OT: News Article on "Tin Whiskers" Ruining Electronics

[Lambs, Dick & Judy]

A recent Associated Press article discusses a topic that's received much
attention on this reflector:   the negative consequences of
environmental restrictions on lead in solder for electronics.  The
primary concern the article mentions is that tin, when in an alloy
absent of lead, promotes the spontaneous  growth of tiny  "tin whiskers"
that can short traces in circuit boards.  Failures stemming from
whiskers are cited in electronics ranging from consumer items to
satellites. The article as it appeared in my local newspaper had a very
dramatic photo of whiskers on a tin-plated tuning capacitor.

 http://www.theworldlink.com/articles/2007/10/06/news/doc4707c03901b23958789121.txt

I should note, for newcomers to the reflector, that Elecraft's list of
approved solders specifically cautions against using any that are lead
free:

http://www.elecraft.com/TechNotes/N0SS_SolderNotes/Elecraft-Recommended%20Solders%2009JAN2007.pdf     



Dick, K0KK
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[Don Wilhelm-4]

Typical of news reports, the media seems to concentrate on the
sensational.  Certainly, the proliferation of throw-away consumer
electronics ending up in landfills is a grave concern for adding to the
lead content of our environment, and I applaud the efforts to keep that
to a minimum.

But, consider just how many ham rigs end up in landfills - not many in
my opinion.  We have many avid collectors of old ham gear and in many
cases, boat anchors are a prized possession.  Lead-free solders are a
real salvation for manufacturers (BTW, the K3 and later K2 boards are
RoHS compliant) who can implement the lead-free techniques.  For
personal soldering, I chose to use my 63/37 alloy solder, and I know
that little of it will ever find its way to the landfill.

The 'tin-whiskers' problem is one that exists mainly at the chip level.  
The migration of conductive paths between pins that can be soldered by
hand techniques is *not* a problem because the 'whiskers' typically do
not extend that far.  It is a problem inside the chips where distances
are measured in angstroms rather than in fractional inches or millimeters.

Bottom line - while you may eventually see this 'tin whiskers' problem
resulting in IC failures, it will not be apparent in the soldering that
we hams do, even with the fine pitch SMD devices.

73,
Don W3FPR

Dick & Judy Lamb wrote:

> A recent Associated Press article discusses a topic that's received
> much attention on this reflector:   the negative consequences of
> environmental restrictions on lead in solder for electronics.  The
> primary concern the article mentions is that tin, when in an alloy
> absent of lead, promotes the spontaneous  growth of tiny  "tin
> whiskers" that can short traces in circuit boards.  Failures stemming
> from whiskers are cited in electronics ranging from consumer items to
> satellites. The article as it appeared in my local newspaper had a
> very dramatic photo of whiskers on a tin-plated tuning capacitor.
> http://www.theworldlink.com/articles/2007/10/06/news/doc4707c03901b23958789121.txt 
>
>
> I should note, for newcomers to the reflector, that Elecraft's list of
> approved solders specifically cautions against using any that are lead
> free:
>

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[N2EY]

In a message dated 10/19/07 12:28:43 AM Eastern Daylight Time,
[hidden email] writes:


> But, consider just how many ham rigs end up in landfills - not many in
> my opinion.

Agreed - for two reasons.

One is that there simply aren't that many ham rigs around, compared to other
electronic devices such as TVs or computers.

But the big reason is that we hams try to get as much use out of a piece of
equipment as possible, rather than just tossing it in the trash when something
newer comes along, or it develops a problem. Even a rig that is judged "not
worth fixing" becomes a parts source to keep others going.

The computer this was written on is a Dell Dimension XPS R400. It was
intercepted on its way to the dumpster a year or so ago. It cost more than a K3-100
when it was new (about 1999?) yet it was considered to be worthless trash in
less than a decade. A little work and it does the job.

Maybe there's a message there we hams need to spread.

