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March 2013

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From:
Wayne Thayer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wayne Thayer <[log in to unmask]>
Date:
Sat, 2 Mar 2013 01:50:50 +0000
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This sounds intriguing!  Even without teardrops, it sounds like it is significantly earlier than would be expected.

Is there any kind of stress riser at this point, such as would be caused by pattern plating the vias?  Is there an indication of etching problems at this juncture?

Was the board powered during this test?  Internal heat generation causing heavy board stress?

Please provide pix!!


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Friday, March 01, 2013 4:06 PM
To: [log in to unmask]
Subject: Re: [TN] Conductive path failure in thermal cycling

ENIG

Ioan Tempea, ing.
Ingénieur principal de fabrication / Senior Manufacturing Engineer [signature002]<http://www.digico.cc/>

950 RUE BERGAR, LAVAL, QC, H7L 5A1<http://g.co/maps/2gh3f>
T+ 1 (450) 967-7100, EXT244
------------------------------------------------------------------------
  [signature001] <http://www.facebook.com/pages/Digico/277076778479>
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Lauréat Dunamis 2012<http://digico.cc/dunamis-2012/>
Entreprise manufacturière / Gestion du capital humain

De : [log in to unmask] [mailto:[log in to unmask]]
Envoyé : March-01-13 2:30 PM
À : TechNet E-Mail Forum; Ioan Tempea
Objet : Re: [TN] Conductive path failure in thermal cycling

Hi Ioan - what is the assembly surface finish?

Dave Hillman
Rockwell Collins
[log in to unmask]<mailto:[log in to unmask]>



From:        Ioan Tempea <[log in to unmask]<mailto:[log in to unmask]>>
To:        <[log in to unmask]<mailto:[log in to unmask]>>
Date:        03/01/2013 10:40 AM
Subject:        [TN] Conductive path failure in thermal cycling
Sent by:        TechNet <[log in to unmask]<mailto:[log in to unmask]>>
________________________________



Dear Technos,

RoHS assembly, soldered with SAC305 alloy, 0.075" thick 14 layers PCB, failing after 250 cycles (-20 C to 125 C).

Failure mode is crack between the traces and pad at 3 places. Happens on 2 TH components. Traces are 0.0055" wide, pads are 0.022" in diameter on the via side or 0.065" on the component side. There is no tear dropping.

Should I bother figuring out if manual soldering of the TH component fragilizes the trace-pad junction, or this is an obvious case of design induced failure?

Thanks,

Ioan Tempea, ing.
Ingénieur principal de fabrication / Senior Manufacturing Engineer [signature002]<http://www.digico.cc/>

950 RUE BERGAR, LAVAL, QC, H7L 5A1<http://g.co/maps/2gh3f>
T+ 1 (450) 967-7100, EXT244
------------------------------------------------------------------------
 [signature001] <http://www.facebook.com/pages/Digico/277076778479>
------------------------------------------------------------------------
Lauréat Dunamis 2012<http://digico.cc/dunamis-2012/>
Entreprise manufacturière / Gestion du capital humain


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