Exactly, I agree...hole wall separation, when present, in my experience is
easily differentiated between the normal 'visible' demarcation line...and
when I do not see this line the vast majority of the time it is because it
is the copper smeared during grinding/polishing which an additional etch and
mylar usually clear up...
Franklin
----- Original Message -----
From: "Pete menuez" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, January 11, 2005 7:07 AM
Subject: Re: [TN] Inner layer to barrel connection quality
> This is probably a normal (acceptable) condition. As to why earlier
> sections showed no demarcation line and this one did may be the amount of
> etch used to expose the demarcation line. Some shops like to etch as
> little
> as possible - to just expose the demarcation - so they don't discolor the
> electroless. Electroless copper, if this is what was used, may turn black
> making the connection look separated.
>
> It is always a good idea to review the sections prior to etch to see if
> there is any separation. Some one may want to challenge me on this but
> generally if you have post separation you will see it before etch. (An
> exception to this is if the cross section grinding smeared copper across
> the
> interface hiding the separation.)
>
> pete
>
>
>
>
>
>>From: "Finks, Tim (Healdsburg)" <[log in to unmask]>
>>Reply-To: TechNet E-Mail Forum <[log in to unmask]>, "Finks, Tim
>>(Healdsburg)" <[log in to unmask]>
>>To: [log in to unmask]
>>Subject: [TN] Inner layer to barrel connection quality
>>Date: Mon, 10 Jan 2005 14:15:29 -0800
>>
>>I have PTH cross-section images which show a visible interface between
>>inner
>>layer foils and the PTH plating. Earlier, similar, board cross-sections
>>show
>>no discernable interface - the inner layer foil and the barrel plating
>>appear to be integral.
>>
>>What should I see when I have an acceptable PWB?
>>
>>
>>
>>Regards,
>>
>>Tim Finks
>>
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