Hi John,
This buckling up of the traces does not require a z-axis force, you can get what you see by compressing the traces in their long direction, as for instance somewhat stretching them during heating to peak reflow and than compressing them as the PCB contracts on cooling.
Werner
-----Original Message-----
From: John Burke <[log in to unmask]>
To: [log in to unmask]
Sent: Wed, Feb 3, 2010 12:43 am
Subject: Re: [TN] track lifting
Pearl what hit that a truck?
Only thing I am having trouble understanding is the bends on the two leads
on the right (the two on the left are also looking broken at the pad
interface.)
The bends on the 2 interconnects on the right suggest that the side that we
were looking at was forced mechanically up in the Z axis, the two traces on
the left broke off at the pad interface while on the two on the right the
trace came up with the pads and the z axis force was then removed causing
that bend in the trace.
I would bet a lunch on all four pads we are looking at being delaminated
from the laminate underneath.
John Burke
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, February 02, 2010 3:11 PM
To: [log in to unmask]
Subject: Re: [TN] track lifting
Hi Pearl,
Here's your picture:
http://stevezeva.homestead.com/files/Track_Lifting.JPG
What I see in the picture is that BGA (it is a BGA isn't it?) was almost
ripped-off the board somehow.
The traces are stretched and the soldermask has been torn up from the board.
The root cause is that something mechanically hit the BGA and ripped up pads
and traces. Is there any other marks on the BGA?
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of pearl petras
Sent: Tuesday, February 02, 2010 5:13 PM
To: [log in to unmask]
Subject: [TN] track lifting
While we wait for IPC to set up a picture site, could I impose on Steve to
post another picture?
Any comments as to what could possibly be the root causes of this is much
appreciated.
Thanks so much
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