OT: RoHS and Lead?

Excuse the OT post, but I figured people in this group may have an answer 
for this odd question:

In transitioning to RoHS, can you mix Lead-free parts into a standard PbSn 
process?  The idea is to start buying RoHS parts while depleting the 
existing stock of PbSn components.

Good? Bad? Ugly?

Thanks,


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Euredjian
eCinema Systems, Inc.

To send private email:
x@y
where
x = "martineu"
y = "pacbell.net"

Martin,

Ugly, I am told.

Because of the temperature differences, there can be some real 
reliability problems (cold joints, or no joints).

My best bet is to tell you to contact the RoHS solder suppliers.  Those 
guys are the ones that have to make a living doing it, and their 
presentations (in my experience) are absolutely the best ones.

For example:

http://www.efdsolder.com/PDF/EFD_-_Lead_Free_Frequently_Asked_Questions.pdf

Austin

Martin wrote:

> Excuse the OT post, but I figured people in this group may have an answer 
> for this odd question:
> 
> In transitioning to RoHS, can you mix Lead-free parts into a standard PbSn 
> process?  The idea is to start buying RoHS parts while depleting the 
> existing stock of PbSn components.
> 
> Good? Bad? Ugly?
> 
> Thanks,
> 
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Martin Euredjian
> eCinema Systems, Inc.
> 
> To send private email:
> x@y
> where
> x = "martineu"
> y = "pacbell.net"
> 
> 
> 

"Martin" <0_0_0_0_@pacbell.net> wrote in
news:XiBxf.287$or4.4@newssvr12.news.prodigy.com: 

> Excuse the OT post, but I figured people in this group may have an
> answer for this odd question:
> 
> In transitioning to RoHS, can you mix Lead-free parts into a standard
> PbSn process?  The idea is to start buying RoHS parts while depleting
> the existing stock of PbSn components.
> 
> Good? Bad? Ugly?
> 
> Thanks,
> 

You are going to have no real problems soldering leadfree parts with tin-
lead solder. The big exception to this are BGAs. The ball of a BGA is 
solder. If it is leadfree, it will need to be soldered at a higher 
temperature. You CM will need to know this.

Many parts have been supplied leadfree for several years. This includes 
many of the passives that you probably are already using. They might not 
have been labeled as such.

We have started using lead free pcbs as well. In our case we have opted for 
ENIG (electroless nickel/immersion gold). They are easy to solder with PbSn

No one really knows the long term effects of moving to RoHS. I am hoping 
that the EU decides that July is too soon since industry is not really 
ready. Nevertheless, I think it is prudent to plan for it to happen. For 
example, try buying Altera PLDs. They seem to be readily available in lead 
but not available in the lead free versions (of course, Altera claims they 
have both). Part of this situation is caused because everyone 
(distributors, manufacturers, etc) wants to get rid of their non RoHs 
inventory. It's hardest on those of us on the end of the chain, since we 
have the least amount of time to transition.

I think one of the biggest problems will be for products that have 
relatively long lives and small volume. I have already seen parts that were 
discontinued just because the mfr didn't want to change to a lead free 
process. How many designs will have to be completely redone, just to deal 
with a part that has been obsoleted prematurely. Even if you could buy 
enough existing material, you still couldn't ship the existing design 
because there it will never be a RoHS compliant part.

I would bet that this whole RoHS (just the lead part) is going to cost many 
billions of dollars, with very little improvement overall in the 
environment. The amount of lead in a typical pcb is very small compared to 
car batteries, old CRTs, etc.

Sorry for the rant, I'm sure most of you have heard it before (probably 
coming out of your own mouth).



-- 
Al Clark
Danville Signal Processing, Inc.
--------------------------------------------------------------------
Purveyors of Fine DSP Hardware and other Cool Stuff
Available at http://www.danvillesignal.com

> No one really knows the long term effects of moving to RoHS.

That's the bottom line.  I think you can mix component types, but, even if 
you had RoHS-only, your statement holds.  The whole RoHS thing is a disaster 
waiting to happen, simply because of the way it has been approached. 
But...what do I know?

