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Rob Spiegel
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Re: Lead free solder SUCKS...
Rob Spiegel   2/1/2012 8:24:56 AM
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You make a point that hadn't occurred to me, Oldtimer, and that's the notion the miniaturization could aggravate the problem with tin whiskers. The whiskers don't matter unless they create a short. The likelihood of creating a short will increase with miniaturization.

oldtimer8080
User Rank
Gold
Re: Lead free solder SUCKS...
oldtimer8080   1/31/2012 10:19:09 PM
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Yes, I would say that the problem involves several issues.

The " lead free " solder is actually a compromise solution to get the RoHS certification. I've perviously tested several early types of lead-free solders before RoHS made lead an issue....I wont go into the politics of why I don't follow RoHS guidelines when doing rework, I just know and have personal experience with improper bonding and contact issues with lead free solder. It appears that the stuff I discovered 20 years ago still applies today.

I looked at the process curves for device mount and proper contact to get a proper solder joint. We used to have a bigger " window " of solderability when working with tin-lead ( and even silver ) solders. That " window " is significantly closed with RoHS solder. There isn't much time to be at the higher temperatures before you heat damage the GPU in my example.

I had looked at this issue to make sure the builds at Cray were done with reliability, as much of the original systems were built by hand with MANY custom wires to get the speeds we got.

If we had been forced to use the RoHS solder specs over 20 years ago, our Crays would never have had the reliability they had.

 

On the ( officially a ) Metal Migration issue, repeated high heat levels make the whiskers grow. This is an atomic level problem based on movement of charged elements.

What we see today with component failures today is a result of the miniturization and crowding of internal IC components. 

( This is what information you gain when you work around a team of experts in their fields and take tke courses they offer at your local Community College )

 

 

 

oldtimer8080
User Rank
Gold
Re: Lead free solder SUCKS...
oldtimer8080   1/31/2012 10:19:08 PM
NO RATINGS
Yes, I would say that the problem involves several issues.

The " lead free " solder is actually a compromise solution to get the RoHS certification. I've perviously tested several early types of lead-free solders before RoHS made lead an issue....I wont go into the politics of why I don't follow RoHS guidelines when doing rework, I just know and have personal experience with improper bonding and contact issues with lead free solder. It appears that the stuff I discovered 20 years ago still applies today.

I looked at the process curves for device mount and proper contact to get a proper solder joint. We used to have a bigger " window " of soderability when working with tin-lead ( and even silver ) solders. That " window is significantly closed with RoHS solder. There isn't much time to be at the higher temperatures before you heat damage the GPU in my example.

I had looked at this issue to make sure the builds at Cray were done with reliability, as much of the original systems were built by hand with MANY custom wires to get the speeds we got.

If we had been forced to use the RoHS solder specs over 20 years ago, our Crays would never have had the reliability they had.

 

On the ( officially a ) Metal Migration issue, repeated high heat levels make the whiskers grow. This is an atomic level problem based on movement of charged elements.

What we see today with component failures today is a result of the miniturization and crowding of internal IC components. 

( This is what information you gain when you work around a team of experts in their fields and take tke courses they offer at your local Community College )

 

 

 

Rob Spiegel
User Rank
Blogger
Re: Lead free solder SUCKS...
Rob Spiegel   1/31/2012 3:06:41 PM
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Good explanation Oldtimer. This sounds less like a tin whisker problem and more like a problem that comes from using lead-free solders from a process point of view. Is that right?

oldtimer8080
User Rank
Gold
Lead free solder SUCKS...
oldtimer8080   1/31/2012 12:18:48 AM
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I have a stack of $400 ( ebay price now ) HP dvXXXX series motherboards and computers with GPU issues. That includes  the Compaq line too.

 

The issue is common with HP dv units, there is a lawsuit over the issue claiming improper design of the heatsinks AND defective GPUs suppied by nVidia.

 

The problem can be traced to overheat conditions by a gap between the GPU and the heat sink; many people try to fix it with the " penny " insertion. However, if the GPU gets hot enough, the heat cracks the BGA in several places, rendering the video nonop.

