[Robotgroup] lead free soldering advice

[Leslie Filip]

Thanks for the informative post. I did not mean to freak anyone out,  
but just pass along something that was news to me.

Mr. Poo-Poo


On May 24, 2007, at 10:32 AM, vkonradi wrote:

> All consumer electronics sold in Europe are now lead-free, and have  
> been for some time.  And a lot of stuff sold in the US is also lead- 
> free right now, because these products are international in  
> nature.  Any consumer product marked CE for instance must be lead- 
> free.
>
> There were problems at one time with tin whisker growth, and they  
> maybe they aren't 100% solved.  But obviously they are largely  
> solved, since your cell phone works.  Certain long-life items such  
> as telcom equipment are currently exempted and may still contain lead.
>
> Mechanical robustness of lead-free solder, and resistance to  
> thermal expansion difficulties in extreme temperature are still  
> issues.  That's why for instance automotive electronics currently  
> have an exception and may contain lead.
>
> Lead-free solder melts at a higher temperature.  It requires a  
> higher temperature PCB.  Both reflow and wave soldering are a  
> little trickier.  But these are essentially solved problems.
>
> The point of all the above being we don't need to freak out about  
> lead-free.  It is a current reality worldwide.
>
> Hey, lets celebrate the fact that we won't be landfilling nearly as  
> much lead for the acid rain to leach into the soil.
>
> If anyone wants RoHS details, such as the actual European  
> directives, classifications, exemptions, etc. please email me and  
> I'll send them to you.  I have more information on this that you  
> want to know.
>
> ----- Original Message ----
> From: Def Egge <robodigest at innervate.com>
> To: The Robot Group Mailing List <robotgroup at puremagic.com>
> Sent: Thursday, May 24, 2007 10:01:34 AM
> Subject: Re: [Robotgroup] lead free soldering advice
>
>
> At 01:42  2007-05-24, you wrote:
>> The following message is brought to you by Mr. Poo-Poo:
>>
>> I was talking to an engineer friend who designs circuit boards for a
>> living the other day. He gave me some advice about lead free solder -
>> don't use it. Apparently the lead keeps crystalline "whisker"
>> formations in check. He said the lead free solder starts to corrode
>> immediately after use, and in the process forms microscopic
>> conductive whiskers that grow over time, eventually shorting with
>> other traces. It is for this reason that the US military forbids the
>> use of lead free solder. Apparently they don't want equipment failing
>> in the field. Neither do I. Although in truth I rarely use my
>> equipment these days anyway, much less out in a field.
>>
>> Bye now,
>> Mr. Poo-Poo
>> _______________________________________________
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>> Robotgroup at puremagic.com
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>
>
> How rapidly do these tin whiskers grow?
>
> I understand the continued use of lead-based solders in military and
> satellite applications where mission-critical considerations outweigh
> lead-free considerations.  Certainly, the assured recycling of
> electronic components (the mechanism is left as an exercise to the
> reader) would lessen the probability of exposure to lead, cadmium,
> mercury, etc.
>
> Relatively speaking (compared to the MTBF for individual component
> points-of-failure), how likely are these to be the primary cause of
> consumer-grade electronics failures?  Is the expected useful life of
> your iPod, motherboard, HDTV likely to be affected?
>
>
> All the best....
>
> Mike
>
>
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