I've had conversations with people from various companies across markets who 
have told me that their whole R&D budget for a year would be consumed if 
they decided to re-design every product in their product line to meet RoHS. 
Most will discontinue some products and retool a few and simply make others 
not available to the EU.

I think you are right, mass-market producers (cell phones, PC's, etc) 
probably got it together 'cause they are used to very short product cycles 
anyway.  An associate of mine visited a phone manufacturer at the Consumer 
Electronics Show and asked them when they were going to fix a bug on one of 
their fairly new high end phones.  The answer was to get the new model that 
just came out.


To go back to the topic of the thread, the gravest concern is that of mid to 
long term reliability of RoHS or mix-technology assemblies.  This whole mess 
could actually result in MORE electronic trash being produced until 
metalurgy/chemestry/whatever goes through the required process of "natural 
selection".


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Euredjian
eCinema Systems, Inc.

To send private email:
x@y
where
x = "martineu"
y = "pacbell.net"

Martin schrieb:
>>No one really knows the long term effects of moving to RoHS.

I am not so sure about this. There are people who are doing lead free
for decades now. For example in cases where you can not tolerate the
alpha particles emitted by the lead.
Or in cases where your electronic is inside a strong magnetic field.
(High Energy Physics)

Kolja Sulimma

Kolja Sulimma wrote:
> For example in cases where you can not tolerate the
> alpha particles emitted by the lead.

In its naturally abundant form, lead is stable. It does not emit
alpha (or any other) particles...

> Or in cases where your electronic is inside a strong magnetic field.
> (High Energy Physics)

Can you explain how and why lead behaves differently in strong
magnetic fields than the ROHS materials?

This whole ROHS thing is such an idiotic thing to do that it
is really frightening how easy it was to drag the whole industry
into it...

"Only two things are infinite - the universe and human stupidity,
and I'm not sure about the former." A. Einstein


Dimiter

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------

"dp" <dp@tgi-sci.com> wrote in message 
news:1137154709.867377.108660@g49g2000cwa.googlegroups.com...
> Kolja Sulimma wrote:
>> For example in cases where you can not tolerate the
>> alpha particles emitted by the lead.
>
> In its naturally abundant form, lead is stable. It does not emit
> alpha (or any other) particles...
>
Yeah, but only 1.4% of naturally occuring lead is not radiogenic. The rest 
comes from decay of thorium, actinium and uranium. Some of those radioactive 
elements are likely to mixed in with your lead.
Cheers, Syms.

http://en.wikipedia.org/wiki/Lead#Isotopes
http://periodic.lanl.gov/elements/82.html

Symon wrote:

> Yeah, but only 1.4% of naturally occuring lead is not radiogenic.

Radiogenic and stable - non-radioactive.

> The rest comes from decay of thorium, actinium and uranium.

This is what radiogenic means; the result (in this case) being
stable isotopes.

> Some of those radioactive elements are likely to mixed in with your lead.

Ummm, what? Any figures? Did you ever try to add up the percentages of
Pb, Sn and other listed materials at the label of some soldering
wire?

Such nonsense - like the entire multi-billion euro ROHS exercise
(we have yet to see into whose pockets the billions will flow).

Dimiter (over and out...)

------------------------------------------------------
Dimiter Popoff               Transgalactic Instruments

http://www.tgi-sci.com
------------------------------------------------------

Dimiter,
I'll try again. ;-)
Production of Solder and Flux with Low Radioactivity
http://hep1.snu.ac.kr/misc/nim1997.ps

Quote:-
"The lead in solder typically contains trace amounts of U238, Th 232 and 
K40."

I agree the RoHS is nonsense. However, Kolja is correct that putting lead in 
solder makes it slightly radioactive. Not because of the lead; because of 
the contaminants. The contaminants are present as most lead is radiogenic.

Cheers, Syms.

p.s. Here's another link!
http://www.puretechnologies.com/category_s/17.htm 

All,

The presence of the U238 to Pb206 chain in lead is well known.

