Jack
One big thing to get out of all this is understanding what one expects to see on the cross section. In other words, how does the cross section compare to the artwork. Are we looking at a plane layer, a 10 mil wide conductor, or the space between two non-connected features? That information affects the intrepretation of the cross section.
From the description of the history of this board, one might suspect an artwork flaw that leads to the thin trace or process instability at the supplier that results in cracked via barrels. Neither of these defects creates confidence in the delivered quality from the supplier. Beyond resolving the immediate cause of the failures, you should understand what allowed a change to occur at your supplier and determine if they can be fixed or if you need to move on to a different supplier. Of course, if a new supplier isn't thoroughly evaluated for process control and quality systems..........
Don Vischulis
-----Original Message-----
>From: Jack Olson <[log in to unmask]>
>Sent: Feb 7, 2008 5:43 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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