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Typical Prescott ball solder - Coutesy of Chipworks

Copper pillar connection found on Presler and Yonah CPUs - Couresy of Chipworks
The first looks inside Yonah and Presler reveal some interesting techniques regarding the manufacturing process

Chipworks, a company that reverse engineers semiconductors, had the chance to crack open two of Intel's newest 65nm CPUs.  The company was excited to find that typical solder connections had been completely replaced with copper pillar interconnects. 

“Previous Intel processor generations such as the ‘Prescott’ used conventional flip-chip technology with lead-tin (Pb-Sn) solder balls,” adds Dick James, senior technology advisor at Chipworks. “For the Yonah and Presler, Intel has switched to a process that uses plated copper pillars to form the interconnection between die and board. This reduces the lead content over traditional flip-chip packaging even in the latest “Pb-free” devices. This is the first processor seen by Chipworks to use this advanced flip-chip technique.”

The move from solder to other lead-free manufacturing processes was mandated by RoHS and other legislation in Europe several months ago.  However, Intel engineers seem to have gone beyond the mandate by replacing solder altogether instead of just removing the lead content. 


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advantages?
By Visual on 1/27/2006 4:53:47 AM , Rating: 2
say, are there any performance or financial advantages of this new tech? cos i somehow doubt intel did it for the environment.




RE: advantages?
By tuteja1986 on 1/27/2006 5:26:01 AM , Rating: 2
Some country are forcing lead free product :! like australia. Like Gigabyte launched few 100% lead free boards.


RE: advantages?
By JackPack on 1/27/2006 5:26:47 AM , Rating: 1
It's slightly cheaper and more reliable.

But the most important point is that the packaging needs to be Pb-free due to RoHS mandate, or it won't be allowed into the EU. Deadline is July.


RE: advantages?
By theapparition on 1/27/2006 7:26:53 AM , Rating: 1
Eh, it's certainly NOT cheaper, and the reliability studies are just beginning (vs. 50years of data using tin-lead). If it was cheaper, people would have started using it years ago.

You are correct on the deadline. If anyone wants to sell anything in Europe, better make it Rohs compliant.

Intel probably went "above and beyond" the current requirements since the Rohs directive has cut-in dates for various banned substances, and they updated their processes so they don't have anything thats listed on the "potentially banned" list.

For example, PVC is not banned, but it is on Rohs and WEEEs "watched" list and may be banned in the future. So the direction for new design is to not use PVC, so later you don't have to make a change when it is banned.

More money now, but future proofing it saves money in the long run.


RE: advantages?
By vsridhar420 on 1/27/2006 5:37:13 AM , Rating: 3
What's the worry ? If it is good for environment it is good isn't it ? Why question the motives ? If Intel saves some money with this, it will encourage other companies to look at it too. Anyway, Intel should have used this feature for better PR.


RE: advantages?
By Eris23007 on 1/27/2006 1:47:31 PM , Rating: 1
quote:
If it is good for environment it is good isn't it ?


"Good" is a statement of opinion, not fact. Lead is far from proven to be "bad" for the environment.

This lead-free business may end up being extremely bad for the tech industry. Do some research on "Tin Whiskers". This is a known problem with lead-free solder.

In fact, I would not be surprised if Intel chose copper due to the tin whisker issue, despite the fact that copper is *way* more expensive than pb-free solder. It may also be a performance/heat thing. Still, I have a very tough time with the idea that the benefits of this whole lead-free business really outweigh the costs.


RE: advantages?
By mindless1 on 1/28/2006 8:13:54 AM , Rating: 2
So true, only those standing to gain by going lead-free or those deluded by propaganda are rapidly accepting the changeover. It is expected that there will be quite a bit of teething pains to this switch in general and I can only hope Intel has spent several years researching this instead of just trying to jump on the boat as quickly as possible.


RE: advantages?
By Shining Arcanine on 1/27/2006 10:19:43 AM , Rating: 2
Copper has a lower electrical resisitivity than solder, and it is second only to silver barring superconductors. The only reason Intel has not used it until now is probably cost, as copper is becoming more and more expensive. It is probably more expensive for Intel to cede the European market to AMD; hence why they are doing this.

by the way, this means less heat.


RE: advantages?
By mindless1 on 1/28/2006 8:15:58 AM , Rating: 2
It could easily have been for lack of manufacturing technology or reliability issues.

It is not certain that any random switch to copper will make any difference at all, particularly if the bonding isn't as good as was achieved with the solder.


RE: advantages?
By oTAL (blog) on 1/29/2006 11:20:11 PM , Rating: 2
"Copper has a lower electrical resisitivity than solder, and it is second only to silver barring superconductors."
Hmmm... Gold?


and AMD?
By bupkus on 1/27/2006 9:22:15 AM , Rating: 2
What does AMD use?




RE: and AMD?
By JonB on 1/27/2006 10:54:11 AM , Rating: 2
RoHS
By Brian23 on 1/27/2006 3:43:57 PM , Rating: 2
This whole RoHS thing is just a bunch of crap. The whole reason for it is not because it's safer or better for the environment. The reason for it is that it makes it harder for foreign companies to sell their products in Europe. Since NAFTA went into effect, they can’t charge taxes on imported goods so they came up with this RoHS idea to have the same effect as an import tax.

Lead free solder is not as good as lead solder. I work for a company that makes equipment that’s used by both civilians and the US military. Our company started converting all our products to be RoHS compliant, but when we did, the military stopped purchasing them. When our sales people checked into this we found out that the military WILL NOT buy anything that is RoHS compliant because it’s less reliable than a product that is not RoHS compliant. So now our company is going to build 2 versions of every product: one for civilian use, and one for military use.




RE: RoHS
By mindless1 on 1/28/2006 8:18:35 AM , Rating: 2
I agree, lead-free solder is not as good but you're quite wrong about motivations being to make it harder for foreign companies to sell in Europe. It's a given that the large volume import products will switch so if anything it's more of a problem to the smaller European companies to do their own R&D towards a reliable process.


By flilp1 on 1/30/2006 11:47:51 AM , Rating: 2
The Intel CPB (Copper Pillar Bump) interconnect as shown is not a Pb free joint. Visual examination of the solder between the CPB and substrate pad shows that that the solder is 63Sn/Pb (dark spots are lead).

Intel is using the CPB to mitigate problems with electromigration (EM) in the interconnect. Simple EM explantion is that metals can move when exposed to electron flow. With solder due to the current density at the chip pad. This has become a major issue at the ~50um opening to the chip used by Intel. With the large diameter CPD the current is well distributed by the time it reaches the solder and EM is much less of an issue. For a good overview of EM, review the ERA Technology report to the EU at http://europa.eu.int/comm/environment/waste/pdf/er....

On Oct 21, 2005 the EU formally allowed any Pb based solder to be used in what is called a FCIP (Flip Chip in Package). See item 15 of the decision located at http://europa.eu.int/eur-lex/lex/LexUriServ/site/e....




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