73 de Jim, N2EY


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[Mike S-8]

At 12:28 AM 10/19/2007, Don Wilhelm wrote...
>The 'tin-whiskers' problem is one that exists mainly at the chip
>level.
>The migration of conductive paths between pins that can be soldered by
>hand techniques is *not* a problem because the 'whiskers' typically do
>not extend that far.  It is a problem inside the chips where distances
>are measured in angstroms rather than in fractional inches or
>millimeters.

Not according to NASA studies. They state "Whiskers as long as a few
millimeters are not uncommon..." -
http://nepp.nasa.gov/whisker/background/index.htm

Common through hole IC packages (DIP) have 2.54mm center to center,
which means ~1 mm air gap between pins, and that is also a _very_
common hole spacing pattern for discrete components. Here's an example
of non-"chip level" failure caused by tin whiskers:
http://nepp.nasa.gov/whisker/photos/pom/2004april.htm


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[Don Wilhelm-4]

Mike and Jack,

My apologies for posting based on my lack of knowledge.

Thanks for the educational updates.  I certainly am not prone to argue
with the NASA research folks.
I do recall that it was a big concern inside ICs back in the 1980s and
90s when I was closely associated with the industry and more and more
density was being crammed inside those multi-legged critters.

I am surprised at the magnitude of inconsistencies and uncertainties
still present in the research data.
It is very interesting to find that dipping with tin-lead solder appears
to inhibit the growth, so those of us using tin-lead solders are
actually helping a bit to inhibit the growth - but then we don't re-tin
the full length of all the leads on all components either, so there is
remaining exposure.

So based on reading those articles - my conclusion is that we should
continue using the tin-lead solder and discourage the use of lead-free
solder for as long as we are able to do that.  Since the tin-whisker
induced failures seem to take about a year or more to develop, I might
consider extended warranty coverage for any expensive electronic devices
as more and more of them move to RoHS compliance.  This is really a
two-edged sword.

73,
Don W3FPR

Mike S wrote:

> At 12:28 AM 10/19/2007, Don Wilhelm wrote...
>> The 'tin-whiskers' problem is one that exists mainly at the chip level.
>> The migration of conductive paths between pins that can be soldered
>> by hand techniques is *not* a problem because the 'whiskers'
>> typically do not extend that far.  It is a problem inside the chips
>> where distances are measured in angstroms rather than in fractional
>> inches or millimeters.
>
> Not according to NASA studies. They state "Whiskers as long as a few
> millimeters are not uncommon..." -
> http://nepp.nasa.gov/whisker/background/index.htm
>
> Common through hole IC packages (DIP) have 2.54mm center to center,
> which means ~1 mm air gap between pins, and that is also a _very_
> common hole spacing pattern for discrete components. Here's an example
> of non-"chip level" failure caused by tin whiskers:
> http://nepp.nasa.gov/whisker/photos/pom/2004april.htm
>
>
>
>

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[Matt Palmer-4]

main problem with the article is both space programs and military are
exempt from being ROHS compliant, so why would lead free solder be in
a satellite?


Matt
KD8DAO
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[Don Wilhelm-4]

It is not all in the solder, the problem even for RoHS exemptions is the
tin plating on the components.
73, Don W3FPR

Matt Palmer wrote:
> main problem with the article is both space programs and military are
> exempt from being ROHS compliant, so why would lead free solder be in
> a satellite?
>
>  
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[David Cutter]

The problem with ROHS compliant soldering is that you must not be able to mix it up with leaded solder.  So, a manufacturer has to have one or the other, or separate lines running one each exclusively.  So, if the manufacturer wants volume production capability it has to move over to lead-free and dispense with leaded all together in a practical set-up.

BTW, I don't think there are any cases of death by poisoning from leaded solder: it's now only a case of environmental issues (ie politics).

David
G3UNA

>
> From: "Matt Palmer" <[hidden email]>
> Date: 2007/10/19 Fri PM 04:27:15 BST
> To: [hidden email]
> Subject: Re: [Elecraft] OT: News Article on "Tin Whiskers" Ruining Electronics
>
> main problem with the article is both space programs and military are
> exempt from being ROHS compliant, so why would lead free solder be in
> a satellite?
>
>
> Matt
> KD8DAO
> _______________________________________________
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