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February 2010

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Subject:
From:
Steve Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steve Gregory <[log in to unmask]>
Date:
Tue, 2 Feb 2010 21:25:57 -0500
Content-Type:
text/plain
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text/plain (116 lines)
REALLY? Enough to stretch traces and tear up soldermask? Wow!

I have never seen anything like that!

Steve

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Tuesday, February 02, 2010 8:12 PM
To: [log in to unmask]
Subject: Re: [TN] track lifting

 Hi Steve & All,
A 'mechanical hit' would not cause this.  While the pic is less than fully illuminating, I have seen similar 'buckle ups' with Pb-free solders/soldering before.
We need to remember, that SAC is 40% stiffer than SnPb, has a higher yield strength and creeps about a factor of 50 slower—it thus, becomes a mechanically significant layer with a higher CTE than Cu and the PCB(x,y).

Werner

 


 

 

-----Original Message-----
From: Steve Gregory <[log in to unmask]>
To: [log in to unmask]
Sent: Tue, Feb 2, 2010 6:10 pm
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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