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Author Topic: Lead free solder question  (Read 13662 times)
AF5CC
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« on: July 15, 2013, 08:48:40 AM »

I know that most of the new radios feature lead free solder due to EU regulations.  I also have heard that this type of solder will "grow whiskers" over time, leading to all sorts of problems.  Is this really true?  Does this mean that most of our new radios have a fairly short life expectancy due to this solder type?

John AF5CC
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K8AXW
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« Reply #1 on: July 15, 2013, 08:59:31 AM »

Daymn!  If this is so, does that mean that I'm gonna have to start shaving my gear?
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KC9NVP
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« Reply #2 on: July 15, 2013, 09:53:09 AM »

Do a google search on "Tin Wisker" and you will come up with a lot of information, and yes it will be a problem.

David
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K5LXP
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« Reply #3 on: July 15, 2013, 09:56:25 AM »

Tin is what grows the whiskers, and lead is a very effective way to stop it.  In lieu of lead other metals are used in various proportions like copper and silver.  The downside is these alloys cost more and can cause other process and reliability issues like crystallization, wettability, and high reflow temperatures.  Because of this even in the EU where all this crap started they still allow lead solders for medical and commercial equipment, and I recall military and space qualified equipment must use leaded solders.  There's no magic lead-free bullet yet (solder or projectile).  The products where lead free is a success is largely in the consumer market, where the products are landfilled before they have a chance to fail from solder joint issues.  I would count amateur equipment among those in the consumer market.  If the days of disposable radios aren't here already, it's not far down the road.

Mark K5LXP
Albuquerque, NM
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AF5CC
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« Reply #4 on: July 15, 2013, 10:20:27 AM »

Thanks for the replies so far.  So what will probably be the life expectancy of most new radios before the tin grows and causes failure?
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KA4POL
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« Reply #5 on: July 15, 2013, 10:42:45 AM »

Al hit the nail right on the head, we are going to start a razor business  Grin.
Some interesting information can be found at: http://nepp.nasa.gov/whisker/
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KB4QAA
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« Reply #6 on: July 15, 2013, 11:04:54 AM »

Thanks for the replies so far.  So what will probably be the life expectancy of most new radios before the tin grows and causes failure?
Tin whisker growth is not predictable.  For a better understanding of the phenomenon, please read some of the references.
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W0BTU
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« Reply #7 on: July 15, 2013, 01:42:58 PM »

Tin is what grows the whiskers, and lead is a very effective way to stop it.  In lieu of lead other metals are used in various proportions like copper and silver.  The downside is these alloys cost more and can cause other process and reliability issues like crystallization, wettability, and high reflow temperatures. 

We use an AIM lead-free alloy of tin, copper, and 2.5% silver for some products that my company manufactures. The silver alloy we buy because it reduces the melting point, but are you saying that silver might help reduce "whiskering"? Just curious, even though tiny tin whiskers likely would not hurt in this application.
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G3RZP
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« Reply #8 on: July 15, 2013, 01:48:19 PM »

A couple of the major pacemaker manufacturers have gone to lead free, even though they don't need to if they have to meet EU regulations. I am told that the  manufacturers are confident that they won't have a tin whisker problem, and although the average life of a pacemaker is 8 to 10 years, they are still confident that even those rare low demand ones that can last 20 years before the battery discharges won't have a problem.

My feeling is 'YMMV'.............
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W0BTU
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« Reply #9 on: July 15, 2013, 01:52:15 PM »

I thought I read somewhere that the vacuum of space could cause tin whisker growth inside satellites. However, I think it also can occur at atmospheric pressures.
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KE3WD
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« Reply #10 on: July 15, 2013, 02:08:19 PM »

Recently read an engineering article from NASA in which the engineers presented data and microphotographs of the whisker phenomenon happening even on Gold plated and Gold over Nickel connections, relay parts and such.  They were as surprised to find the problem associated with Gold as I am.  A very few airplane incidents have been attributed to this problem. 

So it is not just lead-free solder and it is not just consumer appliances where this whisker problem can crop up.  But it is also important to understand the stats here from existing data.  Not *every* unit presents with this problem.  Matter of fact, right now it is still the minority of examples. 


73
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W1JKA
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« Reply #11 on: July 15, 2013, 02:34:02 PM »

A ham told me that the whisker and longevity concerns of current rigs is directly related to the lineage and inherent hormonics of the particular brand/model  in question.
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K2OWK
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« Reply #12 on: July 15, 2013, 04:12:22 PM »

Led free solder is useless. It does not adhere well, it is a total pain to use. I tried it a few times to give it a chance. Found it to be pure garbage in many ways. I also believe it uses Altimity metal in place of lead. Thank heaven here in the US lead/rosin core radio solder is still available to consumers. I have stocked up on it from Radio Shack just in case.

My opinion.

73s

K2OWK
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AA4PB
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« Reply #13 on: July 15, 2013, 04:18:12 PM »

One of the PCB mfgs I use (Express PCB) offers boards in leaded or lead-free. They warn that lead-free boards should not be removed from the package until you are ready to assemble them.
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W0BTU
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« Reply #14 on: July 15, 2013, 06:03:59 PM »

Led free solder is useless. It does not adhere well, it is a total pain to use. I tried it a few times to give it a chance. Found it to be pure garbage in many ways.

Well, I don't know if I would go quite that far!  Smiley  But tin/lead solder IS certainly much nicer to work with. Personally, I would certainly rather use that, and I do when I can.

Among other reasons, we use lead-free tin/copper/silver solder for ROHS compliance (such as overseas products) and because I don't want anyone here breathing anymore lead vapors than necessary. And the flux in it makes less of a mess than rosin.

Quote
I also believe it uses Altimity metal in place of lead.

Do you mean antimony? I have heard of lead-antimony solder, but don't remember why it is used in solder. The lead-free stuff we use doesn't contain it, as far as I know.
« Last Edit: July 15, 2013, 06:08:33 PM by W0BTU » Logged

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