Ioan,
I have seen many of these types of failures on smaller and larger traces, typically over time. Vibration, thermal stress, and gravity have influences on lead land connections. We have circuit board that are mounted vertically and large ceramic capacitors fell off of the board over time. Opened up the cabinet to find caps laying on the floor, boards still in service. I have seen traces between lands crack over time, most likely due to thermal stress as no large components were mounted anywhere near the crack.
Pat
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Monday, March 04, 2013 6:23 AM
To: [log in to unmask]
Subject: Re: [TN] Conductive path failure in thermal cycling
Thanks Dave,
Completely lost trace of Steve, please check this link http://ipc-technet.groupsite.com/galleries/show/25304
Unfortunately, I only have 1 pic.
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
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[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-04-13 9:09 AM
À : TechNet E-Mail Forum; Ioan Tempea
Objet : Re: [TN] Conductive path failure in thermal cycling
Hi Ioan - I have recently ran into an plating process issue with immersion silver - the term being used to describe the anomaly is "trench etch". This defect is made worst by lead-free soldering processes where copper dissolution comes into play. Your defect sounds like it could be "trench etch" but you have ENIG and not immersion silver. Please send Steve a couple of pictures of your defect and we'll try to sleuth out the root cause.
Dave
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 03:08 PM
Subject: Re: [TN] Conductive path failure in thermal cycling
Sent by: TechNet <[log in to unmask]<mailto:[log in to unmask]>>
________________________________
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
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[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]> [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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