[tinwhiskers] Re: - RoHS & BGAs!!!

  • From: "Meschter, Stephan J \(US SSA\)" <stephan.j.meschter@xxxxxxxxxxxxxx>
  • To: <tinwhiskers@xxxxxxxxxxxxx>
  • Date: Thu, 19 Feb 2009 18:22:53 -0500

GEIA-HB-0005-2 has a decent section on tin plague/tin pest and includes
a bunch of references to work that was done in the 60s.

Another good summary can be found in Klein-Wassink, Soldering in
Electronics.

Steph

-----Original Message-----
From: tinwhiskers-bounce@xxxxxxxxxxxxx
[mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Parnagian, Edward
Sent: Thursday, February 19, 2009 6:20 PM
To: tinwhiskers@xxxxxxxxxxxxx
Subject: [tinwhiskers] Re: - RoHS & BGAs!!! 

Thank you, Stephan!

Quite frankly, I've been so concerned about whiskers, brittleness and
cleanliness issues that tin plague has fallen below my radar.  I really
was unaware of the effects of antimony on tin plague.

Best regards,
Ed

-----Original Message-----
From: tinwhiskers-bounce@xxxxxxxxxxxxx
[mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Meschter, Stephan
J (US SSA)
Sent: 2009 Feb 19 8:45 AM
To: tinwhiskers@xxxxxxxxxxxxx
Subject: [tinwhiskers] Re: - RoHS & BGAs!!!

If you are setting up equipment in Alaska subject to prolonged periods
of continuous cold, you may want to consider the Lead-free AIM Castin
alloy since it contains antimony, known to prevent tin pest. There has
been some work showing that the impurities in current Lead-free solder
are enough to suppress pest for most normal applications, however, each
situation should be considered individually (D. Hillman SMTA 2007 and
2008).

If you haven't already looked at them, you may also find info in the
GEIA-STD-0005-1, GEIA-STD-0005-2, GEIA-STD-0005-3, GEIA-HB-0005-1,
GEIA-HB-0005-2, and GEIA-HB-0005-3 useful. In addition to reliability,
they capture many other aspects of lead-free such as program management,
rework and repair, configuration management, supplier flow down,
logistics, etc. They are a rapidly evolving document set, because
lead-free information is changing so quickly. But they are our
documents, to use and to shape as we see fit.

Good luck,
Stephan Meschter


-----Original Message-----
From: tinwhiskers-bounce@xxxxxxxxxxxxx
[mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Bob Landman
Sent: Wednesday, February 18, 2009 2:01 PM
To: tin whiskers forum
Cc: tinwhiskers@xxxxxxxxxxxxx
Subject: [tinwhiskers] Re: - RoHS & BGAs!!!

ENIG is what we use (zero problems) and our assmbler is not fond of
imAg.  We are in the same environment you are (electric utilities) so
I would not recommend imAg.

You said volume is small so boards have to remain untarnished for a
long time.

Bob

Sent from my iPhone

On Feb 18, 2009, at 1:21 PM, "Parnagian,
Edward"<ed.parnagian@xxxxxxxxxxx
 > wrote:

