Hi Ioan - two possible root cause areas to consider: (1) possible that you
have a plating defect of some type at the trace-to-pad transition. A cross
section might be useful; (2) You mentioned that you are doing leadfree
soldering with SAC305. You may have a copper dissolution issue in which
the soldering process is reducing the copper trace-to-pad thickness to a
point of cracking. Again, a cross section may shed more light on the
issue.
Dave
From: Ioan Tempea <[log in to unmask]>
To: <[log in to unmask]>
Date: 03/04/2013 08:25 AM
Subject: Re: [TN] Conductive path failure in thermal cycling
Sent by: TechNet <[log in to unmask]>
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
------------------------------------------------------------------------
[signature001] <http://www.facebook.com/pages/Digico/277076778479>
------------------------------------------------------------------------
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
------------------------------------------------------------------------
[signature001] <http://www.facebook.com/pages/Digico/277076778479>
------------------------------------------------------------------------
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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