Hi Kathy,

Did a little surfing to see if I could find some images similar to yours.
Didn't find any, but did find some interesting sites that >may< be relevent.

First one is a link about glass compression. This happens when the laminate
is compressed with fast heat-up rates. Said to possibly be a cause for
drilling problems including delamination. Go to:

http://www.arlonmed.com/applications/compres.htm

Next is a link from a manufacturer of entry and back up materials. They make
a backup material called "SlickBack" (pretty catchy name huh?). There's some
good SEM images there of hole wall quality using their material vs standard
materials...

http://www.lcoa.com/pages/slickback_mg.htm

The last link has standard guidelines for feed and speed rates used for
different laminates, hole sizes, stack heights, how many hits a tungsten
carbide bit should take before replacing, etc. Good reference page.

http://www.holders.co.uk/kennametal_overview.htm

As "murphy" always has it, you don't find out about these problems until
AFTER you build the assemblies huh? Same logic always goes for misloaded
components, it's NEVER the 1-per, it's always the 50-per...such is our life
(GRIN)

-Steve Gregory-


> I have a few assemblies that a customer had asked me to look at and I
> noticed an oddity around the vias.  It looks like there is delamination
> around the vias.  Steve was kind enough to post these photo's on his web
> page for all to view.  I need to know if this is delamination or just
> haloing. I saw an issue like this a long time ago (15 years ago) and at
> that time we scrapped them because we didn't know what the issue was caused
> by.  Some at that time thought the drill bit for that size was either
> pushed to fast through the material causing a slight delanmination or the
> drill bit was dull.
>
> I appreciate any assistance or thoughts on the issue.  I have already
> suggested that a cross section may have to be completed.
>
> http://www.stevezeva.homestead.com
>
> Thanks in advance.
>
> Kathy
>