Franklin,
From what I can see in these microsections, I would point the finger towards
the chemical processes, mainly because the innerlayers on these images do no
present any evidence of rough drilling (although you did mention the
nailheading, and it would be good to put up an image of this).
I can see glass fibers protruding into the hole, very possibly because of
lack in glass etch (as Susan has pointed out).
In addition, you could look into your primary metallization process (you
didn't write what it was - electroless or some kind of "direct") or into the
current values of the electroplating.
I think it would help all of us understand if you could put some images of
the entire length of the hole - it does matter where you see the faults
(entrance vs. middle) and BTW - how thick is your board, how many holes were
drilled per drill, what drill parameters, what board material ?
Regards,
Yehuda
Yehuda Weisz
Tel: (972)-3-6342045
Cel: (972)-53-556897
----- Original Message -----
From: "Franklin D Asbell" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, March 30, 2004 12:45 AM
Subject: [TN] Hole wall quality
> I've been asked to evaluate some images, hole wall plating defects, and
try to locate the cause.
>
> The information available to me are these are drilled 0.021" holes, they
were drilled one panel up, four panels total, and there was only one 0.021"
tool per spindle. The spindles were new or repoints. Upon evaluating the
bits nothing really jumped out as bad...another image not posted shows
excessive nailheading.
>
> I'm open to any and all comments...as well as a list of items I can begin
checking...thanks
>
> I've posted the images at http://asbell.net/images.htm
>
> Franklin
>
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