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July 2011

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Subject:
From:
Bev Christian <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Bev Christian <[log in to unmask]>
Date:
Sun, 24 Jul 2011 08:55:24 -0400
Content-Type:
text/plain
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text/plain (149 lines)
Steve,
I am not going to put words in Vahid's or Ron's mouth, but I would expect
that in answer to your first question it would either be really, really
hard, if not impossible. And let's face it, it was a good marketing move,
whether it was initially intentional or not.

"...is lead-free solder the green "environmentally responsible" success that
was purported and mandated to all of us?"
The answer to that is of course NO. I think it is an unmitigated disaster
where we have traded one environmental issue for several we know even less
about - more energy use, more tin and silver mining, more silver potentially
killing micro-organisms, tin whiskers, drop failures, premature aging of
components because of manufacturing heat stress, more brittle board
materials and the list can be lengthened by others.  Some of these are
straight out enviro in nature the others are indirectly because they lead to
more scrap.
Bev  

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Saturday, July 23, 2011 10:37 PM
To: [log in to unmask]
Subject: Re: [TN] Lead Free solder has performed well...

Ron,

You know as well as I do, that the reason we were all told that we HAD to to

convert to lead-free, was because it was going to be the "environmentally 
responsible" thing to do. It wasn't because we wouldn't be able manufacture 
iPhones and the like because of the higher density and tighter lead pitches.

So I find the positive spin put out about lead-free solder after the "cows 
have been let out of the barn" so to speak, interesting.

Don't you think that problems with solder shorts could be addressed by 
optimizing board and pad layout, stencil specifications, printing processes,

and reflow parameters? Wouldn't have that been the answer rather than 
switching to another solder alloy that has questionable environmental 
benefits over tin/lead solder?

So, the question still remains (and many are still asking); is lead-free 
solder the green "environmentally responsible" success that was purported 
and mandated to all of us?

Steve

-----Original Message----- 
From: Ron Lasky
Sent: Saturday, July 23, 2011 12:15 PM
To: [log in to unmask]
Subject: Re: [TN] Lead Free solder has performed well...

Folks,

Pete is correct.  I never said lead-free implementation was a grand success.

These were Rob's words in his blog post 
(http://www.designnews.com/author.asp?section_id=1389&doc_id=231199&f_src=de
signnews_gnews).

I have said repeatedly that adequate lead-free reliability has been 
demonstrated for consumer products like mobile phones, PCs, portable 
electronics with service lives less than 5 years.  This level of reliability

has been demonstrated in numerous studies and more importantly with field 
data.  Vahid Goudarzi, of Motorola, stated that field reliability of 
lead-free assembled mobile phones has been equal or better than leaded 
assembly units.  His data go back to 2001 (not 2006, Motorola started early 
for reasons discussed below).

The reason Motorola shipped early with lead-free products is due to the fact

that lead-free solder does not spread as well.  Because of this poorer 
spreading, Motorola was able to decrease lead spacings without getting 
shorts, thus increasing the amount of electrical function in a smaller 
space.  Since increased function in a smaller space is the defining 
attribute of portable electronics, the importance of this lead-free 
advantage cannot be overstated.  Admittedly, lead-free's poorer wetting is a

challenge in other regards, especially hole fill in wave soldering, but the 
Motorola Droid X2 could not be assembled with leaded solder, there would be 
too many shorts.  Since the packaging density of the iPhone and similar 
devices is on a par with the Droid X2, I suspect this statement is true for 
most mobile products.

I have also repeatedly stated that lead-free reliability for long term 
service, mission critical devices has not been demonstrated.  As a result, 
these types of devices should not consider lead-free solder at this date.

I regularly discuss these topics in my blog 
(http://blogs.indium.com/blog/an-interview-with-the-professor).  The most 
recent post shows a striking photo of leaded solders too good spreading for 
portable electronics.


Cheers,

Ron

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