comment could be legit, since sometimes it is the plating that breaks free from the land/pad. I don't really see how "too much gold" is the problem, but could easily see it being poorly plated gold, or one of the other plating layers.

 

[VirtualLarry]

Do you guys remember the statement that Intel made about SIMMs, in terms of tin-plated versus gold-plated contacts, and gold-plated sockets?

Gold-on-gold, or tin-on-tin was OK, but not gold-on-tin or vice versa.

 

[zephyrprime]

Lead free solder is definitely more brittle. It is much easier to fracture a lead-free solder joint than an old tin/lead one. With the old tin/lead soldered boards, often times if a component was physically damaged it would rip the land/pad off the circuit board, or rip the leads off the component. With the new lead-free solder, the fracture typically occurs at the solder joint.

And that's how it should be! A metal-metal bond should be stronger than a metal-plastic bond. Down with lead-free solder! Bring back the lead! Damn the europeans!

 

[Zodiark1593]

Wonder why we went lead free for stationary computers. Not like some little kid is gonna crack open a desktop, shove his face in, and start sucking on the little bits of solder. Amirite?

 

[Homeles]

Wonder why we went lead free for stationary computers. Not like some little kid is gonna crack open a desktop, shove his face in, and start sucking on the little bits of solder. Amirite?

Where does that computer go when it's broken? In a landfill. That's when it becomes a hazard, as it could pollute the water supply.

 

[ShintaiDK]

Where does that computer go when it's broken? In a landfill. That's when it becomes a hazard, as it could pollute the water supply.

Is there even any industrialized nation left that does that?

 

[Homeles]

Landfills? Yeah, they're all over the US. RoHS was Eurpoean legislation though, so I have no idea about that side of the ocean.

 

[Charles Kozierok]

Around here computers are not supposed to go into landfills. But my guess is that many do anyway.

If the boards are reprocessed and the lead recovered, they should be able to continue to use lead solder. Since we're talking about a specialty product here, I would think they could ensure the devices are disposed of correctly.

 

[Ajay]

A lot of US computers and electronics wind up in India (I think) where they are stripped down for used components. Our collection site separates electronic devices, appliances, etc.

Still, I'm sure some wind up in the landfill.

 

[Idontcare]

Wonder why we went lead free for stationary computers. Not like some little kid is gonna crack open a desktop, shove his face in, and start sucking on the little bits of solder. Amirite?

As a parent and a chemist I actually worry a great deal about potential lead-exposure vectors for my children.

And one of the things I learned was that lead can be contained in, and on, just about anything that looks remotely like a toy and the regulations basically say it is ok provided the item in question has a label on that says "this is not a toy".

My aunts are notorious in my family for buying decorative items that look like super fun toys - we are talking about trucks, dolls, etc - only they are supposed to be decorations for old ladies homes - stuff that sits on an end-table or a mantle. But they are made to look just like toys, and guess what they are full of? Lead. And I'm not talking about buried inside under plastic and paint, they can have lead right on the surface and be viewed as ok.

But along comes a 2yr old visiting toddler and they see the "toy" and pop it into their mouths. Aunts think its cute, the chemist in me screams and I become the bad guy because I take the "lead-based toy" away from the kid. Turn it over and sure enough it will have stamped on it "this is not a toy".

The "this is not a toy" stamp is the manufacturers get-out-of-jail-free card. So long as they put that somewhere on the item they can basically shove as much lead and cadmium into it as they like.

/end PSA

 

[Plimogz]

Mmmm sweet, sweet cadmium. Melts in your mouth and your hands. And then melts your bones. Lovely.

As if off-shoring jobs and manufacturing to developing countries wasn't awful enough for workers and the middle-class economy, now the first-world can go back to enjoying poisonous toys and jewelery in happy meals and on the aisles of wall-mart.

 

[ssm0002]

Chinese love RoHS. Planned obsolescence for the electronics they make for us westerners. Tin wiskers short your electronics and now you have to buy replacements.

 

[Idontcare]

Chinese love RoHS. Planned obsolescence for the electronics they make for us westerners. Tin wiskers short your electronics and now you have to buy replacements.

In the end we all get what we deserve, for better or for worse.

 

[meloz]

Chinese love RoHS. Planned obsolescence for the electronics they make for us westerners. Tin wiskers short your electronics and now you have to buy replacements.

'The Chinese' did not come up with requirement for lead free electronics. In fact, when you look at air quality in Beijing you realize the Chinese government has put aside environmental and health concern for short term economic gains.

It was necessary to go for lead free solder, though. For everyone, not just Chinese or Europeans. People do not realize the impact of lead in electronic gadgets which look so benign (until you have to get rid of them), and too many of the electronics were ending up in landfills and polluting local water supplies.

It might be bit of a hassle but industry will come around and things will sort out. The transition to lead free has been mostly free of problems.

 

[bononos]

Do you guys remember the statement that Intel made about SIMMs, in terms of tin-plated versus gold-plated contacts, and gold-plated sockets?

Gold-on-gold, or tin-on-tin was OK, but not gold-on-tin or vice versa.

Yeah it was strange that some simm sticks were plated with gold, shouldn't be more expensive that way?

 

[Idontcare]

'The Chinese' did not come up with requirement for lead free electronics. In fact, when you look at air quality in Beijing you realize the Chinese government has put aside environmental and health concern for short term economic gains.

It was necessary to go for lead free solder, though. For everyone, not just Chinese or Europeans. People do not realize the impact of lead in electronic gadgets which look so benign (until you have to get rid of them), and too many of the electronics were ending up in landfills and polluting local water supplies.

It might be bit of a hassle but industry will come around and things will sort out. The transition to lead free has been mostly free of problems.

The switch to lead-free gasoline was a good move too. Definitely helped with lead in air pollution.

 

[red454]

I take all the dead computers and components from friends / relatives / coworkers and take them to the local Tox-Drop. Where do they go from there? Supposed to be recycled or disposed of 'properly'...