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 >