Scott,
I concur with you assessment. It might be easier to see if Al's
photomicrograph was in color. This defect might have past the
fabricators electrical test because the break may not have been
completely around the via. But it does look serious enough that it
wouldn't have taken much stress (handling or thermal) to cause it to
open at the customer site.
Regards,
George
George M. Wenger, Andrew Corporation
Reliability / FMA Engineer
Base Station & Subsystems Group
40 Technology Drive, Warren, NJ 07059
(908) 546-4531 [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Scott B. Westheimer
Sent: Thursday, November 04, 2004 6:43 PM
To: [log in to unmask]
Subject: Re: [TN] Via hole failures (with pictures)
The void seems to be in the center of the hole and circular. This is
normally caused by air entrapment during the electro copper process
after
drilling. However, most of the time the voiding due to these is larger
so it
is possible that there was a thermal cycle was performed prior to tin
and
the board expanded and fractured. The picture is not that clear. I do
not
see a lot of roughness due to drilling so I would assume that it is due
to
air entrapment and I would ask the supplier why it was not caught during
electrical test
----- Original Message -----
From: "Al Onderick" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, November 04, 2004 5:55 PM
Subject: [TN] Via hole failures (with pictures)
>I have a couple of boards that have failed at a customer site. After
> testing, a via was identified as open. The following link is a picture
of
> the cross section.
>
> http://www.tier1gear.com/temp/via_crack.jpg
>
> The board was .062, the via .010 and the surface finish immersion
white
> tin.
>
> I would appreciate any insight into what may cause a failure like
this.
>
> Al Onderick
> National Instruments
>
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