Hi Victor,
I have your pictures posted. Sorry I didn't post them earlier but there's
been a few fires here at work. I only posted three of them because it looks
like there were duplicates of the same sort of images. This all looks
purely intentional to me. I have seen the same sort of layout
recommendations for decoupling caps in a few vendor guidelines...
http://stevezeva.homestead.com/SMT_Cap_Pads-1b.JPG
http://stevezeva.homestead.com/SMT_Cap_Pads-1c.JPG
http://stevezeva.homestead.com/SMT_Cap_Pads-1e.JPG
Steve
Steve
On Tue, Nov 15, 2016 at 11:50 AM, <[log in to unmask]> wrote:
> Steve,
>
> Can you please post this pics to the forum for me, Thanks,
>
> Back side of BGA. Ceramic capacitors skew from center of pad. Any Pro
> and Cons on this practice. Perhaps, spacing violation????? Analysis is
> pending/Ongoing......
>
> Victor,
>
> -----Original Message-----
> From: Leadfree [mailto:[log in to unmask]] On Behalf Of Steve Gregory
> Sent: Wednesday, February 03, 2010 11:57 AM
> To: [log in to unmask]
> Subject: Re: [LF] [TN] track lifting
>
> Hi Werner,
>
> I didn't know you wanted me to post the picture last night, so I got it up
> now. It's at:
>
> http://stevezeva.homestead.com/files/Werner_Buckle.jpg
>
> I'm working swing shift now...
>
> Steve
>
> -----Original Message-----
> From: Leadfree [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
> Sent: Wednesday, February 03, 2010 9:41 AM
> To: [log in to unmask]
> Subject: Re: [LF] [TN] track lifting
>
> Hi Everybody,
> I sent Steve another 'buckle-up' trace lifting picture to put on his site.
> So now, together with Brian's case we have 3 documented occurrences.
> So, please, as I wrote to Brian:
>
> I would appreciate pictures, possibly also to Steve, that I could use in
> my reliability column—this is a failure mode fairly new and unknown to
> most people.
> If you could, I also would appreciate the base material, the peak reflow
> temperature, the cooling rate after reflow, the Cu trace thickness and
> whether it was covered with solder, and what solder. I now, its asking a
> lot, but only with all the pertinent info can we make sense of this.
>
> Werner
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Stadem, Richard D. <[log in to unmask]>
> To: TechNet E-Mail Forum <[log in to unmask]>; Werner Engelmaier <
> [log in to unmask]>
> Sent: Wed, Feb 3, 2010 9:33 am
> Subject: RE: [TN] track lifting
>
>
> Like Steve, my first thoughts were that the BGA in the picture was
> apparently impacted, or somehow lifted and then put back down and reflowed.
> However if that had happened, it could not have happened without many
> other traces on each side of the lifted ones also being lifted and damaged,
> but they are not.
> Therefore I agree with Werner, that this is a case of damage due to severe
> CTE mismatch. I have never seen this before.
> Burke, I'll take you up on that bet. I doubt that there will be any
> delamination issues. This appears to be a case where the PWB expanded and
> shrunk back in the X and Y axis during reflow or temperature cycling, but I
> doubt that it saw any significant Z-axis expansion.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
> Sent: Wednesday, February 03, 2010 8:13 AM
> To: [log in to unmask]
> Subject: Re: [TN] track lifting
>
>
>
> Hi Brian,
> I would appreciate pictures, possibly also to Steve, that I could use in
> my reliability column—this is a failure mode fairly new and unknown to
> most people.
> If you could, I also would appreciate the base material, the peak reflow
> temperature, the cooling rate after reflow, the Cu trace thickness and
> whether it was covered with solder, and what solder. I now, its asking a
> lot, but only with all the pertinent info can we make sense of this.
> Werner
>
>
>
>
>
>
> -----Original Message-----
> From: Brian Chandler <[log in to unmask]>
> To: [log in to unmask]
> Sent: Wed, Feb 3, 2010 7:28 am
> Subject: Re: [TN] track lifting
>
>
> We just conducted a study on acceptable strain levels for lead free
> products.
> Our BGA test coupons showed this exact result from excess strain.
>
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