- The x-ray can help out with location of trace on board and cross
section coupon.
- The gerber file will also assist with trace location on bare board.
- The IPC TM650.
- The fact that all failures are within One Date Code is a big clue.
- Ask vendor for yield % on this date code at factory.
- Once the assembly has failed the hot test will it recover, test good,
when board surface temperature returned to ambient?
- At ICT test run heat gun over board to possibly cause failure.
Stay in touch.
Victor,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Thursday, February 07, 2008 5:44 PM
To: [log in to unmask]
Subject: Re: [TN] FAB: Thin Trace Failures
I may owe the group an apology...
For the curious, I'll answer the questions people asked me:
- the product has been in production for a long time with no problems.
- product must operate at 125C, so after ICT we do a "hot" functional
test.
- all at once we had massive fallout, ICT okay, hot NOT.
- failures in random locations, unpredictable
- same vendor, all boards from same same date code
- bare-board vendor on chinese holiday, no response yet
We sent a few failed assemblies out to be analyzed, and the
picture I provided in the link below was the first thing we got back,
but with no analysis
Since then we have found cracked via barrels, which seems
to be a more likely culprit. (but I'm no expert)
If I asked for help without waiting for enough supporting info,
I'm sorry.
but I would like to know more about "cross section artifacts"?
Where can I learn about that?
I can't visualize how the cross section could be a normal beginning
or an ending of a trace, but maybe I'm showing my ignorance
willing to learn,
Jack
.
On 2/7/08, [log in to unmask] <[log in to unmask]>
wrote:
>
> Beware of cross section artifacts. If this is not the sites you were
> aiming for it may not be a defects. Could the beginning of a trace
or
> the ending. I see this often.
>
>
> Victor,
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
> Sent: Thursday, February 07, 2008 9:33 AM
> To: [log in to unmask]
> Subject: [TN] FAB: Thin Trace Failures
>
> Has anyone ever seen a cross-section like this?
>
> http://www.frontdoor.biz/PCBportal/opentrace.jpg
>
> (ignore the words on the pic, just a guess)
>
> Can you point me in the right direction for cause?
>
> thanks,
> Jack
>
>
>
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