Just go back a few years to our alpha particle contamination issue!

http://direct.xilinx.com/bvdocs/whitepapers/wp208.pdf

The solder bumps were roughly 50 counts per hour (alpha emission).

That led to one soft error in 80 days on a 2V6000 (roughly 1200 solder 
bumps).

Believe me, replacing every part that had the contamination was not 
something Xilinx would ever like to do ever again!

It had just one bright side:  it made everyone aware of the issue, and 
also made them aware of cosmic ray induced SEUs.  So all the work we had 
done to improve our hardness to upsets began to be noticed...

http://tinyurl.com/c575m

Now an alpha is stopped by a piece of paper, so only flip chip parts, 
with 'solder' bumps, were affected (in our product line).

The solution is purified lead, which is known as ultra-low alpha 
emitting, which comes in at less than 0.01 counts per hour.  Even lead 
which is completely pure will be "activated" by errant cosmic rays, and 
will eventually start emitting alphas again as some lead transmutes to 
polonoium, thorium, etc.

http://products.teckcominco.com/Products/AdvancedMaterialProducts.html

So, is lead stable?  Maybe 1500 meters below ground, or at the bottom of 
the ocean (like IBM buying old ship's ballast lead for their packages 
after they first encountered the issue).  But once you have it at sea 
level (or higher), alphas begin to happen again.

http://www.research.ibm.com/journal/rd/494/gruber.html

As well there are isotopes which have billion year, and hundreds of 
thousands of year half life which can not be separated adequately, so 
when these finally break down, you are left with the series that now 
emits alphas every few days/weeks/months again...

http://www.lbl.gov/abc/wallchart/chapters/03/1.html

http://eesc.columbia.edu/courses/ees/lithosphere/labs/lab12/NuclearTable1.html

'Lead free' just means you didn't intentionally put any lead into the 
mix, but with leaded fuels still used in parts of the world, turns out 
that even organic materials have lead in them!  And they emit alphas. 
That makes packaging SRAM chips a real pain (just go ask Cypress) as 
just about anything you use as a binder in eopoxy for packaging emits 
some low level of alphas!

http://www.eetimes.com/news/semi/showArticle.jhtml;jsessionid=ZTPV3Z0NYUA1QQSNDBOCKHSCJUMEKJVN?articleID=19400052&_requestid=150196

http://tinyurl.com/944q8

And, Chernobyl didn't help.  Nor does bessemer steel processing (which 
concentrates atmospheric radioactive materials, and binds them into 
steel).  Nor the processing of scrap that accidentially contaminates 
tons of material with medical radiological chemical wastes.

If you haven't been bit by alphas (yet), then you should go make sure 
you will not be!

If you are buying ASIC's, well you better go make sure your supplier 
knows what they are doing!  An alpha problem there will drive you nuts.

IBM has been bit, HP has, ... and Xilinx has (we are the some of the few 
who at least admitted it, faced it head on, and 'solved it' for our 
customers!)

RoHS does nothing whatsoever for the alpha problem.  You will need to 
buy low alpha, or ultra low alpha RoHS compliant solder pastes, balls, 
etc. if that is part of your business!

And you will need to test for it, monitor manufacturing processes, use 
independent work stations and tools to prevent cross contamination ....

So much fun.

Austin

Symon wrote:

> Dimiter,
> I'll try again. ;-)
> Production of Solder and Flux with Low Radioactivity
> http://hep1.snu.ac.kr/misc/nim1997.ps
> 
> Quote:-
> "The lead in solder typically contains trace amounts of U238, Th 232 and 
> K40."
> 
> I agree the RoHS is nonsense. However, Kolja is correct that putting lead in 
> solder makes it slightly radioactive. Not because of the lead; because of 
> the contaminants. The contaminants are present as most lead is radiogenic.
> 
> Cheers, Syms.
> 
> p.s. Here's another link!
> http://www.puretechnologies.com/category_s/17.htm 
> 
>