I also vote for a XS artifact.
This is a common distraction when you are not in the center of a t but
hit the edge of a feature. Further grinding should make this look like
an open or a full thickness copper foil depending if you are grinding
into an feature edge or away from a feature edge.
Sincerely,
Paul Reid
Program Coordinator
PWB Interconnect Solutions Inc.
235 Stafford Rd., West, Unit 103
Nepean, Ontario
Canada, K2H 9C1
613 596 4244 ext. 229
Skype paul_reid_pwb
[log in to unmask] <mailto:[log in to unmask]>
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
Sent: Thursday, February 07, 2008 12:28 PM
To: [log in to unmask]
Subject: Re: [TN] FAB: Thin Trace Failures
Thanks for the response.
We have random failures on assemblies that have been heated up, only on
one batch of boards.
The guy doing the cross-section implied that he found this almost by
accident. By recommending a "referee" sample are you saying we should we
see the same thing in the same spot on a different board (from the same
lot)?
I'm curious how you could accept this condition on planes and not
suspect that there would be trace layers with the same condition.
I'm not disputing what you say, just trying to understand...
Jack
On 2/7/08, Kerry Bode <[log in to unmask]> wrote:
>
> Jack,
>
> This condition is most likely to occur when the board fabricator was
> processing the inner layer. The resist coating used for imaging may
> have had an air pocket at that location causing a lifted resist
condition.
> Then during the etching process the chemical etch solution undercut
> the resist. From my prospective this is an anomaly and is classified
> as an etch down condition. If the remainder of the sections do not
> exhibit the condition, a referee cross-section of the same serial
> number would acceptable. Based on the cross-section photo it appears
> to be a ground or power layer, if so IPC specification allowance for
this condition.
>
> Regards
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Olson
> Sent: Thursday, February 07, 2008 8:33 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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