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December 2015

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Subject:
From:
"Gerald Bogert (Contractor)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Gerald Bogert (Contractor)
Date:
Tue, 1 Dec 2015 16:16:35 -0500
Content-Type:
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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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