> Hello, Hani!
>
> At the moment we are using immersion silver, but our CM is now
> trying to direct us toward electroless nickel, immersion gold.
>
> The decision on underfill is still in limbo.
>
> Both of our main circuit assemblies have ECG frontends, so given the
> high impedance and low signal voltages associated with ECG, we know
> that getting adequate cleanliness is going to be a battle.
> Consequently, we are again pushing the CM out of their comfort zone
> by asking for an aqueous flux followed by a rigorous cleaning
> process to remove all ionic residues.
>
> Best regards,
> Ed
>
> -----Original Message-----
> From: tinwhiskers-bounce@xxxxxxxxxxxxx
[mailto:tinwhiskers-bounce@xxxxxxxxxxxxx
> ] On Behalf Of AL-Yousef, Hani E
> Sent: 2009 Feb 18 11:19 AM
> To: tinwhiskers@xxxxxxxxxxxxx
> Subject: [tinwhiskers] Re: - RoHS & BGAs!!!
>
> Ed,
>
> I am afraid we don't use enough volume either for a manufacturer to
> run
> a special device for us.
>
> How about underfill, when should be concerned about that?
>
> Are you using ENIG for PCB finish?
>
> Do you have recommendation with the silk screening process regarding
> cleanliness and RoHs?
>
> Thanks I appreciate the advice.
>
> Hani
>
> -----Original Message-----
> From: tinwhiskers-bounce@xxxxxxxxxxxxx
> [mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Parnagian,
> Edward
> Sent: Wednesday, February 18, 2009 9:52 AM
> To: tinwhiskers@xxxxxxxxxxxxx
> Subject: [tinwhiskers] Re: - RoHS & BGAs!!!
>
> Hani,
>
> Most of us in high reliability industries - mine is medical
> defibrillators - don't generate enough volume to be able to convince
> an
> Analog Devices to run separate ball formulations.  My advice is to
> talk
> with someone like Amkor who at one time was willing to obtain dies
> from
> the original manufacturer and then package the dies with tin lead
> (SnPb)
> balls. The catch is that some original manufacturers are unwilling to
> give them permission to do so and/or won't honor warranty on the
> device.
> Do NOT try reballing devices that have already been balled; you will
> not
> get consistent metallurgy between the balls and the die.  Some will be
> good, and some will be terrible.
>
> Alternatively, build your design for lead-free but use only low silver
> BGAs.  SAC105 balls held down with SAC305 perform almost as well as
> SnPb.  If you can find SAC105 with a sprinkling of magnesium, the
> impact
> strength is actually superior to that of SnPb, and the thermal cycle
> life is still much better, as well.
>
> The overall market place has still not come to face the harsh
> realities
> (limitations) of the early decisions associated with SAC305, but a lot
> of people are desparately working on it.  My guess is that the
> transition to a real solution without lead is a decade away - at best.
> Until then lots of pain for people whose products have to last more
> than
> a couple of years.
>
> Best regards,
> Ed
>
> -----Original Message-----
> From: tinwhiskers-bounce@xxxxxxxxxxxxx
> [mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Bob Landman
> Sent: 2009 Feb 18 9:51 AM
> To: tin whiskers forum
> Cc: <tinwhiskers@xxxxxxxxxxxxx>
> Subject: [tinwhiskers] Re: - RoHS & BGAs!!!
>
> Hani,
>
> Some companies still offer BGA in tin-lead (Lattice Semi is one of
> them). I recently helped to convince Analog Devices to put tin-lead
> balls on a MEMS device for an aerospace firm as the devices were
> popping off after reflow.
>
> Your hardware designers need to push the envelope harder. Demand tin-
> lead solder balls.
>
> Bob
>
> P.S. Later today I'll get you other papers on the subject.
>
> Sent from my iPhone
>
> On Feb 18, 2009, at 9:24 AM, "AL-Yousef, Hani
> E"<Hani.AL-Yousef@xxxxxxxxxxxxxxxxxxxx
>> wrote:
>
>> Bob,
>>
>> We are forced to use SAC BGA since that is the only thing available
>> for
>> that part. I guess your advice would be, look for another part that
>> comes in tin lead.  I have to work on the firmware guys for that.
>>
>> Would happen to have any white papers, experiments documentations,
>> application notes that state the concerns that you shared?
>>
>>
>>
>> Thanks,
>> Hani
>> -----Original Message-----
>> From: tinwhiskers-bounce@xxxxxxxxxxxxx
>> [mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Bob Landman
>> Sent: Wednesday, February 18, 2009 12:19 AM
>> To: tinwhiskers@xxxxxxxxxxxxx
>> Subject: [tinwhiskers] Re: - RoHS & BGAs!!!
>>
>> Hani,
>>
>> Your equipment should be exempt from RoHS requirements.  Do not use
>> SAC
>> solders or SAC BGAs if you expect a 20+ year life.  The mechanical
>> vibration from switching your reclosers will shake the BGAs off their
>> pads.  Mechanical shock is the nemisis of SAC alloys, especially at
>> low
>> temperatures.  Outside on a pole in Alaska is going to cause
>> failures.
>>
>> See
>>
>
http://ap.pennnet.com/display_article/312379/36/ARTCL/none/none/1/Detect
>> ing-Brittle-Fracture-Failures/
>>
>> Bob Landman
>> H&L Instruments, LLC
>> www.hlinstruments.com
>>
>>
>>
>> -----Original Message-----
>> From: tinwhiskers-bounce@xxxxxxxxxxxxx
>> [mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of AL-Yousef,
>> Hani E
>> Sent: Friday, February 13, 2009 11:27 AM
>> To: tinwhiskers@xxxxxxxxxxxxx; TechNet E-Mail Forum;
>> RoHSUSAPushback@xxxxxxxxxxxxxxx; SMART Group smart-e-link
>> Subject: [tinwhiskers] - RoHS & BGAs!!!
>>
>>
>> Hello All,
>>
>> I am in the hunt for information on how to best evaluate whether
>> underfill is needed for SAC BGA when soldered with SAC paste.
>>
>> Also, part of my evolution is to find the right solder, flux and
>> chemistry to clean afterwards. Further specify a cleanliness level.
>>
>> I guess one has to find to the right test to use to evaluate these
>> parameters.
>>
>> Our products are expected to last for 20+ years while mounted
>> outside on
>> a power distribution pole mounts.
>>
>>
>> I can use all the help I can get.
>>
>> Thanks
>> Hani
>>
>>
>>
>>
>>
>>
>
>
>
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