Connie ,
I just can guess , what are those imperfections :
1)  traces left on innerlayers from surface preparation such as scraches
craetaed by baskets or conveyor system . They should be considered maily as
aesthetic problem.
2) imperfections in preprepregs such as local de-wetting .
3) contamination of innerlayers by water , residues of chemicals etc.
We made some tests on no.1 by multi thermal shocks and those never created
delamination , as well as no 2 .
Contamination of innerlayers are deadly and in most causes are leading to
delamination .
From your describtiob I can guess , that the problem is only visual .
Regards

At 09:41 05/11/98 CST, you wrote:
>                Good Morning,
>
>I don't know how to explain this, but here goes... I have a bare board with,
>what appears to be, delamination but I don't think it is.(can't identify any
>layer separation).  There are four spots in the board (not on surface) that
>are much lighter than the rest of the board.  These areas are in line with
>each other.  Someone said it looked like a 'shiner'.  Has anyone heard this
>term before?  If so, what is it, what causes this condition, and is there
>any document referring to the acceptability of the condition?  I looked
>through the IPC-A-600, but couldn't find anything that resembled this.
>
>>From someone who's trying to learn...
>ps(I'm not real familiar with bare board acceptability conditions like this
>so be gentle)
>
>Connie Korth
>K-Byte Hibbing Manufacturing
>
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Edward Szpruch
Eltek Ltd - Israel
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