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December 2015

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Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, David Hillman <[log in to unmask]>
Date:
Tue, 1 Dec 2015 15:52:39 -0600
Content-Type:
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text/plain (226 lines)
Hi Gerald - based on the time history listed in the report, the appearance
of the solder joint and the technologies on the board (plated thru hole), I
would surmise that the solder alloy is tin/lead and not lead-free. However,
there is no technical information listed in the report to confirm that
assumption. Hopefully, more detailed information on the solder joint
failure would be released in the future but given the circumstances of the
accident, no other information may be forthcoming.

Dave Hillman
Rockwell Collins
[log in to unmask]


On Tue, Dec 1, 2015 at 3:16 PM, Gerald Bogert (Contractor) <
[log in to unmask]> wrote:

> Is the solder ROHS compliant Pb-free and if so could this be related to the
> joint crack?
>
> On Tue, Dec 1, 2015 at 3:22 PM, Upton, Shawn <[log in to unmask]>
> wrote:
>
> > I'm curious about the solderjoint itself.  Looks like poor wetting, but
> it
> > looks like what they show as cracking looks more like a lifted land.
> Also,
> > what is the discoloration on the green trace running away from the land?
> > Reminds me of a board that I saw where the copper was damaged by battery
> > acid.  Is that just an artifact from the conformal coating being removed
> > during inspection?
> >
> > The more I look at it, the more it looks like the crack goes all the way
> > around the joint though, can see a faint line most of the way down the
> > fillet.
> >
> > The DB-looking connector is corroded, but across from that it looks like
> a
> > transformer got attacked by the seawater also--so not fully conformally
> > coated?  I could see wear and tear on the DB, but I would have thought
> the
> > whole board would be conformally coated.  Speaking of which, I wonder if
> > that is where the cracks live, under that transformer-looking thing.  All
> > the other components look like they would have "give" for thermal
> > expansion/contraction.  Well, maybe not the TO cans I guess, but the
> photo
> > makes it look like that particular crack was relatively away from
> > everything else.  But if the iron core was being attacked by seawater,
> > well, maybe that is where the rust color on the cracked solderjoint is
> from.
> >
> > That, or maybe it's under the relay--the lead itself is very rounded,
> > making think it's a relay pin.  Which would sit flush on the board, and
> > perhaps yank.  Certainly "clicks" on accuation.  But then the rust would
> > come from...? the iron core inside the relay?
> >
> > Anyhow, I looked through the report, and while it's huge it appears it is
> > the typical cascade of failures--not one thing but rather several things
> > went wrong, each compounding the prior.
> >
> > Shawn Upton
> >
> > -----Original Message-----
> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
> > Sent: Tuesday, December 01, 2015 3:15 PM
> > To: [log in to unmask]
> > Subject: Re: [TN] Airbus crash pinned (in part) on solder joint failures
> >
> > I did a little more digging on the Esterline web page and looked at the
> > photo a little closer, and that relay doesn't fall into the ones that
> have
> > the space restrictions. This is the relay that is on that board:
> >
> > http://us.leachint.fr/aerospace/f250/
> >
> > Steve
> >
> > On Tue, Dec 1, 2015 at 12:41 PM, Steve Gregory <[log in to unmask]>
> wrote:
> >
> > > There is something that I noticed on the photo of the electronic
> module.
> > > The board on the left that has the four Leach relays looks like there
> > > was a violation of a documented recommendation by Leach of the
> > > positioning of the relays next to each other. The document states that
> > > the permanent magnet inside the relay could affect the performance of
> > > another relay next to it if it is oriented in the same direction and
> not
> > separated by at least 1/8":
> > >
> > > http://www.leachintl2.com/english/english1/vol0/properties/N023eng.htm
> > >
> > > It looks to me like all four are oriented the same way and looks to me
> > > like they're closer than 1/8" = .125" = 3.175mm to each other. What do
> > > you think?
> > >
> > > Steve
> > >
> > > On Tue, Dec 1, 2015 at 11:37 AM, Stadem, Richard D. <
> > > [log in to unmask]> wrote:
> > >
> > >> Agreed. There was no redundancy here, nor was there an effective
> > >> default condition.
> > >>
> > >> -----Original Message-----
> > >> From: TechNet [mailto:[log in to unmask]] On Behalf Of Ahne Oosterhof
> > >> Sent: Tuesday, December 01, 2015 11:35 AM
> > >> To: [log in to unmask]
> > >> Subject: Re: [TN] Airbus crash pinned (in part) on solder joint
> > >> failures
> > >>
> > >> Figure 35: Electronic Module of RTLU
> > >>
> > >> Not much of a failure to cause the loss of life and an aircraft!
> > >>
> > >> Conclusion: End-use of a board module dictates extreme level of
> > >> attention to design and testing protocols.
> > >>
> > >> Ahne.
> > >>
> > >> -----Original Message-----
> > >> From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Buetow
> > >> Sent: Tuesday, December 1, 2015 6:28 AM
> > >> To: [log in to unmask]
> > >> Subject: [TN] Airbus crash pinned (in part) on solder joint failures
> > >>
> > >> Here's the report:
> > >> http://kemhubri.dephub.go.id/knkt/ntsc_home/ntsc.htm
> > >>
> > >>
> > >>
> > >> Discussion of the electrical short and cracked solder joint begins on
> > >> page 104.
> > >>
> > >>
> > >>
> > >>
> > >>
> > >> Best,
> > >>
> > >>
> > >>
> > >> Mike
> > >>
> > >>
> > >>
> > >> Mike Buetow
> > >>
> > >> PCD&F/Circuits Assembly
> > >>
> > >> w/m: 617-327-4702
> > >>
> > >> @mikebuetow
> > >>
> > >>
> > >>
> > >> The 2015 CIRCUITS ASSEMBLY *Directory of EMS Companies:*
> > >> circuitsassembly.com/dems
> > >>
> > >>
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> > >
> >
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