Since I have already been trained as an expert in soldering ( SMT and micro manipulator work ) I researched and purchased the proper tools. I have examined the YouTube videos on the " oven fix " and looked at the rework requirements to do a professional job without buying $1k worth of equipment.

 

The trick is to PREHEAT the board at 385F, then give it a hot shot with hot air at 420F AND NO MORE!!

The absolute max is around 430F. Anything higher will result in desoldering the surrounding SMT chips. I have the special tips for the hot air rework station.

 

What you want is the eutectic state in the BGAS to repair the cracks, not an actual liquid flow.

 

This is the engineering description of what the oven fix does. The pros spend $1 to $2k on a rework ststion that does the same thing on a bench top, preheat and hot air carefully controlled.

If you do this at home, buy a cheap, non contact IR thermometer to use with your paint stripper gun...

 

This problem is the reason I keep using tin/lead and silver solder when i do rework. I DESPISE the problems lead-free solder has created.

The " tin whisker " problem impact ALL devices, not just soldered ones. I've seen electron microscope pictures of IC fails ( some I induced ) at Cray Research.

Metal Migration was a common knowledge thing with IC vendors.

 

Rob Spiegel
User Rank
Blogger
Re: Planned obsolescence: A real design approach
Rob Spiegel   1/27/2012 3:22:14 PM
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That's a great story, Ratsky. iPads have become famous for their toddler-friendliness. We've all heard the stories of kids playing on the iPad before they know how to walk or talk. Buying stuff while the parents are not looking is a new one on me.

Ratsky
User Rank
Platinum
Re: Planned obsolescence: A real design approach
Ratsky   1/27/2012 3:12:03 PM
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Yup!  My grandson just turned 3.  He got his first iPhone (enabled only for WiFi) at 15 months! It was his daddy's, and had been replaced by a newer model.  In no time, he was quite adept at using it to watch videos, and knew all of the gestural motions.  He had learned all this by watching his parents use it, and started to grab it just before the upgrade.  After a few months of enjoying HIS phone, he decided his parents' phone were BETTER, and soon started the grab and flip routine again.  Fortunately for him, a new iPhone came out, and Mommy and Daddy upgraded, etc.  THEN they bought an iPad; within 3 weeks, it also was "his", although he did graciously allow M & D to use it sometimes.  Now he has a Kindle too, and uses all 3 devices at his whim!  He even bought a season series of kiddie videos with the Kindle (a parent had forgotten to log out of the Store after buying something) last week while we were visiting.  Folks found out when the charges hit the credit card!  Makes my wife and I feel REALLY old!

Rob Spiegel
User Rank
Blogger
Re: Planned obsolescence: A real design approach
Rob Spiegel   1/27/2012 2:38:29 PM
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I agree, Ratsky. I have a BB for work. My personal phone is a dumbphone. I use it primarily to logistics (calling someone and saying, "Where did you say you lived" or that I'm stuck in traffic and running late. So I don't care about features. Life is much different from my 16-year-old daughter who lives for the features. My guess is this is a worldwide generational phenomenon.


Ratsky
User Rank
Platinum
Re: Planned obsolescence: A real design approach
Ratsky   1/26/2012 3:14:44 PM
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My BB is provided by my employer, and it's a "hand-me-down" from someone else (who probably upgraded to an iPhone or Android).  The LG is my own, and contract expired years ago; I changed the plan to prepaid (3rd-party provider) about 15 months ago.  Costs me on average less than $10/month for mine, less than $3 for my wife's!  You're right, of course about smartphones being amortized over the contract duration. You can beat this, though, by buying a slightly used one on-line (or refurbs from 3rd-party resellers like I use) for less than that battery replacement cost I mentioned, and going pre-paid.  You'll never get the "latest and greatest", but if it does what you need it to do, who cares?

Rob Spiegel
User Rank
Blogger
Re: Planned obsolescence: A real design approach
Rob Spiegel   1/26/2012 2:57:02 PM
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Good point, Ratsky. There seems to be an increasing velocity of products that are disposable after a short lifetime. Smartphones take the top spot for expensive products that become throw-aways quickly. The subsidies on the cost of smartphones hide the high cost of these devices (we pay for them in the monthly billing). New features make each generation obsolete in a year to 18 months.

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