Looks like pink ring. On small holes their is a slight separation at the
inner layer and when it goes through the electroless and copper plating
chemicals attack the oxide and dissolve it. This normally only happens on
small holes unless your drilling is extremely bad.

Scott
Scott B. Westheimer
Gul Technologies PTE
5709 Clarks Fork Drive
Raleigh, North Carolina 27616
Phone: (919)713-4358
Fax: (919)713-4358
Cell: (919)649-1510
Email: [log in to unmask]
http:///www.gultech.com
----- Original Message -----
From: "Lum Wee Mei" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 19, 2003 7:56 PM
Subject: [TN] What is this defect?


> Hello,
>
> I have a defect that looks like delamination. One important observation
> noted is that this defect is found only around PTH vias NOT component
> holes. In addition, this "suspected delamination" surfaces are very flat
> to touch - no bulging. I do not think it is delamination because I have
> never seen delamination occurs around PTH. However, I am be wrong. This
> defect appear in several areas on the board but funny observation is
> that 3 out of 5 pcs of the fabricated boards have the same defect at the
>
> same locations, around P3 and P4. The only difference is the intensity
> of the defect.
>
> This is a 8-layer design with L4 as power and L5 as ground. As such,
> clearances are expected for pads not to be shorted to these
> layers.However, instead of solid round clearance around the pads,
> irregular shapes are found. In one of them, the clearance actually
> overlap each other. The layer stackup is as follows :
>
> ---------------------------18um
>       prepreg 1080+7628
>  -----------------------core 0.21mm(35um/35um)
>       prepreg 1080*2
>  -----------------------core 0.21mm(35um/35um)
>       prepreg 1080*2
>  -----------------------core 0.21mm(35um/35um)
>       prepreg 1080*2
>  ---------------------------18um
>
> I have seek Steve's kind assistance to download 4 pictures of the
> defects. Kindly look at them. I would appreciate your opinions on :
> 1. If this is not delamination, what defect is it?
> 2. What is or are the likely cause(s)?
> 3. Does it has impact to reliability?
>
> Thanking you all in advance.
>
> Regards,
> Wee Mei
>
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